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What is a Stroke? By Jane Brody
A stroke is a sudden disruption of the blood supply to a part of the brain, which in turn disrupts the body function controlled by that brain area. Without a source of fresh blood, brain cells are deprived of oxygen, which can paralyze or kill them, depending on how long the deficit lasts. Though cell paralysis is often reversible and the lost function is regained after a while, the death of brain cells is permanent, usually leaving lasting disability. Sometimes, however, uninjured cells can take over the lost functions.
Strokes are of three major types:
- Thrombotic - The most common type, it arises in arteries supplying the brain that have become partly closed by the fatty deposits of atherosclerosis. Blood flow around the obstructions is slowed so clots can form and lodge in the clogged vessel, blocking the blood supply to a part of the brain. (An identical process in the coronary arteries is the primary cause of heart attack.)
- Embolic - In these cases, a wandering clot becomes lodged in a cerebral artery and, as in the thrombotic stroke, blocks the blood flow.
- Hemorrhagic - Sometimes, because of a weakness present from birth or as a result of uncontrolled high blood pressure, a "blowout" occurs in a cerebral artery and a leakage of blood or a hemorrhage results. The fatality rate from this type of stroke is extremely high and the chances of complete recovery are slimmer than with strokes caused by clots.
Can a stroke be prevented?
With or without full recovery, a stroke and the damage it causes is a devastating experience. Though little progress has been made in reducing the death rate among the victims of stroke, much is known about how to prevent it. Prevention can be accomplished through knowledge of factors leading to increased risk of stroke. Since most of these factors are identical to those that increase the chances of a heart attack, preventing one may prevent both.
Oral Contraceptives
Women who suffer migraine headaches while taking birth-control pills that contain estrogen, face an increased risk of stroke. The pill is also a stroke hazard to women in their 40s,especially those who smoke. Of course, other factors linked to stroke, such as being male, black or genetically prone to atherosclerosis, are not under your control. But even here greater attention to life habits and underlying disease that are also linked to stroke can reduce risk substantially.
What are the warning Signs?
One such problem, called transient ischemic attacks, or TIAs, actually serves as a warning sign of an impending stroke. Recognition and prompt treatment can avert a serious stroke. A TIA, actually a mini-stroke caused by a temporary loss of blood supply to a part of the brain, usually lasts only a few minutes and nearly always less than an hour, with complete recovery within a day. Symptoms are often vague and confusing, and because they are temporary, people tend to brush them off. However, any of the following symptoms, even in people as young as 30 or 40. should be brought to a doctor's attention without delay:
- Weakness or numbness in an arm, hand, leg or
facial muscles, usually only on one side of the body.
- Difficulty speaking, understanding speech or
swallowing.
- Failing or blurry vision in one or both eyes.
- Deafness or ringing in the ears.
- Clumsiness or mild loss of balance; dizziness or
fainting, often with double vision.
- Sudden, unexplained headache; abrupt person-
ality disturbances (irritability, impatience, suspiciousness); impaired judgment or forgetfulness.
Four out of five stroke victims have a history of TIAs and 35 percent of them suffer a stroke within five years, unless treated. Effective treatment includes the use of anticoagulant drugs, small daily doses of aspirin or surgery. Stroke-preventing operations include surgery to clean out the carotid arteries, blood vessels in the neck that are the main source of the brain's blood supply.
Jane Brody
Medical Editor, The New York Times
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