Neurosurgery: Half a Brain Is Better

Many a baby is born with strawberry or port-wine patches on his face, and although these disfiguring birthmarks have given rise to a lot of old wives’ tales and maternal self-reproach, most have no medical significance. An exception is the massive port-wine stain with which Michael Wood was born nearly five years ago. The huge birthmark extended from around the right eye down the side of his face to the neck.

To doctors in Brantford, Ont., the mark was the identifying surface symptom of a rare and frightening condition called the Sturge-Weber syndrome. The stains are caused by an excessive growth of blood vessels, and those in the skin are matched by others under the scalp and on the surface of the brain. In a few weeks, or at most months, a child with such a mark develops disabling seizures and convulsions. Even if these can be controlled by drugs, the dosage must be so heavy that by the time he is ten or twelve he will be oversedated to the point of grogginess.

Fluent Prattle. The Brantford doctors sent the baby to the Hospital for Sick Children in Toronto. There, when Michael was 41 months old, Neurosurgeon Bruce Hendrick cut out the entire right half of his brain. Hendrick by now has done 17 such operations, or hemispherectomies. The youngest patient was 26 days old and weighed five pounds.

Michael Wood is now doing well, and will start kindergarten in January. When he is taken to Dr. Hendrick for a checkup, he trots in and prattles as fluently as the average tot of his age. If he still had all his brain, Michael would be paralyzed on his left side, walking lamely if at all, not talking, and suffering daily or more frequent seizures despite drug treatment.

Alpine Tracings. Sturge-Weber babies are not the only ones who suffer epileptoid seizures of this type. Their cases happen to be the most severe and rapidly progressive, making it imperative that the neurosurgeon operate in infancy. Much more common are cases in which there is no clear warning signal at birth. The seizures begin a few months later and gradually become more frequent and severe. In such cases the cause is brain damage, but not as the result of birth injury. The damage may be the result of infection or biochemical poisoning during gestation and may appear as scarring of the brain. Similar effects may arise when children of any age suffer head injuries.

In most cases the damage is confined to one side of the brain. This is fortunate, because surgery is impossible if both sides are damaged. In operable cases, the damaged side of the brain produces abnormal electrical activity, making the electroencephalogram (brainwave tracing) look like one of the Alps’ more jagged ranges. Worse, the damaged side interferes electrically with the undamaged side and sets off abnormal activity there. It does not matter which side of the brain is dominant*: damage on either side will involve both hemispheres and eventually produce crippling disabilities.

If the damaged hemisphere can be removed before a child has developed right-or left-handedness or has learned to speak, so much the better. In such a case, the question of removing the dominant side does not arise. Says Hendrick: “The brain is very malleable in infants and hasn’t established any habits, so there is a better chance of the function of the damaged areas being taken over by the undamaged areas. For instance, early damage might not affect normal speech development. But a child having a stroke later, say at six or seven, is in big trouble.”

Tractor Driving. David Webster had the more slowly developing type of seizure from unexplained brain damage, beginning when he was ten months old. He was a trial to his foster parents at Thornhill, outside Toronto. Says Mrs. Willi Smith: “He had to take about nine pills a day and he still had a couple of attacks just about every day. Somebody always had to be with him on the stairs for fear he would slip. They have these attacks if they have the slightest little scare—like slipping on a polished floor. His behavior wasn’t all that good, and the nuns at the convent school couldn’t really teach him anything.”

David had his hemispherectomy when he was 14. Mrs. Smith says: “You just wouldn’t believe the difference after the operation. He used to look sort of vacant, but his whole face has changed. Only a year and a half after his operations, he’s doing seventh-grade work. He still has a bit of trouble with his right hand, but he’s learned to drive a tractor and he looks after his own cattle —20 head of steer—and he’s learned to do his own bookkeeping.”

In the rare and radical surgery that has wrought such changes, Dr. Hendrick cuts a trap door in the skull, removes the entire neocortex (new brain) and hippocampal area on one side (see diagram), stopping at the midbrain just above the hypothalamus. He puts nothing into the huge cavity that results, because it soon fills up with cerebrospinal fluid. The operation, he says, “is not exciting—it’s terrifying, especially, on young babies. They don’t have much blood anyway, and we have to get into an area that’s all blood vessels. And you have to do a lot of talking to persuade parents to let you remove half of the brain of an infant who is only a few weeks old.”

*In the vast majority of right-handed and in many left-handed people the left side of the brain is dominant, controlling most body movements and such faculties as speech and reading, while the right hemisphere is relatively inactive.