Stroke

Overview

Strokes occur when blood vessels carrying oxygen and other nutrients to the brain become blocked or suddenly burst. Although doctors can sometimes intervene to reduce stroke damage, in many cases the brain cells served by these blood vessels become starved and begin to die off. After the stroke, the resulting damage may impair behavior or body functions controlled by the affected parts of the brain.

On average, someone in the United States has a stroke about once every 45 seconds, for a total of between 700,000 and 750,000 people a year. Strokes are the third-leading cause of death in the United States behind heart disease and cancer, killing about 275,000 people a year. About 5.4 million stroke survivors live in the United States today.

Strokes are closely linked with cardiovascular diseases like atherosclerosis, heart rhythm disorders, heart attacks, heart valve disorders, and especially high blood pressure. While the number of strokes increased nearly 7 percent from 1992 to 2002, the death rate fell nearly 14 percent during that same period. This increased survival rate is due, in part, to advances in diagnostic techniques and new treatments that allow physicians to intervene with less risk to the patient.

This section has more on:

Need-to-know anatomy

The brain is divided up into three main parts: the cerebrum, the cerebellum, and the brain stem. In humans, the cerebrum is the largest part of the brain and is responsible for most higher-level brain functions, including language, consciousness, emotions, integration of sensory stimuli, and some motor functions. The second-largest structure in the brain is the cerebellum. This portion of the brain governs balance and some other aspects of movement. Finally, the brain stem, the smallest part, is the most "primitive" part of the human brain and controls many of the body functions that occur automatically, including heartbeat, blood pressure, and wakefulness. Each part of the brain breaks down into smaller regions that control various body functions and behaviors.

A complex system of arteries, capillaries, and veins provides the brain with blood. Two vertebral arteries run alongside the brainstem and join at the basilar artery. The basilar artery then branches off to the cerebellum and the cerebrum. Branching off the heart, the aortic arch feeds another major pair of arteries, the left and right carotids. At the base of the brain, the vertebrobasilar arteries and the carotid arteries form a structure called the circle of Willis, which gives rise to many of the arteries serving the brain.

Since specific parts of the brain govern specific behaviors and bodily functions, doctors can usually estimate where the brain damage from a stroke occurred by examining the patient. For example, if a stroke victim can't move his or her left arm, a doctor might assume that the stroke damaged the section of the cerebral cortex governing motor function in the right hemisphere (the right side of the brain controls the left half of the body and vice versa).

Causes

Strokes result from an interruption of blood flow to a portion of the brain and the subsequent death of those brain cells. This interruption of blood flow can occur in two different ways: by a blood clot--a thrombus--that gets lodged in blood vessels or by blood vessels that rupture.

Those caused by blocked blood vessels, or ischemic strokes, account for roughly 80 percent of all strokes and can arise in one of two ways: a blockage caused by a blood clot that forms inside the brain or in arteries of the neck (a thrombotic stroke) or a blockage resulting from clots that form in another part of the body and travel to the brain (an embolic stroke).

Thrombotic strokes form most often in arteries damaged by atherosclerosis, a disease in which rough, fatty deposits build up in the walls of the arteries. These deposits gradually narrow the artery, slowing down or even blocking (occluding) the blood flow.

Embolic stroke occurs when a clot breaks loose from the heart or one of the arteries and travels to the brain. The arteries that the clot is moving through are continuously branching off into smaller vessels, so the clot reaches a point where it can go no farther. It then plugs the vessel, blocking off the blood supply.

Hemorrhagic stroke occurs when a blood vessel in or around the brain ruptures. Not only does the ruptured blood vessel deprive the brain of oxygen, but the accumulated blood from the ruptured artery also clots, displacing normal brain tissue and disrupting function. Hemorrhagic strokes occur within the brain itself (intracerebral hemorrhage) or in the space between the brain and the skull (subarachnoid hemorrhage).

One of the causes of hemorrhagic strokes is an aneurysm, an abnormal blood vessel in the brain that contains a weak spot that bulges and finally bursts. Sometimes this weak spot is stretched out over several years by high blood pressure and then bursts suddenly. These cerebral vascular time bombs don't usually cause symptoms before the stroke.

Another cause of hemorrhagic strokes is a cluster of abnormal blood vessels called a cerebral vascular malformation. One type of vascular malformation, an arteriovenous malformation, occurs when a tangle of blood vessels in or around the brain bypasses the normal brain tissue and directly diverts blood from the arteries to the veins.

