National Institute of Neuroscience

Specialties

Brain surgery

Brain surgery is a discipline within neurosurgery that pertains to diseases of the brain for which surgery is indicated. Our team is highly specialized and fellowship trained in performing intricate and complex surgeries of the brain. We perform modern retractorless brain surgery using the latest technological advances.

CEREBROVASCULAR

TRAUMA

HYDROCEPHALUS

TUMORS

CYSTS

Spine  and Peripheral Nerves

The peripheral nervous system is a network of motor and sensory nerves that connect the brain and spinal cord (the central nervous system) to the entire human body.

These nerves control the functions of sensation, movement and motor coordination. They are fragile and can be damaged easily. When one of these nerves suffers serious injury or trauma, surgical treatment may be called for.

VASCULAR

TRAUMA

PERIPHERAL NERVES

TUMORS

DEGENERATIVE DISEASE

INFECTION

Pain & Trigeminal Neuralgia

Trigeminal neuralgia is a chronic pain condition that affects the trigeminal nerve, which carries sensation from your face to your brain. If you have trigeminal neuralgia, even mild stimulation of your face — such as from brushing your teeth or putting on makeup — may trigger a jolt of excruciating pain.

You may initially experience short, mild attacks. But trigeminal neuralgia can progress and cause longer, more-frequent bouts of searing pain. Trigeminal neuralgia affects women more often than men, and it’s more likely to occur in people who are older than 50.

Because of the variety of treatment options available, having trigeminal neuralgia doesn’t necessarily mean you’re doomed to a life of pain. Doctors usually can effectively manage trigeminal neuralgia with medications, injections or surgery.

TRIGEMINAL NEURALGIA

HEMIFACIAL SPASM

GLOSSOPHARYNGEAL NEURALGIA

INTERMEDIUS NERVE NEURALGIA

Neuro-intervention

Neurointervention is a word used to describe a treatment approach to conditions that occur within the vessels of the brain or within the spinal cavity. Utilized in place of more invasive procedures which require opening the skull or exposing the spinal column, neurointerventional procedures are minimally invasive, meaning they can be accomplished through tiny incisions no bigger than the size of a nickel.

In the case of conditions affecting the brain, practitioners first insert a catheter, resembling a long tube, into the groin and then thread it up through the vessels to the problem site. Once the catheter is in place, dependent on the condition, physicians can deliver medications or utilize medical devices to accomplish treatment.

ACUTE ISCHEMIC STROKE

INTRACRANIAL ANEURYSM

FLOW DIVERSION FOR ANEURYSM

ARTERIOVENOUS MALFORMATION

ARTERIOVENOUS FISTULA

CAROTID ARTERY STENOSIS

EPISTAXIS EMBOLIZATION

TUMOR EMBOLIZATION

VENOUS SINUS STENTING

DIAGNOSTIC ANGIOGRAM

Neurological Disorders

Neurological disorders are disorders that affect the central nervous system (brain, brainstem and cerebellum), the peripheral nervous system (peripheral nerves – cranial nerves included), or the autonomic nervous system (parts of which are located in both central and peripheral nervous system).

Neurologists also diagnose and treat some conditions in the musculoskeletal system.

EPILEPSY

MOVEMENT DISORDERS

MULTIPLE SCLEROSIS (MS)

STROKE

HEADACHE

PEDIATRIC

Neuro-Ophthalmology

Neuro-ophthalmologists take care of visual problems that are related to the nervous system; that is, visual problems that do not come from the eyes themselves. We use almost half of the brain for vision-related activities, including sight and moving the eyes. Neuro-ophthalmology, a subspecialty of both neurology and ophthalmology, requires specialized training and expertise in problems of the eye, brain, nerves and muscles. Neuro-ophthalmologists complete at least 5 years of clinical training after medical school and are usually board certified in Neurology, Ophthalmology, or both.

Although some problems seen by neuro-ophthalmologist are not worrisome, other conditions can worsen and cause permanent visual loss, or become life threatening. Sometimes the problem is confined to the optic nerve or the nervous system and other times it is related to a general medical condition. Neuro-ophthalmologists have unique abilities to evaluate patients from the neurologic, ophthalmologic, and medical standpoints to diagnose and treat a wide variety of problems. Costly medical testing is often avoided by seeing a neuro-ophthalmologist.

Some of the common problems evaluated by neuro-ophthalmologists include: optic nerve problems (such as optic neuritis and ischemic optic neuropathy), visual field loss, unexplained visual loss, transient visual loss, visual disturbances, double vision, abnormal eye movements, thyroid eye disease, myasthenia gravis, unequal pupil size, and eyelid abnormalities.

Tumors on and around optic nerve, such as Tuberculum Sellae Meningiomas, Anterior clinoid Meningiomas, Sphenoid Wing Meningiomas, aneurysms around the optic nerve such as Ophthalmic segment ICA aneurysm and neurosurgical diseases such as hydrocephalus and benign intracranial hypertension can cause vision decline and first be diagnosed by a thorough neuro-ophthalmological exam. With extensive subspecialty presence at CIN, and multi-disciplinary approach, patients can get receive effective modern treatment at shortest possible time.

ENT and Endoscopic Surgery

ENT is a specialty dealing with disease of the Ear, Nose and Throats. Such diseases include intractable sinusitis not responding to medical management, nasal polyps, tumors of the nose, ear and throat, such vestibular schwannomas (Acustic neurinomas), squamous cell carcinomas and Esthesioneuroblastoma. Also tumors of the pituitary gland can be reached with an endoscope through the nose and a neurosurgeon takes the tumor out.

Maxillofacial and Cranial Plastic Surgery

This subspecialty deals with diseases such as trauma of the facial bones and reconstruction, as well as plastic surgery to have optimal skin coverage of the face and skull, as well as esthetic surgery of the face usch as rhinoplasty, occuloplasty, and hair implantation.

Related Specialties

National Institute of Neuroscience works with some of the top specialists in their respective fields in offering additional medical and health specialties.

Cardiothoracic and Vascular Surgery

Cardiothoracic surgery is a field that provides surgical intervention for disease processes involving the chest cavity, especially the heart and lungs. Vascular surgeons perform both minimally invasive and open surgical procedures on blood and lymphatic vessels throughout the body, except in the heart and brain. While neurosurgeons perform open and endovascular procedures of the brain, including clipping and coiling cerebrovascular aneurysms, there is some overlap with vascular surgery. Surgeons in both fields are trained to perform carotid endarterectomies(CEA) for correction of carotid artery stenosis. Management of cardiac and vascular disease is important to ensure maximal perfusion of the brain and to prevent ischemic injury. Cardiothoracic and Vascular surgeons also provide access to the spine through thorax and abdomen, for neurosurgical diseases.

General and Laparoscopic Surgery

General surgeons primarily manage diseases of the abdomen, including the stomach, liver, gallbladder, appendix, and small and large intestines. Subspecialties of general surgery include breast, colorectal, endocrine,pediatric, and transplant surgery, and trauma/critical care. Laparoscopic surgery is a new subspecialty focused on minimally invasive approaches, utilizing cameras and small instruments inserted through 3-15 mm incisions. Robotic surgery is evolving from this field. Neurosurgeons, neurointensivists, and trauma surgeons work together closely in managingpatients with brain and spine injuries. Depending on the institution, trauma surgeons may medically manage neurosurgical patients in the surgical intensive care unit (SICU).inal access for neurosurgical patients for shunting procedures.

Internal Medicine and Hospitalist

Internal medicine is the practice of preventing, diagnosing, and treating adult disease. It is a broad medical specialty comprised of subspecialties such as cardiology, pulmonology, nephrology, and gastroenterology. Internal medicine physicians manage patients in both the inpatient and outpatient settings. Hospitalists are a subset of internal medicine physicians who manage acute care of patients within the hospital only. Patients who undergo and successfully recover from neurosurgical intervention may require ongoing care from internal medicine physicians for comorbid diseases.

Pulmonology

Pulmonology is the medical specialty dedicated to management of diseases of the respiratory tract. This includes overseeing mechanical ventilation of patients on life support. Pulmonologists will collaborate with neurosurgeons to optimize the care of patients who suffer from neuro-trauma and critical neuropathology while they are ventilated. They also provide interventional procedures in patients with lung tumors.

Cardiology and Intervention

Cardiologists medically manage diseases of the heart and the circulatory system. Some cardiologists undergo additional training to become interventional cardiologists, who use catheter-based procedures to treat structural heart disease. This includes acute coronary syndrome due to myocardial infarction, otherwise known as a “heart attack.” Patients with hypertension, atrial fibrillation, and other cardiac diseases should see their cardiologist regularly. Progression of these diseases can cause devastating neurologic defictits,such as aneurysm rupture or ischemic stroke. Many neurosurgical patients need cardiological clearance prior to surgery or neuro-intervention.

Psychiatry and Psychotherapy

Human’s body and brain are intricately related to our mind & soul. Many patients with serious neurological and neurosurgical diseases benefit from psychiatric evaluation and psychotherapy. California Institute of Neuroscience offers a comprehensive Neuro-Psychiatric program. Dr. Ashmallah has a long experience in Psychiatry and Shushan Khachatryan offers psychotherapy.

Cerebrovascular

Cerebrovascular disease refers to a group of conditions that can lead to a cerebrovascular event, such as a stroke resulting from Carotid Stenosis, Irregular Heart Rhythm, Ruptured Cerebral Aneurysm, Arteriovenous Malformation (AVM), Dural Arteriovenous Fistula (DAVF), Cavernous Malformation. These events affect the blood vessels and blood supply to the brain.
If a blockage, malformation, or hemorrhage prevents the brain cells from getting enough oxygen, brain damage can result.

Intracranial Aneurysms

Intracranial aneurysms are common vascular diseases, found in 1-3% of the population1,2. It constitutes of a localized abnormal dilatation of a cerebral artery. Over time, the blood flow within these arteries continuously pounds against the wall, especially at the point where the vessel divides. The resultant wear and tear lead to the thinning of the wall, followed by gradual dilation of the weakened segment.

Circle of Willis

The most common location of the cerebral aneurysms is a circle of arterial connections at the base of the brain, called the circle of Willis. The purpose of this arterial circle is to provide an alternative supply to certain areas of the brain if the primary vessel supplying that area got occluded. The point where the vessels divides and communicates, is highly exposed to the wear and tear due to the turbulent blood flow, leading to a higher risk of aneurysm formation.

Aneurysm Types

Aneurysms can be divided into three types based on their shape:

  • Saccular aneurysms “Berry aneurysms” (see figure): These are the most common type of aneurysms, forming around 80-90% of all intracranial aneurysms. The berry-like dilation usually occurs at sites where a certain blood vessel leaves the parent artery, or at the side of bifurcation of the parent artery. They are also the most common cause of subarachnoid hemorrhage following their rupture.


Figure : Saccular aneurysm on the left Middle Cerebral Artery

  • Fusiform aneurysms: (see figure) These aneurysms occur as a result of circumferential dilation of the vessel, due to a weakened segment of the wall. They have lower risk of rupture compared to saccular aneurysms, but they also expose patient to embolic strokes.


Figure: Fusiform aneurysm at the pericallosal artery.There is a concurrent saccular aneurysm at the callosomarginal artery

  • Dissecting aneurysm (see figure). A dissecting aneurysm is caused by a tear in the inner arterial wall (Intima), which may result in a outpouching on one side of the artery wall and an obstruction of blood flow through the artery. Dissecting aneurysms may occur spontaneously or secondary to trauma. Dissecting aneurysm might put patient at risk for embolic stroke as well as rupture depending on type. They are classified in 4 types. Grade 1 describes mild intimal injury or irregular intima. Grade II entails dissection with a raised intimal flap, intramural hematoma with luminal narrowing >25%, and/or intraluminal thrombosis. Grade III involves a pseudoaneurysm. Vessel occlusion or thrombosis is grade IV. Finally, grade V – the most severe – is vessel transection.


Figure : Dissecting PICA-aneurysm. A: Preoperative Angiogram. B: Intraoperative image. C: Intraoperative image after wrap-clipping.

References

  1. Vlak MH, Algra A, Brandenburg R, Rinkel GJ. (2011). Prevalence of unruptured intracranial aneurysms, with emphasis on sex, age, comorbidity, country, and time period: a systemtatic review and meta-analysis. Lancet Neurology. 10(7): 626-636.
  2. Rinkel GJE, Djibuti M, Algra A, van Gijn J. (1998). Prevalence and risk of rupture of intracranial aneurysms: a systematic review. Stroke. 29: 251-256.

Subarachnoid Hemorrhage

Subarachnoid hemorrhage (Bleeding) refers to the presence of blood within the subarachnoid space, which is a space that lies between the brain and the arachnoid layer surrounding the brain. Direct, high-pressure bleeding from the artery leads to direct compression of the brain structures, and increased pressure within the brain, leading to neurological symptoms. Furthermore, the chemical substances in the blood may cause other arteries to constrict, and going into the spasm, reducing the blood flow to other areas of the brain, leading to stroke. Vasospasm1 is one of the most important determinants of outcome after a ruptured aneurysm is treated. Vessels of the brain are especially prone to vasospasm during the first 3 weeks after a subarachnoid bleeding. The spasm peaks at 2 weeks after a subarachnoid bleeding. Furthermore, the blood may disturb the usual uptake of cerebrospinal fluid, which is normally produced and taken up within the brain. This uptake disturbance by the blood may lead to fluid buildup within the brain, which is called hydrocephalus. Up to 30-50% of patients with subarachnoid hemorrhage die at the scene before reaching hospital. Of the remaining 50-70%, one third pass away during the first month, one third will be dependent during the rest of their life and only one third return to a normal independent life, making subarachnoid bleeding a seriously dangerous condition. Non-aneurysmal spontaneous subarachnoid hemorrhage secondary to a rupture of a small artery or vein usually has a typical pattern of the subarachnoid blood being in the perimesencephalic cistern. It is usually not associated with all the complications such as vasospasm and hydrocephalus2.

Symptoms

In most cases, unruptured aneurysms are asymptomatic and are detected on imaging studies done for other reasons. In some cases, however, as a direct compression, they may present as:

  • Headache
  • Numbness, or weakness of one side of the face
  • Dilated pupil
  • Change in vision
Imaging

As they arise from the blood vessels, aneurysms are better detected using angiography (images of the blood vessels), including computed tomography angiography (CTA, see figure), magnetic resonance angiography (MRA), or, most accurately, digital subtracted catheter angiography.


Figure : Subarachnoid bleeding. A: Preoperativ CT of the brain. B: Postoperative CT after clipping of a ruptured Anterior communicating artery (Acom) anuerysm

Natural History of Unruptured Aneurysms

Aneurysms can continue to grow due to continuous blood flow, leading to direct compression on the surrounding brain structures, leading to neurological symptoms.

Moreover, due to thinning of the aneurysmal wall that worsens as the aneurysm continues to grow, there is an increased risk of rupture, leading to subarachnoid hemorrhage.

Size3, location3, and form4,5 of an aneurysm are important determinants for risk of rupture. Although there has been extensive research showing that smaller aneurysms have small risk of annual bleeding, there are many small aneurysms that cause subarachnoid bleeding. Therefore, diagnosis of an unruptured aneurysm needs expert assessment for potential treatment.

Natural History of Ruptured Aneurysms causing Subarachnoid Hemorrhage

Risk of re-bleeding of a ruptured aneurysm during the first month after a subarachnoid bleeding is almost 50%. Therefore, a ruptured aneurysm needs to be treated.

Irrespective of treating a ruptured aneurysm, the nature of subarachnoid bleeding exposes the patient for risk of Vasospasm and Hydrocephalus. Approximately one third of patients with subarachnoid bleeding develop Vasospasm during the first 3 weeks after the bleeding.

Approximately one fourth of the patients with subarachnoid bleeding develop Hydrocephalus.

Treatment

Clipping: Aneurysms can be treated through opening the skull (craniotomy) and clipping the aneurysm (see figure 5 and video 1). Clipping of the aneurysm is a permanent treatment.


Figure : Basilar tip aneurysm.
See Video : Orbitozygomatic craniotomy for clipping of a Basilar tip aneurysm.

Endovascular coiling (embolization): Aneurysms can also be treated by the endovascular route. The aneurysm is reached by inserting a wire, usually through the groin and sometimes through the arm, that will be forwarded to the brain vessels, through which the aneurysm can be filled with coils that make the blood flow within the aneurysm to clot. Coiling of the aneurysm needs to be followed over years as the coils within the aneurysm, over time, get impacted and more coiling might be necessary (see figure).


Figure : Pre-procedural and post-procedural images of coiling of an aneurysm. A and B: Pre embolization. C and D: Post embolization.

By-pass: Certain large aneurysm cannot be treated by clipping or coiling. The flow by and through the aneurysm, makes it larger over time. Reversing the flow, will make the aneurysm disappear. Flow-reversal is provided either through an endovascularly placed pipeline, or by a classic by-pass procedure, through which, extra blood flow is provided to brain from one of the arteries of the neck so that the flow around the aneurysm changes and it will disappear.

Clipping or Coiling?

Clipping entails opening the skull, which takes a few hours, while coiling goes often through the groin and the procedure takes shorter time, so that in general, endovascular coiling has less immediate morbidity for patients. Over time, however, there are important benefits of clipping. The most important benefit is that once an aneurysm is clipped, then it is treated and risk of developing an aneurysm at the same location is gone, while with endovascular coiling, the treated aneurysm needs to be followed over the years so that the coil material will not be compressed by the blood flow and new aneurysm would develop at the same location. This means more angiograms, each with its own, even though small, risks.

The location, size, form, neck-to-dome-ration of the aneurysm, patient’s neurological status, and age of the patients are important determinants of treatment. Each patient needs to have a tailored treatment strategy based on these parameters.

There are many studies in the literature performed to answer what is the best treatment for ruptured and unruptured aneurysms. Generally, we recommend clipping of aneurysms in younger patients who have many years to live and coiling of the older patients. Certain aneurysms cannot be coiled irrespective of age and therefore they need to be clipped6.

What happens after a subarachnoid bleeding caused by a ruptured aneurysm?

The aneurysm needs to be treated as risk of re-bleeding is high. Many patients have concurrent hydrocephalus, which needs immediate treatment by inserting a tube so called ventriculostomy into the brain, releasing the pressure off the brain.

Two main conditions can be associated with subarachnoid bleeding: Hydrocephalus and Vasospasm.

Hydrocephalus: Some patients can over time be weaned off of ventriculostomy but those that will not, will need to convert the ventriculostomy to a permanent ventriculoperitoneal shunt7.

Vasospasm: One third of patient with subarachnoid bleeding develop Vasospasms1. Patients are daily screened for vasospasm by Transcranial Doppler (TCD) measuring the speed of blood flow through the vessels. Vasospasms can be treated medically by raising the blood pressure in order to provide more blood flow to the brain, increasing the blood volume by giving patient more fluids and by increasing the blood’s rheological properties so that it flows better to the brain. Vasospasm that does not respond to medical treatment, can surgically be treated by undergoing a catheter angiogram while the interventionalist either injects medicines directly into the blood vessel that is in vasospasm, or dilates the spastic vessel by a balloon, the so called balloon angioplasty. Vasospasm is a feared natural complication of subarachnoid bleeding. Untreated, it leads to brain infarct (Stroke). Long-term outcome of treated ruptured aneurysm, is proportional to presence of secondary strokes caused by Vasospasms, making treatment of Vasospasm as one of the man priorities of subarachnoid-bleeding-treatment.

References

  1. Proust F, Hannequin D, Langlois O, Freger P, Creissard P. (1995). Causes of Morbidity and Mortality After Ruptured Aneurysm Surgery in a Series of 230 Patients. Stroke. 26: 1553-1557.
  2. Raya A, Zipfel GJ, Diringer MN, Dacey Jr. RG, Derdeyn CP, Rich KM, Chicoine MR, Dhar R. (2014). Pattern Not Volume of Bleeding Predicts Angiographic Vasospasm in Nonaneurysmal Subarachnoid Hemorrhage. Stroke. 45: 265-267.
  3. Wiebers DO, Whisnant JP, Huston J, 3rd, Meissner I, Brown RD, Jr., Piepgras DG, et al. (2003). Unruptured intracranial aneurysms: natural history, clinical outcome, and risks of surgical and endovascular treatment. Lancet. 362(9378): p. 103-10.
  4. Lindgren, A.E., et al. (2016). Irregular Shape of Intracranial Aneurysm Indicates Rupture Risk Irrespective of Size in a Population-Based Cohort. Stroke. 47(5): p. 1219-26.
  5. de Rooij, N.K., et al. (2009). Configuration of the circle of Willis, direction of flow, and shape of the aneurysm as risk factors for rupture of intracranial aneurysms. J Neurol. 256(1): p. 45-50.
  6. Spetzler, R.F., et al. (2015). The Barrow Ruptured Aneurysm Trial: 6-year results. Journal of Neurosurgery. 123(3): p. 609-17.
  7. Adams H, Ban VS, Leinonen V, Aoun SG, Huttunen J, Saavalainen T, Lindgren A, Frosen J, Fruanberg M, Koivisto T, Hernesniemi J, Welch BF, Jaaskelainen JE, Huttunen TJ. (2016). Risk of shunting after aneurysmal subarachnoid hemorrhage: a collaborative study and initiation of a consortium. Stroke. DOI: https://doi.org/10.1161/STROKEAHA.116.013739

Arteriovenous Malformation (AVM)

Arteriovenous malformations (AVMs) are abnormal connections between the arteries and veins, bypassing the capillary system. They can occur in the brain and the spinal cord. In the brain, they have a propensity of being close to the ventricles, which are cavities within the brain that produce and contain the cerebrospinal fluid. They can also be associated with brain aneurysms.

Brain AVMs are present in 0.02% of population, and have an annual incidence of 1 in 100,000 people. The cause of AVMs is not clear. Most people are born with them, but they can occasionally form later in life. They are rarely passed down among families genetically.

In the normal circulation, the arteries are responsible for taking oxygen-rich blood from the heart to the brain. Then the blood passes through a network of small blood vessels called capillaries that connect arteries to veins and deliver oxygen to the cells. Veins return blood with less oxygen to the lungs and heart. An AVM disrupts this vital process.

In most cases, AVMs remain asymptomatic, and are found incidentally on images done for unrelated disorder or at autopsy. However, as AVMs create a shortcut for blood to pass directly from high-pressure arteries to low-pressure veins and bypass tissue, it can lead to tissue damage, bleeding and death of the nerve cells. Over time, some AVMs get progressively larger as the amount of blood flow increases. As a result, symptoms may include, headache, seizure, weakness, numbness or paralysis, loss of vision, difficulty in walking and balance (Ataxia), difficulty in speaking (Dysphasia), and confusion or inability to understand others, depending on the location of the AVMs.

In some cases, a weakened blood vessel may burst, spilling blood into the brain (hemorrhage) that can cause stroke and brain damage. Smaller AVMs tend to bleed more and larger AVMs tend to cause seizure and neuronal damage.

Medical attention should be sought if any signs or symptoms of a brain AVMs are noticed, such as seizures, headaches or other symptoms. A bleeding brain AVM is life-threatening and requires emergency medical attention. The annual risk of bleeding from a previously unruptured AVM is between 2-4% per year. Unruptured AVM’s have been studied extensively and a common accepted classification exists that correlates relatively well with which AVMs that need surgery. The Spetzler-Martin classification takes into account the size of the AVM, the pattern of its venous drainage and its location in areas of brain with more or less important functions. Low-grade AVM’s are usually operated and high-grade AVMs are usually not operated. Mid-grade AVMs can be divided into sub-groups that can benefit form operation. Over the years, with the advent of endovascular therapy, the arterial blood flow to the AVM, is slowly closed changing it from a larger size to a smaller size and hence converting a previously inoperable AVM to an operable. Definitive therapy of AVMs is surgery unless they are located in a certain location of the brain where surgery would give the patient too much deficit. For these cases, stereotactic radiation such as Gamma Knife can be a good option. Gamma knife radiation takes up to 2 years to affect the AVM and during this time, the AVM is still at risk of bleeding. Some studies have shown a slight increase in the bleeding rate of the AVMs after gamma knife radiation.

Endovascular therapy is not a definitive treatment option. It only improves surgical outcome. Closure of some of the AVMs vessels and associate aneurysms makes surgery easier. If the vessels of the AVMs are closed by endovascular treatment, over time, new pathological vessels will develop in the AVM and cause to enlarge.

