VIRGINIA BRAIN & SPINE CENTER
Close-up of large MCA aneurysm on Angiogram
Large MCA aneurysm on Angiogram
Large MCA aneurysm on MRA
CT of the brain with subarachnoid hemorrhage
Carotid angiogram with ICA stenosis
Normal carotid angiogram
Angiogram of the Posterior Cerebral Circulation (left side only)
Carotid arteries on CTA
Postop Angiogram with coils filling aneurysm
Postop Carotid Angiogram
Preop Carotid CTA
Large MCA aneurysm on MRI
Large MCA aneurysm on CT
MRI of the brain demonstrating new strokes
Angiogram of the Anterior Cerebral Circulation (left side only)
Carotid artery on Angiogram
Preop Angiogram of Basilar Tip Aneurysm
Large MCA aneurysm following clip placement
Normal CT of the brain
The head receives blood from the heart through four main blood vessels in the neck. Two carotid arteries, one on each side, ascends in the front of the neck and two vertebral arteries, one on each side, ascends in the back of the neck. The common carotid artery splits into an external carotid artery that supplies the face and scalp primarily and an internal carotid artery that supplies the brain. The vertebral arteries join to form the basilar artery which supplies the cerebellum, brain stem, and other back portions of the brain. The basilar artery and internal carotid arteries terminate and split into the cerebral arteries that supply blood to specific parts of the brain.
The carotid arteries are the primary source of blood to the majority of the brain except for the cerebellum, the brain stem, and parts of the occipital lobe. The common carotid artery (CCA)can be palpated, or felt, with gentle pressure on the side of the neck. The common carotid artery splits in the neck to form the external carotid artery (ECA) and the internal carotid artery (ICA). The external carotid artery primarily supplies blood to the face and scalp while the internal carotid artery primarily supplies blood to the brain. There is a lot of collateral, or overlapping, flow however. The internal carotid artery enters the skull and terminates in the anterior cerebral artery (ACA) and middle cerebral artery (MCA). The split in the common carotid artery into the internal and external carotid arteries is a common site for carotid stenosis. The split in the internal carotid into the anterior and middle cerebral arteries is a common site for cerebral aneurysms.
The cerebral arteries supply blood to the entire brain. There are four main blood vessels that travel in the neck that supply blood to the cerebral arteries. In the front of the neck, are the twointernal carotid arteries that contribute to the anterior circulation of the brain and in the back of the neck are two vertebral arteries that contribute to the posterior circulation. The internal carotid artery enters the skull and splits into an anterior cerebral artery and a middle cerebral artery. The two vertebral arteries enter the skull and join together to form the basilar artery. The basilar artery then splits into the two posterior cerebral arteries. There is significant collateral, or overlapping, flow among the different arteries.
The anterior cerebral arteries supply the medial portion of the front half of the brain. The most important part of the cortex in this area is the area that controls motor strength to the legs. Lack of blood flow through the anterior cerebral arteries can therefore result in a stroke causing weakness in the leg.
The middle cerebral arteries supply the blood to the cerebral cortex other than the very medial portions. The most important parts of the brain in this area are those that contribute to motor strength to the body and language functions. Lack of blood flow through the middle cerebral artery can therefore result in a stroke causing weakness or problems with language.
The posterior cerebral arteries supply the medial portion of the back half of the brain and part of the deep nuclei. The most important part of the cortex in this area is the primary vision area. Lack of blood flow through the posterior cerebral artery can therefore result in partial vision loss.
The basilar artery supplies the brain stem and cerebellum. Lack of blood through the basilar artery and its branches can result in devastating neurological symptoms due to a stroke in the brain stem.
Carotid stenosis is narrowing of a blood vessel such that blood flow is significantly decreased to the brain. The most common cause of this is atherosclerosis. Atherosclerosis is the build-up of fat, cholesterol, and calcium along the inside wall of the blood vessel. Factors that contribute to atherosclerosis include smoking, diabetes, and hypercholesterolemia (high cholesterol). Platelets in the blood can attach to this plaque and cause further obstruction of blood flow. Pieces of the plaque can break off and cause a stroke. A stroke is a sudden loss of blood flow to a portion of the brain that results in loss of neurological function. If the symptoms last less than 24 hours then this is called a transient ischemic attack (TIA or "mini-stroke"). Common neurological symptoms of a stroke or TIA include sudden loss of strength or strange sensations on one side of the body, difficulty talking, or loss of vision in one eye.
