Stroke : Resourceful Brain, Drugs to Inhibit Clots

by Food and Drug Administration (FDA)

(Page 2 of 3)

Resourceful Brain

The brain is resourceful. After brain swelling goes down following a stroke, small blood vessels around the blocked area enlarge to allow more blood flow to the damaged section. Some incapacitated cells may recover partially or completely. In many cases, other brain cells can assume the functions of the damaged ones. This is especially true of infants and young children, whose nervous systems are still developing.

"Less than 1 in every 50,000 newborns suffers a stroke caused by clots that travel from the fetal or placental circulation around the time of birth," says Rebecca Ichord, M.D, a pediatric neurologist at Johns Hopkins University Hospital, Baltimore, Md. "Newborn infants do remarkably well and have less long-term disability than an adult with a comparable injury. Even though part of the brain is damaged, infants have other healthy brain cells that aren't dedicated to any particular function as yet, and these take over for the damaged cells."

Each of the two hemispheres of the brain controls the opposite side of the body. Paralysis on the right side of the body means that the left side of the brain (the dominant hemisphere in a right-handed person) is injured. As speech and language are associated with areas in the left brain, individuals with left-brain damage may have trouble with speaking and understanding, a condition called aphasia.

A right-brain stroke may leave persons with a paralyzed left side and spatial-perceptual deficits — difficulty in judging distance, size, position, and speed. They may not know whether they're standing or sitting upright or leaning. Because they may not sense where they are in the road or how near they are to the next car, driving should be left to others.

Both types of brain injury may result in memory loss and personality changes. Stroke victims may also suffer from visual field defects and hearing loss on one side of the body, called "one-sided neglect." The condition may cause problems in something as basic as getting dressed — they may neglect their left side, for example, and put only the right arm in a sleeve, or the right foot in a shoe. When these people see their own arm and leg lying beside them, they often think someone is in bed with them and become incensed. In her memoir, Reprieve, Agnes de Mille, who had left-brain injury, tells of losing track of her "lost" right hand and hunting for it among the bedclothes.

Drugs to Inhibit Clots

As blood clots play a major role in causing thrombotic and embolic stroke, agents that inhibit blood from coagulating may prevent clot formation. Physicians have several such drugs at their disposal, including the workhorse of the medicine chest — aspirin — to treat those who've had TIAs or previous stroke.

Aspirin works by preventing blood platelets from sticking together. The amount of aspirin for optimum stroke prevention is controversial.

"We don't know exactly how much aspirin is best for stroke prevention," says Chung Hsu, M.D., Ph.D., professor of neurology at Washington University School of Medicine, St. Louis, Mo. "The literature appears to suggest if a patient can tolerate four aspirin (325 mg each) a day, that's probably the preferred treatment. However, on four aspirin a day, some patients have side effects. If the patient can't take four, I'll try three, then two. On some patients I would try one a day." Many physicians use as little as one baby aspirin (80 mg) daily.

Allergy, stomach irritation, or more serious gastrointestinal complaints are the chief side effects of aspirin. And in some people, especially the very old, aspirin is just not effective.

Aspirin's easy availability has led many to take it without their doctors' recommendation, but this practice may be unwise. The physician labeling for aspirin states that aspirin is safe and effective for reducing the risk of recurrent TIAs and stroke in men who have had transient ischemia of the brain due to emboli and recommends a dosage of 1,300 mg a day, in divided doses. However, it also states there is inadequate evidence of effectiveness in women and no evidence of benefit in treating completed strokes in men or women. The labeling advises persons who have had TIA symptoms to have a complete medical and neurologic evaluation to rule out other disorders that resemble TIAs. A study in the Jan. 7, 1994, British Medical Journal stressed that people at low risk of stroke should not take aspirin because it may cause bleeding into the brain. There is no evidence that daily use of aspirin will prevent strokes in people who have never had a TIA or other symptoms.

Late in 1992, FDA approved Ticlid (ticlodipine), another anti-platelet drug for stroke prevention that's labeled for use in patients who cannot tolerate aspirin. In the Ticlodipine Aspirin Stroke Study, a large, multicenter randomized study, researchers found that Ticlid was superior to aspirin for preventing thrombotic stroke in both men and women who had recently had a TIA, or who had had a minor nondisabling stroke. Compared to aspirin, Ticlid reduced the overall risk of stroke an additional 24 percent.

"If somebody fails on aspirin, that's an indication to try Ticlid," says Hsu. "We use it in a selected group of patients because it's more expensive than aspirin and in approximately one out of every 100 patients, its use is associated with neutropenia, a blood side effect [reduction in the white blood cells that fight infection]. Also, patients must be monitored carefully, because some get diarrhea and rash."

People taking Ticlid must have complete blood counts taken every two weeks during the first three months of treatment to check for neutropenia, which is usually reversible when Ticlid is stopped.

Another clot-preventing drug is Coumadin (warfarin), which interferes with the production in the liver of certain proteins that are necessary for blood coagulation. Use of warfarin carries a risk of hemorrhage, but treatment with low doses has been very successful in preventing embolic stroke in people who have atrial fibrillation or heart valve abnormalities.

About the Author

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