Electrodes in the Brain

For the most dramatic form of epilepsy, the grand mal that throws its victims to the ground in fits, drugs often offer dramatic relief. Strangely, it is a less violent form of the disorder, the so-called psychomotor type, for which drugs do least. For some 50% of psychomotor epileptics, or at least 160,000 Americans, surgery is the only recourse. But in many cases surgeons hesitate to cut out those parts of the brain in which electrical impulses are misfiring and causing all the trouble. For if they cut out too much tissue or cut in the wrong place, they may leave their patient deprived of memory.

Through the Guides. The solution to that problem, suggests a U.C.L.A. research team, is a procedure for precise brain mapping that is as drastic as it is technically delicate. First a bunch of holes are drilled into the patient's skull; metal guides are screwed into place and steel electrodes are jabbed through the guides, as far as two inches into the brain, to make a special kind of electroencephalogram (EEC). The electrodes are left in place for three weeks or so, and repeated EEGs are taken--when the patient is asleep, during a spontaneous seizure, or when the doctors induce a seizure with a drug or electricity. The position of the implanted electrodes is changed if necessary. Then, after the offending part of the brain is accurately located, it is cut out.

Torturous as it sounds, the method is essentially painless. It is admittedly cumbrous and timeconsuming, says

Neurosurgeon Robert W. Rand, but is desirable in cases where ordinary EEGs, made with electrodes placed on the scalp, fail to show clearly the side of the brain in which the misfiring is more pronounced. The deeply implanted electrodes, penetrating the temporal lobe to reach the hippocampus* or even part of the cerebellum, sometimes reveal focal areas of electrical misfiring that surface EEGs have missed entirely. If there is misfiring on only one side, it can usually be detected readily, and relieved by surgical removal of the proper piece of brain tissue. If there is misfiring on both sides, surgeons cannot cut out both offending pieces of brain without damaging or destroying memory.

Subtle Injury. The U.C.L.A. team, with Dr. Charles H. Markham as neurologist and Dr. Paul H. Crandall doing most of the surgery, has now followed 19 patients for two years or more. In three cases, even the deeply implanted electrodes failed to show a decisive focus of abnormal activity on one side, so no surgery was attempted. Of 16 patients who had operations, ten are now free of seizures, and two have improved although they still have occasional seizures. Three got no benefit, and one died from a hemorrhage not connected with the operation.

The U.C.L.A. work has also pinpointed one of the causes of epilepsy. In most psychomotor cases, the researchers say, the trouble stems from "birth injury," though not the physical damage associated with old-fashioned use of high forceps during a difficult delivery. The injury is far more subtle, often undetectable when it occurs. It results when the brain, or especially sensitive parts of it like the hippocampus, are starved of oxygen or exposed to physiological poisons. Evidence for this, says Dr. Crandall, has been found in scarring of the brain tissues removed in all operations.

*So named because of a fancied resemblance to the sea horse; it lies below the temporal lobes and toward the middle of the skull.

This file is automatically generated by a robot program, so reader's discretion is required.