Medicine: Second Opinions on the Bypass

When it was first attempted nearly 20 years ago, the operation was hailed as a marvel of technical virtuosity and medical logic. Cerebral bypass surgery was designed to circumvent one of the most common causes of strokes: a blockage in one of the arteries that carry blood to the brain. To reroute blood around a blocked vessel, the surgeon uses a nearby, less vital artery to build a bypass road. Taking this detour, blood continues to flow to the brain, and the risk of a stroke's occurring is presumably lessened.

The operation involves advanced microsurgical techniques, the joining of arterial walls with thread finer than a human hair, and exquisitely delicate maneuvers by the surgeons. Nonetheless, hundreds of doctors have mastered its intricacies, and the operation has been performed on thousands of patients around the world. There is just one problem: for most patients, it does not seem to help.

That was the conclusion of an eight-year, $9 million study reported in last week's New England Journal of Medicine. The study, financed by the National Institute of Neurological and Communicative Disorders and Stroke (NINCDS), in Bethesda, Md., involved 1,377 patients at 71 leading medical centers in such cities as Budapest, Kyoto and Cleveland. Each of the subjects had experienced either a minor stroke or warning signals known as transient ischemic attacks. Such attacks, which may result in dizzy spells, temporary loss of vision or speech, or numbness in a hand or limb, signal that arteries supplying various parts of the brain have become narrowed and a stroke may be imminent.

All the patients were given careful medical attention, including drugs to reduce the risk of blood clots and control high blood pressure, which is frequently a contributing factor in stroke. Roughly half the participants were randomly assigned to undergo bypass surgery to connect the superficial temporal artery, which nourishes the scalp, to an artery on the surface of the brain. (The scalp has an ample supply of blood from other vessels.) The central question posed by the investigators: Would the surgery reduce the incidence of future strokes and stroke-related deaths? Their conclusion: "The answer is no." In fact, the operation may actually increase the risk of stroke in certain patients.

The results came as a surprise to doctors involved in the study. "We started off because we were encouraged by the operation," says Dr. Henry Barnett, professor of neurology at the University of Western Ontario in Canada and chief coordinator of the project. "Disappointing is the one single word that describes it best of all." Even worse, the study showed that among patients who underwent the surgery, there were 14% more fatal and nonfatal strokes than among those who did not have the operation. The reasons for this finding are not entirely clear, though some doctors speculate that the increased blood flow resulting from the surgery may cause damaging changes in blood-pressure levels in the brain. Also, any operation, particularly around the brain, carries a certain risk. What is clear, says Dr. Sydney Peerless, who directed the surgical aspects of the study, is that for most patients, "the risks discount the benefits." Says Peerless, chairman of neurosurgery at Western Ontario: "I'm one of the first to do this operation. Now I've stopped."