Surgery of brain AVMs includes preoperative embolization followed by surgery that entails taking the skull bone off, opening the thick layer of the brain called dura and through microsurgery with operative microscope, slowly closing the feeding arteries off before closing its draining veins off and resecting it. AVMs can be associated with aneurysms as well. These aneurysms can be treated during the preoperative embolization or during surgery. (See figure )


Figure : Ruptured AVM. A: Axial pre-operative CT Scan, B: Coronal pre-operative CT Scan. C: Cerebral angiography lateral view, D: Cerebral angiography frontal view, E: Axial post- operative CT scan, F: Coronal post-operative CT Scan.

Cerebral Proliferative Angiopathy (CPA)

Cerebral Proliferative Angiopathy (CPA), previously known as diffuse nidus type AVM, is a brain vascular malformation separated from classic brain AVM. CPA is a separate clinical entity different from cerebral AVMs, because normal brain is interspersed with the abnormal vascular channels.

CPA is present in 3.4% of all brain AVMs. It is more common in women than men with a F:M ratio of 2:1.

Medical attention should be sought if any signs or symptoms such as seizures, headaches or other neurological symptoms are noticed.

Cerebral angiography is the gold standard for diagnosis. In contrast to classical AVM, there are usually absence of early venous drainage, absence of a dominant feeder, a fuzzy appearance of nidus, distinguishing CPA.

The treatment for Cerebral Proliferative Angiopathy carries the risk of neurological damage attributable to the interspersed normal neural tissue and thus it is usually limited to those patients presenting with severe symptoms. Surgical resection is less of an option. Surgery is usually reserved for CPA-complications such as bleeding. Radiosurgery is the treatment of choice for CPA.

Dural Arteriovenous Fistula (DAVF)

Dural arteriovenous fistulas (DAVFs) (see figure) are defined as direct shunts between arteries and venous sinuses or cortical veins with no transitional capillary network contained within the leaflets of the dura mater, the thick layer of the meninges that covers the brain. They are supplied by branches of the carotid and vertebral arteries before they penetrate the dura.  This disease is principally an arteriovenous shunt, in which high-pressure arterial blood flows into a low-pressure venous system. Due to chronic high pressure, the veins over time become arterialized but as the veins are not made for high-pressure, they are at risk of bleeding.

DAVFs account for 10-15% of all intracranial vascular lesions, with 61-66% occurring in females. The mean age of presentation is 50 years. They account for 6% of supratentorial and 35% of posterior fossa vascular malformations.

The most common location, accounting for 63% of cases, is adjacent to the transverse sinus, with a slight left-sided predominance. The epicenter of these DAVFs is usually at the junction of the transverse and sigmoid sinuses. Other common locations are in the tentorium and posterior cavernous sinus. A common arterial supply is by the posterior meningeal branch of the vertebral artery. Patient symptoms depend on the location and pattern of venous drainage of the DAVF, the most common symptoms being pulsatile tinnitus, occipital bruit, headache, visual impairment, and papilledema.

The diagnostic test of choice is cerebral angiography. The Borden and Cognard classification systems stratify DAVFs based on severity, with the most significant marker of higher grade being venous drainage over the cortical surface of the brain, placing the patient at risk for bleeding.

Indications for intervention include neurologic dysfunction, hemorrhage, and refractory symptoms. Options for intervention include, surgery to close the arteriovenous shunt, endovascular embolization, and stereotactic radiosurgery.

With cases associated with significant bleeding, surgery is recommended to both close the DAVF and evacuate the bleeding.

The major complication of surgery is rapid blood loss. In the literature, surgery is more likely to offer permanent resolution of the DAVF than embolization.


Figure : Ruptured Dural Arteriovenous fistula (DAVF).

A: Axial non-contrasted CT head showing a left temporal intraparenchymal hematoma
B: Coronal non-contrasted CT head
C: Postoperative imaging after surgical evacuation of hematoma and closure of DAVF

Cavernous Malformation (CM)

Cavernous malformations (CMs) are clusters of abnormal, stretched-out, thin-walled blood vessels filled with blood, hence the name “cavernous”. These blood vessel malformations can occur in the brain or spinal cord. (see figure).

CMs account for an estimated 8-15% of all intracranial and spinal vascular malformations, and have an incidence of one in 100-200 people. The exact cause is unknown, and least 20% of these lesions have the familial form, especially prominent in the Hispanic population. Genes associated with CM have been identified on chromosomes 3 and 7. Symptomatic lesion peak during third to fourth decade, and has no gender preference.

In most cases, CMs remain asymptomatic and are seen as an incidental finding on brain imaging done for other reasons. When the lesion continues to expand, it causes direct compression on the surrounding neurological structure. Moreover, depending on the activity of the lesion, the risk of rupture and bleeding varies. Hereby, the clinical deficits of the bleeding, depends on location of the lesion. Any of the following symptoms may occur, including seizures, weakness in arms or legs, visual problems, balance problems, memory and attention problems, headaches.

Fortunately, bleedings resulting from CMs, are relatively ‘low-pressure’-bleedings, compared to bleedings caused by aneurysms and AVMs. CMs have a tendency to come closer to the surface each time they bleed. A majority of CMs are associated with an enlarged vein called Deep Venous Anomaly (DVA). DVAs drain normal brain and happen to be larger in the part of brain where large veins do not exist. Therefore, the acronym anomaly is used. As the DVAs drain normal brain and they are attached to the CM in many cases, the DVA should not be resected. Taking the DVA out would cause a venous infarction of the area of the brain that the DVA drains.

Diagnosis

CMs are part of a group of lesions known as “angiographically occult vascular malformations.” This means that they are not visible on an angiogram. Angiograms cannot visualize CMs because blood flow through these types of lesions is slow.

Magnetic resonance imaging (MRI), with and without contrast remains the best means of diagnosing CMs. MRI scans may need to be repeated to analyze a change in the size of a cavernous malformation, recent bleeding, or the appearance of new lesions.

Treatment

Many CMs are quiet and unless not on easily accessible surface of the brain or spinal cord, should be left alone. If they show increase in size, or start bleeding, surgical resection needs to be considered. Surgical resection needs to take into consideration, the size, activity and location of the CM in the brain (see video 2 and 3) and the spinal cord (see video 4) in order to tailor the best possible therapy for the patient with least side effects.


Figure : Brainstem Cavernous malformation (CM) involving the pons and the midbrain Pontomesencephalic). A: Sagittal T1-weighted MRI with contrast. B. Axial T2-weighted MRI

Mesencephalic CM:
Craniotomy for resection of Mesencephalic Cavernous malformation
See Video: https://www.youtube.com/watch?v=SlmgRv5mbEA

Pontomesencephalic CM:
Craniotomy for resection of Pontomesencephalic Cavernous malformation
See Video: https://www.youtube.com/watch?v=v69SP1Yytuw

Spinal cord CM:
Resection of spinal cord Cavernous malformation in the thoracic cord.
See Video: https://www.youtube.com/watch?v=wKtI1W8cchk

Cerebral Arterial Insufficiency

Direct and In-direct By-pass

Cerebral artery bypass is utilized for mainly 4 categories: complex aneurysms that are not amenable to clipping or coiling, atherosclerotic narrowing of vessels leading to too little blood flow to the brain, Moyamoya disease, and tumor-invaded important vessels where blood flow to the brain needs to be maintained.

By-pass can be Direct or In-direct. Direct by-pass also known as extracranial-intracranial (EC-IC) bypass can provide blood flow to the anterior circulation of the brain (Carotid circulation) or the posterior circulation (Vetebrobasilar Circulation) of the brain.

Direct by-pass can be low-flow or high flow. Low flow grafts provide a flow rate of 15-25 ml/min, whereas high flow grafts provide a flow rate of 70-140 ml/min. Moderate to high flow grafts have a flow rate of 40-70 ml/min.

Moya Moya

Moya Moya disease is a condition in which part of the brain’s arteries (the anterior circulation), start to disappear. In an attempt to get more blood, the brain makes small fragile arteries to compensate for the lsos of blood flow. On an angiogram these blood vessels look like “Puff of Smoke’, thereby the name Moya Moya, which in Japaneese means “Puff of Smoke”. It is more commmon in patients with asian heritage. Suzuki has classified this disease in 6 stages. Stage 1 has mild stenosis of distal ICA, as well as MCA and ICA, while in stage 6, diatal ICA as well as MCA and ICA are gone and there is extensive growth of small vessel both fron small bracnhes of ICA and ECA. It affects the pediatric population as well as adult. It usually leads to stroke. Risk of ischemic stroke is higher than hemorrhagic. The annual risk of ischemic stroke is about 14% and the annual risk of hemorrhagic stroke (Bleeding) is 4%. The posterior circultion of the brain is not affected in Moya Moya.

Treatment consists of Cerebral Revascularisation through a procedure that is called By-pass.

There are 2 types of By-pass: Direct By-pass when a vessel is connect to another vessel, and Indirect By-pass in which the brain is stimulated to make its own vessels.

Direct By-Pass

If Moya Moya is not advacned and there are some good caliber vessels left, patient’s own vessel providing blood to the skin (STA) can be connected to patient’s brain vessels (MCA). This procedure is called STA-MCA-By-Pass. This method brings immediate blood flow to the bain

Indirect By-Pass

If Moya Moya is advacned and there is no good caliber artery left for direct by-pass then indirect by-pass can be performed. It takes 6 months before brain develops a new circulation thorugh indirect by-pass. There are 2 types of Indirect By-Pass

EDAS (Encephalo Duro AngioS ynangiosis)

Here a skin vessel (STA) is dissected and brought and put on the brain surface. Over time this blood vessel stimulates blood vessel evelopment on the brain surface. It usualy takes 6 months.

EDAMS (Encephalo Duro Angio Myo Synangiosis)

Here, a head muscle (Temporalis Muscle) is put on the brain surface. The surface of the muscle will make connections with the brain and over 6 months the brain will develop many small blood vessel connections that provide the brain with blood.

Moya Moya Disease can be distinguished from Moya Moya Syndrome. In Moya Moya Syndrome, the disease does not follow the typical pattern of Moya Moya Disease such as, some arteries are affected and some not but the treatment is the same.

Trauma

Traumatic subarachnoid hemorrhage (tSAH)

Subarachnoid hemorrhage (SAH) entails bleeding in the arachnoid space, which lies between the surface of the brain and the arachnoid mater. Trauma is the most common cause of SAH and is associated with high morbidity. The incidence of traumatic SAH in patients with traumatic brain injury (TBI) ranges from 26%-53%1. Mortality can be as high as 50% in those with severe TBI1. Mechanisms of injury include rotational acceleration causing short-lasting oscillatory movements of the brain, vertebrobasilar artery stretch due to hyperextension, sudden rise of intra-arterial pressure from a blow to the cervical carotid artery, tearing of the bridging veins or pial vessels and diffusion of blood from the contusion into the subarachnoid space.Traumatic SAH is distinctly different than spontaneous SAH, which usually originates from a ruptured aneurysm. Traumatic subarachnoid hemorrhage (tSAH) involves cortical surfaces in contrast to spontaneous subarachnoid hemorrhage, which usually involves the basal cisterns. Traumatic subarachnoid hemorrhage usually does not put patient at risk for vasospasm and potential secondary ischemic stroke, in contrast to spontaneous subarachnoid hemorrhage. Therefore isolated traumatic subarachnoid hemorrhage usually has a good outcome.

Cerebral Contusion

Hemorrhagic contusion, also known as traumaticcerebral contusion, is typically caused by sudden deceleration, where the brain impacts on bony prominences as in a coup or contrecoup injury3. An area of high density is observed on CT scan3. Traumatic cerebral contusions usually expand over time3. They may appear with a delay, but most present by 72 hours following injury3. Late expansion up to 1 week after trauma is not very unusual. Patients with deteriorating neurologic status, medically refractory intracranial hypertension, mass effect on CT or large-volume traumatic cerebral contusion (>50 ml) should undergo surgical evacuation immediately3. Individuals with GCS 6-8 and frontal or temporal contusion volume >20 ml and mid-line shift ≥ 5 mm and/or compressed basal cisterns should also receive surgical evacuation3. Non-operative management includes maximal medical therapy with hypertonic saline to keep serum sodium up to 155 for osmotic drive of the extracellular fluid out of the brain for cerebral relaxation, prophylactic seizure therapy, close surveillance of neurological exam in the ICU and serial imaging, for neurologically intact patients with controlled intracranial pressure and no significant mass effect on CT3.

Skull fracture

Closed
A closed fracture is a simple fracture of the skull3. Closed fractures may be managed operatively or non-operatively. Indications for surgery include hematoma formation, dural penetration, sinus involvement, presence of infection and bony depression >1 cm3.

Open
An open fracture is a compound fracture of the skull3. These may also be managed surgically or non-surgically depending on the risk factors as listed above for closed fractures3. Open – contaminated A contaminated fracture suggests infectious involvement of the fracture that may affect the brain. A contaminated fracture should be taken to the operating room for debridement, and the patient should receive parenteral antibiotics.

Epidural hematoma

Epidural hematoma (EDH) is most commonly caused by traumatic laceration of the middle meningeal artery in the foramen spinosum, a bony channel of the skull. Another cause is bleeding from a skull fracture onto the epidural space. Blood forms between the skull and the outer covering of the brain, called the dura mater. Blood expansion is limited horizontally by suture lines but may continue to bleed vertically. This tends to be a slow process resulting in a “lucid interval” for patients that may last up to 24 hours, in which they do not experience neurologic deficits. However, eventual brain compression causing mass effect and even herniation may result in sudden neurologic deterioration. Epidural hematomas are diagnosed using CT scan, indicating a lentiform pattern of bleeding. Patients with epidural hematoma>30 cm3 on imaging, with or without an altered neurologic exam, should undergo surgical evacuation immediately3. Those with an intact exam and hematoma volume 30 cm3 may be monitored with serial CT scans in the neurologic ICU3.

Subdural hematoma

A subdural hematoma (SDH) is defined as a collection of blood between the outer layers that cover the brain, the dura mater and the arachnoid mater. The most common cause of subdural hematoma is trauma. Anticoagulation therapy and coagulopathy are less common causes. In younger individuals trauma is usually caused by motor vehicle collision, while in the elderly population, falls are the most common cause. As older individuals have greater age-related brain atrophy, they can accommodate larger hematoma collections without presenting symptomatically. This is a reason why the elderly most commonly present with chronic subdural hematoma (cSDH), while young persons become symptomatic acutely. The mechanism of injury is related to either hematoma formation around a focus of severe parenchymal injury, which presents acutely, or bridging vein laceration in the subdural space from acceleration-deceleration injury, which most commonly presents in the chronic setting.

Hyperacute

The hyperacute phase of subdural hematoma formation takes place in approximately the first hour following hemorrhage. CT scan reveals a fluid collection relatively isodense to the adjacent cortex, although mixed density may be observed due to a mixture of clot, serum and ongoing unclotted blood4.

Acute

Acute SDH (aSDH) occurs in the first 1-3 days following hemorrhage. The classic finding on head CT is a crescent-shaped hyperdensity adjacent to the inner table, many times associated with brain edema. The four possible locations are over the convexity, interhemispheric, layered on the tentorium and in the posterior fossa. Convexity aSDH is generally less threatening than a temporo-parietal aSDH of the same size3. Operative indications include aSDH thickness greater than 1 cm or midline shift greater than 5 mm on CT scan. In the absence of these imaging findings, exam findings that prompt surgery include a drop in the GCS of 2 points or greater from time of injury to admission, asymmetric or fixed and dilated pupils, or intracranial pressure greater than 20 mm Hg3. Craniotomy is undergone for surgical drainage. Mortality is reported to be 50-90%, with the elderly and individuals on anticoagulation experiencing higher mortality rates3.

Sub-acute

The time period of a sub-acute SDH ranges between 3 days and 2-3 weeks. Sub-acute SDHs appear isodense on head CT. Membrane formation occurs after 4 days of SDH formation3.

Chronic

A chronic SDH (cSDH) is any SDH present for greater than 3 weeks. As discussed above, cSDH most commonly occurs in the elderly, with average age of 63 years3. Although falls are the most common cause, others include alcohol abuse, seizures and anticoagulation/coagulopathy3. Bilateral cSDH occurs in about 20-25% of cases3. cSDH is hypodense to brain parenchyma on head CT. Grossly, the blood appears to have a “motor oil” consistency that does not clot3. Presenting symptoms may be minor, including headache, confusion and language difficulties (such as word-finding problems). In more severe cases, symptoms may include hemiplegia, focal seizures or varying degrees of coma3. Symptomatic cSDH or those greater than 1 cm in maximum thickness should undergo surgical drainage. Burr hole drainage is the most common procedure, with either 2 burr holes or 1 large bur hole placed. Subdural drain may be placed. Craniotomy is less common.

Ventriculostomy

Ventriculostomy may refer to placement of an external ventricular drain (EVD) for diagnosis and surveillance of intracranial pressure (ICP) and CSF-diversion as temporary treatment of hydrocephalus. EVDs are generally placed in the setting of trauma or aneurysmal rupture. Most patients are acutely ill and have hydrocephalus from CSF outflow obstruction or non-obstructive hydrocephalus due to resorption disturbance from intraventricular or subarachnoid hemorrhage. All patients with EVDs are monitored in the neuro-ICU. Placement can be done at the bedside. The approach is usually from the right frontal lobe (Kocher’s point) to the foramen of Monroe, although anywhere in the lateral ventricle such as Keen’s point, Frazier’s point and Dandy’s point are reasonable but less accessible in a bed-side setting6. CSF is drained via a catheter from the ventricle to an external drainage bag. Resistance to flow is adjustable. Intracranial pressure (ICP) is simultaneously monitored through a transducer on the EVD. After the patient is stabilized and pathology source removed, resistance is increased to maximum threshold, at which time CT scan is obtained. Should the ventricles remain stable in size, suggesting normal CSF outflow through the ventricular system, the EVD can then be removed. This is also done at the bedside. Endoscopic Third Ventriculostomy (ETV) is indicated for obstructed hydrocephalus. It is a procedure in which the floor of the third ventricle is endoscopically enlarged to allow for greater CSF flow through the third ventricle. It is usually used in setting of tectal tumors or aqueductal stenosis and seldom used in traumatic setting. The success rate is estimated to be approximately 56% and is most successful for infants with untreated aqueductal stenosis3. Overall success is dependent on patient age, pathology type, and shunt history3.

ICP monitoring

Various forms of intracranial pressure (ICP) monitoring exist for patients in critical condition, typically following traumatic injury. Indications include EDH, SDH, ICH, contusion, brain herniation and severe edema. ICP monitoring allows neurosurgeons to medically maintain ICP within normal range (typically < 20 mm Hg) or may prompt emergent surgical treatment, as necessary. The most reliable method is an intraventricular catheter, also known as an external ventricular drain (EVD), discussed separately. An advantage of the EVD is that it allows therapeutic drainage of CSF to decrease ICP directly, although it may be difficult to insert into compressed or displaced ventricles. When an EVD is not possible, the next best possible option is an intraparenchymal monitor, which is also a catheter inserted in to the right or left prefrontal cortex. Less accurate methods include a subarachnoid screw (also known as a bolt) or a subdural or epidural catheter.

Decompressive craniectomy

Decompressive craniectomy is a procedure in which part of the skull is removed in the setting of intracranial hypertension and marked cerebral edema, generally following traumatic injury. The skull flap is left off for an indeterminate period of time, typically 2-3 months, to allow the brain to first expand without compression by the skull and then for swelling to resolve. A unilateral craniectomy or hemicraniectomy, is indicated for unilateral hemispheric swelling and midline shift after traumatic brain injury, ischemic stroke or SAH5. A major complication of this approach is brain herniation through the surgical site, from a craniectomy that is too small in proportion to the extent of the injury. Bilateral craniectomy can be considered for diffuse cerebral edema5. This may be performed as two separate craniectomy sites or a bifrontal craniectomy that extends from the floor of the anterior fossa to the coronal suture and the pterion bilaterally5.

References

Modi NJ, Agrawal M, Sinha VD. Post-traumatic subarachnoid hemorrhage: A review. Neurol India 2016;64, Suppl S1:8-13

Lee KH, Lukovits T, Friedman JA.“Triple-H” therapy for cerebral vasospasm following subarachnoid hemorrhage. Neurocrit Care. 2006;4(1):68-76.

Greenberg M. Handbook of Neurosurgery. 6th ed. New York: Thieme Medical Publishers, 2005.

Brant WE, Helms CA. Fundamentals of Diagnostic Radiology. Lippincott Williams & Wilkins.2007;ISBN:0781761352.

Schirmir CM, Ackil AA, Malek AM. Decompressive craniectomy. Neurocrit Care. 2008;8:456-470.

Mortazavi MM, Adeeb N, Griessenauer CJ, Sheikh H, Shahidi S, Tubbs RI, Tubbs RS. The ventricular system of the brain: A comprehensive review of its history, anatomy, histology, embryology, and surgical considerations. Childs Nerv Syst. 2014;30:19-35.

Hydrocephalus

 

Hydrocephalus is a condition in which the ventricles within brain enlarge. It can be communicating or obstructive. Obstructive hydrocephalus can result from congenital lesions preventing normal flow through the ventricular system such as aqueductal stenosis or a tectal glioma compressing the cerebral aqueduct. It can cause headache, nausea, vomiting, altered mental status, and gaze problem. A special type of hydrocephalus is Normal Pressure Hydrovephalus (NPH), which is associated with enlarged ventricles (Ventriculomegaly) but without abnormally increased intracranial pressure. NPH can present with classical traide of Gait disturbance, bladder dysfunction and mental and memory difficulties.

Hydrocephalus
Figure: T1-weighted MRI showing enlargement ventricles.

Endoscopic third ventriculostomy, or ETV, is indicated for patients with obstructive hydrocephalus. The obstruction typically occurs around the tectum due to a tumor in the aqueduct or congenital aqueductal stenosis. It can also be considered in patients with development of subdural hematomas after shunting. An opening is created in the floor of the third ventricle and the membrane of Lilliequist1 using an endoscope placed in the ventricular system through a burr hole. This allows the cerebrospinal fluid to flow directly to the basal cisterns, bypassing any obstruction. Complications include hypothalamic injury, injury to the pituitary stalk or gland, transient cranial nerve III and VI palsies, injury to the basilar artery, posterior communicating artery, or posterior cerebral artery, uncontrollable bleeding, cardiac arrest, and traumatic basilar artery aneurysm. Overall success rate is about 56%. Pathologies such as tumor, previous shunting or subarachnoid hemorrhage, prior whole brain radiation, and adhesions decrease the success rate. The ETV Success Score is on a scale of 0-90% and is calculated based on age, etiology, and shunt history.

References

  1. Mortazavi MM, Rizq F, Harmon O, Adeeb N, Gorjian M, Hose N, Modammadirad E, Taghavi P, Rocque BG, Tubbs RS. Anatomical variations and neurosurgical significance of Liliequist’s membrane. Childs Nerv Syst. 2015 Jan;31(1):15-28. doi: 10.1007/s00381-014-2590-5. Review. PMID: 25395307

A lumbar-peritoneal shunt (LP shunt) provides a channel for drainage from the lumbar thecal sac into the peritoneal cavity. They are mainly used for communicating hydrocephalus, with causes such as pseudotumor cerebri or CSF fistula.

A ventriculoatrial (VA) shunt allows for drainage of CSF from the brain into the right atrium of the heart via the superior vena cava. This is the treatment of choice when VP shunt is precluded by abdominal abnormalities such as surgery, peritonitis, or morbid obesity. VA shunts in particular are associated with higher rates of septicemia. They are also associated with nephropathy when placed during childhood.

A ventriculoperitoneal shunt, or VP shunt, is one type of permanent cerebral shunt that allows for alleviation of raised intracranial pressure caused by hydrocephalus. This procedure involves placement of a ventricular catheter in the lateral ventricle and ipsilateral drainage to the peritoneal cavity. This is the most commonly used shunt today.

