2 The condition, current treatments and procedure
2.1 Obsessive-compulsive disorder (OCD) is a mental health condition in which a person has obsessive thoughts (repeated, unwanted and unpleasant thoughts, images or urges). The person feels compelled to carry out compulsive (repetitive) behaviours to try to relieve the unpleasant feelings brought on by the obsessive thoughts.
2.2 NICE's guideline on obsessive-compulsive disorder and body dysmorphic disorder describes the treatment of OCD. Treatment options include psychological interventions and drug treatment (usually selective serotonin reuptake inhibitors).
2.3 Deep brain stimulation for OCD is done under general or local anaesthesia. A stereotactic frame may be used. MRI or CT imaging, or both, are used to identify the target area of the brain (commonly, the anterior limb of the internal capsule). Two small holes are drilled in the skull and electrodes are implanted into the target area. The electrodes are connected to an implantable neurostimulator by leads, which are tunnelled under the skin of the neck and scalp. The neurostimulator is surgically placed into a subcutaneous pocket below the clavicle. Postoperative imaging is usually used to confirm the location of the electrodes. A handheld remote-control programming unit is used to turn the neurostimulator on or off and adjust stimulation parameters to find the right level of stimulation.
2.4 Although the mechanisms of action of deep brain stimulation are not fully understood, the aim of the procedure is to reduce the obsessive-compulsive thoughts and behaviours. A potential advantage of the procedure is that the stimulation can be adjusted according to the clinical effect and if necessary, stopped completely. It can be used as an adjunct to medication and as an alternative to neurosurgery for treatment-resistant OCD.