Monday, May 28, 2007

When half a brain is better than a whole. . .

A fascinating article showing how the brain is able to heal and reroute functionality, even when half of it is removed. Here are a few excerpts:

The operation known as hemispherectomy—where half the brain is removed—sounds too radical to ever consider, much less perform. In the last century, however, surgeons have performed it hundreds of times for disorders uncontrollable in any other way. Unbelievably, the surgery has no apparent effect on personality or memory.

The first known hemispherectomy was performed on a dog in 1888 by German physiologist Friedrich Goltz. In humans, neurosurgeon Walter Dandy pioneered the operation at Johns Hopkins University in 1923 on a brain tumor patient. (That man lived for more than three years before ultimately succumbing to cancer.). . .

Nowadays, the surgery is performed on patients who suffer dozens of seizures every day that resist all medication, and which are due to conditions that mostly afflict one hemisphere. "These disorders are often progressive and damage the rest of the brain if not treated," University of California, Los Angeles, neurosurgeon Gary Mathern says. Freeman concurs: "Hemispherectomy is something that one only does when the alternatives are worse."

Neurosurgeons have performed the operation on children as young as three months old. Astonishingly, memory and personality develop normally. A recent study found that 86 percent of the 111 children who underwent hemispherectomy at Hopkins between 1975 and 2001 are either seizure-free or have nondisabling seizures that do not require medication. The patients who still suffer seizures usually have congenital defects or developmental abnormalities, where brain damage is often not confined to just one hemisphere, Freeman explains.

Another study found that children that underwent hemispherectomies often improved academically once their seizures stopped. "One was champion bowler of her class, one was chess champion of his state, and others are in college doing very nicely," Freeman says.

Of course, the operation has its downside: "You can walk, run—some dance or skip—but you lose use of the hand opposite of the hemisphere that was removed. You have little function in that arm and vision on that side is lost," Freeman says.

Remarkably, few other impacts are seen. If the left side of the brain is taken out, "most people have problems with their speech, but it used to be thought that if you took that side out after age two, you'd never talk again, and we've proven that untrue," Freeman says. "The younger a person is when they undergo hemispherectomy, the less disability you have in talking. Where on the right side of the brain speech is transferred to and what it displaces is something nobody has really worked out."


Ulrich Mohrhoff said...

You got your title wrong. Half a brain is always better than none.

M.C. said...

Yes I sure did.

Anonymous said...

Stan Gooch's "Double Helix of the Mind" book is excellent on this topic -- Robert Ornstein's right-left brain dichotmy is a science myth. What's worse is when they just sever the corpus callusom because the brain's cross-wiring becomes hay-wired