Radiosurgery may bring improvement for patients with extremely severe obsessive-compulsive disorder (OCD) when other treatments have failed, according to a study in the January issue of Neurosurgery, official journal of the Congress of Neurological Surgeons.

Dr. Douglas Kondziolka and colleagues of University of Pittsburgh report promising results of radiosurgery in three patients with very severe, "medically refractory" OCD. Although further research is needed, radiosurgery could provide a new treatment alternative for the most extreme and difficult cases of OCD.

The patients were two women and one man with extremely severe OCD-on a standard OCD severity scale, two of the patients scored 39 out of 40. Despite taking multiple medications, all patients continued to have severe and disabling OCD symptoms. For example, one woman spent hours washing every day and had not left her house for a year.

After exhausting all other treatment options, the three patients underwent radiosurgery. In this procedure, a gamma knife is used to deliver an intense beam of radiation targeted precisely to the anterior cingulate cortex, the area of the brain responsible for OCD symptoms. Radiosurgery was originally developed as a way of using radiation to destroy brain tumors, as an alternative to surgery.

The experimental procedure was tried only after careful evaluation. In addition to meeting criteria for extreme OCD, the patients had to request radiosurgery, and the procedure had to be recommended by at least two psychiatrists. All radiosurgery procedures were performed without complications; the patients were followed for up to 4 1/2 years.

"All patients noted significant functional improvements and reduction in OCD behavior," Dr. Kondizolka and co-authors write. For example, the patient obsessed with washing reduced her bathing routine from four to two hours per day and was able to leave the house for daily activities.

The other two patients also improved; one had a 90 percent reduction in her OCD severity score. The improvements occurred gradually, typically peaking between two and four months. All patients had to continue taking medications-one patient's OCD symptoms began to worsen again when he stopped taking medications.

Although most patients with OCD improve with drug treatment, some continue to have severe and disabling symptoms even with extensive medications. Some patients have benefited from an anterior cingulotomy. More recently, deep brain stimulation (DBS)-using electrical stimulation applied to disrupt abnormal brain activity-has been approved for use in severe OCD.

Although preliminary, the new results suggest that radiosurgery could offer a valuable new option for those most severe cases of OCD. Radiosurgery has some potential disadvantages compared to DBS: the procedure is irreversible and doesn't allow adjustment of stimulation patterns, which is possible with DBS. On the other hand, radiosurgery doesn't require implanted electrodes and generators and avoids the equipment-related complications that are possible with DBS.

Much more research will be needed before radiosurgery can be widely recommended for patients with severe OCD. Dr. Kondziolka and colleagues call for studies comparing radiosurgery with DBS, including the benefits, risks, and costs of the two treatments.