Efficacy and Adverse Events of Bilateral Single-shot VC/VS Gamma Capsulotomy for OCD: a Pilot Study

Inclusion Criteria: * A DSM-V diagnosis of OCD as the main diagnostic entity. If comorbid axis I or II disorders are present, OCD symptoms are the most troublesome among disorders. * Age range between 18 and 65 years old. * At least 5 years of OCD symptoms. * "Yale-Brown Obsessive-Compulsive Scale" (YBOCS) scores greater than 26 (or greater than 13, for isolated obsessions or compulsions). * Refractoriness criteria fulfilled. * To be accepted by the "best estimate" method as a treatment refractory patient. It consists in the careful examination of each patient's history by two OCD specialists, so as to confirm refractoriness status. Refractoriness criteria: * At least 3 serotonin reuptake inhibitors (selective or not) have been tried before. One of these trials must have included clomipramine. All drugs were used for a minimum of 12 weeks, at the maximum doses or the maximally tolerated doses. * Previous participation in a cognitive behavior therapy program (exposure and response prevention), for a minimum of 20 hours' time; or participation for some time, without subsequent adherence, due to severe OCD symptoms, and acceptance of the independent review board. * YBOCS scores reductions after adequate drug therapy and psychotherapy not better than 25 %, or confirmation of no clinical improvements by the mental health professionals who were responsible for the treatments of the patient. * By the end of adequately conducted pharmacological trials, "Clinical Global Impression" (CGI) scores not better than minimal improvement. * Previous use of at least two antidepressant augmentation strategies (such as the association of a typical or atypical antipsychotic, another serotonin reuptake inhibitor, a benzodiazepine, an anticonvulsant or an antiglutamatergic medication), in adequate doses for a sufficient period of time, without satisfactory responses. Exclusion Criteria: * Less than 18 years or more than 65 years of age. * Past history of head injury, with posttraumatic amnesia. * Past or general medical condition, or neurological illness with brain compromise (severe and in active phase) * History of physiological effects of a substance, as determinant of psychopathological symptoms, or cumulative signs of alcohol or drug abuse in the Central Nervous System (such cortical atrophy), confirmed by a neuroimaging scan. * Pregnancy or lactation. * Refusal to participate in radiosurgical procedures. * Refusal to sign the Patient Information and Consent Form, or refusal to take part in this study. * History of mental retardation and/or being unable to understand the Patient Information and Consent Form, confirmed by poor performance on neuropsychological tests.