Brain stimulation for the treatment of epilepsy.

Direct brain stimulation is an emerging treatment of epilepsy. Scheduled or responsive stimulation has been applied. The most explored targets for scheduled stimulation are the anterior nucleus of the thalamus and the hippocampus. The anterior nucleus of the thalamus was studied in a large multicenter trial. There was a significant seizure reduction with the stimulator "on" versus "off" during several months after stimulator implantation. The hippocampus as stimulation target has not yet been studied in a large randomized trial. Responsive stimulation applies a stimulus whenever epileptiform activity occurs. It requires on-line detection of epileptiform activity. This concept is based on the observation that epileptiform activity during functional mapping can be aborted by brief pulses of cortical stimulation. Current technology is able to detect seizure activity intracranially on-line and delivers a high frequency stimulus if epileptiform activity is detected. A large randomized multicenter trial has been conducted testing this system for focal epilepsy.