Striking Back at Stroke

by Food and Drug Administration (FDA)

At the time, the president's personal physicians believed it was necessary to keep from the public the truth about the president's health. With the second World War not yet won, they would neither confirm nor deny that he was ill and told no one, not even his family, that he had serious heart problems and blood pressure as high as 260/150. But Americans could see for themselves that the president was failing rapidly. The signs of it were in his face, and in the reduced vigor of his voice. Still, it came as a shock when Franklin D. Roosevelt died of a massive cerebral hemorrhage nearly 50 years ago.

President Roosevelt was one of 129,144 Americans who died of stroke in 1945. Today, with a population almost twice as large, about 150,000 people die of the half million who are stricken each year. Another 200,000 are left with some disability. Although the statistics are looking better, stroke remains the third leading cause of death, preceded only by heart disease and cancer.

A stroke is damage to brain cells resulting from an interruption of the blood flow to the brain. The brain must have a continual supply of blood rich in oxygen and nutrients for energy. Although the brain constitutes only 2 percent of the body's weight, it uses about 25 percent of the oxygen and almost 75 percent of the glucose (sugar) circulating in the blood. Unlike other organs, the brain cannot store energy. If deprived of blood for more than a few minutes, brain cells die from energy loss and from certain chemical interactions that are set in motion. The functions these cells control — speech, muscle movement, comprehension — die with them.

Dead brain cells can't be revived, but in recent years the Food and Drug Administration has approved new drugs that may prevent stroke in susceptible people and in those who have already had a stroke.

The majority of strokes are caused by blockages in the arteries that supply blood to the brain. (These are called ischemic strokes or infarctions, just as a heart attack — in which the heart muscle is deprived of blood — is called myocardial infarction.) The blockages may be caused by a clot, or thrombus, that forms on the inner lining of a brain or neck artery already partly clogged by atherosclerotic plaque — deposits of fat- containing materials and calcium.

Although atherosclerosis, or hardening of the arteries, is primarily a disease of the elderly, the process may begin as early as childhood. Autopsies of soldiers who died in the Korean and Vietnam wars showed that atherosclerosis was already evident in the arteries of many of the young men.

A blood clot formed in another part of the body may also cause stroke. Usually, a wandering clot like this — called an embolus — breaks off from plaque in an artery wall, or originates in the heart.

Emboli may form in rheumatic heart disease, after a heart attack, or during atrial fibrillation, an abnormal heart rhythm. Instead of beating forcefully to fill the ventricles (the larger heart chambers that pump blood to the lungs and throughout the body), the atria (smaller heart chambers) beat irregularly and don't empty fully, causing blood to stagnate in the heart and form clots. If one lodges in a brain artery, a stroke results.

The most serious kinds of stroke occur not from blockage, but from hemorrhage, when a spot in a brain artery weakened by disease — usually atherosclerosis or high blood pressure — ruptures or begins to leak blood. If an artery inside the brain ruptures, it is called a cerebral hemorrhage. When a blood vessel on the brain's surface ruptures, filling the space between the brain and the skull with blood, it is known as a subarachnoid hemorrhage. This type of stroke may also be caused by an aneurysm, a section of the artery wall so thin that it may balloon out and burst, especially when high blood pressure is present. (In many cases, people are born with these fragile spots in a brain artery wall, or may develop weak spots in arteries due to malformed blood vessels or hemorrhagic disease.)

Not only does the part of the brain served by the blood vessel die in hemorrhagic strokes, but blood may spurt out so forcefully that surrounding brain cells are damaged. A large clot may form and press on adjacent brain tissue, increasing pressure inside the skull and causing swelling. Hemorrhagic strokes account for less than 20 percent of all types of strokes, but are far more lethal, with a death rate of over 50 percent.

Strokes caused by emboli or hemorrhage usually strike suddenly, with little or no warning, and do all their damage in a matter of seconds or minutes. In thrombotic strokes, symptoms often progress by steps. A slight clumsiness on arising in the morning may be followed by loss of half the field of vision in both eyes by breakfast time (which the victim may not be aware of) and an inability to speak. Paralysis in one arm may be followed in the course of several hours or a day or so by complete paralysis on that side of the body.

Distinguishing a Stroke from a TIA

Any evidence of disruption of blood supply to the brain (such as inability to grasp with one hand or difficulty speaking) that lasts longer than 24 hours may be used to diagnose stroke. Effects of a stroke can range in severity from a slight one-sided facial sagging that disappears within two weeks to inability to walk or loss of control of bodily functions that lead to long- term problems such as incontinence. The kind of disability a stroke victim is left with depends on the location and extent of brain damage.

An incident involving physical symptoms that last less than 24 hours (usually not longer than a few minutes or hours at most) and leave no permanent disability is called a transient ischemic attack (TIA) or "ministroke." A TIA is a signal that the brain's blood supply has been temporarily interrupted, either from small clots that lodge in a tiny brain artery and then dissolve spontaneously, or from briefly reduced blood flow in narrowed arteries.

The most commonly reported symptoms of a TIA include temporary difficulty in speaking or understanding the speech of others; minor numbness or weakness of the face, arm or leg on one side of the body; unsteadiness, dizziness or falls; and blurred vision or sudden blindness in one eye that may last a few minutes. A TIA may occur shortly before a stroke occurs, or may be a predictor of future stroke. Some individuals have repeated attacks of TIAs without any serious consequences, but these symptoms should not be ignored and need immediate medical attention.

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.