Cerebrovascular Disease

Cerebrovascular refers to blood flow within the brain. Cerebrovascular disease includes all disorders in which an area of the brain is temporarily or permanently affected by bleeding or lack of blood flow. Cerebrovascular diseases included stroke, carotid stenosis, vertebral stenosis and intracranial stenosis, aneurysms and vascular malformations.

Restrictions in blood flow may occur from vessel narrowing (stenosis), clot formation (thrombosis), blockage (embolism), or blood vessel rupture (hemorrhage). Lack of sufficient blood flow (ischemia) affects brain tissue and may cause a stroke.

Cerebrovascular Disease Statistics

  • Stroke is the third leading cause of death in the United States. Of the more than 700,000 people affected every year, about 500,000 of these are first attacks, and 200,000 are recurrent. About 25 percent of people who recover from their first stroke will have another stroke within five years.
  • Stroke is a leading cause of serious long-term disability.
  • Each year, an estimated 30,000 people in the United States experience a ruptured cerebral aneurysm and as many as 6 percent may have an unruptured aneurysm.

Cerebrovascular Diagnostic Tests

The majority of cerebrovascular problems can be identified through diagnostic imaging tests. These tests allow vascular specialists to view the arteries and vessels in and around the brain and the brain tissue.

Cerebral angiography: Arteries are not normally seen in an X-ray, so contrast dye is used to view them. The patient is given a local anesthetic, the artery is punctured, usually in the leg, and a needle is inserted into the artery. A catheter (a long, narrow, flexible tube) is inserted through the needle and into the artery. It is then threaded through the main vessels of the abdomen and chest until it is properly placed in the arteries of the neck. This procedure is monitored by a fluoroscope (a special x-ray that projects the images onto a TV monitor). The contrast dye is then injected into the neck area through the catheter, and x-ray pictures are taken.

Carotid duplex (doplar ultrasound): In this procedure, ultrasound is used to help detect plaque, blood clots, or other problems with blood flow in the carotid arteries. There are no known risks and this test is noninvasive and painless.

CT Scan: A diagnostic image created after a computer reads x-rays. In some cases, a medication will be injected through a vein to help highlight brain structures. Bone, blood and brain tissue have very different densities and can easily be distinguished on a CT scan. A CT scan is a useful diagnostic test for hemorrhagic strokes because blood can easily be seen. However, damage from an ischemic stroke may not be revealed on a CT scan for several hours or days and the individual arteries in the brain cannot be seen. CTA allows clinicians to see blood vessels of the head and neck and is increasingly being used instead of an invasive angiogram.

Electroencephalogram (EEG): A diagnostic test using small metal discs (electrodes) placed on a person’s scalp to pick up electrical impulses. These electrical signals are printed out as brain waves.

Lumbar puncture (spinal tap): An invasive diagnostic test that uses a needle to remove a sample of cerebrospinal fluid from the space surrounding the spinal cord. This test can be helpful in detecting bleeding caused by a cerebral hemorrhage.

Magnetic Resonance Imaging (MRI): A diagnostic test that produces three-dimensional images of body structures using magnetic fields and computer technology. It can clearly show various types of nerve tissue and clear pictures of the brain stem and posterior brain. MRI of the brain can help determine whether there are signs of prior mini-strokes. This test is noninvasive, although some patients may experience claustrophobia in the imager.

Cerebral Magnetic Resonance Angiogram (MRA): This is a noninvasive study which is conducted in a Magnetic Resonance Imager (MRI). The magnetic images are assembled by a computer to provide an image of the arteries located in a patient’s head and neck. The MRA shows the actual blood vessels in the neck and brain and can help detect blockage and aneurysms.

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Stroke

Stroke is an abrupt interruption of the constant blood flow to the brain that causes loss of neurological function.& The interruption of blood flow can be caused by a blockage, leading to the more common ischemic stroke, or by bleeding in the brain, leading to the more deadly hemorrhagic stroke.  Ischemic stroke constitutes an estimated 80 percent of all stroke cases.  Stroke may occur suddenly, sometimes with little or no warning, and the results can be devastating.