For any shunt, obstruction is the most common cause of malfunction, with the most common site being proximal at the ventricular catheter. Other etiologies of malfunction are problems with valve mechanism and distal occlusion in the peritoneal catheter (or atrial catheter in a VA shunt below). Infection, erosion through skin, and seizures are also potential complications. There is a 17% incidence of inguinal hernia with VP shunts specifically. Peritonitis is another potential complication. VP and VA shunts need to be lengthened with growth in children and adolescents.

A ventriculopleural shunt is another cerebral shunt that drains from the lateral ventricle to the pleural cavity. It is used if patient would not be a candidate for Ventriculoperitoneal Shunt.

Ventriculostomy (EVD: External Ventricular Drain)

Ventriculostomy is a procedure allowing for cerebrospinal fluid (CSF) drainage from the cerebral ventricles to alleviate elevated intracranial pressure secondary to communicating or non-communicating hydrocephalus. The skull, dura mater, and brain parenchyma are penetrated to access the lateral ventricle, usually from the non-dominant lobe (the right frontal lobe in most individuals). An external ventricular drain (EVD) is a temporary catheter used for this purpose, draining CSF external to the body. This greatest risk of this procedure is infection and meningitis.

Cysts

 

Arachnoid Cyst

Arachnoid cysts are a congenital abnormality that arise from splitting of the arachnoid membrane during development and contain CSF-like fluid. They account for approximately 1% of all intracranial masses and are most commonly located in the middle fossa, cerebellopontine angle (CPA), suprasellar region, and the posterior fossa, although they may also occur in the spinal canal. Intracranial arachnoid cysts are most often asymptomatic, unless in the suprasellar region. The incidence is 5/1000. Men are 4 times as likely to be affected as women. As many are discovered incidentally on imaging, current recommendations are to follow-up with imaging in 6-8 months to rule out size expansion. They are followed over time and if stable, imaging can be repeated with large intervals in asymptomatic patients unless the lesion becomes symptomatic. Should symptoms occur, they are most commonly associated with signs of intracranial hypertension, including headache, nausea and/or vomiting, and lethargy. Symptomatic arachnoid cysts are more common in children. The Galassi classification scheme classifies arachnoid cysts in the middle cranial fossa based on size and degree of displacement of adjacent brain. Type I are small and spindle-shaped, limited to the anterior portion of the middle cranial fossa below the sphenoid ridge, and have free communication with the subarachnoid space. Type II have a superior extent located along the sylvian fissue, displace the temporal lobe, and have slow communication with the subarachnoid space. Type III are large and fill the whole middle cranial fossa, displace the temporal, frontal, and parietal lobes often causing midline shift, and have little communication with the subarachnoid space.

Treatment of symptomatic arachnoid cysts involves surgery. The preferred intervention is craniotomy and excision of the cyst wall with fenestration into the basal cisterns (marsupialization), or endoscopic cyst fenestration through a burr hole where the wall of the shunt is opened towards one of the subarachnoid cisterns. Scarring can impair flow through the subarachnoid space resulting in shunt dependency. It may also lead to cyst reaccumulation by blocking the fenestration created intraoperatively. Shunting the cysts is another option which is falling out of favor or if other options fail. This has a low morbidity and mortality and a low rate of recurrence. However, the patient becomes shunt dependent, with associated risk of shunt-malfunction and shunt-infection.

Brain Cysts

A brain cyst or cystic brain lesion is a fluid-filled sac in the brain. They can be benign (not cancer) or malignant (cancer). Benign means that the growth does not spread to other parts of the body. A cyst may contain blood, pus, or other material. In the brain, cysts sometimes contain cerebrospinal fluid (CSF). CSF is a clear liquid that bathes and cushions the brain and spinal cord. Some brain cysts begin before birth.

Even if a brain cyst is not cancer, it can still cause problems. The cyst may press against brain tissue and cause symptoms, such as headache, vision problems, or nausea. If this happens, you may need surgery to remove the cyst. In some cases, if the cyst is small and not growing and is not likely to cause symptoms, your healthcare provider may advise watching it instead of surgery.

Colloid Cyst

A colloid cyst is a slow-growing benign tumor that makes up less than 1% of all intracranial neoplasms. It is a neuroepithelial cyst composed of a fibrous, epithelial-lined wall filled with a mucoid or dense hyloid substance. It is most commonly found in the anterior portion of the third ventricle, where it may cause obstructive hydrocephalus by blocking outflow of CSF from the lateral ventricles through the foramina of Monro. Average age of diagnosis ranges from 20-50 years. Many colloid cysts are less than 1 cm in size and are asymptomatic. Larger cysts associated with obstruction present with symptoms of intracranial hypertension or chronic hydrocephalus. These include headache, gait disturbance, disturbance in mentation, nausea and/or vomiting, and blurred vision. Emergent symptoms include papilledema, gait disturbance, hyperreflexia, and positive Babinski reflex. Imaging with CT or MRI typically demonstrates hydrocephalus of the lateral ventricles only.

Surgical removal is the treatment of choice. If the cyst is severely attached to it vicinity including structures such as fornix (important for memory), thalamostriate veins (occlusion leads to serious complications including stroke of the thalamus) and choroid plexus (with risk of bleeding), bilateral shunting can be considered. In this case, risks of shunt dependency, tumor progression, and sudden neurologic deterioration due to hypothalamic compression remain without surgical intervention. Therefore, surgical resection is the treatment of choice.

Pineal Cyst

Pineal cysts are typically small, benign, non-neoplastic tumors originating from glial cells within the pineal gland. Prevalence on imaging is 1-4% of intracranial masses, with peak incidence occurring in late childhood (10-14 years of age) and falling throughout adulthood1. Women are more commonly affected than men1. Should a pineal cyst enlarge to a great extent, symptomatic presentation includes hydrocephalus, gaze paresis, and hypothalamic symptoms as discussed above. Positional headaches have also been associated with pineal cysts specifically. Asymptomatic pineal cysts 1.

References

  1. Al-Holou AN, Terman SW, Kilburg C, Garton HJL, Muraszko KM, Chandler WF, Ibrahim M, Maher CO. (2011). Prevalence and natural history of pineal cysts in adults: clinical article. Journal of Neurosurgery. 115(6): 1106-1114.

Rathke’s Cleft Cyst

This is a congenital, non-neoplastic, primarily suprasellar lesion that is derived from remnants of Rathke’s pouch. Rathke’s pouch is an embryological derivative of the oropharynx that develops into the anterior pituitary gland, or adenohypophysis. These masses are found in approximately 15% of autopsies, with a 2:1 female predilection. They most commonly present in adulthood after significant enlargement has occurred. Symptoms include visual disturbance from optic chiasm compression, pituitary dysfunction, and headaches. In contrast to craniopharyngiomas, Rathke’s cleft cysts arise from the pars intermedia of the pituitary, have a cell lining composed of single layer cuboidal epithelium, and the cyst contents resemble motor oil. Surgical treatment is recommended, with the procedure entailing partial excision and drainage – unlike craniopharyngiomas. There is an 18% recurrence rate following surgery.

Tumors

 

Brain Tumors

A brain tumor is a mass or growth of abnormal cells in your brain.

Many different types of brain tumors exist. Some brain tumors are noncancerous (benign), and some brain tumors are cancerous (malignant). Brain tumors can begin in your brain (primary brain tumors), or cancer can begin in other parts of your body and spread to your brain (secondary, or metastatic, brain tumors).

How quickly a brain tumor grows can vary greatly. The growth rate as well as location of a brain tumor determines how it will affect the function of your nervous system.

Brain tumor treatment options depend on the type of brain tumor you have, as well as its size and location.

Benign Tumors

Meningioma

These are the most common primary intracranial tumor, comprising 14.3-19% of primary intracranial neoplasms. They are defined as slow-growing, well-circumscribed, benign lesions with pathologically distinct “psamomma bodies,” or calcifications. Meningiomas arise from arachnoid cap cells and thus can arise from any structure in the CNS that is covered by arachnoid mater, a meningeal layer surrounding the brain and spinal cord beneath the skull and vertebrae. The peak incidence occurs at 45 years of age and is more common in females, with a male: female ratio of 1:1.8. Women are even more likely than men to have spinal meningiomas, with reported incidence 3.37 times more likely in women1. Only 1.5% of meningiomas occur in childhood and adolescence. Of those lesions, 19-24% are associated with neurofibromatosis type 1 (NF1). Meningiomas are most commonly located in the parasagittal space (20.8%), followed by convexity (over the surface of the brain – 15.2%), within the tuberculum sellae (12.8%), and the sphenoidal ridge (11.9%).

Histopathology is used to guide WHO grading, which has 3 levels. Meningothelial, psammomatous, and microcystic meningiomas – amongst others – are the lowest grade, WHO I. These have low risk of recurrence following gross total resection and aggressive growth. Chordoid, clear cell, and atypical meningiomas are WHO grade II. Papillary, rhabdoid, and anaplastic lesions are malignant, WHO grade III. These have the highest risk of recurrence and aggressive growth. Brain invasion by meningiomas independently should not be used to associate with malignancy, but there is higher risk of recurrence. Metastases overall are extremely rare.

Symptoms are associated with tumor location, but many meningiomas remain asymptomatic for years, even throughout a patient’s entire life. A common presenting symptom is seizure due to irritation of the cerebral cortex with supratentorial meningiomas.

Asymptomatic meningiomas found incidentally on imaging are recommended to be followed up with imaging in 3 months to rule out aggressive growth and on a 6-month follow-up and if still stable, on a 1-year follow up and if still stable, then with annual imaging every 2-3 years.

The first-line treatment for symptomatic meningiomas is surgical resection. If patients are not surgical candidates or the tumor is inaccessible, malignant, or recurrent, radiation therapy may be considered. Radiation therapy may also be used as an adjunct for partially resected lesions. Note that there are reports converting a grade I benign meningioma to a higher grade more aggressive tumor. Therefore, it is our opinion that if an asymptomatic meningioma continues to grow and is surgically resectable, or if it causes symptoms, it should be resected as the first-line therapy.

As these tumors tend to be bloody, preoperative embolization and autologous blood donation are essential for uncomplicated surgical removal.

The Simpson grading system is used to evaluate the extent of resection, with grade I being macroscopically gross total resection with removal of dural attachment and abnormal bone, and grade V being simple decompression with or without biopsy, without tumor removal. Degree of tumor resection is the most significant factor associated with recurrence. Recurrence after total removal occurs in 11-15% of cases but 29% with partial removal2. Convexity meningiomas may recur more rapidly than skull base meningiomas, and thus Simpson grade I resection is recommended3.

Convexity Meningioma

One of the most common locations of meningiomas (12.8%). Recurrence depends on grade, with 1.5% five-year recurrence for benign lesions and 44% for malignant/atypical meningiomas1.

Olfactory Groove Meningioma

Account for 9.8% of meningiomas. Remain asymptomatic until lesion has grown significantly in size. May cause Foster Kennedy Syndrome, which has a triad of symptoms: anosmia, ipsilateral optic atrophy (due to compromise of the nerve), and contralateral papilledema (due to compromise of the venous flow). Can also be associated with mental status changes and urinary incontinence due to frontal lobe mass effect. Lesions located posteriorly within the olfactory groove may cause visual impairment due to compression of the optic chiasm and/or optic nerves. Very large lesions may cause seizures or short-term memory loss due to compression of the fornix. Lesions > 3 cm in size are difficult to resect completely and have higher morbidity and mortality. Surgical resection entails gross total resection. For smaller tumors than 4 cm, it can be done through frontotemporal craniotomy but for tumors larger than 4 cm, it needs extrnsive skull base approach through a bicoronal craniotomy and naso-orbital osteotomy through the frontal sinus, in order to access the olfactory groove and resect the origin of the tumor in order to avoid recurrence1.

References

  1. Kshettry VR, Hsieh JK, Ostrom QT, Kruchko C, Benzel EC, Barnholtz-Sloan JS. (2015). Descriptive epidemiology of spinal meningiomas in the United States. Spine. 40(15): E886-E889.
  2. Yamashita J, Handa H, Iwaki K, et al. (1980). Recurrence of intracranial meningiomas, with special reference to radiotherapy. Surg Neurol. 14: 33-40.
  3. Hasseleid BF, Meling TR, Ronning P, Scheie D, Helseth E. (2012). Surgery for convexity meningioma: Simpson Grade I resection as the goal. Journal of Neurosurgery. 117(6): 999-1006.
  4. Morokoff AP, Zauberman J, Black PM. (2008). Surgery for convexity meningiomas. Neurosurgery. 63(3): 427-434.
  5. Mortazavi MM, Mantovani A, Da Silva HB, and Sekhar LN F (2015). Olfactory groove and planum sphenoidale, and tuberculum sellae meningiomas In Sekhar LN, Fessler RG (second edition), Atlas of Neurosurgical Techniques. Brain. (pp. 227-237) New York, NY: Thieme Publishers.

Malignant Tumors

Glioma/Astrocytoma

Glioma is a general name for any primary CNS tumor of glial origin. Gliomas may be classified by cell type, grade and location. Gliomas of different cell types include astrocytoma, ependymoma, oligodendroglioma, oligoastrocytomas, ganglogliomas and optic nerve glioma. Location may be supratentorial or infratentorial, meaning above or below the tentorium, a meningeal layer that separates the cerebrum from the cerebellum and brainstem. Supratentorial locations are more common in adults and infratentorial locations are more common in children. Grading is based on tumor pathology and involvement. WHO grades I-II are generally benign while III-IV are malignant. WHO grade I has low proliferation rate and may be cured with surgical resection alone1. These typically occur in younger individuals, for instance, juvenile pilocytic astrocytoma. WHO grade II is more infiltrative but still has pathologic features of benign tumors including well-differentiated cells. With recurrence, these tumors may progress to malignancy1. WHO grade III tumors have malignant features, including high mitotic activity and nuclear atypia1. These should be treated with adjuvant radiation and/or chemotherapy in addition to surgical resection. Astrocytomas broadly can be WHO grade I-III. WHO grade IV lesions are cytologically malignant, mitotically active, necrosis-prone neoplasms with poor prognoses1. These include glioblastoma multiforme and embryonal tumors.

Glioblastoma

Glioblastoma multiforme (GBM) is the most severe presentation of astrocytoma, classified as WHO Grade IV. Distinguishing criteria include microvascular proliferation and necrosis.

There are 3 known genetic pathways that may be dysregulated: receptor tyrosine kinase (RTK), phosphatidylinositol-3-OH kinase (PI3K)/AKT/mTOR, and the p53 and retinoblastoma (Rb) tumor suppressor pathways.

Primary GBMs comprise the majority of GBMs, most commonly occurring in older patients (mean age 55 years) with a rapid clinical course.


Figure : Glioblastoma multiforme (GBM) A: Axial T1-weighted MRI with contrast. B. Sagittal T1-weighted MRI. C. Coronal T1-weighted MRI.

Secondary GBMs arise from malignant degeneration of WHO grade II or III astrocytomas in younger patients (mean age 40 years) and progress more slowly than primary GBMs.

The endpoints of surgery for GBMs are cytoreduction, relieving mass effect, and obtaining tissue for histological and molecular analysis. Standard therapy for GBM combines surgery, radiation, and temozolomide (temodar) chemotherapy. Temodar is member of the oral alkylating agent class of chemotherapeutic agents. It is metabolized to an active agent at physiological pH, which has a cytotoxic effect on tumor cells due to addition of alkyl groups to DNA. This typically causes irreparable damage to tumor DNA in addition to side effects due to damage of host DNA, typically in fast growing cells (i.e. hair and gastrointestinal mucosa). Surgical resection should aim for gross total resection with preservation of eloquent and critical structures. Awake craniotomy is performed for lesions in eloquent brain regions. Studies have shown that excision of 97% or more of a GBM is associated with increased survival time and likely also improves time to tumor progression.

See Video: https://www.youtube.com/watch?v=4CAwuhEfdyg

5-aminolevulinic-acid (5-ALA) may be used to visually identify the tumor intraoperatively. It is metabolized into fluorescent porphyrins that are taken up by malignant glioma cells.

Partial GBM resection carries risk of postoperative hemorrhage and/or edema, known as wounded glioma syndrome, with risk of herniation. Therefore, patients with extensive, multicentric, or bilateral cortical involvement are not candidates for surgical debulking.

Patients who are not surgical candidates due to tumor location in eloquent or inaccessible areas of the brain or inability to undergo general anesthesia may undergo stereotactic biopsy instead. However, stereotactic biopsy may underestimate GBM in up to 25% of cases due to sampling error.

Recurrent GBM may be treated with the chemotherapeutic agent Bevacizumab, known as Avastin. It is a recombinant human monoclonal antibody that prevents the proliferation of blood vessels by blocking vascular endothelial growth factor A (VEGF-A). Cancers such as GBM upregulate VEGF concentrations to promote angiogenesis for supporting growth of the tumor cells. Avastin has increased tendency to bleed as a side effect and is reserved for recurrent glioblastomas. Other chemotherapeutic agents include Nivolumab (Opdivo). Nivolumab is a human monoclonal antibody directed against the negative immunoregulatory human cell surface receptor Programmed death-1 (PD-1). Nivolumab binds and blocks the activation of PD-1. Activated PD-1 inhibits T-cell activation and effector function through the suppression of P13k/Akt pathway activation.

Brainstem Glioma

Brainstem gliomas are a heterogenous group of low and high grade tumors that typically present with cranial nerve palsies and white matter tract findings. They are more likely to occur during childhood and adolescence, with 77% of those affected less than 20 years of age. They are also more likely to be malignant and invasive. Common symptoms include gait disturbance, headache, nausea and vomiting, diplopia, facial asymmetry, distal motor weakness, papilledema, and hydrocephalus depending on the tumor location in the brainstem. Patients less than 2 years of age may present with failure to thrive.

Lower grade tumors have a predilection for the upper brainstem, while high grade tumors (such as glioblastoma) are more likely to arise in the lower brainstem. The four growth patterns of brainstem gliomas are diffuse, cervicomedullary, focal, and dorsally exophytic. All diffuse tumors are malignant, most being anaplastic astrocytomas and glioblastomas. In contrast, most cervicomedullary and focal neoplasms are low-grade astrocytomas. Dorsally exophytic tumors may be an extension of the focal growth pattern, with many being low grade gliomas including pilocytic astrocytomas and gangliogliomas. Surgery is only recommended for removal of dorsally exophytic tumors with radical subtotal resection. Complications include exacerbation of pre-operative symptoms such as ataxia and cranial nerve palsies, although these usually resolve over time. Long-term survival tends to be favorable with low incidence of disease progression at follow-up. Radiation therapy is the next in line for treatment when surgery is not possible. Most children with malignant brainstem gliomas die within 6-12 months of diagnosis.

Tectal Glioma

This is a subgroup of brainstem gliomas mainly comprised of low-grade astrocytomas. The average age of presentation is 6-14 years of age. The most common complication is obstructive hydrocephalus, with associated symptoms of headache, nausea, and vomiting. Focal neurologic deficits are rare, and may include gaze disturbances. Long-term management with Endoscopic Third Ventriculostomy (ETV) or Ventriculoperitoneal shunt (VPS) for hydrocephalus is recommended, due to low risk of progression and morbidity of surgery. Tumor progression is described in 15-25% of cases and may be treated with stereotactic radiosurgery. (See figure)


Figure : Axial T1-weighted MRI with contrast showing tectal glioma with obstructive hydrocephalus.

Pontine Glioma

Pontine gliomas are another subtype of brainstem gliomas, also known as diffuse intrinsic pontine glioma. These are generally malignant, aggressive, infiltrative tumors with a poor 5-year survival rate of <1%. Children are mainly affected. Symptoms are due to cranial nerve palsies, including problems with eye and facial movements, speech, chewing, and swallowing. Other symptoms include extremity weakness and ataxia. Due to the infiltrative nature of these neoplasms in a sensitive brain region, surgical resection is not recommended. Radiation therapy is first-line for palliative therapy with symptomatic improvement. However, rapid progression still occurs within a year of treatment. Chemotherapy is experimental at this time.

Chordoma

Chordomas are rare tumors with an incidence of 0.51 cases/million arising from the remnant of the primitive notochord, which typically develops into the nucleus pulposus of the intervertebral disks. Although they may arise anywhere along the neuroaxis, they tend to arise at the two ends of the primitive notochord. 35% occur at the cranial end in the spheno-occipital region at the clivus and 53% occur in the spine at the sacrococcygeal region.

Cranial chordomas occur most frequently in patients 50-60 years of age with an approximately equal male:female incidence. The most common presentation is of cranial nerve palsy typically involving the oculomotor or abducens nerve. In contrast, spinal chordomas occur more commonly in males and in older patients. As they most commonly occur in the sacrum, presenting symptoms include pain, sphincter disturbance, or nerve root symptoms from local nerve root compression.

These tumors are generally slow growing, locally aggressive, and osseodestructive. They are difficult to excise completely, have a high recurrence rate, and can metastasize in late stages, most commonly to the lung, liver, and bone. Pathologically they are distinguished by physaliphorous cells, a type of vacuolated cells likely representing cytoplasmic mucus vacuoles. Radiographically chordomas appear lytic with calcifications, and they enhance on CT with contrast. Bony destruction is commonly seen on CT and MRI with spinal chordomas.

Gold-standard treatment is wide en-bloc surgical excision with postoperative radiation, including high-dose radiation such as proton beam therapy. There is a high risk of surgically induced metastasis, which is reduced by piecemeal tumor removal. Decompression should be avoided for this reason. Resection of sacral chordomas is complicated by injury to nerve roots responsible for bowel and bladder function risking incontinence. If the nerve roots extending up to S1 are spared, there is a 50% chance of retaining normal bowel and bladder control. If the S1 level is not spared, the patient will likely have impairment of bowel and bladder continence. (See figure)


Figure : Cranial chordoma. A. Axial T1-weighted MRI with contrast B. Coronal T1- weighted MRI with contrast. C. Sagittal T1-weighted MRI with contrast.

CNS-Lymphoma

CNS lymphomas may be classified as primary or secondary. Primary CNS lymphoma is a rare, malignant neoplasm that originates with the CNS and comprises 0.85-2% of all brain tumors. Men are more commonly affected, with a male: female ratio of 1.5:1. The median age at diagnosis is 52 years. These may occasionally metastasize outside the CNS. Immunocompromised patients such as AIDS and transplant patients are more likely to be affected than the general population. They also have a younger overall median age of diagnosis at 34 years. Primary CNS lymphoma may occur supra- or infratentorially. Supratentorial locations include the frontal lobes and basal ganglia as well as periventricular regions. The most common infratentorial location is the cerebellum.

Secondary CNS lymphoma is due to metastatic spread of systemic lymphoma, usually non-Hodgkin’s lymphoma, generally occurring in 1-7% of all lymphoma patients.

Primary and secondary CNS lymphoma present in similar ways. The most common symptoms arise from epidural spinal cord compression and carcinomatous meningitis, with multiple cranial nerve deficits. Seizures also commonly occur. Other non-focal, non-specific symptoms include mental status changes and symptoms indicating increased intracranial pressure, including headache and nausea and vomiting. Focal symptoms such as hemimotor or hemisensory deficits, aphasia, and visual field deficits may also be present.

First-line treatment following biopsy is radiation therapy with choice of adjuvant chemotherapy. For large tumors causing mass effect, severe perifocal brain edema and/or seizure, total resection is preferred. Chemotherapy has been shown to prolong survival in non-immunocompromised patients. Choice agents are methotrexate and rituximab. Generally, surgery is only for biopsy and confirmation of diagnosis but for larger lesions causing mass effect or severe edema or intractable seizure, total resection during open biopsy is recommended. These tumors are also highly responsive to steroids. Unfortunately, recurrence rate is high at 78% at 15 months following treatment. Median survival after radiation is 10 months, with 5-year survival 3-4%. One-year survival after gross total resection is estimated to be 56.6% and 31.8% following partial resection1. Intraventricular methotrexate has been shown to prolong median time to recurrence to 41 months. Prognosis is worse in immunocompromised individuals such as AIDS patients, with median survival only 3-5 months. This is generally due to opportunistic infection and not CNS complications.

Chondrosarcoma

A chondrosarcoma is a malignant cartilaginous tumor. They are lobulated tumors with calcifications. Despite the name, it is clinically a less aggressive tumor than chordomas. However, it is resistant to chemotherapy and radiation. Symptoms include back or thigh pain, sciatica, bladder problems, and unilateral edema. Surgical resection is the mainstay of therapy.

