Kennedy's brain surgery is risky, doctors say

Targeted brain surgery like that chosen for Sen. Edward M. Kennedy is a delicate balance - removing as much of the tumor as possible without damaging the patient's ability to walk and talk.

"The surgeon usually does as much as possible within the bounds of safety. We do not want to do neurological damage in an effort to remove as much of the tumor as possible," said Dr. Mark Gilbert, a brain tumor expert at the University of Texas M.D. Anderson Cancer Center in Houston.

He spoke in Chicago at a conference attended by 30,000 cancer specialists featuring three hours of presentations Monday on experimental treatments for brain tumors.

Kennedy, 76, was scheduled to undergo the surgery Monday at Duke University Medical Center. He was diagnosed last month with a malignant glioma, a lethal type of brain tumor. A statement from his office said the surgery would be followed by chemotherapy and radiation.

These operations usually start with the patient heavily sedated as surgeons cut through the scalp and remove a small area of the skull bone to expose the brain. The tumor usually is not on the surface, so surgeons must choose a path through the brain to get to it, said Dr. Matthew Ewend, neurosurgery chief at the University of North Carolina, Chapel Hill.

To avoid cutting through vital areas controlling speech, doctors often bring the patient back to consciousness and stimulate tissue in the planned approach with a probe.

"We'll have them do language tests like hold up pictures, name objects, repeat words, hold a conversation," Ewend explained. "There's lots of local anesthesia, so this is not painful," he stressed.

Similar tests for brain areas that control movement can be done while the patient is unconscious, with a small electrical current to the brain. The patient doesn't have to be awake for doctors to see the reflex responses.

Once they see a safe path, the patient is put under again while the tumor is removed. That takes about three to four hours, Ewend said.

A less common approach is totally awake surgery, with the patient just under local anesthesia.

"That's the best way you can determine if you're incurring neurological impairment" as the operation proceeds, said Dr. Kevin McGrail, neurosurgery chief at Georgetown University Medical Center.

"It's a safe way to do the operation, but it can sometimes be very stressful on the patient," who is aware of what's going on even though it is not painful, he said.