STROKE

DEFINITION

A stroke is the sudden death of cells in a limited part of the brain caused by a reduced flow of blood to the brain.

DESCRIPTION

Blood brings oxygen and nutrients to brain cells and also removes waste products from cells. A stroke occurs when blood flow is interrupted to part of the brain. Without blood, brain cells quickly begin to die. The effects of a stroke depend on the part of the brain affected. A stroke may cause paralysis, speech problems, loss of memory or reasoning ability, coma, or death.

More than half a million people in the United States experience a stroke each year. Stroke is the third leading cause of death in this country and the leading cause of disability. Two-thirds of all strokes occur in people over the age of sixty-five. They affect men more often than women, and blacks more often than whites.

Stroke is a medical emergency that requires immediate medical attention. The sooner treatment is received, the better the chances of survival. At one time, nine out of ten people died after a stroke. Because of improved treatment methods, less than three out of ten people who suffer a stroke die from the experience.

CAUSES

There are four main types of strokes. They are:

• Cerebral thrombosis
• Cerebral embolism
• Subarachnoid hemorrhage
• Intracerebral hemorrhage

Cerebral thrombosis and cerebral embolism account for about three-quarters of all strokes.

Cerebral thrombosis occurs when a blood clot forms inside the brain, stopping the flow of blood to or from the brain. The medical term for blood clot is thrombosis. The most common cause for the formation of a blood clot is the hardening of the arteries, or atherosclerosis (see atherosclerosis entry).

A cerebral thrombosis occurs most often at night or early in the morning. It is often preceded by a transient ischemic attack (TIA), which is also referred to as a mini-stroke. A TIA may act as a warning sign that a full stroke is likely to occur.

Cerebral embolism is also caused by a blood clot. The clot, however, forms elsewhere in the body then travels through the bloodstream to the brain. Once in the brain, it produces effects like those of cerebral thrombosis.

Subarachnoid hemorrhage and intracerebral hemorrhage are caused when blood vessels in the brain break. Blood vessels sometimes develop weak spots in their walls. These weak spots are called aneurysms (pronounced AN-yu-RIHZ-umz; see cerebral aneurysm entry). When an aneurysm breaks, blood flows out of the blood vessel into the surrounding tissue and brain cells begin to die rapidly. An intracerebral hemorrhage takes place inside the brain. A subarachnoid (pronounced sub-uh-RAK-noyd) hemorrhage occurs on the surface of the brain.

SYMPTOMS

The symptoms of a stroke caused by an embolism usually appear suddenly and are most intense right after the stroke occurs. With a thrombosis, the stroke comes on more slowly. In either case, symptoms include:

• Blurring or decreased vision in one or both eyes
• Severe headache, often described as "the worst headache of my life"
• Weakness, numbness, or paralysis of the face, arm, or leg. These symptoms usually occur on one side of the body only
• Dizziness or loss of balance or coordination

DIAGNOSIS

Rapid diagnosis is essential in successful treatment of stroke. A doctor will first look for symptoms. He or she will then look at the patient's medical history for the presence of risk factors in the patient's background and a description of when and how symptoms appeared.

If stroke is suspected, more sophisticated tools are used for diagnosis. Imaging techniques will show whether the stroke was caused by a blood clot or a hemorrhage. This information is needed to begin the correct type of treatment. Blood and urine tests are also carried out. Other tests used to determine if a stroke has occurred include an electrocardiogram, angiography, or ultrasound tests.

TREATMENT

Immediate Intervention

Stroke treatment usually occurs in two phases. The first phase involves immediate steps to save the patient's life. In many cases, this involves dissolving the blood clot. The most effective substance currently available for this step is tissue plasminogen activator, or tPA. In order to be effective, tPA must be given to the patient within three hours of the stroke. In such cases, tPA goes to the blood clot and begins dissolving it immediately. The normal flow of blood to the brain is restored.

Some patients can not be given tPA. For example, the doctor may not know exactly when the stroke occurred. In these cases, other blood-thinning agents can be used. The substance known as heparin is often used. Even ordinary aspirin can be effective in dissolving the blood clot.

The primary goal in treating brain hemorrhages is to relieve pressure on the brain. Certain drugs can be used for this purpose. They include urea, mannitol, and the corticosteroids.

In some cases, surgery can be used to treat brain hemorrhages. A surgeon can close off blood vessels that have ruptured (broken open) in order to stop bleeding and help reduce pressure on the brain.

Rehabilitation

Once a patient's condition has been stabilized, rehabilitation can begin. Rehabilitation refers to a variety of methods for helping a patient recover normal functions to the extent possible. The patient may also need to learn how to use existing functions to take the place of those lost by the stroke.

About 10 percent of all patients who survive a stroke recover completely. Another 10 percent suffer severe disability and require institutional care for the rest of their lives. The remaining 80 percent of stroke survivors are able

A hemorrhagic stroke (left) compared to a thrombotic stroke (right). (Reproduced by permission of

Hans & Cassady, Inc.