Esthesioneuroblastoma

Esthesioneuroblastoma, also known as olfactory neuroblastoma, is a malignant tumor arising from the neural crest cells of the upper nasal tract that commonly extends intracranially. It is extremely rare, with an annual incidence of 0.4 per 1,000,000 people. It affects a wide age group ranging from 3 to 90 years, with one peak between the second and third decade of life and a second peak between the sixth and seventh decades. The most common symptoms are epistaxis (76%), nasal obstruction (71%), tearing (14%), pain (11%), diplopia, proptosis, anosmia, and endocrinopathy. MRI can be used for imaging. Treatment is most commonly with surgical resection followed by radiation therapy. Chemotherapy may be added on as well, of which platinum-based chemotherapy is the standard. Diagnostic biopsy is typically done by otolaryngology in office prior to surgery. The Kadish system is most commonly used to clinically classify extent of disease and correlates with survival:

  • A: Confined to nasal cavity
  • B: Extension to paranasal sinus
  • C: Local extension (orbit or cribiform plate)
  • D: Distant metastasis

Pathologic grading may be undergone using the Hyams grading system, which is used to classify all upper respiratory tract carcinomas for nuclear pleomorphism, mitotic activity, presence of rosettes, necrosis, and summates. Grade 1 and 2 lesions have been shown to have a benign disease course while grades 3-4 confer a poor prognosis.

Surgical treatment involves endoscopic tumor resection. Should the tumor extend to the inferior lateral orbit or maxilla, lateral rhinotomy may be utilized to access and excise the lesion. Many institutions use a purely endoscopic approach so long as negative margins are obtained. If not, conversion to an open approach is necessary. Some institutions may opt for stereotactic radiosurgery instead.

The mean overall survival is 7.2 ± 0.7 years. Mean progression free survival is 4.8 ± 0.7 years. Five-year survival is 63%, and 10-year survival is 40%. The most significant prognostic factors are Kadish staging, lymph node involvement, and age at diagnosis.

Choroid Plexus Carcinoma

Choroid plexus carcinoma is a malignant variant of the benign choroid plexus papilloma, a rare neuroepithelial tumor arising from the choroid plexus in the interventricular space. The choroid plexus is responsible for producing the cerebrospinal fluid (CSF) that is within the ventricles and surrounds the brain and spine1. These tumors are most commonly located in the lateral or fourth ventricles or the cerebellopontine angle from extension of the choroid plexus through the foramen of Luschka. Infratentorial locations are more common in adults, while in pediatric patients, supratenotrial locations are more common. Symptoms arise from increased intracranial pressure related to hydrocephalus such as headache, nausea, vomiting and craniomegaly. Other possible symptoms include seizure, subarachnoid hemorrhage and focal neurologic deficit such as hemiparesis, sensory deficits, cerebellar signs or cranial nerve palsy of the oculomotor (CN III), trochlear (CN IV) or abducens (CN VI) nerve. Hydrocephalus may be caused by overproduction of CSF, obstruction of CSF outflow by tumor or communicating hydrocephalus from blockage of CSF reabsorption by CSF-borne particulates.

Surgical resection is the choice of therapy for both benign and malignant lesions. Surgery can be complicated by tumor fragility and bleeding of the choroidal arteries. If gross total resection is not possible during the first procedure, a second and even third are recommended until complete resection is achieved, as five-year survival is 84%. In one study, recurrence rate following gross total resection was 9.6% and required repeat surgery2.

Malignant Meningioma

Malignant meningiomas are WHO grade III lesions characterized by anaplastic, papillary, or sarcomatous pathology. They have a greater recurrence risk than classic, benign meningiomas and typically more aggressive growth. They are characterized by cortical invasion and rapid recurrence following surgical resection. Frequent mitotic figures (≥4 mitoses per high-power field) or papillary features are strong pathological predictors of malignancy. Younger patients are more commonly affected. Surgical resection should be attempted and is first-line regardless of recurrence. Radiation therapy may be attempted if the patient is not a surgical candidate or declines surgical intervention after recurrence. These tumors may be bloody and steps including preoperative embolization of the arterial feeders should be taken to minimize blood loss in surgery, including early interruption of tumor blood supply during surgery prior to central debulking, dissection of the tumor capsule from the brain by dissecting and coagulating vascular and arachnoid attachments, and removal of attached bone and dura when possible. The Simpson grade establishes the extent of meningioma resection during surgery and correlates this with risk of symptomatic recurrence. Grade I entails complete removal with resection of underlying bone and associated dura. There is a 9% symptomatic recurrence at 10 years after resection. Grade II describes complete removal of the tumor and coagulation of the dural attachment. There is a 19% symptomatic recurrence at 10 years after resection. Grade III is complete removal without resection or coagulation of the dura, with 29% of patients experiencing symptomatic recurrence at 10 years after resection. Grade IV is subtotal resection, and 44% of patients have symptomatic recurrence at 10 years after resection. Finally, grade V is simple decompression with or without biopsy, and there is a 100% symptomatic recurrence at 10 years after surgery. Recently, the Simpson grading scheme has been called into question for different histological meningioma types. As convexity meningiomas tend to recur more rapidly than skull base meningiomas, Simpson grade I resection should be the goal22, meaning the goal is complete resection of the meningioma including its origin, attached dura and involved boned, in order to minimize future recurrence.

Ependymoma

An ependymoma is a neoplasm originating from the ependymal cells lining the ventricular system of the CNS. In children, these tumors most commonly occur in the posterior fossa, usually originating from the part of the roof of the 4th ventricle called the inferior medullary velum whereas in adults, they are more common in the spine. Sixty-nine percent of intracranial ependymomas occur in pediatric patients with a mean age of 17.5 years across all patients. There are about 200 cases of pediatric intracranial ependymoma per year. Prognosis is worse with younger age. Ninety-six percent of intraspinal ependymomas occur in adults with a mean age of 40 years in all patients. Ependymomas can spread throughout the CNS via seeding through the CSF. Higher grade lesions are more likely to do this. WHO Grade I subtypes include myxopapillary ependymoma and subependymoma. WHO Grade II variants include cellular, papillary, clear cell and tanycytic (rare). WHO Grade III class ependymomas are anaplastic. Due to high propensity of seeding local metastasis, the entire spine needs to undergo diagnostic MRI to rule out drop-metastasis.

Intracranial ependymomas tend to be benign and most often occur in the floor of the 4th ventricle. As such, symptoms secondary to increased intracranial pressure due to hydrocephalus are most common, such as headache (80%), nausea and vomiting (75%), ataxia and vertigo (60%), seizures and cranial nerve palsies of the abducens (VI) and facial (VII) nerves. MRI is used for neuroimaging.

First-line treatment is neurosurgical intervention and gross total resection1. Lumbar puncture should be undergone 2 weeks following surgery to exclude seeding. Ependymomas are sensitive to radiation therapy, which can be administered postoperatively. Radiation therapy as an adjuvant to surgical resection increases 5-year survival from 20-40% to 40-80%. Adults fare better than children, with an 80% five-year survival compared with a 20-30% five-year survival in pediatric patients. Recurrence can occur at initial site of treatment following gross total resection. Seeding via CSF is another cause of treatment failure, occurring in 9-25% of patients.

Medulloblastoma

Medulloblastomas are the most common pediatric brain malignancy, peaking in the first decade of life with a median age of diagnosis of 5-7 years. Girls have significantly better outcomes than boys. These tumors are embryonal in origin arising from neuroectodermal cells within the cerebellum. As they tend to arise in the cerebellar vermis and grow into the roof of the 4th ventricle, associated symptoms are generally related to hydrocephalus – headache, nausea, vomiting and ataxia. All medulloblastomas are classified as high grade or WHO grade IV, pathologically. Seeding throughout the neuroaxis is a problem, with 10-35% of patients presenting with seeding at diagnosis. Poor prognostic indicators include younger age (especially < 3 years), metastatic or disseminated disease, inability to perform gross-total resection (particularly with residual > 1.5 cm2) and histological differentiation along glial, ependymal or neuronal lines.

The treatment of choice for medulloblastoma is surgical debulking of the tumor to the greatest extent possible, followed by radiation therapy. Radiation to the whole craniospinal axis is necessary as the tumor has a high propensity to recur and spread via seeding. As the tumor is usually in a high risk location – the floor of the 4th ventricle, immediately adjacent to the facial colliculus in the pons – leaving residual is preferred to total resection to avoid neurologic deficit. Adjuvant chemotherapy may be used in patients with recurrent lesions or poorer overall outcomes. Commonly used agents are lomustine, cisplatin and vincristine. Up to 40% of patients with posterior fossa tumors may require permanent ventriculoperitoneal shunt following surgery.

Atypical Teratoid Rhabdoid Tumor (AT/RT)

This is an aggressive embryonal malignancy unique to the CNS. Infants and children are predominantly affected, with more than 90% of patients < 5 years of age, and most < 2 years. A minority of AT/RT are associated with primary renal rhabdoid tumor. There is a genetic relationship with deletion or monosomy of chromosome 22. Half of AT/RTs are located in the posterior fossa, particularly within the cerebellopontine angle. Thirty-three percent of patients have CSF seeding on presentation. Most die within 1 year of diagnosis.

Malignant Nerve Sheath Tumor

Malignant peripheral nerve sheath tumors – also known as malignant schwannomas, neurofibrosarcoma, and neurosarcoma – are a rare disease of the connective tissue surrounding nerves. There is a strong association with neurofibromatosis, especially type 1. Lifetime risk in patients with NF1 is estimated to be 8-13%. Symptoms of a malignant nerve sheath tumor include painless swelling of the extremities, difficulty moving an affected extremity, soreness, neurologic deficit, pain or sensory abnormality, dizziness, and balance problems.

Diagnosis is made using biopsy. First-line treatment is surgical excision with wide margins. Radiation therapy is usually undergone following surgery. Invasive tumors may require limb amputation. Chemotherapy is a possible adjuvant treatment. Thirty-nine percent of patients experience tumor metastasis, especially to the lung. Poor prognostic factors are large primary tumor (> 5 cm), high grade, neurofibromatosis, presence of metastasis, and young age.

Metastatic Brain Tumor

Metastases to the brain are the most common brain tumor. Imaging studies show that they comprise approximately 30% of cases. Unfortunately, 70% of these patients will have multiple lesions on imaging at the time of symptom onset. If only a solitary lesion is noted and the patient has a history of cancer, biopsy should be undergone as primary CNS tumor is more likely. The median survival with optimal treatment is 26-32 weeks, thus the aim of management is largely palliative1. Patients with neurologic symptoms have a median survival of 1 month without treatment. Other indications for resection are if the tumor is giving neurological compromise and/or if no primary tumor is present and the tumor needs to be resected for obtaining diagnosis. In our opinion, if the tumor is resectable, it is better to resect it than only obtaining a surgical biopsy, if surgical risks are reasonable.

The incidence of new cases of metastatic tumor in the U.S. has reached 170,000 annually. Most tumors spread hematogenously, but direct extension can occur. Cerebral metastases are in part due to lack of efficacy of most chemotherapeutic agents beyond the blood-brain barrier (BBB). Others can even weaken the BBB temporarily and promote CNS seeding.

The most common cancers with spread to the brain are lung cancer (44%), breast (10%), kidney – renal cell carcinoma (7%), GI tract cancers, especially colorectal cancers (6%), melanoma (3%), and undetermined source (10%).

Small-cell lung cancer is specifically most likely to metastasize to the CNS, with an 80% metastasis rate in patients with survival of 2 or more years after diagnosis. These tumors are highly radiosensitive and may be treated with radiation therapy with possible adjuvant chemotherapy.

Melanoma metastasis usually involves the pia and arachnoid meningeal layers. Surgical resection is first-line treatment, as these tumors are radioresistant. If gross total resection is not possible (i.e. > 4 metastases or inaccessible location), stereotactic radiosurgery and chemotherapy may be considered. Melanoma metastases are especially prone to bleed.

The most common tumors that metastasize to the brain in children are neuroblastoma, rhabdomyosarcoma, and Wilm’s tumor.

Signs and symptoms of metastatic disease are dependent on tumor location. Mass effect with large tumors or blockage of CSF drainage causing hydrocephalus results in symptoms due to increased intracranial pressure, including headache – present in 50%, the most common presenting symptom – and nausea and vomiting. Focal neurologic deficits due to compression of brain parenchyma or edema are also common. Seizures occur in 15% of patients. Mental status changes such as depression, lethargy, apathy, and confusion are also possible.

The typical workup of a patient with suspected metastasis to the brain is:

  1. CT of chest, abdomen, and pelvis with contrast to locate primary tumor
  2. Radionuclide bone scan (particularly in prostate, breast, kidney, thyroid, and lung cancers)
  3. Mammogram in women
  4. Prostate specific antigen (PSA) in men
  5. PET scan

References

  1. Taillibert S, Delattre JY. (2005). Palliative care in patients with brain metastases.Current Opinions in Oncology. 17(6): 588-592
  2. Vanuytsel LJ, Bessell EM, Ashley SE, Bloom HJ, Brada M. (1992). Intracranial ependymoma: long-term results of a policy of surgery and radiotherapy. International Journal of Radiation Oncology, Biology, and Physics. 23(2): 313-319.
  3. Mortazavi MM, Griessenauer CJ, Adeeb N, Deep A, Bavarsad Shahripour R, Loukas M, Tubbs RI, Tubbs RS. (2014). The choroid plexus: a comprehensive review of its history, anatomy, function, histology, embryology, and surgical considerations.Child’s Nervous System. 30(2): 205-214.
  4. Jeibmann A, Wrede B, Peters O, Wolff J, Paulus W, Hasselblatt M. (2007). Malignant progression in choroid plexus papillomas.Journal of Neurosurgery. 107: 199-202.
  5. Bierman PJ. (2014). Surgery for primary central nervous system lymphoma: Is it time for reevaluation? 28(7): 632-637.
  6. Louis DN, Ohgaki H, Wiestler OD, Cavenee WK, Burger PC, Jouvet A, Scheithauer BW, Kleihues P. (2007). The 2007 WHO classification of tumours of the central nervous system.Acta Neuropathol. 114(2): 97-109.

Skull Base Tumors

Planum Sphenoidale Meningioma

Meningiomas in this location arise from the flat segment of the sphenoid bone anterior to the chiasmatic sulcus within the anterior cranial fossa.

References

  1. Mortazavi MM, Mantovani A, Da Silva HB, and Sekhar LN F (2015). Olfactory groove and planum sphenoidale, and tuberculum sellae meningiomas In Sekhar LN, Fessler RG (second edition), Atlas of Neurosurgical Techniques: Brain. (pp. 227-237) New York, NY: Thieme Publishers.
Tuberculum Sellae Meningiomas

The tuberculum sellae is the bony elevation between the chiasmatic sulcus and the sella tursica. It is 2 cm posterior to the olfactory groove and lies within the middle cranial fossa. These meningiomas are most commonly associated with visual loss due to compression of the optic chiasm, causing bitemporal hemianopsia. Differentials on imaging may include pituitary macroadenoma. These tumors usually involve the optic canals and encase internal carotid and/or anterior cerebral arteries. They can encase the superior hypophyseal artery. They can breach into the sphenoid sinus. Surgical resection requires especial techniques including extradural resection of the anterior clinoid process on the side with most vascular encasement. After entering the dura, the falciform ligament of the ipsilateral optic nerve needs to be sectioned in order to let the optic nerve be mobilized and avoid optic nerve injury. The origin of the tumor at the tuberculum sellae needs to be drilled even if it would risk to open towards the phenoid sinus. Before resecting the tumor, the contralateral falciform ligament needs also to be sectioned in order to mobilize both optic nerves. Also, a majority of the tumors have extension into the optic canal and this technique gives access to resecting those extensions. Avoiding doing this, would not only risk putting tension on the optic nerves during resection of the tumor, but also risk leaving tumor residuals in the optic canals and risk of recurrence of the tumor. Once this important step is done, tumor needs to be dissected off potentially encased internal carotid artery and or anterior cerebral artery. Not unusually, we see the superior hypophyseal artery in the midst of the tumor. It needs to be dissected and saved. Central debulking is key here as the space surrounding the tumor is small and surrounded by both optic nerves, cerebral arteries and pituitary stalk. Once central debulking has shrunken the tumor, the entire tumor can be resected. If sphenoid sinus is opened, it can be filled with abdominal fat graft and covered with autologeous pericranium. Classification for surgical resection is proposed by Sekhar-Mortazavi1.

References

  1. Mortazavi MM, Mantovani A, Da Silva HB, and Sekhar LN F (2015). Olfactory groove and planum sphenoidale, and tuberculum sellae meningiomas In Sekhar LN, Fessler RG (second edition), Atlas of Neurosurgical Techniques: Brain. (pp. 227-237) New York, NY: Thieme Publishers.
Petroclival Meningioma

Petroclival meningiomas may arise off the petrous or clival bones and are in close proximity to the sphenoid bone and cavernous sinus. Surgery can be challenging due to proximity and adhesion to cranial nerves, major blood vessels, and the brainstem1. Cranial nerve morbidity and motor deficits are the common postoperative neurological complications after resection of petroclival meningiomas1. These tumors are among the most challenging tumors in skull base surgery. They often involve both the middle and posterior cranial fossae, being both supra-, and infratemtorial. This means that they need extensive combined approaches for gross total resection. Tailored skull base approach for this type of tumor is a combined petrosal approach which includes a temporal craniotomy and a retosigmoid craniectomy, in order to access the pre-sigmoid area where the posterior petrous bone is at the junction of the middle and posterior cranial fossae. The posterior petrous bone just posterior to the posterior semi-circular canal is drilled. The space if then offers, will be enough to remove the tumor. Many cranial nerves are usually attached to the tumor and many times the abducens (6th cranial nerve) and cochlear (part of the 8th cranial nerve) although not injured, can become dysfunctional after surgery if not already. Many patients come with facial weakness and hemi-body weakness as the infratentorial part of the tumor compresses the brain stem. Many tumors encase the basilar artery and its branches partially and careful dissection needs to be done. The trochlear (4th cranial nerve) nerve is especially prone to injury as it is closely adjacent to the edge of the tentorium and access to the intradural compartment requires sectioning of the tentorium and closing of the adjacent superior petrosal sinus. Closure of the superior petrosal sinus does not cause patient harm as its venous return usually re-routs through the inferior petrosal sinus and other veins. Sometimes, these tumors extend anteriorly to the cavernous sinus as well, requiring a tailored skull base approach with a modified frototemporal craniotomy with zygomatic osteotomy in access to the approaches described above for full access and resection of the tumor. Sometimes the tumor extends inferiorly down to beyond foramen magnum, necessitating adding a far-lateral or extreme lateral craniectomy to the above skull base approaches. (See figure)


Figure : Petroclival Meningioma. A. Axial T1-weighted MRI with contrast B. Axial T2- weighted MRI. C. Coronal T1-weighted MRI with contrast. D. Sagittal T1- weighted MRI.

References

  1. DiLuna ML and Bulsara KR. (2010). Surgery for petroclival meningiomas: A comprehensive review of outcomes in the skull base surgery era. Skull Base. 20(5): 337-342.
Pineal region tumors

There are many different tumors that may arise in the pineal region. They may be neoplastic or non-neoplastic in origin. These include tumors of pineal glandular tissue – pineocytomas and pineoblastomas; glial cells – astrocytomas, oligodendrogliomas, and glial cysts; arachnoid cells – meningiomas and arachnoid cysts; ependymal lining – ependymomas; sympathetic nerves – chemodectomas; germ cells – choriocarcinoma, germinoma, embryonal carcinoma, endodermal sinus tumor, and teratoma; and remnants of the ectoderm – epidermoid or dermoid cysts. Germ cell tumors are the most common mass type. Despite the diversity of tumor classifications, symptomatic presentation is similar. Obstruction of cerebrospinal fluid outflow through the aqueduct may cause obstructive hydrocephalus, with associated symptoms of headache and nausea and vomiting. Compression of the brainstem and cerebellum are possible. Due to vicinity of the tectum and the quadrigeminal plate, symptoms may include abnormal eye movements, such as the inability to look upward and diplopia, ataxia, and disequilibrium are among other symptoms. Endocrine dysfunction is a rare complication arising from disruption of pineal gland function and potential compression of the nearby hypothalamus. Symptoms may include diabetes insipidus, the inability to regulate water homeostasis, and slowing of growth in children and adolescents. Surgical resection of pineal tumors is preferred for management. Guidelines for treatments and outcome of pineal tumors were recently published1.

References

  1. Abecassis IJ, et al. A single Institute Experience with Pineal Region Tumors: 50 tumors Over 1 Decade. Operative Neurosurgery. (A head of published)
Dermoid

Dermoid cysts are rare, benign brain lesions, accounting for 0.3% of all brain tumors. They are developmental tumors arising from early ectodermal tissue, and can contain keratin, cellular debris, hair, and sebum. They are most commonly located in the midline within the posterior fossa in adults and the lower spine in children and adolescents. They are associated with other congenital anomalies in up to 50% of cases. Dermoid cysts within the spinal tract typically have a dermal sinus tract draining to the skin and thus have high rates of recurrent bacterial meningitis. Complete surgical resection is the treatment of choice.

Epidermoid

Epidermoid cysts are also rare neoplasms, comprising 0.5-1.5% of brain tumors and peak at 40 years of age. Like dermoids, they too arise from early ectodermal tissue, but unlike dermoid cysts, contents are generally limited to stratified squamous epithelium, keratin, cellular debris, and cholesterol, with occasional hair. They are most commonly located in the cerebellopontine angle, fourth ventricle, suprasellar region, and spinal cord and are usually lateral. These are isolated lesions and may even occur iatrogenically following lumbar puncture in the lower spine. Very rarely do these lesions behave malignantly so as to destroy bone or degenerate to squamous cell carcinoma. Complications including aseptic meningitis and hydrocephalus may arise from cyst rupture. A rare variant of aspetic meningitis called Mollaret’s meningitis is associated with epidermoid cysts specifically. Complete surgical excision is first-line treatment, with care not to spill cyst contents. In comparison with Dermoids, Epidermoids are usually located laterally and Dermoids are more located medially.

Pituitary Adenoma

Pituitary adenomas are extremely common skull base lesions, constituting 10-15% of all intracranial neoplasms7. Whereas non-secretory pituitary adenomas are often clinically silent, secretory adenomas can cause various clinical symptoms related to the hormone produced7. Prolactin and growth hormone secretion are most frequently experienced, comprising 35% and 20% of all pituitary adenomas, respectively, but adrenocorticotropic hormone and thyroid-stimulating hormone production occur in some1,2. Medical management is possible, for instance dopamine agonists such as cabergoline and bromocriptine can be used to suppress prolactin secretion. Cabergoline is more effective than bromocriptine hormonally but is known to be associated with valvular heart disease and lung fibrosis. Should any sellar mass enlarge to a great extent, compression of the pituitary gland can produce hypopituitarism, while compression of the optic chiasm commonly results in visual disturbance. Compressive or hormone-related symptoms typically prompt surgical resection. Transsphenoidal surgery is the treatment of choice, with cure rates of approximately 85% for microadenomas, defined as being ≤ 1 cm in diameter, but lower for macroadenomas. Injury to the carotid artery is a serious intraoperative complication. Therefore, pituitary tumors with significant extension to the cavernous sinus and lateral to the internal carotid artery, or those with significant extension above the optic chiasm are proposed to undergo craniotomy alone or craniotomy in combination with endoscopic traanssphenoidal approach to minimize risk of injury to internal carotid artery and optic chiasm. Perioperative complications include hormonal disruption due to injury to the pituitary, especially diabetes insipidus secondary to alterations in antidiuretic hormone (ADH) secretion from the posterior pituitary3. This is typically transient. Recurrence of pituitary adenomas is about 12% within 4-8 years following surgery.

