In select, therapy resistent patients with Obsessive Compulsive Disorder (OCD) Deep Brain Stimulation (DBS) has been used as a treatment. DBS is a therapy modality in which electrodes are implanted within specific sub-structures of the brain in order to modulate the activity in targeted neural circuits associated with different neurological disorders. The results of this novel approach to psychiatric disorders have been optimistic. This study aims to investigate wether or not the distance to target location has an influence on the outcome.

In order to deliver DBS, leads containing four electrodes are implanted into the brain target in the ventral capsule/ventral striatum (VC/VS). After an optimization period, patients enter a triple blind randomised two fazed crossover design of two periods of three months. In both crossover branches, patients, evaluating psychiatrist and psychologist are blinded for the stimulation conditions. These conditions are stimulation ON (at optimal parameters) and stimulation OFF. Stimulation parameters are constant during the entire period. During the second crossover branch, stimulation conditions are reversed for all patients.

Inclusion Criteria:

• Diagnosis of OCD following the diagnostic and statistical manual of mental disorders-fourth edition (DSM-IV) criteria for OCD (300.3).
• Failure of documented trials of pharmacotherapy, following an appropriate treatment algorithm for OCD.
• Failure of documented trial of cognitive and behavioural therapy
• Duration of illness: min. 5 year
• Y-BOCS at least 30/40.
• Age: 20-65 year

Exclusion Criteria:

• DSM-IV diagnosis on axis 2 of severe personality disorder in cluster A or B, especially in the case of heightened risk for acting-out behavior.
• DSM-IV diagnosis on axis 3 of organic brain pathology or significant abnormalities on MRI.
• Present or past history of psychotic symptoms.
• Present substance abuse, or instable remission of substance abuses (i.e. no substance abuse during the last 12 months).
• Any disorder affecting cognitive functioning, other than motor tics and Gilles de la Tourette's Syndrome
• Mental retardation. A minimum threshold of cognitive skills is needed for adequate reporting on questionnaires and evaluation, and for technical handling of the instruments in a later faze.
• The patient must be juridical free.