Brain stimulation for treatment of refractory epilepsy.

OBJECTIVE: We review the targets of the deep brain and the responsive neurostimulation system (RNS) to identify the best optimal stimulation parameters and the best mode of stimulation, whether cyclical, continuous, or smarter.

DATA SOURCES: This review is based on data obtained from published articles from 1950 to 2013. To perform the PubMed literature search, the following keywords were input: deep brain stimulation (DBS), RNS, and refractory epilepsy.

STUDY SELECTION: Articles containing information related to brain stimulation or RNS for the treatment of refractory epilepsy were selected.

RESULTS: The currently available treatment options for those patients who resist multiple antiepileptic medications and surgical procedures include electric stimulation, both direct and indirect, of brain nuclei thought to be involved in epileptogenesis. The number of potential targets has increased over the years to include the anterior nucleus of the thalamus, the centromedian nucleus of the thalamus, the hippocampus, the subthalamic nucleus, the caudate nucleus, and the cerebellum, among others. The results of a randomized controlled trial and the RNS trial were published to reveal the effectiveness.

CONCLUSIONS: Although statistically significant reductions in seizures have been observed using several different stimulation techniques, including vagus nerve stimulation, DBS, and RNS, these effects are currently only palliative and do not approach the efficacy comparable with that seen in resection in appropriately selected patients. More research is needed to determine optimal stimulation targets and techniques as well as to determine which epilepsy patients will benefit most from this technology.