References

  1. Alvero R: Pituitary Adenoma, in F.F. Ferri, Editor (2017). Ferri’s Clinical Advisor 2017, Philidelphia: Elsevier, Inc.
  2. Mortazavi MM, Suriya SS, Quadri SA, Khan MA, Hassanzadeh T, Adeeb N, Fard SA, Rezaee O, Tubbs RS. Current Concepts for Surgical Resection of Pituitary Adenoma: A Systematic Review with Meta-analysis. 85th AANS Annual Scientific Meeting, 22-26 April 2017.
  3. Sekhar L, Mantovani A, Mortazavi M, Schwartz TH, Couldwell WT. (2014). Open vs endoscopic: when to use which. Neurosurgery. 61(Suppl 1): 84-92.
Craniopharyngioma

These are tumors that develop from residuals of Rathke’s pouch in the sella tursica. Rathke’s pouch is an embryological derivative of the oropharynx that develops into the anterior pituitary gland, or adenohypophysis. Craniopharyngiomas make up 2.5-4% of all brain neoplasms. Approximately 50% occur in early childhood, most commonly between ages 5-10 years. They are commonly located in the anterior superior margin of the pituitary, although some may arise within the third ventricle. These lesions generally have both solid and cystic components, including cholesterol crystals and calcifications. Large tumors can cause hormonal dysfunction due to compression of the pituitary gland. First-line treatment is surgical removal. Recurrence most often occurs if excision is not complete, typically arising less than 1 year following surgery. Mortality can occur from hypothalamic injury and hormonal dysregulation, but 5-year survival is about 55-85%. Radiation therapy for craniopharyngiomas is controversial with side effects of endocrine dysfuntion, optic neuritis, and dementia and should be avoided in pediatric patients. Most important aspect of surgical removal of these tumors lies in being very careful not injuring its posterior margin that not unusually is attached to the hypothalamus. Hypothalamus injury risks to affects patients water regulation and eating habits throughout their life. It is recommended to leave some tumor residual attached to the hypothalamus and bears a good neurological outcome rather than perform a gross total resection but have a patient with disturbed satiety center function who will be in a state of constant uncontrollable eating.

Hypothalamic Hamartoma

A hamartoma is a malformation of cells found within the local region that resembles a tumor, but is not a true neoplasm. Hypothalamic hamartomas therefore rare, non-neoplastic congenital malformations originating from the inferior hypothalamus or tuber cinereum. The tuber cinereum is gray matter situated between the mammillary bodies and optic chiasm and a part of the hypothalamus. Hypothalamic hamartomas may occur in association with Pallister-Hall syndrome, which is caused by a defect in the GL13 gene. Seizures are the most common symptomatic presentation, especially gelastic seizures, which involve brief fits of unprovoked laughter. These seizures may degenerate into epileptic encephalopathy including complex partial seizures, drop attacks, and tonic-clonic seizures. Precocious puberty is another presentation due to release of gonadotropin-releasing hormone (GnRH) from hamartoma cells. These are the most common CNS lesion to cause precocious puberty. Developmental delay and behavioral disturbances are also possible.

The pathology of hypothalamic hamartomas may be pedunculated (parahypothalamic) or sessile (intrathalamic). Pedunculated hamartomas have a more narrow base attached to the floor of the hypothalamus without distortion of the third ventricle. Sessile hamartomas have a broad attachment to the hypothalamus and arise from within the hypothalamus, distorting the third ventricle. Therefore, precocious puberty is more commonly associated with pedunculated hamartomas and seizures with sessile hamartomas.

Precocious puberty can be managed medically with GnRH analogs, which suppress GnRH release. Anti-epileptics may be used to manage seizures. Indications for surgery are inadequate medical management or neurological deficit due to mass effect of the lesion. Risks of surgery include cranial neuropathy and stroke for pedunculated hamartoma resection and memory impairment, endocrine disruption, and weight gain for sessile hamartoma removal. Same principles of surgery as for craniopharyngiomas apply to this. Please see above. During surgical resection, it is important, not to injure the hypothalamus.

Choroid Plexus Papilloma

Choroid plexus papillomas are benign, WHO grade I, tumors of the choroid plexus, which produces the cerebrospinal fluid (CSF) that surrounds the CNS. These are the most common type of choroid plexus tumor. Transformation to malignancy is rare. Choroid plexus tumors comprise 0.4-1% of all intracranial neoplasms. Seventy percent of those affected are less than 2 years of age. They are typically found supratentorially in children and infratentorially in adults (unlike most other tumors). The most common presenting symptoms are related to increased intracranial pressure from hydrocephalus including headache, nausea/vomiting, and craniomegaly (head enlargement). Hydrocephalus may arise either from overproduction of CSF or blockage of CSF outflow.

Surgical resection is the best treatment option. Bleeding from choroidal arteries is the most common complication and may necessitate shunt placement. Recurrence is relatively rare. (See figure)


Figure : Choroid Plexus Papiloma. A. Sagittal T1-weighted MRI with contrast B. Axial T1- weighted MRI with contrast. C. Sagittal T2-FLAIR D.Axial T2- FLAIR MRI.

Vestibular Schwannoma (Acoustic Neuroma)

Vestibular schwannomas, also previously known as acoustic neuromas, are common, histologically benign tumors of the vestibulocochlear nerve (cranial nerve VIII) found in the cerebellopontine angle (CPA). Their name comes from their more common location arising from the inferior division of the vestibular nerve of cranial nerve VIII. They comprise 8-10% of all intracranial tumors with an annual incidence around 1.5 cases per 100,000 population. Symptoms arise generally after 30 years of age. Early symptoms include hearing loss (usually high frequency), tinnitus (high-pitched), and dysequilibrium. Hearing loss is insidious and progressive. Only 10% of patients experience sudden hearing loss. Larger tumors may cause facial numbness or weakness, headache, and focal brainstem signs including weakness. Workup for all patients involves brain MRI with and without contrast and audiometrics. Most vestibular schwannomas are unilateral. Bilateral vestibular schwannomas are characteristic of neurofibromatosis type 2 (NF2, discussed under neurosurgical syndromes).

Management options include expectant management for small non-progressive asymptomatic tumors, radiation therapy, surgery, and chemotherapy. About 83% of vestibular schwannomas show little or no growth and may be conservatively managed in the absence of symptoms and small in size. Large tumors (> 25 mm diameter) should be treated with microsurgical resection in order to minimize mass effect and decompress the brainstem. Patients with contraindications to surgery such as the elderly or those with co-morbidities may undergo stereotactic radiosurgery (SRS) instead. Treatment approach for symptomatic, small (

Radiosurgery and SRS better preserve hearing than microsurgery, especially for larger-sized tumors and in patients with greater preoperative hearing loss. However, direct cochlear nerve monitoring intraoperatively has improved preservation of hearing following microsurgery. In contrast, trigeminal neuropathy has a greater incidence with SRS, particularly for large tumors with high doses of radiation. This is not a common complication of microsurgery. Although the goal of surgery is total tumor resection, this may not be possible due to the proximity of the facial nerve. However, near total or subtotal resection both have excellent long-term tumor control with only observation or postoperative radiation. Facial nerve’s course, from its emergence form the brainstem, through its course within the temporal bone of the skull base and over the face has been classified by multiple authors. Surgery can be achieved through a Retrosigmoid craniectomy for all the tumors that do not have extension beyond the fundus segment of the facial nerve’s course within the temporal bone of the skull base1,2. If the tumor extension is lateral to the fundus, a middle fossa approach can be utilized.

Postoperative complications include facial nerve damage, with inability to close the eyes; vestibular nerve damage, a common complication with nausea, vomiting, and potential long-term ataxia; lower cranial nerve deficits, with problems swallowing and risk of aspiration; and brainstem dysfunction, with ataxia and contralateral paresthesia. CSF fistula, rhinorrhea, meningitis, and stroke are also possible complications. CSF rhinorrhea is the most common surgical complication, occurring in 4-27% of cases. This may resolve on its own (25-35%) or require surgical re-exploration and shunt placement. Hearing loss has been found to be worse with retrosigmoid than middle fossa craniotomy, even when controlling for tumor size3. Preservation of functional hearing after gamma knife radiosurgery is high with 49% of patients in one clinical trial retaining functional hearing at 10-year follow-up4.

References

  1. Mortazavi MM, Adeeb N, Latif B, Watanabe K, Deep A, Griessenauer CJ, Tubbs RS, Fukushima T. Gabriele Fallopio (1523-1562) and his contributions to the development of medicine and anatomy. Childs Nerv Syst. 2013 Jun;29(6):877-80. doi: 10.1007/s00381-012-1921-7. PMID: 22965774
  2. Tubbs RS, Fries FN, Kulwin C, Mortazavi MM, Loukas M, Cohen-Gadol AA. (2016). Modified skin incision for avoiding the lesser occipital nerve and occipital artery during retrosigmoid craniotomy: potential applications for enhancing operative working distance and angles while minimizing the risk of postoperative neuralgias and intraoperative hemorrhage. Journal of Clinical Neurosurgery. 32:83-87.
  3. Wilkinson EP, Roberts DS, Cassis A, Sochwartz MS. (2016). Hearing outcomes after middle fossa or retrosigmoid craniotomy for vestibular schwannoma tumors. J Neurol Surg B Skull Base. 77(4): 333-340.
  4. Boari N, Bailo M, Gagliardi F, Franzin A, Gemma A, del Vecchio A, Bolognesi A, Picozzi P, Motini P. (2014). Gamma Knife radiosurgery for vestibular schwannoma: clinical results at long-term follow-up in a series of 379 patients. Journal of Neurosurgery. 121 Suppl: 123-142.
Trigeminal Schwannoma

These are uncommon, benign tumors also comprised of schwann cells, like vestibular schwannomas. However, they surround the trigeminal nerve (cranial nerve V). They make up 0.2% of all intracranial neoplasms. Peak incidence is between the 3rd and 4th decades of life. Symptoms are related to trigeminal nerve dysfunction, including facial pain, numbness, or weakness. Surgical resection is usually curative with preservation of trigeminal nerve function and thus first-line treatment1. (See figure)


Figure : Trigeminal Schwannoma. A. Axial T1-weighted MRI. B. Axial T1-wieghted with contrast. C. Sagittal T1-wieghted MRI with contrast.

References

  1. Ramina R, Mattei TA, Soria MG, da Silva EB, Leal AG, Neto MC, Fernandes YB. (2008). Surgical management of trigeminal schwannomas. Neurosurgical Focus. 25(6): E6.
Glomus Tumor

Glomus tumors, also known as paragangliomas, are rare neuroendocrine neoplasms arising from paraganglion cells of the neural crest. Ninety-seven percent are histologically benign with most showing slow growth. Most are located in the abdomen (97%), with only 3% located intracranially. Some may secrete catecholamines, which can cause life-threatening hypertension and/or cardiac arrhythmias. Up to 50% are inherited, with the rest being sporadic. Most of them are sensitive to radiation as the main treatment or in order to shrink the tumor for resection of a smaller residual. Some glomus tumors can be observed or managed medically with alpha- and beta-blockers as needed for hormone secretion. For those that require resection, surgery has usually been first-line but the advent of radiosurgery has provided an alternative. Studies have shown good tumor control with low risk of cranial nerve injuries following gamma knife radiosurgery1-3.

References

  1. Chen PG, Nguyen JH, Payne SC, Sheehan JP, Hashisaki GT. (2010). Treatment of glomus jugulare tumors with gamma knife radio surgery. Laryngoscope. 120: 1856-1862.
  2. Jacob JT, Pollock BE, Carlson ML, Driscoll CL, Link MJ. (2015). Stereotactic radiosurgery in the management of vestibular schwannoma and glomus jugulare: indications, techniques, and results. Otolaryngol Clin North Am. 48(3): 515-526.
  3. Sanna M, Piazza P, Ho Shin S, Flanagan S, Mancini F.(2013) Microsurgery of Skull Base Paragngliomas. New York, NY: Thieme Publishers.

Neurosurgical Syndromes

Neurofibromatosis, type 1 & 2

Neurofibromatosis is the most common neurocutaneous disorder. The two most common types are neurofibromatosis 1 (NF1, also known as Von Recklinghausen’s Disease) and neurofibromatosis 2 (NF2). The incidence of NF1 is 1/3000 births versus 1 in 40,000 for NF2, making NF1 much more common. NF1 is associated with an abnormality of chromosome 17, while NF2 is associated with a defect of chromosome 22. Up to 50% of cases of NF1 and NF2 may be inherited in an autosomal dominant fashion.

Diagnostic criteria for NF1 are two or more of the following: ≥6 café au lait spots, ≥2 neurofibromas of any type or 1 plexiform neurofibroma, optic glioma, ≥2 Lisch nodules (pigmented iris hamartomas), distinctive osseous abnormality such as sphenoid dysplasia or thinning of long bone cortex, and a first degree relative with NF1 by this criteria. Schwannomas are associated with NF1, but bilateral vestibular schwannomas are only seen in NF2. Pheochromocytomas and intellectual impairment may also be seen in NF1. Management of optic gliomas in NF1 is usually conservative, as most rarely involve the nerve and are non-progressive. Intracranial tumors should be managed using the same criteria as in the general population.

Definitive diagnostic criteria for NF2 are as follows: bilateral vestibular schwannomas on imaging or a first degree relative with NF2 and either a unilateral vestibular schwannoma at age nd to 3rd decades of life with rapid hearing loss and multiple associated tumors. The second form is milder, presenting later in life with slower loss of hearing and fewer associated tumors. Bilateral vestibular schwannomas are best excised surgically when small in order to maximize hearing preservation. If removal of 1 tumor restores hearing, the second tumor may be observed or removed surgically as well. A subtotal resection may be undergone to avoid total deafness. Stereotactic radiosurgery is another option. Most patients will become eventually become deaf.

Hereditary Hemorrhagic Teliangiectasia (HHT, aka Osler Weber Randu)

Hereditary hemorrhagic telangiectasia (HHT, also known as Osler-Weber-Rendu syndrome) is a genetic vascular disease inherited in an autosomal dominant fashion. Capillaries become slightly enlarged with low flow. About 1 in 5,000 people are affected. Cerebrovascular malformations include telangiectasias, arteriovenous malformations (AVM, discussed separately), and venous angiomas and aneurysms. A common presenting symptom is recurrent epistaxis. Surgery is only necessary for evacuation of a hematoma or diagnosis. It also may be considered for recurrent hemorrhages or medically intractable seizures.

Foster Kennedy syndrome

This is a syndrome typically produced by olfactory groove or medial third sphenoid wing tumors, such as meningiomas. The classic triad of symptoms is ipsilateral anosmia, ipsilateral central scotoma, and contralateral papilledema. Central scotoma occurs due to optic atrophy from tumor compression of the optic nerve. Papilledema results from increased intracranial venous pressure.

Tuberous sclerosis

Tuberous sclerosis has a prevalence of 1 in 6,000-10,000 live births. The clinical triad of symptomatic presentation is seizures, mental retardation, and sebaceous adenomas. Subependymal nodules (“tubers”), a type of hamartoma, are a common intracranial finding. Hamartomas occur throughout the entire body. Subependymal giant cell astrocytomas are also seen. There are two tumor suppressor genes that are commonly mutated, TSC1 on chromosome 9 (encoding hamartin), and TSC2 on chromosome 16 (encoding tuberlin).

Von Hippel-Lindau Disease (VHL)

This is a familial disorder presenting with hemangioblastomas of the cerebellum, retina, brainstem, and spinal cord. Pheochromocytomas and renal cysts and tumors are also commonly seen. The main genetic mutation is inactivation of a tumor suppressor gene on chromosome 3, and it is inherited in an autosomal dominant fashion. It occurs in 1 in 31,000-36,000 live births. Thirty percent of patients with cerebellar hemangioblastomas have VHL. The age of presentation is variable.

Wyburn-Mason syndrome:

Wyburn-Mason syndrome is considered one of the nonhereditary congenital neurocutaneous disorder and is characterized by arteriovenous malformations (AVMs) of eyes and brain, typically involving the retina, visual pathways, midbrain, and facial structures. In contrast to other neurocutaneous disorders, Wyburn-Mason syndrome does not commonly cause cutaneous manifestations. Common presenting symptoms includes seizure, mental changes, hemiparesis, and papilledema, which are frequently a source of hemorrhage, unlike the hemangioma of SWS.

Acute Ischemic Stroke

Intra-arterial treatment for Acute Ischemic Stroke (AIS)

Ischemic Stroke is the most common type and accounts for 87% of all strokes. [1] It occurs due to blockage of blood vessel usually by a blood clot or by fatty deposits. In treatment of Acute Ischemic Stroke (AIS), the primary goal is to quickly restore blood flow by dissolving the clot through clot bursting medication or by physically removing the clot through intra-arterial treatment. The clot bursting medication such as intravenous tissue plasminogen activator (t-PA) can be given up to 4.5 hours of symptom onset. Some patients may not be eligible to receive t-PA due to illness, blood disorders, recent surgery or concurrent use of other medication which can interfere in the effects of t-PA. Due to narrow treatment window of t-PA and its effectiveness in small percentage of patients who have large vessel occlusion, the optimal treatment of AIS is Intra-arterial treatment which is a technique of navigating catheters into the brain blood vessels and either dissolve the clot by giving local intra-arterial t-PA, or by physically removing the clot which is called Mechanical Thrombectomy. (see figure):

Thrombectomy can be done by using aspiration devices or by using Retrievers with maximum effectiveness when it is performed within 6 hours of onset of stroke symptoms. (see figure) In some studies, mechanical thrombectomy has shown good clinical outcome if it is done within 8 hours of stroke onset. [2] The effectiveness of mechanical thrombectomy beyond 8 hours of stroke onset is unknown.

The treatment of Ischemic Stroke is dependent and the primary goal of mechanical thrombectomy is to restore blood flow by removing the blockage from affected brain blood vessel.


Figure : Mechanical thrombectomy of acute ischemic stroke due to blood clot (Image courtesy of Stryker Neurovascular)


Figure :Acute Ischemia Treatment progression by mechanical thrombectomy using retriever (Image courtesy of Stryker Neurovascular)


Figure : Left ICA, MCA and ACA clot on cerebral angiogram (A) Before mechnical thrombectomy (B) After mechnical thrombectomy


Figure : Blood clot removed by stent retriever

References

  1. American Heart Association. Heart Disease and Stroke 2017 Statistics At-a-glance.
  2. Wahlgren, N., Macho, J. Killer M., Liebeskind D., Jansen O. Final Results from the Trevo Study (Thrombectomy Revascularization of large Vessel Occlusions in acute ischemic stroke). International Stroke Conference, 2012.

Arteriovenous Fistula

Brain and spine Arteriovenous Fistulas (AVF) embolization

Arteriovenous Fistula (AVF) is an abnormal connection between an artery and a vein. The normal blood circulation involves flow of blood from artery to capillaries to a vein. With an AV fistula, capillaries are bypassed making a direct flow between an artery and a vein which ultimately reduces the blood supply to the tissues otherwise supplied by the normal capillaries. AV fistula is an acquired lesion which means someone is not born with it but acquired later in life due to infection, traumatic injury, tumor, surgery or in some cases without any precipitating event. Please read more in the Dural Arteriovenous Malformation (DAVF) chapter.

AV fistula can be treated by endovascular embolization, open surgery or by combination of both methods. Endovascular embolization is a minimally invasive procedure in which endovascular surgeon makes a small incision in groin area. The surgeon then passes the navigating tube through the femoral artery and advances up into the artery which is forming AV fistula. Through this navigating tube, the surgeon then injects an embolizing agent such as glue like substance (usually onyx), micro coil or a metallic stent to physically block the blood supply of AV fistula. In some cases, open surgery (Craniotomy or Laminectomy) is required after endovascular treatment to physically remove the AV fistula.

Please see section of neurosurgical procedures for more information on open surgical treatment of brain and spine AV fistula.

Arteriovenous Malformation

Brain and spinal Arteriovenous malformation (AVM) embolization

An Arteriovenous Malformation or AVM is an abnormal tangle of blood vessel connecting an artery to a vein. An AVM can develop anywhere in the body but occurs most often in the brain or spine. The causes of AVM are unknown but most brain AVMs are congenital which means someone is born with one. The feeding artery of an AVM directs blood away from the normal brain tissue causing symptoms which may include headache, seizures, weakness or numbness, difficulty speaking, confusion, vision loss. In extreme cases, the blood vessel forming AVM, may burst from the high pressure of blood flow which can cause bleeding in the brain, a condition called hemorrhagic stroke. Please read more in the AVM chapter.

The treatment options for AVM aim to reduce the blood flow to the feeding artery of AVM thus reducing the risk of bleeding from AVM. The treatment options include surgical removal or endovascular embolization of AVM. The endovascular embolization of AVM is a minimally invasive procedure in which endovascular surgeon or neuro-interventionalist makes a small incision in the groin and passes a navigating tube from the femoral artery. The tube is then advanced up in one of the artery forming AVM and an embolizing agent such as glue like substance or micro coils are injected to block the blood supply to AVM. (see figure): In some cases, AVM embolization is done before its removal by open surgery to reduce its size or the likelihood of bleeding. (see figure):

Please see section of neurosurgical procedures for information on open surgical treatment of brain and spine AVM.


Figure : Cerebral angiogram showing AVM embolization (A) Before embolization (B) Complete obliteration of AVM after embolization


Figure : Surgically resected AVM

Carotid Artery Stenosis

Carotid Artery Stenting and Angioplasty

Carotid arteries are the major blood vessel, one on each side of neck that supply the blood to the brain. These carotid arteries can be narrowed (stenosis) due to buildup of plaque inside their lumen, reducing the blood supply of brain and increasing the future likelihood of stroke. Plaque develops due to deposition of cholesterol, fat, and other substances, a condition called Atherosclerosis. The risk factors that can contribute in atherosclerosis or plaque development in carotid arteries include family history of atherosclerosis, age, hyperlipidemia (high levels of cholesterol), hypertension (high blood pressure), diabetes, smoking, obesity, and sedentary life style.

Carotid artery stenosis, in some cases, can be present without any symptoms. If narrowing of carotid arteries is serious enough to block the blood supply to the brain, it can show signs and symptoms of mini-stroke which is also called Transient Ischemic Attack (TIA). The signs and symptoms of TIA may include

  • sudden loss or blurring of vision
  • sudden weakness or numbness of one side of face or other part of body
  • difficulty in speaking or slurred speech
  • confusion
  • dizziness or difficulty in maintain balance
  • severe headache
  • difficulty swallowing

A TIA is a medical emergency and immediate treatment is needed because it may progress to a major stroke. In a recent study, it was shown that the risk of development of an ischemic stroke is 8% at one year after TIA. [1]

The treatment of carotid artery stenosis include lifestyle changes, medical management, Carotid endarterectomy (CEA), Carotid artery stenting (CAS) and carotid artery angioplasty. The choice of treatment option recommended by your physician depends on the percentage of narrowing of your carotid artery and the severity of your symptoms.

CAS and angioplasty is a minimally invasive procedure and performed endovascularly in an Angio Lab. In angioplasty and stenting, your endovascular surgeon will make a small incision in your groin and pass navigating catheter through femoral artery up to carotid artery. The surgeon will then introduce a balloon at the site of narrowing and inflate it. This technique will open up the narrowing and restore the blood flow. This can be combined with the placement of a metallic stent to keep the vessel open and to reinforce its walls. The balloon is then deflated and removed from the body, leaving the stent inside the carotid artery. (see figure): Over time, cells lining the carotid artery will go around the stent to hold it in place. Before the stent placement procedure, you will be pre-treated with aspirin and clopidogrel which will be continued for 6 months after the procedure. Beyond 6 months of dual antiplatelet therapy, you will on aspirin indefinitely.

Please see neurosurgical procedures for information on carotid endarterectomy.


Figure : Carotid artery stenosis treatment by Stenting (Image courtesy of Stryker Neurovascular)


Figure : Carotid artery stenosis treatment progression by stenting and angioplasty (Image courtesy of Stryker Neurovascular)


Figure : Carotid artery stenting (CAS) (A) before placement of stent (B) after placement of stent

References

  1. Uehara T, Minematsu K, Ohara T, Kimura K, Okada Y, Hasegawa Y, Tanahashi N, Suzuki A, Takagi S, Nakagawara J, Arii K, Nagahiro S, Ogasawara K, Uchiyama S, Matsumoto M, Iihara K, Toyoda K; PROMISE-TIA study Investigators.. Incidence, predictors, and etiology of subsequent ischemic stroke within one year after transient ischemic attack. Int J Stroke. 2017 Jan;12(1):84-89.

