Deep brain stimulation for refractory epilepsy: extrathalamic targets

Epilepsy is a neurological disorder that affects 1-2% of the population. The majority of epileptic patients achieve a good seizure control with the current available treatments. However, there is a subgroup of patients that remain severely disable despite the variety of anti-epileptic drugs, the possibility of surgery for resection of the epileptogenic foci in selected patients, and vagal nerve stimulation; various lines of research are being carried out to look for new treatment alternatives. Deep brain stimulation (DBS) of the thalamus has emerged as a therapeutic alternative for patients who remain incapacitated; the efficacy of this new therapy is subject of several studies, and its effectiveness and safety has not been established yet. There are other targets for deep brain stimulation that may be useful for drug-resistant epilepsy. Experiments with animal models and preliminary human studies have shown encouraging results with DBS on cerebellum, subthalamic nucleus, substantia nigra, hippocampus and cerebral cortex, among others. The purpose of this review is to revisit the studies that have been carried out on these brain nuclei, as targets for DBS for drug-resistant epilepsy. Studies have shown varying degrees of effectiveness, and there is a need for controlled trials to draw any definite conclusions.