Stroke: Definition and Overview

What causes a stroke?

A stroke is damage to brain tissue caused by a disruption in blood flow to the brain. Strokes can be fatal and can result in temporary or permanent disability. Common aftereffects of a stroke include paralysis, weakness, muscular contractions, loss of sensation, and speech difficulties. Stroke is the third largest cause of death in the United States, and it is estimated to affect as many as 700,000 Americans each year.

What are the two types of strokes?

There are two types of strokes: ischemic and hemorrhagic. Ischemic strokes, which account for 70% to 80% of all strokes, occur when fatty material or a blood clot blocks one of the blood vessels in the brain. Without the oxygen and nutrients carried in blood, brain cells can die within minutes. Hemorrhagic strokes occur when arterial blood leaks into the brain. This not only deprives some areas of the brain of blood and oxygen, but the accumulated blood may also exert pressure on surrounding tissue and cause further brain damage.


What are the risk factors of strokes?

Some risk factors for stroke cannot be controlled. These include age (risk increases with age), gender (men are at greater risk than women), race (African-Americans are at greatest risk), and a family history of stroke. Other risk factors, including the following, can be avoided or managed:

What are the symptoms of a stroke?

Until recently, strokes were viewed fatalistically: Doctors thought that once a stroke was in progress, there was nothing they could do to prevent the destruction of brain cells. Now, clot-dissolving drugs such as tissue plasminogen activator (tPA) are used to reduce the brain damage associated with ischemic strokes. However, these drugs must be taken within three hours of the onset of symptoms to be effective. Obviously, then, it is important to recognize the early symptoms of a stroke. However, studies suggest that only about 57% of people can correctly identify at least one of the five warning signs of a stroke, listed below:

If you notice yourself or anybody else experiencing these signs, get medical help immediately.

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