Diagnostic Angiogram

Diagnostic cerebral and spinal angiogram

Diagnostic cerebral and spinal angiogram is a minimally invasive diagnostic test which is used to acquire high resolution images of blood vessels of brain and spinal cord. It serves as a definitive diagnostic test to detect or confirm many abnormalities of blood vessels of brain and spinal cord which include:

  • narrowing or blockage of blood vessels
  • carotid stenosis
  • brain aneurysms
  • brain and spinal arteriovenous malformation (AVM)
  • brain and spinal arteriovenous fistula (AVF)
  • brain tumor

In some instances, diagnostic angiogram is performed before open surgery of head, neck, and spine to evaluate arteries of head and neck and to provide additional information on abnormalities seen on MRI or CT scan.

Diagnostic angiogram is commonly performed under conscious sedation which means patient will be awake but very sleepy due to the effects of sedative medications. After administering local anesthesia, the physician will make a small incision in the groin area to gain the access of femoral artery. Subsequently he or she will place a navigating catheter in the femoral artery and advance up to blood vessels of brain and spinal cord. Contrast dye is injected into those blood vessels though another small tube and then a series of x-ray images are taken from different angles to evaluate the blood vessels of head and neck. The procedure is performed under Digital Subtraction Radiography (DSA) which means the bone is subtracted from the images to see the blood vessels. After the angiogram is completed, all tubes are removed and incision site is closed.

Diagnostic angiogram is the foundation of all neuro-interventional procedures and provides a therapeutic tool for many vascular disorder of brain and spinal cord.


Figure : Diagnostic Cerebral Angiogram (A) Anteroposterior view (B) Lateral view

Epistaxis Embolization

Epistaxis (or Nosebleed) is defined as bleeding from the nose which occurs due to burst of a blood vessel within the nose. The nasal cavity has a rich blood supply from both internal and external carotid arteries. More than 90% of nosebleeds occur from the anterior part of the nose in an area known as little’s area which is extremely vascular. The causes of nosebleed include local causes (trauma, inflammation, nasal irritation or tumor), systemic causes (such as any blood disorder) or idiopathic (unknown cause).

Some severe cases of epistaxis with persistent life-threatening nosebleeds may require a procedure called embolization. It is done by endovascular surgeon who makes a small incision in your groin and places navigating catheter into femoral artery which is then advanced up to vessels of face and nose. The surgeon then embolizes the branch supplying the nasal cavity with materials such as gelatin sponge, Gelfoam Powder, polyvinyl alcohol (PVA) particles or platinum coils.

Alternatively, epistaxis can be treated by open surgical ligation of clipping of bleeding artery in the nasal cavity.

Flow Diversion for Aneurysm

Flow diverting stent placement for brain aneurysm

Brain aneurysm, based on the location and size, can also be treated endovascularly by a device called Flow diverter. It is a stent like device which can be placed in the parent vessel across the neck of aneurysm to divert the blood flow away from the aneurysm.

The flow diversion procedure is done to treat unruptured brain aneurysm and it removes the need to enter the cavity of aneurysm which always carries the risk of rupture and subsequent bleeding. Like coil embolization, flow diversion is a minimally invasive procedure performed by endovascular surgeon who will navigate a small tube like catheter through an artery in the groin. The surgeon will advance the catheter up to the vessel of brain from aneurysm is coming off and deploy the flow diverting device in the parent vessel across the neck of aneurysm.(see figure): With this technique, the flow to the aneurysm will be greatly diminished which will allow closure of aneurysmal sac.


Figure : Flow-Diverting Stent Aneurysm Treatment (Image courtesy of Stryker Neurovascular)


Figure : Cerebral angiogram showing deployment of flow diverting stent

Intracranial Aneurysm

Brain aneurysm coil embolization

An aneurysm is an outpouching or ballooning of a weakened part of a blood vessel. Aneurysms can occur in any part of the body where there is a weak vessel. Brain aneurysms also called Intracranial Aneurysms are the most life threatening as they pose greater risk of rupture if left untreated and bleeding into the brain causing hemorrhagic stroke. Please read more in the Intracranial Aneurysm chapter. In 5 year follow up, the overall risk of rupture of untreated aneurysm is 1.2%. [1]

Based on age, risk factors, size and location of aneurysm and your overall general health, your physician can discuss various treatment options, one of which is coil embolization. Coil Embolization is a minimally invasive procedure in which endovascular surgeon places a navigating small tube through a blood vessel in your groin and advance it up to the vessel of brain from which aneurysm is originating. Through this tube, the surgeon will place tiny soft metal coils within the cavity of aneurysm. These metal coils occupy the space and stay within the aneurysm thus prevent the blood flow from entering the aneurysm. (see figure): The rationale behind this approach is to seclude the aneurysm from general blood circulation which can reduce the risk of rupture and bleeding in to the brain. In order to keep the coils inside the aneurysm, your endovascular surgeon may elect to deploy additional devices in the parent vessel from which aneurysm is coming off. These devices include a balloon (Balloon-assisted coil embolization) or a metal stent (Stent-assisted coil embolization). Balloon-assisted coil embolization involves temporary placing of a removable balloon in order to do further packing of coils inside the cavity of aneurysm. (see figure): In cases of aneurysms with wide neck, stent-assisted coil embolization can be better option which involves permanent placement of a metal stent across the neck of aneurysm which can prevent the coils from coming back into the parent vessel and also provides high packing density inside the aneurysm. (see figure): In a study of treatment of wide neck aneurysms, stent assisted coil embolization provided higher rate of aneurysm occlusion and lower rate of re-treatment at follow up than balloon assisted coil embolization. [2] In stent assisted coil embolization, you will be pre-treated with aspirin and clopidogrel which will be continued for 6 months after the procedure. Beyond 6 months of dual antiplatelet therapy, you will on aspirin indefinitely.

Please see section of neurosurgical procedures for information on surgical clipping of brain aneurysm.


Figure : Coil embolization of brain aneurysm (Image courtesy of Stryker Neurovascular)


Figure : Aneurysm coiling treatment progression. (Image courtesy of Stryker Neurovascular)


Figure : Balloon-assisted coil embolization of brain aneurysm (Image courtesy of Stryker Neurovascular)


Figure : Stent-assisted coil embolization of brain aneurysm (Image courtesy of Stryker Neurovascular)


Figure :Giant anterior communicating artery (Acomm) aneurysm coil embolization (A) before coiling (B) after Coiling

References

  1. Wermer MJ, van der Schaaf IC, Algra A, Rinkel GJ. Risk of rupture of unruptured intracranial aneurysms in relation to patient and aneurysm characteristics: an updated meta-analysis. Stroke. 2007 Apr;38(4):1404-10.
  2. Chalouhi, N., et al., Stent-assisted coiling versus balloon remodeling of wide-neck aneurysms: comparison of angiographic outcomes. AJNR Am J Neuroradiol, 2013. 34(10): p. 1987-92.

Tumor Embolization

Head, Neck and Spine Tumor Embolization

Tumor embolization is an important adjunctive therapy for head, neck and spine tumor management. Tumor embolization is done by endovascular technique which is minimally invasive and it blocks the blood supply to the tumor. In most instances, it is reserved for highly vascularized tumors and it is performed as a preparation for later surgical resection of the tumor. With tumor embolization, the aim is to reduce the blood supply to the tumor which can help reduce the blood loss in actual surgical resection of the tumor. The hyper vascular tumors of head, neck and spine for which embolization may be needed include hemangioblastomas, hemangiomas, meningiomas, juvenile nasopharyngeal angiofibromas, paragangliomas, and intracranial metastatic tumors.

Embolization is performed by endovascular surgeon by performing a small incision in your groin. The surgeon then advances a navigating catheter through the femoral artery up to the artery supplying the tumor. The surgeon then introduces embolization materiel (such as ploy vinyl alcohol, Gelfoam or micro coil) into the tumor supplying artery.

Please see neurosurgical procedures on more information on head, neck, and spine tumor removal surgery.

Venous Sinus Stenting

Venous sinus stent placement for Idiopathic intracranial hypertension (pseudotumor cerebri)

Idiopathic Intracranial Hypertension (IIH) which is also called Pseudotumor cerebri is an uncommon condition, associated with increases intracranial pressure. It mostly affects young obese females. The most common symptoms include headache, visual disturbance and tinnitus (ringing sound in the ear). In about one third of cases, IIH is caused by stenosis (obstruction) of outflow from dural venous sinus. [1] In some studies, stenosis of dural venous sinus has been demonstrated in up to 93% of patients with IIH. [1, 2, & 3]

The treatment of IIH includes medical management and surgical treatment. Medical treatment consists of medications to reduce intracranial pressure by decreasing production of cerebrospinal fluid (CSF) and symptomatic treatment of headache. Surgical treatment of IIH include diversion of CSF by ventriculoperitoneal or lumboperitoneal shunt (VPS or LPS).

Given the fact that the stenosis of dural venous sinus is a causative factor in many cases of IIH, endovascular stenting of dural venous sinus is a therapeutic option for cases of IIH which are resistant to medical treatment. Prior to stent placement in venous sinus, your endovascular surgeon will do a diagnostic angiography and venous pressure measurement. The surgeon will make a small incision in your groin and pass navigating catheters through femoral artery, up in to blood vessels and sinus in your brain. If your surgeon notices significant stenosis of venous sinus, he or she may place a stent in the narrowed part of venous sinus to restore its outflow and to relive the high intracranial pressure. Before the stent placement, you will be pre-treated with aspirin and clopidogrel which will be continued for 6 months after the procedure. Beyond 6 months of dual antiplatelet therapy, you will on aspirin indefinitely.

Please see section of neurosurgical procedures for more information on surgical treatment by shunt placement.

References

  1. Johnston I, Kollar C, Dunkley S, Assaad N, Parker G. Cranial venous outflow obstruction in the pseudotumour syndrome: incidence, nature and relevance. J Clin Neurosci. 2002 May;9(3):273-8.
  2. Farb RI, Vanek I, Scott JN, Mikulis DJ, Willinsky RA, Tomlinson G, et al.: Idiopathic intracranial hypertension: the prevalence and morphology of sinovenous stenosis. Neurology 60:1418–1424, 2003
  3. Higgins JN, Gillard JH, Owler BK, Harkness K, Pickard JD: MR venography in idiopathic intracranial hypertension: unappreciated and misunderstood. J Neurol Neurosurg Psychiatry 75:621–625, 2004

Neurology

Neurological Disorders

Neurological disorders are disorders that affect the central nervous system (brain, brainstem and cerebellum), the peripheral nervous system (peripheral nerves – cranial nerves included), or the autonomic nervous system (parts of which are located in both central and peripheral nervous system).

Neurologists also diagnose and treat some conditions in the musculoskeletal system.

Epilepsy

Epilepsy is a neurological disorder which is characterized by abnormal activity of brain, which causes recurrent and unprovoked episodes of seizure, unusual behavior, altered sensations and sometimes loss of consciousness. These seizures can vary from brief episodes of a few seconds, to long periods of vigorous shaking which can result in physical injuries.

In approximately 6 out of 10 cases, there is no identifiable cause and therefore, it is called idiopathic epilepsy. Seizure with identifiable cause is called secondary epilepsy. The common causes of secondary epilepsy include brain damage after a trauma, stroke, brain tumor, brain infections, and metabolic disorders such as severe variations in blood sodium. Epilepsy can have genetic predisposition. Typically, epilepsy is diagnosed after occurrence of two unprovoked seizures. However, in the setting of an underlying known kncause, some clinicians diagnose it after one unprovoked seizure.

The epileptic seizures are classified into following two major classes:
1) Focal Seizures
2) Generalized Seizures

Focal (Partial) seizures

These result from abnormal activity in one part of the brain. They occur with loss of consciousness. If they start as focal seizure and develope loss of consciousness, the yare called focal (partial) seizures with generalization.

Generalized seizures

They always involve loss of consciousness and are further subdivided into following six types:
i) Tonic-clonic seizure
ii) Tonic seizure
iii) Clonic seizure
iv) Myoclonic seizure
v) Absence seizure
vi) Atonic seizure

The important part of management of epilepsy is finding the underlying cause by performing blood tests, brain imaging preferably MRI and electroencephalogram (EEG). Lumbar puncture for CSF examination can be part of workup if an infectious cause is suspected. In young patients, no cause might be found. New onset in an adult needs to include work-up to rule out mass and tumor as cause of a seizure.

The treatment of epilepsy primarily includes administration of anti-convulsant medication and is managed by general neurologists or epileptologists. The choice of anti-convulsant drug should be considered based on the type of seizure and adverse effects profile. The goal of anti-convulsive medication is to achieve a seizure-free status without major adverse effect. In approximately 60% of patients, this goal can be achieved by anti-convulsant therapy. After 2 to 5 years of successful treatment and being seizure-free, in about 70% of children and 60% of adults, drugs can be withdrawn without any recurrence of seizure. In drug resistant cases, epilepsy surgery can be an option as a last resort. Lobectomy and lesionectomy are two major kinds of surgery which are palliative and potentially curative. Newer techniques include vagal nerve stimulation (VNS) by surgical implantation of a stimulating device and NeuroPace RNS system implantation. These neuro stimulation techniques are approved by FDA for drug-resistant cases of epilepsy.

References

  1. Fisher RS, van Emde Boas W, Blume W, et al. Epileptic seizures and epilepsy: definitions proposed by the International League Against Epilepsy (ILAE) and the International Bureau for Epilepsy (IBE). Epilepsia. 2005 Apr. 46(4):470-2.
  2. “Epilepsy Fact sheet”. WHO. February 2016. Archived from the original on 11 March 2016.

Headache

Headache is defined as sharp, dull or throbbing pain in any region of the head. It can occur on either one side or on both sides. Headaches can be broadly classified into two types: Primary headache and secondary headache.

Primary headaches comprise of 90% of all headaches which are recurrent and benign without any underlying disease. Following are major types of primary headache:

1) Tension-type headache: It the most common type headache which is non-pulsating in nature and can involve both sides and usually not accompanied with other symptoms.

2) Migraine headache: Migraine headache is a common type which is pulsating or throbbing like in nature predominantly involves one side of head. It can be associated with nausea, vomiting, lightheadedness, sensitivity to light or sound.

3) Cluster headache: It is a rare type neurovascular headache which occurs for a short duration and is characterized by severe excruciating pain around the eyes. It is usually associated with tearing of eye and runny nose on the affected side.

4) Trigeminal neuralgia: See Trigemnal Neuralgia.

5) Occipital neuralgia: See Occipital Neuralgia.

6) Secondary headaches: These occur in the setting of an underlying disease. Possible causes of secondary headache include sinusitis, brain tumor,
intracranial hemorrhage, brain aneurysm or arteriovenous malformation, stroke, concussion, carbon monoxide poisoning, Meningitis.

The diagnosis of headache is done by clinical history alone in most cases. If there is presence of any red flag like neurologic symptoms, sudden onset, onset of headache after age of 40 or history of recent trauma, neuro imaging is warranted to rule out any secondary causes. A lumbar puncture can be performed if an infectious cause is suspected.

Treatment of headache depends on the type of primary headache or underlying cause in case of secondary headache.

Movement Disorders

Movement disorders are a collection of complex neurological disorders which are characterized either by insufficient movement called Akinesia/Hypokinesia/Bradykinesia or too much movement called Hyperkinesia, ordisproportionate movement called Dyskinesia. The following are the common movement disorders:

1) Parkinson’s disease: It is a slowly progressive neurodegenerative disorder which is characterized by tremor, rigidity, slowness of movement and imbalance. Pathophysiologically, it is caused by cell degeneration in brain’s basal ganglia. These cells release a neurohormone called dopamine. Decreased level of dopamine leads to symptoms of Parkinson’s disease.

2) Dystonia: This movement disorder is characterized by sustained involuntary muscular contractions associated with twisting, repetitive movements and abnormal posture. It can be focal or generalized. Dystonia can be secondary to another disease or condition such as head trauma, drug side effect or neurological disease like Parkinson’s disease, Wilson’s disease.

3) Chorea: Chorea involves brief, nonrhythmic, jerky, random movements. It often involves athetosis which presents with twisting and writhing movements. The common cause of chorea is Huntington’s disease which is an inherited neurodegenerative disorder. In some cases, chorea is drug-induced secondary to use of anti-psychotics or anti-convulsants.

4) Tardive Dyskinesia: Tardive dyskinesia is caused by long term use of anti-psychotic drugs and dopamine receptor blockers.It is characterized by repetitive, involuntary and purposeless movements which may be manifested as grimacing, lip smacking, tongue protrusion, eye blinking, rapid movement of arms, legs and trunk.

5) Restless Leg Syndrome: Restless leg syndrome is a conditioncharacterized by strong urge for movement of legs occurring typically in the evenings or nights while sitting or lying down due to abnormal sensations in the legs. The urge is relieved with movement of legs. In most cases, the cause of restless leg syndrome is unknown.

6) Tourette’s syndrome: Tourette’s syndrome is a neurological disorder characterized by multiple repetitive episode of motor tics and vocal tics. Typically, it is first noticed in childhood but it may also first appear in teenage years. It is predominant in males than females.

Multiple Sclerosis (MS)

Multiple sclerosis (MS) is an immune mediated inflammatory demyelinating disease. It affects the myelinated axons of the central nerve system, destroying the myelin, an insulativecovering of the axons of brain and spinal cord. The hallmark sign of MS is the occurrence of symptoms separated in time and space, which means symptomatic episodes, lasting for more than 24 hours, occurring months or years apart and affecting different anatomic locations. In many cases, the first symptom appears between the ages of 20 and 40, though it can appear before or after this age range in minority of patients. Each episode results in a variety of symptoms and signs depending on the location of MS lesion in the brain and spinal cord. Common symptoms and signs of MS are as follows:

  • Sensory loss: abnormal sensory feelings such as numbness, tingling or pins-needles sensation. Lhermitte’s sign, an electrical sensation running down the back on bending the neck, can be present.
  • Optic Neuritis: presenting as double vision, red-green color distortion or complete blindness in one eye
  • Motor: due to lesions in spinal cord presenting as muscular weakness or spasms.
  • Autonomic: due to lesion in spinal cord causing bladder, bowel or sexual dysfunction
  • Ataxia: difficulty in coordination and balance
  • Trigeminal neuralgia
  • Depression and unstable mood
  • Heat intolerance
  • Cognitive impairment such as difficulties with concentration, attention, memory, and poor judgment.
  • Loss or difficulty in speech

Based on the clinical criteria, MS is categorized into following four categories:

1) Relapsing-remitting MS (RRMS):
Most common form of MS, presenting with temporary flare ups followed by complete resolution

2) Secondary-progressive MS (SPMS):
In this category, there is continuous decline of neurological deficits. There could be periods of remissions and relapses. Around 65% of cases who were initially diagnosed with RRMS will be transition in to this category at some point.

3) Primary-progressive MS (PPSMS):
It is characterized by slow progression of symptoms without any remissions or relapses.

4) Progressive-relapsing MS (PRMS):
In PRMS, there is steadily progression of symptoms with superimposed acute episodes of relapses with no recovery. It is a rare form occurring in less than 5% of cases.

The cause of MS is unknown. However there are several triggering factors described in the literature which can contribute in the occurrence of MS episode combined with genetic predisposition. Those contributing factors are viral infection affecting immune system and activating auto-reactive T cells, environmental factors such as low exposure to sunlight in regions farther from the equator, smoking and stress. There is reported connection between hepatitis B vaccination and MS but center for disease control (CDC) found lack of strong evidence to suggest such link.

The diagnosis of MS is typically based on the presenting signs and symptoms couples with evidence from imaging and cerebrospinal fluid (CSF) testing. MRI is the most sensitive imaging study which can detect areas of demyelination in brain and spinal cord. Testing of CSF entails the detection of oligoclonal IgG bands which can provide evidence of chronic inflammation in the brain and spinal cord.


Figure: MRI brain image showing hyperintense signals due to demyelination in the T2 (A) and FLAIR (B) images

There is no definite cure for MS but it is managed in 2 aspects:

  1. Symptomatic treatment in acute attacks
  2. Disease-modifying treatment to prevent new attacks and prevent disability.

Acute flare-ups are treated by intravenous steroids, and in some cases, intravenous immunoglobulins and plasmapheresis can be considered. There are several medications which are approved by US Food and Drug Administration (FDA) as disease modifying agents for relapsing MS. These include interferons, glatiramer, Mitoxantrone, Fingolimod, Teriflunomide, Dimethyl fumarate, and TNF inhibitor biologic agents.

Pediatric Neurology

Pediatric neurology is a specialized branch of medicine focused on the diagnosis and management of neurological disorders in neonates, infant, children and adolescents. Those disorders vary greatly and also encompass broad range of congenital abnormalities affecting the brain and spinal cord. Pediatric neurology services often collaborate with pediatric neurosurgeons in pre-op and post-op medical management of surgically treated brain and spine conditions.

Examples of neurological disorders managed by pediatric neurology include:

  • Childhood epilepsy
  • Progressive neuromuscular disorders such as muscular dystrophy
  • Brain tumors
  • Congenital birth defects affecting the brain and spinal cord such as spina bifida
  • Hydrocephalus
  • Movement disorders
  • Childhood stroke
  • Headaches
  • Autism spectrum disorders
  • Behavioral disorders such as ADHD

Stroke

Stroke is neurological vascular disorder occurs when a blood vessel carries oxygen and nutrients to brain is either blocked by clot (ischemic stroke) or ruptures (hemorrhagic stroke).

World health organization defines stroke as “rapidly developing clinical signs of focal (at times global) disturbance of cerebral function, lasting more than 24 hours or leading to death with no apparent cause other than that of vascular origin.”

In United States, more than 795,000 people suffer stroke every year andabout 610,000 of these are new cases, while 185,000are recurrent strokes.

Stroke is fifth leading cause of death in United States and almost 130,000 Americans each year die of stroke.

There are two major types of stroke: Ischemic Stroke and Hemorrhagic Stroke.

Ischemic stroke is the most common type and accounts for 87% of all strokes. It occurs due to blockage of blood vessel usually by a blood clot or by fatty deposits. The blockage can form in the artery supplying the brain or it can develop elsewhere in the body and travel through the blood to an artery in the brain which is called embolism.

Hemorrhagic stroke accounts for 13% of all strokes and results from rupture of a weakened blood vessel with resultant bleeding into the surrounding brain.The most common cause of vessel rupture is uncontrolled high blood pressure. There are three vascularconditions which make blood vessels weak and prone to bleed: Aneurysm, Arteriovenous Malformation (AVM), and Dural Arteriovenous Fistula (DAVF).

Transient ischemic attack (TIA)is ischemic type of stroke which occurs due to temporary blockage of blood flow to the brain and often lasts less than five minutes. It is often labelled as “mini-stroke”. A TIA does not cause permanent neurological deficit but it increases the risk of getting full blown ischemic stroke later.

There are multiple risk factors which increase the risk of stroke. These risk factors are lifestyle risk factors like high blood pressure, high cholesterol, diabetes, smoking, physical inactivity, obesity, stress, atrial fibrillation, atherosclerosis, peripheral arterial disease. There are certain hereditary non-modifiable risk factors such as age, family history of stroke, race. A previous history of TIA, stroke or heart disease also increases the risk of new or recurrent stroke.

The symptoms and signs of stroke depend on the type of stroke and the affected area of the brain by the diseased vessel. The key factor is the sudden onset of any of the following symptoms:

  • Speech difficulty
  • Weakness or numbness of one side of the face, arm or leg. In some cases, both sides may be involved
  • Sudden loss or change in vision in one or both eyes
  • Sudden, severe headache, often described as “the worst headache of life”
  • Dizziness or loss of balance and coordination
  • Sudden confusion or loss of memorySudden c
  • hanges in behavior

American Stroke Association coined an easy to remember pneumonic FASTto spot warning signs of stroke and to seek emergency medical care.

FAST stands for Face drooping, Arm weakness, Speech difficulty and Time to call 911.

The most important step in management of acute stroke is to determine the type of stroke and the areas of brain which are being affected. In addition to history and clinical examination, following investigation studies are important in the early management:

  • Blood test to check baseline levels of blood biochemistry
  • Imaging studies including CT, CTA and MRI. CT head is the most important initial study in acute management of stroke which can rule out hemorrhagic cause of stroke
  • Carotid ultrasound to check for blood flow in carotid arteries
  • Echocardiogram to find a cardiac source of clot in case of ischemia stroke due to large vessel occlusion
  • Cerebral angiogram which is a minimally invasive diagnostic test to acquire high resolution images of blood vessels of brain. It serves as a definitive diagnostic test to detect or confirm vascular abnormalities of brain. It also provides a therapeutic tool for patients who require endovascular treatment.

