New Hi-Tech Images Guide Surgeons' Hands
He couldn't afford to skip surgery, either. Hutton, who installs insulation in houses, had taken a bad tumble off a roof during a seizure and smacked his head. "I just kind of zoned out," he says. Nothing was broken, that time. But he was having 70 seizures a year, sometimes four in a day, and epilepsy medications weren't helping.
But finding the exact spot to cut out was a problem. Bursts of odd electrical activity can be hard to locate using conventional techniques like electrodes on the scalp, especially if the seizure is deeper in the brain as Hutton's was. A scalp electroencephalogram often isn't powerful enough to reveal deep misfires, says Elson So, a neurologist and epilepsy specialist at Mayo, where Hutton was a patient. Surgeons can cut off the top of the skull and lay electrodes all over the brain surface, but exposing so much brain often leads to excess bleeding or a serious infection.
Instead, Hutton benefited from an imaging technique pioneered by So and Robb. "We injected him with a kind of 'radioactive ink' that tags the area of the seizure," says So. The ink, a molecule about as radioactive as a chest X-ray, gloms on to flowing blood. Seizure regions are very active, attracting a lot of blood and thus ink. A scan sensitive to this ink, called SPECT for "single photon emission computed tomography," showed a big clump in Hutton's right temporal lobe. (Positron emission tomography, a related type of scan often used by doctors, is a bit too slow to capture seizure location.)
Next, a computer program lays this image over an MRI, which is better at showing brain anatomy. "Once you get the two images to line up, you have this hot spot located on a map of the brain that a surgeon can use," says Robb. Mayo surgeons opened a small hole in Hutton's skull instead of a large one, and removed an area "smaller than the tip of my thumb," Hutton recalls.
The treatment worked. Today, Hutton is back at his job, has regained the driver's license he'd surrendered, is no longer a dangerous driver, and is seizure-free on a low dose of just one medication. "I even got back into my favorite hobby," he says. "Sky-diving."
The Mayo system, called SISCOM and now used at many hospitals across the country, can help 70 percent of patients like Hutton with temporal lobe epilepsy, estimates So. "It makes surgery a safe option for a lot more people. Without it, and if they don't respond to meds, only about 5 percent of them will ever be able to drive again," he says. Plus, adds Bruce Fisch, director of the epilepsy center at Louisiana State University Health Sciences Center in New Orleans, the pinpoint accuracy "allows you to stay away from important functional areas of the brain" when deciding where to cut.
Carving Out Cancers
One of the major challenges in brain surgery is that the good bits can look a lot like the bad parts. When a tumor has insinuated itself around nerve fibers, removing it without damaging healthy tissue becomes very difficult. "You can't really see bundles of nerve fibers. The surface of the brain all kind of looks like cooked egg whites," says Brigham's Golby. Even an MRI scan often doesn't distinguish a low-grade tumor from its surroundings–which may control speech and vision.
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