Therapeutic brain stimulation for epilepsy

DBS has been a possible therapy for epilepsy for more than 30 years, and now it is moving to the point of clinical utility. Animal models have shown efficacy of DBS at several brain regions, although not all animal studies have shown efficacy. Clinically, an array of sites have been explored, including the cerebellum, anterior nucleus of the thalamus, CM nucleus, hippocampus, subthalamic nucleus, brainstem, and corpus callosum; direct stimulation of the cortex has also been explored. Interest in evaluating these sites for treatment of epilepsy has been enhanced by the success of vagus nerve stimulation for epilepsy and DBS for movement disorders. Literature consists of mostly small and uncontrolled studies that are subject to limitations in interpretation. A pivotal large, double-blind controlled trial of anterior nucleus of the thalamus has recently been completed, and it showed efficacy for partial seizures with or without secondary generalization.28 A controlled trial for RNS is underway.57 In addition, pilot studies of hippocampal stimulation 41,43 are expected to lead to more definitive trials of this site.Brain stimulation for epilepsy holds several challenges for the future. Mechanisms of DBS are poorly understood, although investigations are actively being pursued. Little is known about optimal stimulation parameters. DBS has been little examined in cases of intractable generalized epilepsy. Because DBS carries some risk, mainly of hemorrhage and infection, clinicians will need to develop an effective method of identifying the best candidates. DBS is palliative rather than curative, but experience suggests that this relatively new therapy may be of benefit to some people with otherwise untreatable epilepsy.