Figure: CT head without contrast:
(A) axial image showing hyperdense sign indicative of acute vascular occlusion causing an ischemic stroke.
(B) Axial CT image showing intra cerebral hemorrhage

The medical management of ischemic stroke entails therapy with clot-busting drugs, which should be started within 3 hours of stroke onset. Intravenous tissue-plasminogen activator (t-PA) is the most common drug used for lysis of clot and to restore blood flow in the brain. In hemorrhagic stroke, emergency medical treatment is focused on controlling the bleeding in the brain. It involves lowering of blood pressure, stopping and reversal of any blood thinner medication, preventing vasospasm and seizure, and potential surgery for removal of the bleeding.

In cases of ischemic stroke, endovascular treatment is minimally invasive procedure, which is recommended if medical treatment with IV t-PA fails or contra-indicated and if the clot is in a larger vessel amenable to endovascular treatment, the so called Large Vessel Occlusion (LVO-ischemic stroke).

It involves physical removing of blood clot with the help of stent retrievers and/or aspiration device, process called mechanical thrombectomy. In recent changing standards of ischemic stroke management, endovascular treatment with mechanical thrombectomy is the standard of care if the resources and skilled physicians are available due to better effectiveness and larger treatment window of 8 hours from stroke onset.

Surgical or endovascular treatment of hemorrhagic stroke depends on the vascular abnormalities.

If aneurysm is the source of bleeding then it can be repaired by surgical clipping or by endovascular embolization of metallic coils into the aneurysm.

Arteriovenous malformation (AVM) can be removed surgically or by endovascular embolization of coils or small particles with glue like properties. Often endovascular treatment is done in preparation for surgical removal of AVM.

Dural Arteriovenous Fistula (DAVF) can be treated by neuro-intervention or surgery. The bleeding from a ruptured DAVF can be removed surgically.

References

  1. American Heart Association. Heart Disease and Stroke 2017 Statistics At-a-glance.
  2. Wahlgren, N., Macho, J. Killer M., Liebeskind D., Jansen O. Final Results from the Trevo Study (Thrombectomy Revascularization of large Vessel Occlusions in acute ischemic stroke). International Stroke Conference, 2012.

Pain & Trigeminal Neuralgia

Trigeminal neuralgia is a chronic pain condition that affects the trigeminal nerve, which carries sensation from your face to your brain. If you have trigeminal neuralgia, even mild stimulation of your face — such as from brushing your teeth or putting on makeup — may trigger a jolt of excruciating pain.

You may initially experience short, mild attacks. But trigeminal neuralgia can progress and cause longer, more-frequent bouts of searing pain. Trigeminal neuralgia affects women more often than men, and it’s more likely to occur in people who are older than 50.

Because of the variety of treatment options available, having trigeminal neuralgia doesn’t necessarily mean you’re doomed to a life of pain. Doctors usually can effectively manage trigeminal neuralgia with medications, injections or surgery.

Glossopharyngeal Neuralgia

Glossopharyngeal neuralgia is severe, lancinating pain in the distribution of the glossopharyngeal and vagus nerves. The throat and base of the tongue are most commonly involved with possible radiation to the ear and sometimes to the neck. Salivation and coughing may occur. Triggers include swallowing, talking, and chewing. This is a rarer form of neuralgia, occurring 1 case for every 70 of trigeminal neuralgia. Anesthesia can be delivered using cocaine to the tonsillar pillars and fossa. Failure of relief is an indication for surgical intervention. Microvascular decompression (MVD) as detailed for trigeminal neuralgia is an option. An alternative is surgical sectioning of the glossopharyngeal nerve and upper one third or two fibers of the vagus nerve, whichever is larger via intracranial or extracranial approach. Dysphagia may occur but typically resolves spontaneously. As the vagus nerve is responsible for blood pressure regulation, cardiovascular complications are a serious complication of vagus nerve injury.

Hemifacial Spasm

Hemifacial spasm is characterized by intermittent, painless spasms of the facial muscles involving the facial nerve unilaterally. It may be limited to the upper or lower half of the face only. It usually begins as infrequent contractions of the orbicularis oculi, the muscle that wraps around the eye, and then increases in frequency until visual impairment occurs. This disorder can be associated with trigeminal neuralgia. It is more common in women, on the left side of the face, and usually presents in mid to late adulthood.

The most common cause of hemifacial spasm is vascular compression of the facial nerve at the root exit zone typically by the anterior inferior cerebellar artery (AICA). Other etiologies include tumor or cyst compression of the facial nerve and association with Bell’s palsy.

Surgical management is generally preferred. Medical management may be attempted with local injection of botulinum toxin (Oculinum). Microvascular decompression (MVD) as detailed under trigeminal neuralgia is first-line. Unilateral hearing loss is the most common complication occurring in 13% of cases due to nerve injury. The risk may be reduced by intraoperative monitoring either via intraoperative brainstem auditory evoked potential (BAER) or direct VIII nerve monitoring. Other complications include facial weakness, which usually resolves on its own, gait disturbance, hoarseness or dysphagia due to nerve damage, and aseptic meningitis. Complete resolution of hemifacial spasm occurs in 85-93% of cases. Nine percent experience some relief while 6% do not. Nerve ablation surgery is an alternative to MVD but facial paralysis is a consequence.

Intermedius Nerve Neuralgia

Intermedius nerve neuralgia is a rare disorder involving a branch of the facial nerve, causing brief paroxysms of pain unilaterally in the auditory canal, which can radiate to the parieto-occipital region. It may be idiopathic in origin or secondary to herpes zoster1. It can be confused with glossopharyngeal neuralgia with a primarily otitic component, which may be differentiated with surgical exploration1. Microvascular decompression (MVD) is recommended as first-line management1.

References

  1. Tubbs RS, Steck DT, Mortazavi MM, Cohen-Gadol AA. (2013). The Nervus Intermedius: A Review of Its Anatomy, Function, Pathology, and Role in Neurosurgery. World Neurosurgery. 79(5-6): 763-767.

Trigeminal Neuralgia

Trigeminal neuralgia, also known as tic douloureux, is defined as a sharp, unilateral, electric shock-like pain in the distribution of one or more of the braches of the trigeminal nerve that occurs in paroxysms and only lasts a few seconds at a time. The patient may experience spontaneous remission with pain-free intervals without any treatment. The most common cause is compression of the trigeminal nerve at the root entry zone by the superior cerebellar artery (SCA), and less commonly by a large vein. Other arteries that may be involved are a persistent primitive trigeminal artery or dolichoectatic basilar artery. Alternate etiologies include posterior fossa tumor, such as vestibular schwannoma, and multiple sclerosis plaque within the brainstem.

The annual incidence of trigeminal neuralgia is 4/100,000. Average age is 63, with most cases occurring over the age of 50. There is a slight female predominance, with female: male ratio being 1.8:1. The right trigeminal nerve is more commonly involved, implicated in 60% of cases, whereas the left trigeminal nerve is affected in 39% of cases. Only 1% of patients have bilateral involvement. The maxillary (V2) and mandibular (V3) branches together are most commonly affected (42%), followed by V2 only (20%), then the ophthalmic branch (V1) and V2 (14%). Medical therapy of Trigeminal neuralgia includes treatment with carbamazepine (Tegretol), an anticonvulsant. Second-line therapy is with baclofen (Lioresal), a muscle relaxant that is not as affective as carbamazepine but has fewer side effects. Gabapentin (Neurontin), another anticonvulsant, may be combined with carbamazepine or baclofen.

Cases refractory to medical management may be treated with surgery. Surgical strategy varies by the territory involved and origin of neuralgia. Peripheral nerve ablation and neurectomy are options for distal branch involvement or for patients unable to undergo general anesthesia. However, sensory loss occurs in the targeted nerve distribution and neuralgia may recur as the nerve regenerates. Repeat neurectomy is common. Percutaneous trigeminal rhizotomy (PTR) is another minimally invasive option for patients who are not candidates for major surgery or have a limited life expectancy (< 5 years). This may be used to treat failed peripheral nerve ablation. Techniques include radiofrequency rhizotomy that uses radiofrequency energy to thermocoagulate pain fibers of the trigeminal nerve, glycerol injection into Meckel’s cave, balloon compression of pain fibers inducing mechanotrauma, and injection of sterile boiling water. Common complications include recurrence and dysesthesia. (However, a certain extent of sensory loss, or “numbness”, is expected in successful PTR.) Other adverse effects include alterations in salivation and tear production and meningitis. Microvascular decompression (MVD) (see figure) is nowadays the best treatment with more long lasting effect compared to other alternatives. It is best used for patients with an expected survival > 5 years who are able to undergo a small retrosigmoid craniectomy. The offending artery or vein is dissected off of the root entry zone (Obersteiner-Redlich zone) of the trigeminal nerve a few millimeters distal to its exit off of the brain stem and a Teflon or Dura pledget is put in between so that the pulsations of the vessel should be avoided. Due to movement of the brain with every heart beat and risk of dislocation of this pledget, we usually make the pledget in a horse-shoe fashion to fit around both sides of the nerve and use special glue (Tisseel) to make it firmly attached there.


Figure : Post-operative microvascular decompression CT-Scan. A. Axial B. Sagittal C. Coronal

In younger patients, the thicker layer over the brain, dura is primarily closed. In older patients with thinner dura, we use a piece of patients pericranial or temporalis muscle fascia to patch the dural opening and close it tightly as CSF-leak is a normal complication for this approach. If non-autologous grafts are used there is some low risk of septic meningitis and for this reason and in order to avoid that, we do not use artificial material.  Relief is typically long-lasting, exceeding 10 years in 70% of patients. Dysesthesias are less common than with PTR. Complications include aseptic meningitis in up to 20% of cases and major neurologic morbidity in 1-10% of patients – including vestibulocochlear nerve and facial nerve dysfunction causing hearing loss, deafness, balance problems, and facial paralysis – with a failure rate of 20-25%. Patients with trigeminal neuralgia secondary to multiple sclerosis plaque will not improve with MVD and should undergo PTR instead. One uncommon complication is development of pledget grasnuloma 1. (See figure and video)


Figure : Operative images. A. Accessory Trochlear Nerve B. Microvascular Decompression showing transected tentorium for access to Meckel’s cave. See the deformed Trigeminal nerve.

References

  1. N Adeeb, SA Fard, MA Liker, MM Mortazavi. Trigeminal Teflon Granuloma: A Case Report with Operative Nuances. Journal of Neurological Surgery Part B: Skull Base 77 (S 01), P112 ,2016. DOI: 10.1055/s-0036-1580058

Stereotactic radiosurgery is another minimally invasive option. 80-96% of patients experience significant pain reduction but only 65% will become pain free. It can take up to 3 months for pain relief to occur. Hypesthesia (diminished sensation) is the most common complication and occurs in 20% of cases after first SRS and 32% of those undergoing repeat SRS. The major risk of this treatment is conversion of the trigeminal neuralgia to Anesthesia Dolorosa, a severely painful trigeminal neuralgia involving all 3 branches of the trigeminal nerve and losing all the sensory function in these branches including the sensation of the cornea.

ENT and Plastic Surgery

Otolaryngology, also known as ENT (Ear-Nose-Throat) surgery, is a field focused on all types of head and neck surgery.

Plastic surgeons are trained to perform reconstructive and cosmetic procedures throughout the entire body, including the head and neck. They also manage maxillofacial fractures and provide complex procedures such as vascularized flaps for areas of the skull that needs skin coverage.

Otolaryngologists, plastic surgeons, and neurosurgeons frequently collaborate on surgical procedures. ENT surgeons often provide the approach and closure for neuroendoscopic surgery through the nasal cavity, while neurosurgeons operate at the skull base.

Craniofacial procedures, especially for congenital malformations, also require collaboration between these three specialties.

Degenerative Spine Disease

Degenerative disease can affect the cervical, thoracic, or lumbar spine and is usually associated with aging. It is a chronic disease that can range from being asymptomatic to presenting acutely.

“Spondylosis” is a non-specific term that can be used to refer to degenerative spine disease. Common causes include disc herniation, spondylolisthesis, and spinal stenosis, which are discussed below. Other causes include the formation of bony protrusions known as osteophytes, which may compress nerve roots, and facet joint abnormalities. Complications include radiculopathy, defined as numbness, pain, and/or weakness in the arms or legs due to spinal nerve impingement; and myelopathy, which has similar symptoms due to spinal cord compression. Neurogenic claudication is painful cramping or weakness in the arms or legs due to nerve impingement or inflammation in the spine.

 

Disc Herniation

The intervertebral disc forms a fibrocartilaginous joint between two vertebrae and is comprised of 2 components: an outer, fibrous ring known as the annulus fibrosus, and a gel-like inner core, called the nucleus pulposus.

Most disc herniations are due to protrusion of the nucleus pulposus through the annulus fibrosis. Normal aging entails dehydration, fissuring, and fragmentation of the nucleus pulposus, which predisposes to herniation. Complications arise when the posterior longitudinal ligament is torn, which allows the disc to herniate into the spinal canal and compress either the spinal nerve root or spinal cord. Disk herniations can be median, paramedian, lateral, foraminal and extra-foraminal. Paramedian and lateral disk herniations are most usual. Foraminal disk herniations are usually associated with severe arm or leg pain depending on their location in the spine.

Symptoms depend on the spinal cord level. Disc herniation in the cervical spine typically causes unilateral pain shooting from the neck down the shoulder/arm and possibly into the hand. It is worsened by certain neck motions.

Thoracic disc herniation is rare, accounting for 0.25% of all disc herniation. It can cause pain along the chest wall or, more seriously, gait disturbance, loss of rectal tone, and lower extremity hyperreflexia and clonus.

Lumbar disc herniation involves shooting pain in the legs. Sciatica is a common presentation classically described as shooting pain down the back of the leg. However, pain distribution associated with a lumbar disc herniation may alternatively entail the front or side of the leg. Low back pain may occur concurrently.

For most cases of disc herniation, patients will respond to conservative management with partial or complete resolution of symptoms. This entails non-steroidal anti-inflammatory drugs (NSAIDs) for pain control, exercise, physical therapy, and weight control. For those who experience continued symptoms, epidural corticosteroid injection is a non-surgical alternative to provide immediate to moderately long-lasting relief. Patients may be able to achieve pain control utilizing a combination of conservative management and epidural injection every several months.

The final, definitive step in management is surgical intervention. Patients with unremitting pain or otherwise intolerable symptoms are appropriate candidates.

Cases that involve emergent signs including loss of bowel or bladder function, significant leg weakness especially of acute onset known as caudaequina syndrome – should be taken to surgery immediately.

Surgical approach and procedure is tailored to the spinal level involved.

In the cervical spine, anterior discectomy with or without fusion is most commonly done, where the disc is evacuated from an anterior approach and the spinal column is fused as needed. Modern surgery includes replacing the resected disk with a disk prosthesis. If the operated level is unstable, a fusion is recommended after the disk is resected.

Approach varies for thoracic disc herniation depending on location and quality, where anterior is most commonly used for midline or broad-based herniations or densely calcified discs and posterolateralis recommended for lateral or soft disc herniations. Laminectomy, a direct posterior approach, is not recommended for thoracic disk herniation as it risks to herniate the thoracic cord and cause serious complications. The lamina is a large segment of the bone that forms the boundary of the spinal canal from the posterior aspect.

In the lumbar spine, microdiscectomy is a commonly used, where a herniated disc is removed from a posterior approach under the microscope. Open discectomy is an alternative for severe cases that usually necessitates a laminectomy for better visualization of the disc. These procedures may also involve fusion for stabilization of the spinal column, as needed.

Spinal Stenosis

Spinal stenosis is narrowing of the spinal canal or intervertebral foramina. It may have congenital and degenerative etiologies, the latter of which is more common and will be the focus. Loss of intervertebral disc height and protrusion, facet joint arthropathy, osteophyte formation, and hypertrophy of the ligamentumflavumoccur along a continuum. Each of these processes may result in spinal stenosis. Patients commonly present in the 6th and 7th decades of life.

Symptoms depend on the spinal level involved and are similar to those discussed for disc herniation. In the cervical spine, nerve radiculopathy includes arm pain, paresthesias, and weakness. Lumbar radiculopathy may cause low back pain radiating to the leg, whereas neurogenic claudication causes painful leg cramping. Symptoms of myelopathy, which is discussed in greater detail below, include bowel or bladder incontinence, sudden leg weakness, and gait disturbance. This is an emergent condition that requires immediate surgical decompression. Otherwise, conservative management should be tried, with NSAIDs, physical therapy, and exercise for overweight individuals.

Surgery for lumbar spinal stenosis entails laminectomy for decompression with or without fusion. The presence of spondylolisthesis (discussed below) favors concomitant fusion. Cervical spinal stenosis may also be treated with laminectomy. Alternatively, a corpectomy (Vertebrectomy) may be undergone, which involves an anterior approach with removal of the vertebral body and any osteophytes. A bone graft, known as a strut graft, is then used to replace the space created by removal of the vertebral body.

Myelopathy

Myelopathy is by definition neurologic dysfunction related to direct spinal cord damage. In the degenerative setting, myelopathy is caused by compression secondary to spinal stenosis. Disc herniation, osteophyte formation, and ligamentous hypertrophy may all cause stenosis and myelopathy. Degenerative myelopathy is frequently seen in the cervical spine, known as cervical spondylotic myelopathy. This is the most common type of spinal cord dysfunction in patients older than 55 years. Aside from direct cord compression, microtrauma related to neck flexion and extension and vascular injury may also cause cervical spondylotic myelopathy.

An early sign of cervical spondylotic myelopathy is gait disturbance, often with lower extremity weakness or stiffness. Difficulty running is a common complaint. Cord damage can cause upper motor neuron findings, including hyperreflexia and spasticity in the limbs. With compression of the cervical spine, this would be expected to be pronounced in the legs, while the arms would be prone to lower motor neuron signs, including weakness and hyporeflexia.

If signs of acute compression are present, such as sudden-onset, severe weakness or gait disturbance, or any bowel or bladder incontinence, the patient should be taken to surgery immediately. Otherwise, conservative management with NSAIDs, restriction of high risk activities (such as action sports and heavy lifting), bed rest, and prolonged immobilization with rigid cervical bracing is suggested. Myelopathy that does not respond to nonoperative management or patients with severe symptoms should undergo surgery.

Surgical approach depends on myelopathic etiology. A posterior approach is preferred when ossification of the posterior longitudinal ligament (OPLL) is involved. A laminectomy either alone or in conjunction with instrumentation/fusion, or laminoplasty, may be undergone. Laminectomy alone has a higher incidence of late kyphotic deformity. Laminoplasty may be done should the patient have myelopathic symptoms without axial neck pain.An anterior approach is preferred for correcting kyphotic deformities. The procedure options entail anterior cervical discectomy and fusion (ACDF), corpectomy (removal of the vertebral body) and fusion, or a combination of both.

Infection of the Spine

There are several different categories of spinal infections, including vertebral osteomyelitis, discitis, spinal epidural abscess, spinal subdural empyema, meningitis, and spinal cord abscess. These infections typically present with back pain, fever, and overlying spine tenderness. Major risk factors include diabetes, IV drug abuse, chronic renal failure, alcoholism, and older age. Staphylococcus aureus is the most common infectious agent.

Osteomyelitis

Vertebral osteomyelitis comprises 2-4% of all cases of osteomyelitis and occurs most commonly at the lumbar spine. As the vertebrae receive a rich blood supply, infections may spread hematogenously from distant sites, or they may directly extend from a local infection caused by surgery, trauma, or lumbar puncture. MRI imaging, blood cultures and possible biopsy guide treatment. Over 90% of cases are treated with antibiotics and immobilization. In rare cases with spinal instability due to bony deformity, or those that are refractory to medical treatment, surgery may be needed.

Discitis and Spondylodiscitis

Discitis is inflammation or infection of the nucleus pulposis of the intervertebral disc. This may occur in the pediatric or adult populations. Spondylodiscitis is a combination of discitis and spondylitis, which is inflammation of one or more of the spinal vertebrae. Spondylodiscitis is the most common complication of sepsis or local infection, usually in the form of an abscess. The main causative organisms are Staphylococci and Mycobacterium tuberculosis.Immunocompromised individuals are at risk, especially those with cancer, infection, or who are taking immunosuppressive drugs used for organ transplantation. The most common organisms are Staphylococcus aureus and Escherichia coli. Diagnosis of spondylodiscitis is made via spinal MRI. Most cases are managed non-surgically with antibiotics and immobilization. There is no standard therapeutic guideline; however, IV antibiotics are recommended for 2-4 weeks. Spinal fixation, debridement, and neural decompression may be necessary depending on extent of infection.

Epidural Abscess

Spinal epidural abscess is often associated with vertebral osteomyelitis and discitis. The thoracic spine is most commonly affected. If the spinal cord or nerve roots are involved, the patient may experience symptoms of myelopathy or radiculopathy in addition to fever and local pain. Imaging of choice is MRI. Treatment is controversial. Early surgical drainage combined with antibiotics is recommended in most cases to ensure preservation of neurologic function. Those who present with neurologic deficit such as paralysis rarely recover function, despite undergoing surgery.

Subdural Abscess/Empyema

Subdural abscess or empyema is infection between the outermost layer of the meninges of the spinal cord, the dura and arachnoid mater. Symptoms include back pain, and, in severe cases, myelopathy and caudaequina syndrome from spinal cord cord and nerve root compression.Subdural empyema is a rare infection and is most often due to hematogenous spread of distant infection or adjacent spread from osteomyelitis. The most common organisms are Staphylococcus aureus and streptococci. MRI with contrast is the diagnostic modality of choice, although CT myelography may be considered. Treatment for all cases requires prompt surgical drainage and antibiotic therapy.

References

  1. Greenlee JE. Subdural empyema. Curr Treat Options Neurol. 2003; 5(1): 13-22

Peripheral Nerves

Peripheral Nerves

Your peripheral nerves are the ones outside your brain and spinal cord. Like static on a telephone line, peripheral nerve disorders distort or interrupt the messages between the brain and the rest of the body.

Occipital Neuralgia (Occipital Nerve Entrapment)

The greater or lesser occipital nerves are sensory nerves that branch off the C2 spinal nerve. Entrapment of these nerves causes posterior scalp and upper neck pain, with pain triggered by application of pressure near the occiput. Pain may also occur behind the eyes. Patients typically present complaining of chronic headaches. As such, occipital neuralgia is commonly mistaken for tension or migraine headaches.

The main cause of this syndrome is trauma. Traumatic cervical extension and atlanto-axial subluxation can damage the C2 nerve root and ganglion. Direct injury to the greater or lesser occipital nerve may occur in surgical procedures, for instance if a suture is placed through the nerve during closure of a posterior fossa craniectomy.

Treatment of occipital neuralgia remains controversial. Most cases are self-limited. Nerve block and local steroid injection may provide temporary pain relief. For idiopathic cases, nerve decompression may be most effective. In cases of atlanto-axial subluxation, nerve decompression and atlanto-axial fusion may be recommended.

References

  1. Greenberg M. Handbook of Neurosurgery. 6th ed. New York: Thieme Medical Publishers, 2005.

Radial Tunnel Syndrome (Supinator Syndrome)

The radial tunnel is the space containing the radial nerve as it courses from the humeroradial joint, proximal to the insertion of the supinator muscle, to the distal border of the supinator, just below the elbow. This space also comprises the two main radial nerve branches, the posterior interosseous nerve and superficial radial nerve.

Symptoms arise from compression of the radial nerve branches by the supinator muscle. This may be caused by repeated forceful supination or pronation, or by inflammation of supinator muscle attachments (as in tennis elbow).

Radial Tunnel Syndrome specifically refers to compression of the posterior interosseous nerve at the lateral intermuscular septum of arm, while Supinator Syndrome refers to compression of the posterior interosseous nerve at the arcade of Frohse, although these terms are used interchangeably.

Patients usually present complaining of pain in the dorsal aspect of the upper forearm. Diagnosis can be made with a positive “middle finger test,” in which resisted middle finger extension produces pain. First-line treatment is conservative management, including rest, work modification, NSAIDs for pain control, and physical therapy. Surgical intervention is rarely required, although nerve decompression may be necessary in some cases.

