Chronic deep brain stimulation (DBS) has been a rapidly evolving area of neurotherapeutics since its initial introduction for the treatment of Parkinson's disease and essential tremor in the 1990s. For these conditions, DBS is now considered accepted therapy for patients failing to adequately respond to m- ical treatment. Since the 1990s, new clinical indications, anatomic targets, and technologies have contributed to an expanding role for DBS in...