Stroke Symptoms

Warning signs may include some or all of the following symptoms, which are usually sudden:

  • Dizziness, nausea or vomiting
  • Unusually severe headache
  • Confusion, disorientation or memory loss
  • Numbness, weakness in an arm, leg or the face, especially on one side
  • Abnormal or slurred speech
  • Difficulty with comprehension
  • Loss of vision or difficulty seeing
  • Loss of balance, coordination, or the ability to walk

Types of Stroke and Treatment

Ischemic Stroke
Ischemic stroke is the most common type of stroke, accounting for a large majority of strokes. There are two types of ischemic stroke: thrombotic and embolic. A thrombotic stroke occurs when a blood clot, called a thrombus, blocks an artery to the brain and stops blood flow. An embolic stroke occurs when a piece of plaque or thrombus travels from its original site and blocks an artery. The materials that has moved is called an embolus. How much of the brain is damaged or affected depends on exactly how far downstream in the artery the blockage occurs.

Hemorrhagic Stroke
A hemorrhagic stroke can be caused by hypertension, rupture of an aneurysm or vascular malformation, or as a complication of anticoagulation medications. An intracerebral hemorrhage occurs when there is bleeding directly into the brain tissue, which often forms a clot within the brain. A subarachnoid hemorrhage occurs when the bleeding fills the cerebrospinal fluid spaces around the brain. Both conditions are very serious.

Hemorrhagic stroke usually requires surgery to relieve intracranial pressure caused by bleeding. Surgical treatment for hemorrhagic stroke caused by an aneurysm or defective blood vessel can prevent additional strokes. Surgery may be performed to seal off the defective blood vessel and redirect blood flow to other vessels that supply blood to the same region of the brain.

Recovery and rehabilitation are important aspects of stroke treatment. In some cases, undamaged areas of the brain may be able to perform functions that were lost when the stroke occurred. Rehabilitation includes physical therapy, speech therapy and occupational therapy.

Regardless of what type of stroke has been suffered, it is vital that victims receive emergency medical treatment as soon as possible for the best possible outcomes to be realized.

Transient Ischemic Attack (TIA)
A TIA is a temporary cerebrovascular event that leaves no permanent damage. Usually it entails an artery to the brain is temporarily blocked, causing stroke-like symptoms, but the blockage dislodges before any permanent damage occurs.

Symptoms of a TIA may be similar to a stroke, but they resolve quickly. In fact, symptoms may be so vague and fleeting that people just brush them off, especially when they last just a few minutes. TIA symptoms include:

  • Sudden numbness or weakness of the face, arm or leg, especially on one side of the body
  • Sudden confusion, trouble speaking or understanding
  • Sudden trouble seeing in one or both eyes
  • Sudden trouble walking, dizziness, loss of balance or coordination
  • Sudden, severe headache with no known cause

While there is no treatment for the TIA itself, it is essential that the source of the TIA be identified and appropriately treated before another attack occurs. If you experience TIA symptoms, seek emergency medical help immediately. About 30 percent of all people who suffer a major stroke experience a prior TIA, and 10 percent of all TIA victims suffer a stroke within two weeks. The quicker you seek medical attention, the sooner a diagnosis can be made and a course of treatment started.

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Risk Factors

Although they are more common in older adults, strokes can occur at any age. Stroke prevention can help reduce disability and death caused by the disease. Controllable or treatable risk factors for stroke include:

  • Smoking
  • High blood pressure
  • Carotid of other artery disease
  • History of TIAs
  • Diabetes
  • High blood cholesterol
  • Physical inactivity and obesity
  • Receiving hormone replacement therapy

Uncontrollable risk factors include:

  • Age: People of all ages, including children, have strokes. But the older you are, the greater your risk of stroke.
  • Gender: Stroke is more common in men than in women.
  • Heredity or race: You have a greater risk of stroke if a parent, grandparent, sister or brother has had a stroke. African-Americans have a much higher risk of death from a stroke than Caucasians, partly because they are more prone to having high blood pressure, diabetes and obesity.
  • Prior stroke or heart attack: If you have had a stroke, you are at much higher risk of having another one. If you have had a heart attack, you are also at higher risk of having a stroke.

Carotid Stenosis

The carotid arteries supply oxygen-rich blood to your brain. Plaque forms when the internal carotid arteries become blocked by fat and cholesterol buildup.

Medical Treatment

Treatment is determined by the extent of the narrowing and the condition of the patient.  For many people with arteries narrowed less than 50 percent, medication is prescribed to help reduce the risk of ischemic stroke.  These include medications to control high blood pressure, reduce cholesterol levels, and anticoagulants to thin the blood and prevent it from clotting.