Carotid stenosis can be found after symptoms of a stroke or on a screening exam or test before symptoms have occurred. The diagnosis is made with an imaging study that demonstrates decreased blood flow through the carotid artery. Imaging studies include carotid ultrasound, CT angiogram, MR angiogram, or conventional angiogram. A brain MRI is performed to make the diagnosis of a stroke.
Treatment for carotid stenosis includes medical management, carotid endarterectomy, orcarotid stenting. In patients without a history of stroke or TIA, the risk of having a stroke in the five years following diagnosis is about 11%. A carotid endarterectomy can reduce this risk by greater than 50% and is considered the standard first line treatment option for most patients. Medical management is generally reserved for those patients who are too sick to tolerate surgery. In patients with a history of stroke or TIA, the risk of having a stroke in the five years following diagnosis is about 26%. A carotid endarterectomy can reduce the risk by almost 66% and is considered the standard first line treatment option for most patients. Carotid stenting is a new minimally invasive technology that is an option for patients with symptomatic carotid stenosis who can not tolerate general surgery.
A cerebral aneurysm is an abnormal dilation within a blood vessel that is prone to rupture over time. An aneurysm tends to occur at points where a blood vessel splits into two smaller vessels causing turbulent flow of blood hitting the blood vessel wall. Most aneurysms occur randomly in the population but there are several risk factors including a strong family history, high blood pressure, smoking, and drug use (cocaine). The risk of rupture is between 0.05% and 2% per year depending on size of the aneurysm, location, and specific anatomical features. When an aneurysm ruptures, blood is released around or into the brain causing a subarachnoid hemorrhage. This is a life-threatening event that requires immediate treatment and monitoring within an intensive care unit at a hospital with neurosurgery capabilities. Up to 50% of hemorrhages are fatal. Some aneurysms will be found before they rupture due to headaches or mass effect on surrounding structures. Those that rupture most commonly present with "the worst headache of my life". This may be associated with nausea, sensitivity to light and sounds, or neurological deficits. If the amount of bleeding is significant then it can cause loss of consciousness and even death before arrival to the hospital.
The diagnosis of a ruptured cerebral aneurysm is made based on the history and imaging studies. a CT scan is most often obtained first that will demonstrate blood around the bottom surface of the brain (subarachnoid hemorrhage). Rarely, very large aneurysms can be directly seen on a CT or MRI (see below). If the patient presents several days after the aneurysm ruptured then the CT scan may be negative for subarachnoid hemorrhage. In this case, a lumbar puncture may be performed. A needle is placed within the cerebrospinal fluid space in the back and evidence of prior bleeding within the fluid is found.
If hemorrhage is confirmed or strongly suspected, a study is obtained to find the suspected aneurysm. This is most commonly done with either a CT angiogram, MR angiogram, or aconventional angiogram. These studies look at the blood vessels within the brain and will demonstrate any abnormalities present. A conventional angiogram involves accessing an artery within the leg and sending a catheter within the blood vessels up to the head. Dye is then injected within the blood vessels and then visualized with a series of xrays.
Following a ruptured cerebral aneurysm, a patient is at risk for several major complications related to the bleeding in the head. The first risk is that the aneurysm can re-rupture. This is typically a devastating event that is a significant risk in the few days following presentation. Up to 50% of aneurysms will re-rupture within six months if they are not treated. There are two treatment options to prevent an aneurysm from rebleeding. The standard treatment is acraniotomy for clip ligation of the aneurysm. The aneurysm is exposed and a titanium clip is secured around the neck where it originates from the blood vessel in order to prevent blood from entering it. An alternative treatment is endovascular coiling. This minimally invasive procedure involves filling the aneurysm with tiny coils from inside the blood vessel in order to prevent blood from entering it. The specific procedure that is best in each situation depends on the medical status of the patient and anatomical configuration of the aneurysm.
Once the aneurysm is treated there are still significant risks to the patient. The blood that ruptured around the brain is very irritating to the normal blood vessels. This may causevasospasm in which the blood vessels clamp down and decrease blood flow to the brain. This typically is a significant risk for up to two weeks following a ruptured aneurysm. This is monitored closely with serial neurological assessments to detect new symptoms. The vessels can also be monitored with transcranial doppler (TCD) ultrasound. This is a noninvasive way to monitor the flow of blood through the blood vessels in the head. Vasospasm can be treated by keeping a patient well-hydrated, pushing blood pressure higher, and, if necessary, angioplasty. This involves taking the patient back for an angiogram and injecting medicines directly within the blood vessels that will dilate them back open. If vasospasm is severe and unresponsive to treatments then it can cause a stroke.
