Wide-awake brain surgery requires special care

By Maggie Fox, Health and Science Editor

WASHINGTON (Reuters) - Keeping patients such as Sen. Ted Kennedy awake during brain surgery is standard procedure to ensure no damage is being done to key functions, neurosurgeons said on Monday.

Kennedy, a Massachusetts Democrat diagnosed with brain cancer last month, had 3 1/2 hours of surgery on Monday at Duke University in North Carolina to remove as much of a malignant brain tumor as possible.

Patients are awake during at least part of the procedure to make sure no important sections of brain tissue get removed by mistake, said Dr. Ania Pollack of the University of Kansas Hospital in Kansas City.

In Kennedy's case, the tumor is in the left parietal lobe of the brain -- an area that can include centers of speech and verbal understanding in a right-handed person.

In a telephone interview, Pollack said the surgeons who operated on Kennedy did not say how big the tumor was, how much of it they removed or where in the left parietal lobe it is -- all factors important in predicting side-effects from the surgery.

Extensive imaging using positron emission tomography or PET scans, magnetic resonance imaging and a real-time version called functional MRI all would have been done before surgery started, Pollack said.

"During the incision and opening of the skull, the patient is heavily sedated," Pollack said.

The brain does not have nerves to transmit pain, although the surrounding tissues do.

"You can push it and the patient won't feel it. You can probe it and the person won't know it," Dr. Mark Gilbert, of the University of Texas M.D. Anderson Cancer Center in Houston, told a news conference at a cancer meeting in Chicago.

After the skull is opened, the patient is awakened.

"You have someone on the other side of the anesthesia curtain, either a neurologist or a physiologist, who asks the patient questions or asks the patient to perform certain tasks," Pollack said.

While this is going on, the surgeon is stimulating the brain with an electrode. "If the stimulation of the electrode causes any changes in task performance, we know that we touched an important center of the brain," Pollack said.

"We mark that spot and we know we cannot injure it. That is called cortical mapping."

Kennedy was diagnosed with a glioma, a rare brain tumor that is difficult to remove completely. The tumor cells weave through the nooks and crannies of the brain, neurologists say.

Surgery is not successful unless at least 98 percent of the tumor is removed, Pollack said. Even then, gliomas always come back eventually, she said -- even with chemotherapy and radiation to destroy errant tumor cells.