Surgery

Carotid endarterectomy is a procedure in which the surgeon makes an incision in your carotid artery and removes the plaque using a dissecting tool. Removing the plaque is accomplished by widening the passageway, which helps to restore normal blood flow. Your artery will be repaired with sutures or a patch. The entire procedure usually takes about one or two hours.

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Carotid Angioplasty and Stenting

An alternative form of treatment is available for patients who may be at too high of a risk to undergo surgery. Carotid stenting is a procedure in which a tiny, slender metal-mesh tube is fitted inside your carotid artery to increase the flow of blood blocked by plaque. The stent is inserted after an angioplasty procedure, in which the doctor guides a balloon-tipped catheter into your blocked artery. The balloon is inflated and pressed against the plaque, flattening it and re-opening the artery. The stent acts as scaffolding to prevent the artery from collapsing or from closing up again after the procedure is completed.

Cerebral Aneurysms

A cerebral (or cranial) aneurysm is an area where a blood vessel in the brain weakens, resulting in a bulging or ballooning out of part of the vessel wall. Usually, aneurysms develop at the point where a blood vessel branches, because the “fork” is structurally more vulnerable. The disorder may result from congenital defects or from other conditions such as high blood pressure, atherosclerosis (the buildup of fatty deposits in the arteries), or head trauma.

Aneurysms occur in all age groups, but the incidence increases steadily for individuals age 25 and older, is most prevalent in people ages 50 to 60, and about three times more prevalent in women. The outcome for patients treated before a ruptured aneurysm is much better than for those treated after, so the need for adequate evaluation of patients suspected of having a cerebral aneurysm is very important.

Unruptured cerebral aneurysms can be detected by noninvasive measures, include MRA and a carotid angiogram. A rupture can be detected by a CT scan or lumbar puncture. If these tests suggest the presence of an aneyrysm, formal cerebral angiography may be performed.

People who suffer a ruptured brain aneurysm may have some or all of these warning signs: localized headache, nausea and vomiting, stiff neck, blurred or double vision, sensitivity to light (photophobia), or loss of sensation. Many people with unruptured brain aneurysms have no symptoms. Others might experience some or all of the following symptoms, which may be possible signs of an aneurysm: cranial nerve palsy, dilated pupils, double vision, pain above and behind eye, and localized headache.

When cerebral aneurysms rupture, they usually cause bleeding in the brain, resulting in a interacranial hematoma (a blood clot).. Blood can also leak into the cerebrospinal fluid (CSF) or areas surrounding the brain and cause a subarachnoid hemorrhage. Blood can irritate, damage, or destroy nearby brain cells. This may cause problems with bodily functions or mental skills. In more serious cases, the bleeding may cause brain damage, paralysis or coma. Ruptured brain aneurysms are fatal in about 50 percent of cases.

Surgery

An operation to "clip" the aneurysm is performed by doing a craniotomy (opening the skull surgically), and isolating the aneurysm from the bloodstream using one or more clips, which allows it to deflate. Surgical repair of cerebral aneurysms is not possible if they are located in unreachable parts of the brain. Angiography is used to visualize closure of the aneurysm and preserve normal flow of blood in the brain.

A less invasive technique which does not require an operation, called endovascular therapy, uses micro catheters to deliver coils to the site of the enlarged blood vessel that occludes (closes up) the aneurysm from inside the blood vessel. A procedure called balloon assisted coiling uses a tiny balloon catheter to help hold the coil in place. A procedure called combination stent and coiling utilizes a small flexible cylindrical mesh tube that provides a scaffold for the coiling. Aneurysms may be treated with endovascular techniques when the risk of surgery is too high.

While the best method of securing the aneurysm should be made on an individual basis, in general, patients with a ruptured cerebral aneurysm should be treated as soon as possible. Surgical risks and outcomes depend on whether or not the aneurysm has ruptured, the size and location of the aneurysm, and the patient’s age and overall health.

Post-surgical complications can include vasospasm and hydrocephalus. Vasospasm is a sudden constriction of a blood vessel that reduces the blood flow. Hydrocephalus is a condition in which excess cerebrospinal fluid (CSF) builds up within the ventricles (fluid-containing cavities) of the brain and may increase pressure within the head.

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Vascular Malformations

The term vascular malformation refers to an abnormal connection of an artery, vein, or both. These include malformations of normal veins or arteries leading directly to veins. Vascular malformations are formed as the blood vessels in the brain develop during pregnancy, but the direct cause is unknown.

