Evaluating Unilateral Deep Brain Stimulation in Patients With Obsessive Compulsive Disorder

The investigators previously showed that deep brain stimulation (DBS) in the bed nucleus of the stria terminalis (BNST) reduces symptoms in patients with severe obsessive-compulsive disorder (OCD). Although most patients now receive bilateral stimulation, multiple studies suggest that stimulation of the left BNST might be equally effective. In this study, the investigators will evaluate the effect of unilateral stimulation in OCD patients who currently receive bilateral BNST stimulation to treat their symptoms. We hypothesize that unilateral stimulation of the left BNST will reduce anxious and depressive symptoms, compared to no stimulation. The study entails a double-blinded, randomized cross-over design during which every patient undergoes four stimulation conditions: stimulation of the left, right or bilateral BNST, or no stimulation. During every condition, which takes about fifteen minutes, the patient is exposed to an individually determined stimulus that normally elicits OCD-related symptoms. The patients are then asked to fill out a short questionnaire to evaluate the severity of their symptoms during the four conditions. At the end of the cross-over phase, the stimulation parameters of each patient are restored.