A new clinical guideline published in the journal Neurosurgery recommends deep brain stimulation for cases of obsessive-compulsive disorder that do not respond to medication.

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The guideline states that bilateral stimulation is a “reasonable therapeutic option” for patients who have OCD that does not respond to other treatments.

Unwanted, recurrent, intrusive thoughts and repetitive ritualized behaviors used to relieve anxiety and stress are the “obsessions” and “compulsions” that comprise obsessive-compulsive disorder (OCD). Medications and/or psychotherapy can be used to treat cases of OCD, although 40-60% of patients continue to experience symptoms.

The first study investigating the use of deep brain stimulation to treat OCD took place in the late 1990s. Since then, a number of studies have found it to be a promising treatment for OCD. However, most studies of deep brain stimulation for OCD have involved only small numbers of patients.

Deep brain stimulation involves specific areas of the brain being electrically stimulated via electrodes placed in the brain. This procedure has become a key treatment for Parkinson’s disease and other movement disorders.

For the new guideline, a group of experts – sponsored by the American Society of Stereotactic and Functional Neurosurgery and the Congress of Neurological Surgeons – performed a systematic review of research looking at how effective deep brain stimulation is for treating OCD. From more than 350 available papers, the team identified seven high-quality studies.

Assessing the evidence from these studies, the researchers conclude that deep brain stimulation on both sides of the brain – “bilateral stimulation” – is an effective treatment for OCD. Bilateral stimulation – where the subthalamic nucleus and the nucleus accumbens regions of the brain are stimulated – improved OCD symptoms by around 30% in clinical trials.

The guideline states that bilateral stimulation is a “reasonable therapeutic option” for patients who have OCD that does not respond to other treatments. However, the guideline also observed that there is insufficient evidence for “unilateral stimulation” – where just one side of the brain is stimulated.

Because of the limited numbers of participants in deep brain stimulation trials, the treatment is currently approved by the Food and Drug Administration (FDA) under a “humanitarian device exemption,” with safeguards in place to ensure appropriate use – and prevent overuse – of the procedure to treat OCD.

“These safeguards are valuable in preventing overuse of the therapy,” write the authors in their conclusion. “However, we suspect that rather than achieving its proposed goal, these additional steps are impeding patients who would really benefit from the therapy.”

They make the case that functional neurosurgeons should continue to work with other specialists to ensure that patients with severe OCD that does not respond to other treatments are able to access deep brain stimulation therapy.

However, the authors agree that more research is needed and outline areas to be addressed by future studies. One of these is to clarify which patient groups are the most suitable candidates for this treatment. They write:

OCD comprises different clinical phenotypes. It is possible that particular patient subgroups may respond differently to [deep brain stimulation] and that specific targets may be more suitable to treat a specific set of symptoms. For instance, it has been noted that ‘hoarders’ do not respond as well to [deep brain stimulation] for OCD.”