)

to return to their homes and their daily routines. However, they may require additional therapy and support services.

PREVENTITIVE REHABILITATION. A program of rehabilitation consists of two parts. The first objective is to prevent medical complications of stroke. People who have had a stroke are at high risk for other serious medical problems including a second stroke.

Another possible complication is deep venous thrombosis (a blood clot in a vein). This condition may develop when a limb has become paralyzed and blood is no longer flowing normally in the limb. In such cases, the chance that a blood clot will develop greatly increases. If a blood clot forms and then breaks loose, it may travel to the lungs. In the lungs, it may cause a pulmonary embolism, (a blot clot in the lungs) that can very quickly lead to death.

Stroke patients may be kept on a special program of medication to prevent this complication. The program includes the use of drugs that thin blood out and reduce the chance that blood clots will form.

Once a patient's condition has been stabilized, rehabilitation can begin. Rehabilitation refers to a variety of methods for helping a patient recover normal functions to the extent possible. (© 1993

Mike Moreland

. Reproduced by permission of

Custom Medical Stock Photo

.)

CAT scan of a brain showing a stroke resulting in hemorrhage (white area). (© 1996

Bates, M.D.

Reproduced by permission of

Custom Medical Stock Photo

.)

Another complication of stroke is caused by damage to throat muscles. A stroke patient may find it difficult to swallow normally. Food may get into the lungs, causing pneumonia or other infections. This condition can be treated with breathing exercises and temporary use of soft foods in the diet.

Depression is another side effect of stroke. Depression can be treated with drugs and with counseling that helps patients cope with the conditions caused by the stroke.

REHABILITATIVE THERAPY. Brain cells killed by stroke do not grow back. The functions those cells control may be seriously damaged or lost. For example, cells in one part of the brain control the ability to speak. If those cells are killed, the patient may lose the ability to speak.

Fortunately, surviving brain cells can sometimes be trained to take on new functions and patients may recover some or all of the function lost during the stroke. For instance, areas of the brain that were not previously responsible for a patient's ability to speak may learn how to control speech.

Rehabilitative therapy draws primarily on four types of treatment:

• Physical therapy is used to help patients recover as much of their original body functions as possible. Treatment may involve exercises that help patients regain strength and become better able to move around. A physical therapist can provide advice on aids such as wheelchairs, braces, and canes.
• Occupational therapy helps patients improve self-care skills, such as feeding, bathing, and dressing. The occupational therapist may also help the patient redesign his or her living area or work area to make movement easier. A specialist in speech and language may also be needed to help patients relearn the ability to speak and swallow correctly.
• Mental health professionals treat mental problems, such as depression and loss of memory and thinking skills. They may also provide counseling to help patients deal with the new physical conditions resulting from stroke. Social workers and home caregivers may be needed to help patients adapt to the new challenges of dealing with tasks of everyday lives.
• Support groups can provide an important source of information, advice, and comfort for stroke patients and their families. A support group consists of other individuals who have the same medical problem as the patient.

PROGNOSIS

Prognosis depends on both sex and ethnicity. The highest rate of fatalities occurs in black males (52 percent) and the lowest in white females (23 percent). People who survive stroke may experience a wide variety of disabilities.

PREVENTION

Stroke prevention involves two separate issues. One issue is keeping the patient alive after a stroke. If a stroke patient is treated quickly, chances of survival are much greater. Everyone should become familiar with the symptoms of stroke. When those symptoms appear, a person should seek medical advice as quickly as possible. In many cases, local 911 services may need to be called immediately.

A second issue in prevention is reducing one's risk for the condition. Some steps that one can take to this end include:

• Stop smoking.
• Bring blood pressure under control.
• Get regular exercise.
• Keep body weight down.
• Avoid excessive alcohol consumption.
• Get regular medical checkups and follow the doctor's advice regarding diet and medicines.

FOR MORE INFORMATION

Books

Caplan, L.R., M.L. Dyken, and J.D. Easton. American Heart Association Family Guide to Stroke Treatment, Recovery, and Prevention. New York: Times Books, 1996.

Warlow, C. P., et al. Stroke: A Practical Guide to Management. Boston: Blackwell Science, 1996.

Weiner, F.M., H.M. Lee, and H. Bell. Recovering at Home After a Stroke: A Practical Guide for You and Your Family. Los Angeles: The Body Press/Perigee Books, 1994.

Organizations

National Stroke Association. 96 Inverness Drive East, Suite I, Englewood, CO 80112–5112. (303) 649–9299. http://www.stroke.org.

American Heart Association. 7272 Greenville Ave., Dallas, TX 75231–4596. (800) AHA–USA1 (242–8721). http://www.amhrt.org.

Web sites

"Ask NOAH About: Heart Disease and Stroke." NOAH: New York Online Access to Health. [Online] http://www.noah.cuny.edu/heart_disease/heartdisease.html#S (accessed on October 31, 1999).