Risk factors

Some risk factors for stroke, like age, cannot obviously be changed. For more information on these, see below. For information on factors that can be changed, such as smoking, see the prevention section.

As with most diseases of the circulatory system, your chances of having a stroke increase with age. Gender, race, and family history are also important factors.

Age: Two thirds of strokes occur in people over the age of 65. In adults over 55, the lifetime risk for stroke is greater than 1 in 6. The prevalence of most types of stroke increases every five to 10 years for people 55 to 85.

Gender: In most age groups, men are more likely to have strokes than women. However, about 40,000 more women than men have a stroke each year--most likely because women tend to live longer.

Race: African-American males have the highest risk of stroke. African-Americans have almost twice the risk of a first-ever stroke that Caucasians have. Studies also indicate that Mexican-Americans have a greater incidence of stroke than non-Hispanic whites. Death rates from stroke are highest for African-Americans, followed by Caucasians, Asian and Pacific Islanders, Hispanics, and American Indians.

Family history: Your risk of stroke is greater if a parent, sibling, or grandparent has had a stroke.

Personal history: Your risk of stroke is greater if you have already had a stroke.

Prevention overview

There are many steps you can take now to reduce your risk of stroke. This is doubly true for people with cardiovascular disease. Because stroke is a form of cardiovascular disease, it makes sense that keeping your heart and blood vessels as healthy as possible will reduce your risk of stroke. If you have coronary artery disease, high blood pressure, or high blood levels of cholesterol, it is vital to get regular medical checkups. All of these conditions, which are also risk factors for stroke, can be controlled by proper medical treatment and appropriate changes in diet and exercise regime.

This section discusses stroke prevention and:

Cardiovascular disease and stroke prevention

Treating cardiovascular conditions also reduces the risk of stroke:

  • Controlling blood pressure: High blood pressure (hypertension) is the most important single risk factor for stroke. Even mild hypertension increases risk. In general, an ideal blood pressure is 120/80 or below. Elevated blood pressure promotes atherosclerosis and puts abnormal pressure on blood vessel walls, which can cause a rupture at a weak spot. Hypertension is often called the "silent killer" because there may be no obvious symptoms. So it is important to check your blood pressure regularly. Controlling blood pressure, whether by a low-sodium diet, weight control, regular exercise, stress management, or medication, will reduce your risk of stroke. Medication to control hypertension is effective only if taken on a regular basis, so it is important to follow your doctor's instructions.

    • Treatment of hypertension in older adults is important. However, in the elderly an abrupt fall in blood pressure may actually cause a stroke. As a result, older individuals who need to reduce their blood pressure may need to start with small doses of medication so that blood pressure is reduced gradually.

  • Treating heart disease: A variety of heart conditions, including irregular heart rhythms (atrial fibrillation), heart attacks, and heart valve disorders, can cause stroke. Treatment of these disorders will reduce stroke risk.

Lifestyle factors and stroke prevention

The following changes in lifestyle will help lower your risk of stroke:

  • Stop smoking: Studies confirm that smokers have a higher risk of stroke, regardless of other factors such as age, high blood pressure, or heart disease. The risk declines dramatically within a few years of giving up tobacco.
  • Maintain a healthy weight: Being overweight is linked to high blood pressure, which puts added strain on the heart and blood vessels. Obesity also predisposes a person to heart disease and diabetes, both of which increase one's risk of stroke.
  • Exercise regularly: The percentage of fat in our bodies tends to increase with age. Regular exercise helps keep this increase to a minimum. There appears to be an inverse relationship between exercise and atherosclerosis--i.e., more exercise is linked to lower levels of atherosclerosis. If you have not exercised regularly and would like to start an exercise program, or if you have medical problems or family history of serious disease, consult your physician before beginning an exercise program. Experts recommend at least 20 to 30 minutes of aerobic exercise three to four times a week in order to achieve and maintain an improved level of fitness.
  • Reduce stress: Because stress may increase blood pressure, it is indirectly linked to stroke risk. A one-time stressful event rarely causes a stroke, but long-term unresolved stress can contribute to high blood pressure. Stress management, including relaxation techniques, biofeedback, exercise, and counseling, can--along with medication--reduce blood pressure, thus lowering the risk of stroke.