The ruptured blood can also obstruct the normal circulation of cerebrospinal fluid within and around the brain. This can result in hydrocephalus which is a buildup of cerebrospinal fluid within the normal fluid spaces of the brain. This buildup of fluid can put significant pressure on the normal brain and become life threatening. Hydrocephalus can be treated by placing a drainage tube into the fluid space and allowing the fluid to collect in a drainage bag outside of the head. This is a minor surgical procedure that is often performed at the bedside. If the fluid does not begin to circulate normally on its own then the patient may be taken to the operating room for a permanentventriculoperitoneal shunt (VPS). A VPS involves tunneling a catheter under the skin to allow drainage from the fluid space within the brain to the fluid space within the abdominal cavity.
A number of medical complications can also occur due to the stress of a ruptured aneurysm. It is very common for the heart to have problems although this is most commonly a temporary problem. The heart can be "stunned" and cause heart failure or a heart attack can occur. The patient may have trouble breathing due to loss of consciousness and need ventilator assistance. General medical problems are prone to occur in this situation including pneumonia and blood clots in the legs.
In general, the status of the patient when they present with symptoms is one of the best prognostic indicators of how they will do in the long run. Roughly 60% of patients that present to the hospital will have a good long-term outcome. Further monitoring as an outpatient will be required to confirm that the aneurysm does not recur.
Cerebral Arterio-Venous Malformations (AVM)
A cerebral AVM is an abnormal collection of blood vessels within the brain. Arteries connect directly to veins without the usual intervening capillaries that slows blood flow - this results in high flow within the relatively weaker veins. These are congenital lesions, meaning people are born with them. They can vary in size and symptoms. The biggest concern is that they can spontaneously hemorrhage with a 2-4% risk of bleeding per year. 50% of patients with an AVM will present with a hemorrhage. AVM may also present with seizures or from mass effect on the brain. An AVM may be identified on CT or MRI but is often best characterized with a conventional angiogram. Treatment will depend on the size and location of the AVM, age and medical health of the patient, and whether there are symptoms or a history of hemorrhage from the AVM. Treatment options include observation with serial imaging, embolization, radiosurgery, and surgical resection.
Carotid Endarterectomy (CEA)
A carotid endarterectomy is performed to remove a plaque that is causing carotid stenosis. This surgery is recommended to decrease the risk of having a stroke in the future. A CEA involves making an incision in the front of the neck in order to expose the common carotid artery where it splits into the internal and external carotid artery. The arteries are clamped and blood is temporarily stopped from flowing through the segment that has the plaque. Anelectroencephalogram (EEG) is performed during the surgery to monitor for any changes in brain function while the arteries are clamped. An EEG involves placing probes on the scalp that detect electrical current within the brain. If there are significant decreases in the EEG then blood flow can be restored with a shunt, or rubber tube, during removal of the plaque. Patients can be admitted for surgery on the same day if they are not already in the hospital. They will typically spend one night in the ICU or stepdown unit to monitor for bleeding and blood pressure. Most patients will go home the day following surgery.
Alternatives: Depending on the clinical situation, there may be alternative surgical or non-surgical therapies for the management of carotid stenosis. Treatment may include:
Goals: Based on the diagnosis and symptoms, surgery may be recommended. The goals of surgery are:
Benefits: The benefits include:
Risks: Surgery is a big decision and not recommended lightly. In general, surgery is recommended when the benefits far exceed the expected risks of the procedure. The possible risks may include:
Adverse reaction to anesthesia
Myocardial infarct (heart attack)
Deep venous thrombus or pulmonary embolus
Nerve injury causing weakness of the jaw or tongue or hoarseness
Failure to relieve symptoms
Recurrence of carotid stenosis
Outcomes: No guarantees can be made regarding the outcome following any surgery. However, patients tend to do very well following a carotid endarterectomy. Major complications are very rare. Most patients experience some degree of sore throat or difficulty swallowing for a few days to few weeks following surgery. Most patients spend 1-3 days in the hospital. Light activity is recommended for a few weeks following surgery. Most patients will remain on aspirin following surgery. The risk of stroke is cut by more than 50% compared to best medical therapy alone. Further outpatient studies will be required to monitor for recurrence of carotid stenosis.
