Researchers funded by the National Institutes of Health have developed a flexible brain implant that could one day be used to treat epileptic seizures. In animal studies, the researchers used the device - a type of electrode array that conforms to the brain's surface - to take an unprecedented look at the brain activity underlying seizures.
"Someday, these flexible arrays could be used to pinpoint where seizures start in the brain and perhaps to shut them down," said Brian Litt, M.D., the principal investigator and an associate professor of neurology at the University of Pennsylvania School of Medicine in Philadelphia. The findings appear in this month's Nature Neuroscience. The team will also discuss their findings at the 2011 Society for Neuroscience meeting, Nov. 12-16 in Washington, D.C.
"This group's work reflects a confluence of skills and advances in electrical engineering, materials science and neurosurgery," said Story Landis, Ph.D., director of NIH's National Institute of Neurological Disorders and Stroke (NINDS), which helped fund the work. "These flexible electrode arrays could significantly expand surgical options for patients with drug-resistant epilepsy."
In an animal model, the researchers saw spiral waves of brain activity not previously observed during a seizure. Similar waves are known to ripple through cardiac muscle during a type of life-threatening heart rhythm called ventricular fibrillation.
"If our findings are borne out in human studies, they open up the possibility of treating seizures with therapies like those used for cardiac arrhythmias," said Dr. Litt. Epilepsy surgery could become more analogous to ablation procedures for cardiac arrhythmias. In these procedures electrodes are used to detect aberrant electrical circuits in the heart muscle, which are then interrupted by making tiny lesions in the muscle. A stimulating electrode array might one day be designed to suppress seizure activity, working like a pacemaker for the brain, Dr. Litt said.
The brain contains billions of interconnected neurons that normally transmit electrical pulses. During a seizure, these pulses occur in abnormal, synchronized, rapid-fire bursts that can cause convulsions, loss of consciousness and other symptoms.
More than 20 drugs are on the market for epilepsy, but they do not always provide adequate seizure control. Surgery can be an effective treatment option for people with drug-resistant epilepsy and commonly involves removing, or resecting, an area of the brain where the seizures originate. Electrode arrays are used to map the seizures and guide resection surgery.
The arrays currently used to record seizure activity in patients being considered for surgery consist of electrodes attached to a rubbery base about the thickness of a credit card. These arrays are placed on the surface of the brain, but they are not flexible enough to mold to the brain's many folds. The electrodes are widely spaced and allow for only limited brain coverage.