This section also discusses diet and stroke prevention.

Diet and stroke prevention

Eating foods that are high in fat, cholesterol, and salt can increase your risk of stroke. The following recommendations are among the most important for stroke prevention. In addition, ask members of your healthcare team for help in identifying additional foods to avoid and appropriate substitutes for them.

  • Avoid excess fat: Eating a lot of fat, particularly saturated fat and cholesterol, may contribute to atherosclerosis, which is associated with stroke. Dietary fat and cholesterol may be reduced by limiting the fat or oil added in cooking, trimming fat and skin from meats and poultry, using low-fat or nonfat dairy products, broiling and baking foods rather than frying them, and limiting the number of eggs eaten to no more than three a week.
  • Avoid excess sodium: Excess sodium in the diet is linked to hypertension. Table salt is a major source of dietary sodium. There is also "hidden" salt in most processed foods and canned foods, especially those with listed ingredients that include sodium phosphate, monosodium glutamate, sodium nitrate, and similar compounds. Try to eat fresh food whenever possible.
  • Limit alcohol intake: Individuals who have more than two alcoholic beverages a day are at an increased risk of stroke. For heavy drinkers, the risk of stroke is even greater.

Other modifiable risk factors

Other controllable factors also influence the risk of stroke:

  • Diabetes: The association between diabetes and increased stroke risk seems to be related to the circulatory problems caused by the disease. Good control of diabetes appears to reduce the cardiovascular complications of the disease.
  • Oral contraceptives: Use of oral contraceptives, especially those with a high dose of estrogen, appears to increase the risk of blood clots--including clots that cause stroke--especially in women over age 30. The risk is even higher in women who smoke. If you have stroke risk factors and are using oral contraceptives, you might want to consult your physician regarding alternative methods of birth control.
  • Post-menopausal estrogen use: Recent studies have associated post-menopausal estrogen replacement therapy with a small increase in the risk of stroke.

Symptoms

Once a stroke occurs, it is extremely important for the patient to seek medical care immediately. If you or someone you know experiences stroke symptoms that last for more than 10 to 15 minutes, appear frequently, or seem to get worse, you should call 911 at once and ask the emergency responders for transportation to the nearest emergency medical facility.

Warning signs of a stroke:

  • Sudden weakness, numbness, or paralysis of the face, arm, or leg, especially if on only one side of the body
  • Loss of speech or trouble talking or understanding language
  • Sudden loss of vision, particularly if in only one eye
  • Sudden, severe headache with no apparent cause
  • Unexplained dizziness, loss of balance, or coordination (especially when associated with any of the above symptoms
  • Transient ischemic attacks(TIAs)

Ministrokes, known as transient ischemic attacks, precede about one third of all strokes and can occur hours, days, weeks, or even months before a stroke. TIAs happen when the blood supply to the brain is temporarily interrupted. The symptoms usually occur rapidly and disappear within a short time. For instance, if you experience a sudden loss of vision, or weakness in an arm or leg that disappears, you might be having a TIA. Because TIAs are temporary and the body soon returns to normal, many people ignore these attacks. However, ignoring TIAs is dangerous because they are often early warning signs of a more serious and debilitating stroke in the future.

Tests overview

Because time is a crucial factor during a stroke emergency, and because different types of strokes necessitate different treatments, doctors need to quickly pinpoint the location of a stroke, the type of stroke, and the extent of the damage to make the correct treatment decisions. For example, the physician must differentiate between ischemic strokes (those arising from a blocked blood vessel) and hemorrhagic stokes (bleeding caused by a burst blood vessel) before the appropriate therapy can begin.

Advances in imaging technology can provide physicians with anatomical information that is precise enough to accurately diagnose strokes without actually entering the patient's body. Other techniques that are more invasive allow physicians to view the damage directly.

This section includes information on a variety of noninvasive techniques:

Invasive techniques include:

CT scan

This diagnostic test is generally the first to be administered after a patient with a suspected stroke arrives in the emergency room. It is used to quickly distinguish between an ischemic and a hemorrhagic stroke. In the test, a computer analyzes low-dose X-rays to produce detailed, two-dimensional cross sections of the brain.

