Brain stimulation for epilepsy: can scheduled or responsive neurostimulation stop seizures?

PURPOSE OF REVIEW: Scheduled and responsive direct brain stimulation may be an effective and safe therapy for medically intractable epilepsy. RECENT
FINDINGS: Scheduled stimulation (open loop) has been provided via electrodes implanted in thalamic nuclei, the cerebellum and the hippocampus using devices commercially available for treatment of tremor and Parkinson's disease. Small pilot trials suggest that seizure frequency is reduced in some patients with intractable epilepsy. Responsive stimulation requires systems that detect abnormal electrographic activity and provide stimulation (closed loop). Studies in inpatients and outpatients suggest that abnormal electrographic discharges can be detected before there is evolution into a clinical seizure, and that focal stimulation of the epileptogenic region terminates electrographic seizures and reduces the frequency of clinically evident seizures.
SUMMARY: Direct brain stimulation appears to be safe and may be efficacious in treating medically intractable epilepsy. The optimal location (deep brain or cortical) and characteristics of the stimulation (frequency, current, duration), and whether stimulation should be focal or responsive are still to be determined. If ongoing studies of a deep brain stimulator and of a cranially implanted responsive neurostimulator demonstrate effectiveness, then neurostimulation may become available as adjunctive therapy for medically intractable epilepsy.