Magnets vs. seizures

Magnetoencephalography (MEG) allows physicians to see the brain working. Being able to watch the brain as it functions allows doctors to diagnose and treat conditions and diseases with more accuracy than ever before. Patients with epilepsy, malformations or brain lesions could benefit from this technology.

There are not very many MEG centers in the United States right now. The technology is new and the equipment is very expensive, several million dollars for each unit.

MEG works by mapping magnetic fields from neurons in the brain. Unlike functional MRI, which measures brain activity indirectly through changes related to blood flow, this technology measures brain activity more directly and precisely. This imaging system can pick up activity nearly the moment it happens, allowing doctors to better pinpoint which part of the brain correlates to an action or symptom experienced by the patient.

Dr. Richard Bucholz, chief of neurosurgery at St. Louis University School of Medicine in St. Louis, Mo., says knowing more about how a person's brain works before surgery is very important.
"Imaging technologies like magnetic resonance imaging and CT scans are very good at detecting and depicting the anatomy of the brain. They can show us where a tumor is, for example. But increasingly, in neurosurgery, we're having the issue of where function is located in the brain. It is one thing to know where a tumor is located, it is an entirely different thing to know, for example, where speech is located," he said.

Magnets for the brainMEG measures the brain's magnetic signals for a more direct and precise reading than MRI.

Bucholz says most brain tumors can be removes. The problem surgeons and patients face is whether or not crucial portions of the brain will be damaged during the surgery.

"In the past, the way that was determined was by looking at the normal functional anatomy of the brain, where the motor-cortex was in the normal person, or the speech cortex in the normal person, and then assume that the patient had the same sort of functionalization," Bucholz said.

However, thanks to new imaging technologies, researchers have discovered not every person's brain functions in the same way. Also, tumors often push crucial parts of the brain to another location.

"We have found in numerous examples we can actually go in and take out a brain tumor, which was thought to be non-ressectable by other surgeons. That is one of the reasons why we are so very excited about this technology, that it may empower us to perform surgery and remove tumors in many more patients than we would have thought otherwise based solely on CT and MRI," Bucholz said.

The data gathered by MEG can help surgeons in the operating room. The information is put into a navigational system the surgeon can see while in the operating room.

Patients with epilepsy can have relief from relentless seizures if doctors can pinpoint the exact area of the brain causing the out of control electrical activity behind the seizures. MEG allows physicians to see which areas of the brain are active during a seizure.

"I think that we may have MEG on the very cusp of a very bright future of being able to identify where abnormal function is coming from, be it seizures or movement disorder," Bucholz said.