Magnetic resonance imaging (MRI)

Magnetic resonance imaging is an advanced, noninvasive diagnostic tool that provides a high level of anatomic detail for precisely locating the stroke and determining the extent of damage. Because the MRI is so sensitive, the images it produces are particularly useful to doctors when the stroke involves small blood vessels. The technology uses a combination of radio waves and a strong magnetic field to detect the movement of atoms inside the brain. Because of the magnetic field, doctors perform the test in a room free of metallic equipment. Two recent advances in MRI technology, diffusion weighted imaging (DWI) and perfusion weighted imaging (PWI), allow doctors to detect strokes with more accuracy early in the diagnostic phase of care.

Diffusion weighted imaging follows the random movement of water molecules in the tissues. Because water doesn't move as easily through dead or damaged tissues, doctors can use this technique for imaging stroke victims. Instead of water, perfusion weighted imaging follows blood flow through vascular tissues. Combined use of these two techniques can help doctors distinguish areas of restricted blood flow from areas where the tissue is irreversibly damaged.

Magnetic resonance angiography (MRA)

Similar to magnetic resonance imaging, magnetic resonance angiography uses magnetic fields and radio waves to provide detailed images of the blood vessels in the neck and brain. With magnetic resonance angiography, doctors may inject a "contrast agent" into the patient's bloodstream that causes vascular tissues to stand out against other tissues. The contrast agent provides for enhanced information regarding blood supply and vascular anomalies of the brain. Aside from the IV used to introduce the contrast material into the bloodstream, magnetic resonance angiography is noninvasive and painless.

Computed tomography angiography (CTA)

This noninvasive study provides three-dimensional views of cerebral blood vessels and is sensitive for identifying aneurysms. First, a contrast dye is injected into a vein to make the blood vessels stand out against the surrounding tissue. Then a rotating device passes beams of X-rays through the head and neck to create cross-sectional images. The computer then assembles these into a three-dimensional picture of how blood flows in the brain's arteries and veins.

Transcranial doppler (TCD)

This noninvasive ultrasound procedure allows for the assessment of blood flow through the cerebral vessels. In this test, a small, hand-held probe placed against the skull bounces sound waves off different parts of the brain. Frequency shifts in the reflected sound allow a computer to measure blood-flow velocity. Transcranial doppler is relatively inexpensive, portable, painless, and safe.

Xenon computed tomography

In this imaging procedure, the patient inhales xenon, which enters the blood and then diffuses across the blood-brain barrier. Areas of the brain with low blood flow as a result of stroke or blood vessel blockages receive less xenon, which, because it has a high atomic number relative to body fluids and tissues, can be easily measured through a CT scanner. This relatively expensive procedure is useful for evaluating blood flow in the brain and cerebrovascular disease

Carotid duplex scanning

In this technique, sound waves are bounced off blood vessels to provide detailed information about the anatomy of arteries in the neck. Doctors often use carotid duplex scanning to diagnose blockages in the carotid arteries. The technique is noninvasive and, unlike X-rays, does not expose the patient to radiation.

Radionuclide single-photon emission computed tomography (SPECT) scanning

In this procedure, a small amount of a radioactive substance, called a radionuclide, is injected into the bloodstream, which diffuses the radionuclide through healthy tissues. Tissues with decreased blood flow receive less of the radionuclide. A camera that rotates around the patient picks up photons emitted from the radionuclide. A computer then processes the data into vertical, cross-sectional, or three-dimensional images of relative blood flow in the brain.

Cerebral angiography

Doctors use cerebral angiography to evaluate blood flow to the brain and diagnose cerebral aneurysms and vascular malformations or blood vessel occlusions. The procedure requires injection of a contrast dye through a catheter into a major artery (usually the femoral artery in the thigh). After doctors inject the dye, they take images using X-rays that show the dye flowing through the blood vessels. The procedure usually takes about two hours to perform and typically requires six hours of bed rest when completed.

Transesophageal echocardiography (TEE)

Doctors use this procedure when they suspect that blood clots are forming in the hearts of stroke patients. These blood clots can break loose from the heart tissue and travel through the arteries to the brain, causing a stroke.

In this invasive procedure, the doctor will ask the patient to "swallow" a long, thin flexible tube down the esophagus. A probe at the tip of the tube emits ultrasound waves, which bounce off the heart valves, heart muscles, and other tissues. A transducer measures the returning ultrasound waves and transmits the information to a computer that creates an image of the heart chambers and blood vessels.