Arteriovenous malformations (AVMs)

An AVM is a tangle of abnormal and poorly formed blood vessels (arteries and veins), with a higher rate of bleeding than normal vessels. AVMs can occur anywhere in the body, but brain AVMs present substantial risks when they bleed. Dural AVMs occur in the covering of the brain, and are an acquired disorder that may be triggered by an injury.

AVMs are usually diagnosed through a combination of MRI and angiography. AVMs can irritate the surrounding brain and cause seizures or headaches. Left untreated, AVMs can enlarge and rupture, causing intracerebral or subarachnoid hemorrhage and permanent brain damage. Every year, about four out of every 100 people with an AVM will experience a hemorrhage. Preventing the rupture of vascular malformations is one of the major reasons that early neurosurgical treatment is recommended for AVMs.

A treatment plan is devised to offer the lowest risk, yet highest chance of obliterating the lesion. The three types of treatment available include direct removal using microsurgical techniques, stereotactic radiosurgery, and embolization using neuroendovascular techniques. Although microsurgical treatment affords the opportunity for immediate removal of the AVM, some AVMs may best be treated by a combination of therapies.

Stereotactic radiosurgery is a minimally invasive treatment that uses computer guidance to concentrate radiation to the malformed vessels of the brain. This radiation causes abnormal vessels to close off. Unfortunately, stereotactic radiosurgery is usually limited to lesions less than 3.5 cm in diameter, and may take up to two years to completely obliterate the lesion.

Embolization uses neuroendovascular techniques to guide tiny catheters into the small cerebral vessels of the brain that feed the AVM. Once the catheter reaches the core of the AVM, liquid glue or particles can be injected to occlude portions of the AVM or its feeding arteries. Neuroendovascular therapy can make subsequent surgical removal of an AVM safer, or can reduce the size of an AVM to a volume in which radiosurgery offers a higher efficacy.

Moyamoya disease

Moyamoya disease is a progressive disease of the carotid arteries and their major branches that can lead to irreversible blockage. The name comes from the Japanese word for a "puff of smoke" due to the appearance of the lesions that form. In fact, it affects people of Japanese origin far more commonly than the rest of the population. It is a disease that tends to affect children and adults in the third to fourth decades of life. Children with the disease may have strokes, TIAs, slowly progressive cognitive decline, seizures, or involuntary movements of the extremities. Adults more commonly experience intracranial hemorrhages as a result of the disease.

There are several surgeries that have been developed for the condition, but currently the most favored are: EDAS, EMS, STA-MCA and multiple burr holes.

The EDAS (encephaloduroarteriosynangiosis) procedure requires dissecting a scalp artery over a length of several inches and then making a small temporary opening in the skull directly beneath the artery. The artery is then sutured to the surface of the brain and the bone replaced.

In EMS (encephalomyosynangiosis) surgery, the temporalis muscle, which is in the temple region of the forehead, is dissected and through an opening in the skull, placed onto the surface of the brain.
Other operations include: the STA-MCA (superficial temporal artery-middle cerebral artery) in which a scalp artery is directly sutured to a brain surface artery; and a procedure in which multiple small holes (burr holes) are placed in the skull to allow for growth of new vessels into the brain from the scalp.

Venous angiomas

Patients with venous angiomas may have headaches or seizures, although these symptoms may be unrelated to the angiomas. More commonly, these lesions are asymptomatic and are identified when patients are being evaluated for other conditions. They rarely bleed, so treatment is usually not necessary. They affect approximately 2 percent of the general population.

Vein of Galen malformation (VGM)

A far rarer malformation is the VGM, sometimes detected in prenatal testing, or through heart failure in infants. Occurring during embryonic development, a VGM is an abnormal connection between arteries and the deep draining veins of the brain. Under normal conditions, these arteries and veins are connected by capillaries that function to slow blood flow through the brain, allowing for the necessary exchange of oxygen and nutrients.

A VGM has a thicker wall than an AVM and is unlikely to rupture and bleed. However, because a VGM does not have capillaries, the blood may flow extremely fast, putting excessive strain on the heart, which may result in cardiac failure. It is very important that children suffering from this condition be evaluated and diagnosed by experts so that appropriate treatment measures are taken. Embolization is the method of choice for treating patients with VGMs.

For more information about the treatment of cerebrovascular disease, call LifeBridge Health at 410-601-WELL (9355).

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