New Approaches to Taming Seizures

Date: November 1, 2011

Electrodes implanted in a patient's brain

Patients who have severe epileptic seizures often undergo the removal of a small section of brain suspected of being at the root of the problem. But that doesn’t always stop the seizures, and it’s not a good option if seizures originate in multiple regions or regions that control important functions. But some of these patients may have a new treatment option and better outcomes, thanks to Johns Hopkins neurosurgeons William Anderson and Frederick Lenz.

Anderson implants electrodes in patients’ brains that detect preseizure electrical activity among neurons—and then put out a short, mild blast of electricity that quiets the abnormal discharges. While sending in more electricity sounds as if it ought to make things worse, notes Anderson, it often stops a seizure cold. That could be because the stimulation changes the abnormal activity into a pattern of firing less likely to spread. “The neurons use up their energy when they fire, so they can’t create the spikes that can lead to a seizure,” he says.

In a clinical trial, the technique reduced seizures by an average of about 40 percent without impairing or even bothering patients. It may be even more effective, suggests Anderson, among patients whose seizures can be pinned down to specific areas of the brain. And some of these patients are the ones who aren’t good candidates for tissue removal. “This approach will be the next line of defense,” he says.

Whether the treatment is tissue removal or stimulation, results will be better when doctors can more accurately track down which brain regions lead to seizures and which control key functions. Standard recording and imaging techniques often show that multiple regions are active during a given event or task. “Some active regions may be important to a function, but others may not,” says Johns Hopkins neurosurgeon Frederick Lenz. Identifying which regions are actually the essential ones can be a big challenge.

To find out which regions matter most, Lenz is analyzing data from implanted electrodes to determine which pairs of regions tend to fire synchronously and which regions cause or drive activity elsewhere in the brain. The results may be useful in zeroing in on those areas that can be stimulated for effective treatment of seizures as well as for treatment of the tremors of Parkinson’s disease and chronic pain. “Stimulation is not always effective” he says, “and that may be because we’re applying it in the wrong places.”

• Challenge: Stop seizures without removing tissue
• Approach: Electrically stimulate brain cells, and identify key brain regions
• Progress: A big reduction in seizures, and new insights into which regions matter most