Patients are required to fast for eight hours before the test. Before the tube is introduced, patients will be mildly sedated and asked to gargle an anesthetic to make swallowing the probe less painful.

Treatment overview

Stroke is a medical emergency. Especially if you or loved ones are at risk of stroke, it is vital to know the warning signs of a stroke so that you can seek out prompt emergency medical care.

Doctors today have a range of options to draw from when tailoring treatment for patients. In the acute phase of treatment they can administer drugs that minimize damage to the brain. Clot dissolvers, such as thrombolytic agents, are most effective when used within three hours of a thrombotic or an embolic stroke. There also are new treatments in the pipeline: Clinical trials are underway on several drugs designed to protect brain tissues after a stroke occurs. Further, preliminary studies with techniques that chill the brain have shown that inducing hypothermia may reduce stroke damage.

Doctors also have at their disposal a number of medications to help ward off strokes in high-risk patients, particularly those who have experienced transient ischemic attacks (TIAs) or "ministrokes." These include anticoagulants, such as heparin or warfarin, and antiplatelet agents, including aspirin, dipyridamole, and clopidogrel.

Interventional procedures, too, can help patients with certain conditions that result from or often lead to strokes. For years, doctors "clipped" aneurysms to prevent further bleeding. However, more recently they have honed a number of more sophisticated techniques, including introducing coils into the aneurysms that can prevent rupture without the risks of brain surgery.

This section includes information on:

Drugs for emergency treatment of stroke

The only FDA-approved medication for treatment of an acute ischemic stroke--the kind caused by blood clots that block blood flow to the brain--is a clot-dissolving medication known as a clotbuster. This thrombolytic agent (called tPA for "tissue plasminogen activator") is most effective if administered intravenously within the first three hours after a stroke, so it is extremely important for people experiencing symptoms to get prompt emergency treatment.

New drugs, called neuroprotective agents, that may make the brain more resistant to damage from stroke are being tested in clinical trials at some medical centers.

Drugs for preventing stroke

A number of medications help ward off stroke in high-risk patients. These drugs fall into two major categories: anticoagulants or "blood thinners" (such as heparin or warfarin) and antiplatelet agents (such as aspirin, dipyridamole, and clopidogrel).

This section has more on:

Anticoagulants

Anticoagulants are medications that reduce the ability of the blood to clot by altering the function or production of substances that cause clots. These drugs are often used to treat deep vein thromboses and pulmonary emboli and are effective at preventing a stroke in patients with atrial fibrillation (rapid, irregular twitching of the muscles in the atria of the heart) or some other causes of cardiac embolism.

Heparin: This anticoagulant must be injected under the skin or into a vein--it cannot be taken orally. So it is almost always used in hospitalized patients. Doctors typically prescribe it to reduce the risk of blood clots in the legs and reduce the risk of additional strokes or stroke damage in patients who have been hospitalized for specific types of stroke, such as cerebral sinus thrombosis (in which clots form in veins that drain blood from the brain).

Warfarin: Also known by the brand name Coumadin, this anticoagulant is prescribed to prevent clots in the heart from forming or growing larger. It is taken by mouth, as a tablet. Many other medications interfere with the action of warfarin and the blood's clotting ability. Before starting the drug, you should give the doctor a list of all drugs and herbal supplements you take, and you should not start taking new drugs without first consulting with your doctor. Foods that contain vitamin K, including liver, leafy green vegetables, green tea, and cauliflower, also affect the blood's ability to clot. Patients taking Coumadin should try to avoid large variations in the amount of these foods they consume. Your doctor will monitor your response to the drug through blood tests conducted at regular intervals.

Antiplatelet agents

Antiplatelet agents work by preventing or reducing the occurrence of platelet aggregation of the blood. Platelet aggregation is when disklike components of the blood called platelets migrate to the site of injuries to blood vessels and stick together to form what is essentially a plug. This aggregation can sometimes result in the formation of a thrombus (blood clot) that may totally block the artery or may break loose and block a smaller artery. By preventing platelet aggregation, antiplatelet agents can reduce the risk of stroke in patients who have had transient ischemic attacks (TIAs) or ischemic strokes.

