High-frequency stimulation of deep brain structures in obsessive-compulsive disorder: the search for a valid circuit

Obsessive-compulsive disorder (OCD) is a common, disabling, psychiatric disease combining intrusive thoughts (obsessions) and repetitive behaviours (compulsions). Although most patients respond well to conventional pharmacological and/or psychological therapy, 25-30%, often with extremely severe symptoms, fail to improve after treatment. High-frequency stimulation of deep brain structures (basal ganglia included), a surgical technique developed for movement disorders and otherwise known as deep brain stimulation (DBS), has been proposed as an alternative to ablative surgery for these intractable cases. Here, we review the scientific data that explain why the use of this technique is currently being investigated in OCD, from the first hypotheses based on neuroimaging studies (anatomical and functional) to more recent animal models and clinical observations. The general outcome of each clinical trial is outlined in order to discuss its relation to pathophysiology; however, more specific clinical information (side-effects, latencies, and other behavioural modifications) is not given. Finally, a description of the models of OCD that stem from these data and how they might be affected by DBS is provided.