References

  1. Greenberg M. Handbook of Neurosurgery. 6th ed. New York: Thieme Medical Publishers, 2005.
  2. Tubbs RS, Mortazavi M, Farrington WJ, Chern JJ, Shoja MM, Loukas M, Cohen-Gadol AA. Relationships between the posterior interosseous nerve and the supinator muscle: application to peripheral nerve compression syndromes and nerve transfer procedures. J NeurolSurg A Cent EurNeurosurg.2013; 74(5): 290-3.

Median Nerve Entrapment

Carpal tunnel syndrome

Carpal tunnel syndrome is the most common median nerve entrapment syndrome. It is caused by median nerve entrapment by the transverse carpal ligament at the wrist. Women are 4 times more likely to be affected as men. Most cases are occupation-related, caused by repetitive hand movements. Other causes include systemic illnesses such as rheumatoid arthritis, hypothyroidism, systemic lupus erythematosus, multiple myeloma, and diabetes mellitus, as well as obesity and pregnancy.

Patients present complaining of painful numbness and tingling in the first three digits (thumb, index finger, and middle finger), especially at night while asleep or with wrist flexion. Grip weakness may also be present.The Phalen’s maneuver and Tinel’s sign are physical exam maneuvers that evoke pain in the median nerve distribution, although not perfectly sensitive and thus not necessary for diagnosis. Diagnosis is made on the basis of a complete history and physical exam and can be confirmed by nerve conduction studies.

Treatment is initially managed conservatively, including rest, wearing a wrist splint at night, and with oral pain medications such as NSAIDs. Steroid injection may also be attempted. Most cases improve non-surgically. In those that do not, carpal tunnel release is a common surgical procedure that provides relief in over 70% of patients.

Pronator Teres Syndrome

Pronator Teres Syndrome is a rare cause of median nerve entrapment, in which the median nerve is compressed at the elbow by the two heads of the pronator teres muscle. Symptoms can be similar to carpal tunnel syndrome, including paresthesias in the thumb and index finger and grip weakness. However, distinguishing features include pain and numbness in the palm and easy fatiguing of forearm muscles. Repeated pronation exacerbates symptoms. On exam, palpation over the proximal median nerve elicits tenderness, while resisted pronation evokes symptoms. Rest, massage therapy, and corticosteroid injection can alleviate pain. The vast majority of cases resolve on their own. Surgical decompression may be considered in select cases that do not respond to conservative management.

Anterior interosseous nerve syndrome

This syndrome is another rare median nerve neuropathy. The anterior interosseous nerve is a motor branch of the median nerve. Trauma is the most common cause, including supracondylar fracture, open reduction of a forearm fracture, elbow dislocation, or penetrating injury such as a stab wound. Three muscles are affected: the flexor digitorumprofundus, flexor pollucislongus, and pronator quadratus. Patients complain of forearm pain and weakness making a pincer using the thumb and index finger. Importantly, there is no sensory deficit. Electromyography (EMG) may be used in addition to physical exam findings for diagnosis. Non-surgical management should first be attempted for 8-12 weeks. If unsuccessful, surgical decompression is highly effective as definitive treatment.

References

  1. Greenberg M. Handbook of Neurosurgery. 6th ed. New York: Thieme Medical Publishers, 2005.

Ulnar Nerve Entrapment

Cubital tunnel syndrome

Cubital tunnel syndrome is a common ulnar nerve neuropathy in which the nerve is entrapped at the elbow. It is the second most common peripheral nerve compression syndrome. The cubital tunnel is bordered medially by the medial epicondyle and laterally by the olecranon process and the tendinous arch joining the heads of the flexor carpi ulnaris. The roof is formed by the epicondylo-olecranon ligament. Most cases are idiopathic, although trauma such as elbow fracture or dislocation or repeated motions may cause nerve irritation. Patients with end-stage renal disease undergoing hemodialysis may also be predisposed to this syndrome, due to elbow positioning, vascular access, and underlying disease.

Initially, patients present complaining of parasthesias of the fourth and fifth digits (ring finger and little finger). Syndrome progression presents with hand weakness, specifically with loss of coordination or clumsiness of the affected fingers. Elbow pain, hand cramping, and muscle wasting may also be present. Physical exam findings include Froment’s sign (tested by holding a flat object between the thumb and index fingers, assessing weakness of the adductor pollicis), overt clawing of the fourth and fifth digits, and abduction of the little fingers (Wartenberg’s sign). Diagnosis is made on the basis of history and physical exam findings as well as neurophysiological diagnostic testing such a nerve conduction studies and EMG.

Conservative management is preferred for patients with mild symptoms. Patients who fail nonsurgical management are candidates for surgical treatment. Options include nerve decompression with or without transposition. Simple decompression is recommended in most cases, unless there is a bony deformity or nerve subluxation.

Guyon canal entrapment (ulnar tunnel syndrome)

Guyon canal entrapment is compression of the ulnar nerve at the wrist. The boundaries of Guyon’s canal consist of the superficial palmar carpal ligament superiorly, the deeper flexor retinaculum and hypothenar muscles inferiorly, the pisiform and pisohamate ligamentsmedially, and the hook of the hamate laterally. Guyon’s canal is superficial to the transverse carpal ligament, which is implicated in median nerve compression in carpal tunnel syndrome.

As the ulnar nerve divides into a superficial, sensory branch and a deep, motor branch while passing through the canal, symptoms may present in one of 3 ways:

  • 1: weakness of all the intrinsic hand muscles innervated by the ulnar nerve and numbness and tingling of the fourth and fifth digits and ulnar half of   the palm
  • 2: weakness only
  • 3: sensory deficit only

Proximal injury is more likely to produce motor symptoms with or without paresthesia, while distal injury is more likely to cause isolated sensory problems.

Symptoms may be progressive, beginning as sensory findings only and worsening to include weakness.

Unlike cubital tunnel syndrome, patients may also experience numbness and tingling of the dorsum of the hand. History and physical exam findings are usually sufficient for diagnosis although Nerve Conduction Studies and EMG are often performed to confirm diagnosis

Nonsurgical management is first-line. Surgical decompression is rare but may be considered in refractory cases. Options include simple decompression or decompression with subcutaneous transposition.

References

  1. Cutts, S. Cubital tunnel syndrome. Postgrad Med J. 2007; 83(975): 28-31.
  2. Greenberg M. Handbook of Neurosurgery. 6th ed. New York: Thieme Medical Publishers, 2005.
  3. Vahdatpour B, Maghroori R, Mortazavi M, Khosrawi S. Evaluation of ulnar neuropathy on hemodialysis patients. J Res Med Sci. 2012; 17(10): 905-10.

Lateral Femoral Cutaneous Nerve Entrapment (Meralgia Paresthetica)

The lateral femoral cutaneous nerve is a pure sensory nerve with contributions from the second and third nerves of the lumbar plexus (L2-L3). Compression usually occurs where the nerve passes underneath the inguinal ligament near its attachment to the anterior superior iliac spine of the pelvis. Patients complain of burning pain on the upper, outer aspect of the thigh, occasionally extending from the hip to the knee. Obesity and diabetes are associated with this condition. It has been nicknamed the “skinny pants syndrome” dueto compression by tight clothing or belts. Prolonged standing or running may also cause nerve irritation, and long distance runners may be predisposed. Diagnosis isclinical.

Conservative management provides relief in over 90% of cases. This includes rest, clothing modification, ice application, NSAID use, lidoderm patch, and weight loss in obese patients. Surgical options include nerve decompression, decompression and transposition, and neurectomy. Decompression has a higher failure and recurrence rate compared with neurectomy, butneurectomy has the adverse effects ofdenervation pain and numbness in the nerve distribution.

References

  1. Greenberg M. Handbook of Neurosurgery. 6th ed. New York: Thieme Medical Publishers, 2005.

Spinal Trauma

Fractures and Dislocations

Fractures and dislocations of the spine can be divided based on the location or the mechanism of trauma. Both parameters are important as location of the spine fracture can risk neurological compromise of varying degree. Fractures from the cranio-cervical junction down to thoracolumbar junction can both damage the spinal cord and/or nerve roots, while fractures on the lumbar spine below L1, can only damage nerve roots.

 

 

C1-fracture
The first cervical vertebra or Atlas is a ring. Its major function is to translate the mobility between the skull and the rest of the vertebral column below it. This translation of the mobility is made through the unique form of C1 and C2 along with associated ligaments. Fractures of C1 can be unilateral fracture of the C1-ring or bilateral fractures of the C1-ring that classically are called Jefferson-fractures.

C2-fracture
The C2, also called the Axis, together with C1, translate the mobility form the skull to the rest of the spinal column below it. C2 has a unique form consisting of a ring with an anterior process called the odontoid process or the Dens. C2, beside its classical facets (joints) towards the above-lying C1, and the below-lying C3, has a third pseudo-joint between its odontoid process and C1. C2 and C1 have extensive ligamentous connections between them and towards the skull, being the main parameters of the craniocervical stability. C2 has an elongated section between its superior and inferior facets and hence has an elongated pars interarticularis, which suits well for positioning screws for surgical fixation. Given C2-unique anatomy, fractures of the C2 can include its lamina, its facets, its Pars Interarticularis and the Odontoid Process (Dens). There are 3 types of fractures of the Odontoid Process: Type 1: Fracture above the Transverse Ligament. Type 2: Fracture below the Transverse Ligament but above the body of the C2. Type 3: Fractures at the base of the Odontoid process (Dens).

Hangman fracture
This is a traumatic C2-3 olisthesis. It is due to disruption of the bilateral C2 pars interarticularis, caused by hyperextension and distraction as in high-speed motor vehicle accident. Based on Efendic-classification, there are 3 types:
Type 1: Pars fracture diastase less than 3 mm
Type 2: Pars fracture diastase more than 3 mm
Type 2A: Pars fracture diastase less than 3 mm but with significantangulation
Type 3: Type 1 with BilateralFacet dislocation and/or Traumatic Disk herniation
Type 1 can be treated with brace or Halo. Type 2 and 3 need surgery.

Ligament of the Cranio-cervical
These ligaments are crucial for stability of the cranio-cervical junction. The anatomy and function of each of them are well delineated in the following manuscript.

Sub-axial Fractures (C3-7) All fractures below C2/Axis, are called sub-axial. They usually have a body, pedicles, lateral masses and lamina. The lateral masses are larger than the pedicles in C3-6 and are more suitable for screw placement instead of the small pedicles. C7’s pedicle has a size suitable for screws. Fractures can affect the body, pedicle, lateral mass, lamina and facets. The mechanism of fracture, can be compressive, distractive or translational. We will discuss this more in detail under Thoracolumbar fractures.

Thoracolumbar fractures Fractures occurring in the thoracolumbar spine are among the most common.

Three-Column-Theory
The Anterior Column consists of the Body excludingthe pedicles, the disk and the Anterior Longitudinal Ligament (ALL). The Middle Column consists of the Pedicles, the Posterior Longitudinal Ligament (PLL) and the facets. The Posterior Column consists of the Lamina, the Inter-spinal ligament and the Supra-spinal ligament. Naturally, the more columns involved , the more unstable a fracture is.

Magerl-Classification Another important concept is Magerl’sground-breaking classification of thoracolumbar fractures based on the mechanism of injury. It is important to consider spine fractures together with an associated dislocation.

Type A: Compression Injury
A1: Mild Compression Fracture
A2: Split Fracture
A3: Burst Fracture

Type B: Distraction Injury
B1: Unilateral Facet Fracture/dislocation
B2: CHANCE-fracture: 3 types: Bony, Ligamentous, Mix
B3: Bilateral facet fracture/Dislocation

Type C: Translational Injury
C1: Anteroposterior dislocation
C2: Lateral dislocation
C3: Rotational Dislocation

With the above 3-column-theory and Magerl’s Classification of the mechanism of injury, thoracolumbar fracture/dislocations can be easily classified and be treated thereafter. The above simplifies the communication between the physicians in respect to the type of injury.

Etiology (cause) of the fractures. Traumatic fractures secondary to trauma Pathological fractures, secondary to malignancy. Osteoporotic Fractures secondary to Osteoporosis/Osteopenia. The decision to surgically intervene depends on the stability of the spinal column and involvement of the spinal cord. Most compression fractures do not require intervention and will heal over time as the bone remodels. Bracing (Orthosis) is optional. Burst fractures can be treated conservatively or with surgery depending on degrees of the burst-component, high-loss of the column, kyphotic deformation of the column and presence of posterior element injury. Chance fractures except for non-displaced bone-chance fracture, bilateral facet fractures/dislocations and all translational fracture-dislocation often require surgery to provide greater integrity to the spine and to ensure proper healing. In addition, fractured bone may impinge on the spinal cord and cause neurologic deficits, in which case surgery is emergent. Often, fixation and fusion will be required classically 2 levels above and below the affected segment. If a fracture between a stable segment such as the thoracic and a mobile segment such as cervical or lumbar, the fixation/fusion needs to be 2 levels beyond the transition of the cervico-thoracic and thoracic-lumbar segment. Pedicle screws can add greater support to the fusion. Lateral masses are larger than the pedicles in C1 and C3-6 and are usually used. C2’s pars interarticularis is large and can be used for screw fixation. Corpectomy/Vertebrectomy may be required to resect a severely injured body, especially if the thecal sac is compressed by bone fragment. Bracing may be recommended following surgery.

Sacral Fractures
Fractures of the sacrum are associated with pelvic injuries and usually caused by high-energy, traumatic accidents. Pelvic insufficiency fractures can be seen in older women, especially with osteoporosis. The Denis Classification System is used to assess the stability and extent of neural involvement in sacral fractures.

Case courtesy of Dr Matt Skalski, Radiopaedia.org. From the case rID: 23215

As illustrated above, zone 1 fractures occur lateral to the neural foramina. In zone 2 fractures the neural foramina is involved, but not the spinal canal. Zone 3 fractures are medial to the neural foramina and involve the spinal canal. Zone 3 fractures are sub-divided into 4 different types:
type 1: only kyphotic angulation at the fracture site (no translation)
type 2: kyphotic angulation with anterior translation of the distal sacrum
type 3: kyphotic angulation with complete offset of the fracture fragments
type 4: comminuted S1 segment, usually due to axial compression

Zone 3 fractures have the highest rate of neurologic deficit and may affect bowel and bladder continence or cause sexual dysfunction. These complications may be seen in up to 60% of patients. Zone 2 fractures may be stable or unstable but have increased risk of nonunion and poor functional outcome relative to zone 1 fractures. Zone fractures are associated with nerve injury in only 5% of patients. Typically the L5 nerve root is involved.

Most sacral fractures resolve non-operatively. In those with fracture displacement >1 cm, soft tissue compromise, persistent pain, and neural deficit, surgical intervention may be considered. Closed or open reduction and internal fixation may be undergone with neural decompression as needed.

Coccygeal Fractures
Coccygeal fractures occur following damage to the coccyx, or “tailbone,” of the spine. These may happen as a result of trauma or following childbirth. Risk factors include reduced muscle mass, elderly age, osteoporosis, female gender, and participation in certain activities such as skating. Symptomatic presentation includes localized pain that increases in severity while sitting or rising from a chair, or during bowel movements. Bruising or edema may be observed over the coccyx. Abnormal coccygeal movement may be palpated during a rectal exam by a physician. X-rays may or may not be required for diagnosis.Surgery is rarely required for treatment, only for displaced fractures. Conservative management with use of a donut cushion for sitting is recommended. References Baaj AA, Mummaneni PV, Uribe JS, Vaccaro AR, Greenberg MS. Handbook of Spine Surgery. 2nd Ed. New York: Thieme Medical Publishers, 2016. Kyphoplasty for compression fractures Compression fracture of vertebra is the collapse of vertebral body of spine. These compression fractures of thoracolumbar spine are the most common in elderly and occur in approximately 25% of all postmenopausal women during their lifetime in United States3. Approximately 1.5 million compression fractures of vertebra occur annually in general US population4. The most common cause of vertebral compression fracture is osteoporosis but it can also be caused by trauma, infection, and tumor of spine. Vertebral compression fracture can lead to acute or chronic back pain. Depending on the intensity of your pain, your physician can recommend vertebral kyphoplasty which is a minimally invasive procedure and can be performed under local or general anesthesia. In this procedure, your surgeon will make two small incision in your back through which two specialized tubes are inserted directly into fractured vertebral body. Though each tube, a balloon is inserted on each side and then they are inflated to expand the collapsed vertebral body and to re-establish its original height. This expansion will create an empty space within the vertebral body. Once the desired height is achieved, the balloons are deflated and removed from the body. Subsequently your surgeon will inject highly viscous bone cement which is made of methylmethacrylate. This bony cement will act as an adhesive to stabilize the vertebral body and to prevent the vertebral body from collapse.

References

  1. Baaj AA, Mummaneni PV, Uribe JS, Vaccaro AR, Greenberg MS. Handbook of Spine Surgery. 2nd Ed. New York: Thieme Medical Publishers, 2016.

Spine Tumors

Primary Spine Tumors

Primary spinal tumors may be benign or malignant. Benign causes include vertebral hemangioma, osteoid osteoma, osteoblastoma, aneurysmal bone cyst, osteochondroma, and giant cell tumors of the bone. Malignant tumors include chondrosarcoma, chordoma, and osteogenic sarcoma. Osteoid osteomas and osteoblastomas should be completely excised for cure. Surgical resection may also be attempted for malignant lesions, although prognosis is generally poor and recurrence rate is high. Aneurysmal bone cysts and giant cell tumors can be treated via intralesional curettage.

Metastatic Spine Tumors

Metastatic tumors are the most common malignancy of the spine. The spine has a rich vascular supply that is prone to hematogenous spread from a primary tumor site, including lung, breast, and prostate. Metastatic disease may be found in all spinal compartments but is most often in the extradural space. Prostate and breast cancer may be osteolytic (bone destructive) or osteoblastic (growth stimulating). Lymphoma and lung metastases are osteolytic. Metastatic tumors can cause pathologic vertebral fractures. Decision to operate depends on primary disease progression and spinal stability. In a patient with low disease burden and high quality of life, surgical resection and spinal fusion may be undergone to reverse or limit neurologic deficit and ensure spinal integrity. In a patient with high disease burden and poor prognosis, surgical intervention will be limited, with the goal of providing palliative treatment.

Extradural SpineTumors

The extradural space, outside the spinousdura, is the most common location for spinal tumors, where they may arise in the vertebral bodies or epidural tissues. These comprise 50% of all spinal tumors. They typically arise from the osseous spine, intervertebral discs, and adjacent soft tissues. On imaging, the hallmark is focal displacement of the thecal sac away from the mass. The most common extradural tumors are metastatic, as discussed above. Benign tumors include hemangioma, osteoid osteoma, and osteochondroma. Cysts and other benign tumor-like masses include eosinophilic granuloma, epidural lipomatosis, synovial cysts, and arachnoid cysts. Malignant tumors include chordoma, lymphoma, osteosarcoma, chondrosarcoma, plasmacytoma (as in multiple myeloma), and metastatic disease. The most common presenting symptom for all extramedullary tumors is local pain. Depending on extension, compression of the spinal cord or nerve roots may cause radiculopathy or neurologic deficit. Extradural tumors are amenable to surgical resection, which is recommended to provide symptomatic relief. Adjuvant radiation therapy and/or chemotherapy is recommended for malignant lesions.

Intradural Extramedullary Spinal Cord tumors

This is the second most common location for spinal tumors, where lesions may arise in the leptomeninges or nerve roots. Although these masses are located within the dural sheath, they are outside the spinal cord.Intraduralextramedullary spinal cord tumors make up 40% of all spinal masses. The most common tumor types are meningiomas and neurofibromas, both of which are benign. Symptoms include local or radicular pain, motor deficits, or sensory symptoms. Sphincter disturbance is rare. Spinal schwannomas, sporadic or associated with neurofibromatosis, are benign, slow-growing, and typically intradural. Patients present with local pain and do not develop neurologic deficits until late. In general, tumors producing neurologic symptoms should be surgically resected. For schwannomas specifically, depending on degree of nerve root involvement, the entire nerve root may have to be sacrificed. For benign tumors, recurrence is rare following gross total excision.

Intradural Intramedullary Spinal Cord Tumors

Tumors arising in the spinal cord substance are rare, comprising only 5% of spinal tumors. They can produce devastating sympoms due to white matter tract and grey matter destruction. Lesion types most commonly include astrocytoma and ependymoma. Others may be malignant glioblastoma, dermomid, epidermoid, teratoma, lipoma, or hemangioblastoma.

Ependymomas are the most common glioma of the lower spinal cord, conus, and filum and typically present in adults. They are benign and slow-growing. MRI with contrast should be used to evaluate the entire spinal cord due to CSF seeding. Gold-standard treatment is surgical excision.

For all of the aforementioned tumor types, pain — local or radicular — is the most common presenting complaint. Other symptoms include weakness or sensory loss. Asymptomatic lesions should be monitored with imaging. MRI is recommended. Total excision should be attempted for symptomatic lesions at symptom onset. Gross total resection may be attempted for low-grade astrocytomas with a plane of separation from the spinal cord. For high-grade astrocytomas and/or those without a plane of separation, biopsy alone or limited excision only is recommended. Radiation therapy, with or without chemotherapy, is suggested for high-grade astroctyomas.

Vascular Disorders of the Spine

Most vascular disorders of the spine are due to ischemia or malformations. The posterior third of the spine is supplied by the posterior spinal arteries, while the anterior spinal artery (ASA) supplies the anterior two-thirds of the spine. The ASA receives sparse collateral circulation. The artery of Adamkiewicz, a branch off the aorta, provides circulation at the T8-L1 level through the conusmedullaris. Damage to this artery results in ASA syndrome, characterized by complete motor paralysis below the level of the lesion, loss of pain and temperature sensation at and below the lesion level, and retained proprioception and vibratory sensation. Infarcts are usually caused by aortic insufficiency, including aortic aneurysms, dissections, trauma, atherosclerosis, and surgery. ASA syndrome has poor prognosis and functional recovery. Treatment is supportive.

Vertebral body hemangiomas are the most common primary spine tumor. They are benign and rarely symptomatic, usually requiring no treatment. For those that present symptomatically, treatment options include radiation therapy, embolization, vertebroplasty, or surgery, as a last resort. Other spinal vascular disorders include spinal arteriovenous malformations (AVMs) and arteriovenousfistuals (AVFs), and, rarely, spinal cord cavernomas and venous angiomas.

Spinal Arteriovenous Malformations (AVMs)

Spinal vascular malformations comprise approximately 4% of all primary intraspinal masses. Malformations of the spine include spinal arteriovenous malformation (AVM) and spinal duralarteriovenous fistula (AVF). Spinal AVF is the most common type of spinal vascular malformation in adults and are usually located in the lumbar or lower thoracic spine. AVFs are fed by the radicular artery, forming a fistula at the dural root sleeve and draining into an engorged spinal vein on the posterior cord. Symptoms include low back pain and progressive myeloradiculopathy or caudaequina syndrome. Spinal AVMs have the same pathology as cerebral AVMs, wherein arteries drain into veins without intervening capillaries. They are rare lesions that may occur on, in, or near the spinal cord. Symptoms usually arise acutely from hemorrhage, typically progressive neurologic deficit.

Spinal AVMs may be classified into 4 types:

  • type I: single coiled vessel (dural AV fistula)
  • type II: intramedullary glomus AVM
  • type III: juvenile
  • type IV: intraduralperimedullary (AV fistula)
  • sub-type I: single arterial supply (ASA), single small fistula, slow ascending perimedullary venous drainage
  • sub-type II: multiple arterial supply (ASA and PSA), multiple medium fistulae, slow ascending perimedullary venous drainage
  • sub-type III: multiple arterial supply (ASA and PSA), single giant fistula, large ectatic venous drainage

Individuals with both spinal AVFs and AVM should undergo angiography for pre-treatment planning. AVFs are usually amenable to endovascular techniques using glue but must be
completely occluded to prevent recurrence. Surgery is most commonly used for resection of AVMs, especially those that have hemorrhaged, intradural AVMs, and those that compress the spinal cord.

References

  1. Doppman JL, Di chiro G, Oldfield EH. Origin of spinal arteriovenous malformation and normal cord vasculature from a common segmental artery: angiographic and therapeutic considerations. Radiology. 1985;154 (3): 687-9