Aspirin (acetylsalicylic acid)

Aspirin, a common, over-the-counter pain, fever, and inflammation reducer, is also a good antiplatelet agent that can reduce the risk of stroke in patients who have experienced TIAs or ischemic strokes. Doctors will prescribe a dosage that is appropriate for each patient. Since aspirin can irritate the stomach, doctors might recommend that patients take the medication with water, milk, or food. Patients should also watch for signs of any unusual bleeding and report them to their doctor immediately.

Dipyridamole

Drugs like Aggrenox combine aspirin and another antiplatelet drug, dipyridamole, in one time-release pill. Dipyridamole works in a different way from aspirin to keep platelets from forming a clot. Doctors normally prescribe one pill twice a day. Some patients who take the drug develop a headache that usually subsides in several days. The drug must be swallowed whole, not broken or crushed, for it to work effectively. Patients should watch for signs of any unusual bleeding and report them to their doctor immediately.

Clopidogrel

Clopidogrel, also known by the brand name Plavix, is another antiplatelet agent used to help prevent the recurrence of stroke. Doctors usually prescribe one 75-mg tablet once a day. Patients should watch for signs of any unusual bleeding and report them to their doctor immediately.

Endovascular procedures

Doctors often recommend these relatively new surgical procedures to patients who may not be able to withstand the stresses of major surgery, whether because of advanced age or because they have other serious medical conditions. However, these procedures are appropriate for less frail patients, too. Advantages include local or regional anesthesia instead of general anesthesia, shorter recovery time, less pain, smaller incisions, and less stress on the heart. These procedures may be used to treat aneurysms, cerebral vascular malformations, and arteries that have been occluded by plaque.

  • Treatment of aneurysms: To repair an aneurysm, or a section of a vessel that has ballooned out, surgeons guide a coil (essentially, an artificial graft) into the damaged blood vessel and anchor it into place. This allows blood to flow normally again through the vessel, lowering the patient's risk of a future hemorrhagic stroke. A long plastic tube called a catheter, which has been threaded up through a tiny incision in an artery in the thigh up to the trouble spot, is used to position the coil. X-ray imaging is used to guide the catheter.
  • Treatment of cerebral vascular malformations: Endovascular surgeons may use a "superglue" substance introduced via a tiny catheter to eliminate or reduce the size of the cerebral vascular malformations. Often this facilitates further microsurgical or radiation treatment.
  • Mechanical removal of blood clots: A new tool for treating hemorrhagic stroke is a tiny device used to physically remove blood clots that are blocking blood vessels within the brain. The Food and Drug Administration recently approved one such device, the Merci Retrieval System, which works like a corkscrew to pluck out clots. In nonbleeding (ischemic) strokes, blood clots damage the brain by depriving brain cells of the oxygen and nutrients (carried in the blood) they need to survive. But when used within the first several hours after a stroke, the device can extract clots and may reduce permanent damage.
  • Angioplasty and stenting of vessels in the neck and brain: This new intervention is available at many medical centers. Cerebral angioplasty is similar to the widely used cardiology procedure, in which a tiny balloon attached to the tip of a catheter is threaded into a blocked artery and then inflated. In this case, the vessels are the carotid arteries in the neck, and a tiny tube-shaped bit of wire scaffolding, or a "stent," is inserted into the blockage to keep it open after the balloon has been withdrawn. This procedure often is offered as an alternative to carotid endarterectomy for patients for whom the more invasive surgery is thought to be too risky, whether because of the patient's overall health or because of the location of the blockage. Because angioplasty and stenting is fairly new, researchers are still investigating how well the stents hold up and how well the procedure reduces patients' risk of stroke over the long term.
  • Intra-Arterial Thrombolysis: For this procedure, doctors insert a small catheter into the blood vessels of the brain during cerebral angiography and deliver clot-dissolving medications directly to the blocked blood vessel.

Carotid endarterectomy

Carotid endarterectomy is a surgical procedure used to remove atherosclerotic plaque (fatty deposits associated with cardiovascular disease) from the carotid arteries. For selected patients who have had minor strokes or transient ischemic attacks (TIAs or ministrokes), carotid endarterectomy can be highly beneficial in preventing future strokes.

The primary factor doctors consider when weighing this procedure for an individual patient is the extent to which plaque has narrowed the affected artery ("stenosis"). For patients with less than 50 percent stenosis, the benefits of carotid endarterectomy normally do not outweigh the risks. However, in patients with 70 to 99 percent stenosis who have had recent symptoms caused by the stenosis, the surgery lowers the two-year risk of stroke by about 80 percent.