Craniotomy for Aneurysm
A craniotomy is an open exposure of the brain in order to operate on it. This involves making an incision in the skin and removing a portion of the skull. The dura, or membrane surrounding the brain, is opened and the brain is directly visualized. The blood vessels where aneurysms occur are commonly along the bottom surfaces of the brain. The natural fissures, or separations, between the lobes of the brain are dissected open and the aneurysm is exposed without actually going through the brain tissue. The aneurysm is very carefully exposed in this fashion and a titanium clip is placed around the neck of the aneurysm where it originates from the blood vessel. When surgery on the aneurysm is completed, the surrounding membrane is closed and the bone that was removed is returned to its original position and fastened in place with titanium plates and screws. The skin is typically closed with staples or sutures and gauze wrap is placed around the head. Computer image guidance is sometimes used to create a smaller incision and to help guide the surgery. Computer image guidance involves creating a three-dimensional representation of the patient's head and brain using MRI or CT images.
Following the craniotomy, a patient will spend at least one night in the Intensive Care Unit for close neurological monitoring. If the aneurysm had ruptured before surgery then the patient will be in the ICU for a full two weeks in order to monitor for vasospasm and other complications ofsubarachnoid hemorrhage. If there are no complications, a patient may be discharged from the hospital as early as 2-3 days following a craniotomy for an unruptured aneurysm. Most patients will be placed on a tapering dose of a steroid to minimize swelling and another medicine to prevent seizures.
A craniotomy is generally a safe procedure and outcomes are often more related to how a patient is doing before the surgery. The risk of a major complication following most craniotomy cases is relatively low compared to the risk of not treating the aneurysm. The major risk of surgery is rupture of the aneurysm during surgery and stroke. Other risks include infection or bleeding in the brain, seizure, or new neurological deficits. There are specific risks that depend on the specific part of the brain and blood vessels involved and some cases obviously have higher risks than others. The risk of recurrence following clipping of an aneurysm is extremely low. The ability to clip an aneurysm depends on the specific anatomy of the patient and the aneurysm itself. Some aneurysms may be easier to treat with endovascular coiling.
Endovascular Coiling for Aneurysm
Endovascular coiling of an aneurysm involves accessing the femoral artery in the leg in order to image and treat blood vessel abnormalities in the head from within the blood vessel. Special guidewires and catheters are snaked through the arterial system and into the cerebral arteries. Tiny coils are then packed into the aneurysm from within the blood vessel in order to prevent blood flow in the aneurysm. The risk of a major complication following endovascular coiling is relatively low compared to the risk of not treating the aneurysm. The ability to coil an aneurysm depends on the specific anatomy of the patient and the aneurysm itself. The risk of incomplete filling or recurrent filling of the aneurysm are higher than with open craniotomy for clipping of the aneurysm. However, endovascular coiling is an easier procedure to tolerate for sick patients and some aneurysms are easier to treat in this fashion. The decision to treat an aneurysm with clipping versus coiling is made jointly between the treating neurosurgeon and interventional neurologist.
Surgery for an AVM involves performing a craniotomy to remove the abnormal cluster of blood vessels within the brain. A craniotomy is an open exposure of the brain in order to operate on it. This involves making an incision in the skin and removing a portion of the skull. The membrane surrounding the brain is opened and the brain is directly visualized. When surgery on the brain is completed, the surrounding membrane is closed and the bone that was removed is returned to its original position and fastened in place with titanium plates and screws. The skin is typically closed with staples or sutures and gauze wrap is placed around the head. Computer image guidance is typically used to create a smaller incision and to help guide the surgery. Computer image guidance involves creating a three-dimensional representation of the patient's head and brain using MRI or CT images.
Following a craniotomy, a patient will spend at least one night in the Intensive Care Unit for close neurological monitoring. If there are no complications, a patient may be discharged from the hospital as early as 2-3 days following a craniotomy. Most patients will be placed on a tapering dose of a steroid to minimize swelling and another medicine to prevent seizures. An angiogram will often be obtained after the surgery to confirm that there are no abnormal blood vessels remaining which would continue to have a risk of hemorrhage.
A craniotomy is generally a safe procedure and outcomes are often more related to how a patient is doing before the surgery. The risk of a major complication following most craniotomy cases is well under 5% overall. These risks include infection or bleeding in the brain, stroke, or new neurological deficits. There are specific risks that depend on the specific part of the brain being operated on and some cases obviously have higher risks than others. Special techniques are often employed for areas that are considered "eloquent" such as those for language or motor functions. The risks of having a neurological complication following surgery for an AVM is directly related to the size of the AVM, the location, and how the veins drain within the brain. There is a 5 point grading scale (The Spetzler-Martin Grade) that helps determine whether surgery is the best option. In general, grade 1 and 2 lesions are best treated with surgery and grade 4 or 5 lesions are high risk and surgery is often avoided. Grade 3 lesions may or may not benefit from surgery.