Definition
A stroke is an interruption of the blood supply to any part of the brain. A stroke is sometimes called a "brain attack."

Causes, Incidence, and Risk Factors
Every 45 seconds, someone in the United States has a stroke. A stroke can happen when:

• A blood vessel carrying blood to the brain is blocked by a blood clot. This is called an ischemic stroke.
• A blood vessel breaks open, causing blood to leak into the brain. This is a hemmorhagic stroke.

If blood flow is stopped for longer than a few seconds, the brain cannot get blood and oxygen. Brain cells can die, causing permanent damage.

Ischemic Stroke
This is the most common type of stroke. Usually this type of stroke results from clogged arteries, a condition called atherosclerosis. Fatty deposits and blood platelets collect on the wall of the arteries, forming a sticky substance called plaque. Over time, the plaque builds up. Often, the plaque causes the blood to flow abnormally, which can cause the blood to clot. There are two types of clots:

• A clot that stays in place in the brain is called a cerebral thrombus.
• A clot that breaks loose and moves through the bloodstream to the brain is called an cerebral embolism.

Another important cause of cerebral embolisms is a type of arrhythmia called atrial fibrillation. Other causes of ischemic stroke include endocarditis and the use of a mechanical heart valve. A clot can form on the artificial valve, break off, and
travel to the brain. For this reason, those with
mechanical heart valves must take blood thinners.

Hemorrhagic Stroke
A second major cause of stroke is bleeding in the brain, known as hemorrhagic stroke. This can occur when small blood vessels in the brain become weak and burst. Some people have defects in the blood vessels of the brain that make this more likely. The flow of blood after the blood vessel ruptures damages brain cells.

Stroke Risks
High blood pressure is the number one cause of stroke. The risk of stroke is also increased by age, family history of stroke, smoking, diabetes, high cholesterol, and heart disease.

Certain medications increase the chances of clot formation, and therefore chances for a stroke. Birth control pills can cause blood clots, especially in woman who smoke and who are older than 35.

Men have more strokes than women. But, women have a risk of stroke during pregnancy and the weeks immediately after pregnancy.

Cocaine use, alcohol abuse, head injury, and bleeding disorders also increase the risk of bleeding into the brain.

Symptoms
The symptoms of stroke depend on what part of the brain is damaged. Usually, a SUDDEN development of one or more of the following indicates a stroke:

• Weakness or paralysis of an arm, leg, side of the face, or any part of the body
• Numbness, tingling, decreased sensation
• Vision changes
• Slurred speech, inability to speak or understand speech, difficulty reading or writing
• Swallowing difficulties or drooling
• Loss of memory
• Vertigo (spinning sensation)
• Loss of balance or coordination
• Personality changes
• Mood changes (depression, apathy)
• Drowsiness, lethargy, or loss of consciousness
• Uncontrollable eye movements or eyelid drooping

If one or more of these symptoms is present for less than 24 hours, it may be a transient ischemic attack (TIA). A TIA is a temporary loss of brain function and a warning sign for a possible future stroke.

Signs and Tests
In diagnosing a stroke, knowing how the symptoms developed is important. The symptoms may be severe at the beginning of the stroke, or they may progress or fluctuate for the first day or two. Once there is no further deterioration, the stroke is considered completed.

During physical exam, a doctor will look for specific neurologic, motor, and sensory deficits. These often correspond closely to the location of the injury in the brain. An examination may show changes in vision or visual fields, abnormal reflexes, abnormal eye movements, muscle weakness, decreased sensation, and other changes. A "bruit" (an abnormal sound heard with the stethoscope) may be heard over the carotid arteries of the neck. There may be signs of atrial fibrillation.

Treatment
A stroke is a medical emergency. Doctors have begun to call it a "brain attack" to stress that getting treatment immediately can save lives and reduce disability. Treatment varies, depending on the severity and cause of the stroke. The goal is to get the person to the emergency room immediately, determine if he or she is having a bleeding stroke or a stroke from a blood clot, and start therapy -- all within 3 hours of when the stroke began.

IMMEDIATE Treatment
Thrombolytic medicine, like tPA, breaks up blood clots and can restore blood flow to the damaged area. People who receive this medicine are more likely to have less long-term impairment. However, to receive thrombolytics a person must be evaluated and treated by a specialized stroke team within 3 hours of when the symptoms start. If the stroke is caused by bleeding rather than clotting, tPA can make the damage worse -- so care is needed to diagnose the cause before giving treatment.

In other circumstances, blood thinners such as heparin and coumadin are used to treat strokes. Aspirin and other anti-platelet agents may be used as well.

For hemorrhagic stroke, surgery is often required to remove pooled blood from the brain and to repair damaged blood vessels.

Expectations (Prognosis)
The long-term outcome from a stroke depends on the extent of damage to the brain, the presence of any associated medical problems, and the likelihood of recurring strokes.

Of those who survive a stroke, many have long-term disabilities, but about 10% of those who have had a stroke recover most or all function. Fifty percent are able to be at home with medical assistance while 40% become residents of a long-term care facility like a nursing home.

Complications

• Problems due to loss of mobility (joint contractures, pressure sores)
• Permanent loss of movement or sensation of a part of the body
• Bone fractures
• Muscle spasticity
• Permanent loss of brain functions
• Reduced communication or social
  interaction
• Reduced ability to function or
  care for self
• Decreased life span
• Side effects of medications
• Aspiration
• Malnutrition

Prevention
To help prevent a stroke:

• Get screened for high blood pressure at least every two years, especially if there is a family history of high blood pressure.
• Get regular cholesterol checks.
• Treat high blood pressure, diabetes, high cholesterol, and heart disease if present.
• Follow a low-fat diet.
• Quit smoking.
• Exercise regularly.
• Lose weight (if overweight).
• Avoid excessive alcohol use (no more than 1 to 2 drinks per day).