For this procedure, patients are anesthetized. The surgeon then makes an incision in the neck at the site of the blockage. To reroute blood flow around the problem area, the surgeon may insert a tube into the artery above and below the atherosclerotic plaque. He or she then makes a lengthwise incision along the portion of the artery with the plaque, removes the plaque, and stitches the vessel closed. The surgeon then removes the tube.

Doctors have performed these surgeries for over 40 years. In 1995, doctors in the United States performed about 132,000 carotid endarterectomies.

Stereotactic procedures

Stereotactic techniques, which involve placing markers on the patient's head to create reference points for very precise surgeries, allow surgeons to treat vascular malformations that were previously too difficult to reach. Stereotactic surgeries employ sophisticated computer technology in combination with MRI or CT scans to pinpoint the trouble spot. Using microscope-enhanced methods and delicate instruments, the surgeons can operate without affecting normal brain tissue.

A nonsurgical radiosurgery technique, the CyberKnife, focuses a beam of radiation on a cerebral vascular malformation, causing it to clot and disappear. The technique, often performed on an outpatient basis, usually leaves healthy brain tissue intact.

Revascularization

Revascularization is a surgical technique for treating aneurysms or blocked cerebral arteries associated with atherosclerosis or moyamoya disease (a rare disease resulting in narrow or blocked vessels to the brain and irregular blood vessels). The technique essentially provides a new route of blood to the brain by grafting a blood vessel from the surface of the face near the temple to a cerebral artery through a hole in the skull.

Hypothermia

Preliminary studies with techniques that cool the brain or body suggest that doing so may improve outcomes for stroke patients in a variety of situations. Surgeons operating on stroke patients to correct cerebral vascular malformation and aneurysms, for instance, are finding that if they first chill the patient's brain, he or she may be less likely to suffer another stroke during the surgery. Inducing hypothermia may also give the surgeon extra time to operate.

Studies of patients who are comatose after a cardiac arrest have shown that chilling their entire bodies improves their chances of a favorable neurological recovery. This has led other doctors to try cooling down stroke patients. As with stroke, brain injury in cardiac arrest patients is caused by the interruption of the blood flow to the brain. Currently, doctors are trying to determine how long and to what degree the body should be cooled, and whether the risks of cooling outweigh the benefits in stroke patients.

Managing overview

The outlook for stroke patients has never been more hopeful thanks to tremendous advances in stroke treatment and increasingly sophisticated rehabilitation techniques. This section discusses:

Rehabilitation

The ultimate goal of rehabilitation is to return the patient to as independent a lifestyle as possible. Successful stroke rehabilitation depends on many factors, including the severity of brain damage and the support of family and friends. Not surprisingly, a positive outlook and degree of determination also are key factors in the speed of recovery.

Patients with mild strokes or those who obtained prompt medical treatment may need little or no rehabilitation. Depending on the area of the brain affected by the stroke and the extent of the damage, physical and mental deficits may range from mild to severe.

After a stroke, other blood vessels may be able to take over for the damaged ones. This allows some brain cells to recover, although others may still die. This means that even without rehabilitation, brain function often will improve somewhat. Most stroke patients, however, will benefit from some type of rehabilitation. Even though rehabilitation does not "cure" a stroke in that it does not directly heal a damaged brain, it usually helps people achieve the best possible long-term outcome.

See our special section on stroke rehabilitation.

Disabilities

Different areas of the brain control different bodily functions. When certain areas are damaged by stroke, the functioning of the parts of the body controlled by those areas is impaired. For instance, if the left hemisphere of the brain is damaged, most of the effects will occur on the right side of the body. It's also important to note that areas of the brain that were not damaged will continue to function normally.

Some of the most common results of a stroke are hemiparesis (paralysis on one side of the body), aphasia (inability to speak or to understand language), learning difficulties, memory loss, behavioral/emotional changes, and loss of motor skills.

Support groups

Many patients and their families benefit from support groups. Participants have the opportunity to increase their knowledge of diagnostic and treatment options and to develop problem-solving and coping skills. The support group is intended to be a forum where patients and their families can share experiences and concerns about rehabilitation, depression, and other daily issues. Ask your physician for information.