Understanding what transpires inside another person's head may be difficult for anyone, but for a surgeon about to operate on the brain, that knowledge can be a matter of life and death. New applications of functional MRI may make it a far less dangerous process.
For the past decade, patients undergoing brain surgery have benefited from a procedure pioneered at Yale. Before removing tumors, vascular malformations or other lesions that might cause seizure disorders, surgeons must carefully map the surface of the brain to pinpoint areas vital to language, and the organization of motor function, sensation and vision. Prior to surgery, the surgeon removes a portion of the patient's skull and lays a grid of electrodes over the cortex, the outer layer of gray matter at the brain's surface. The fully conscious patient then completes a series of tasks, during which critical regions of the cortex are identified and mapped as areas to avoid during surgery. The entire process lasts about a week and takes place in the Yale Epilepsy Unit.
The chairman of the Department of Neurosurgery, Dennis D. Spencer, M.D., is exploring the use of the fMRI to achieve results superior to those from the electrode grid. A one-hour fMRI exam may eventually replace the week-long monitoring process that is now the state of the art, says medical physicist R. Todd Constable, Ph.D., an assistant professor who is working on the imaging technology with Dr. Spencer. To test this capability, the research team is correlating fMRI data with the already-proven electrode techniques. Says Dr. Spencer: "Surgeons will eventually be able to understand where language is controlled without having to invade the brain and physically map it."