The U.S. Food and Drug Administration has approved the limited use of a device that sends electrical signals to the brain to ease the symptoms of severe obsessive-compulsive disorder (OCD).

The Reclaim system, made by Medtronic Inc., can be used to treat up to 4,000 people in the United States each year under a humanitarian exemption from the Food and Drug Administration rules, the agency said Thursday.

"Deep-brain stimulation using the Reclaim system may provide some relief to certain patients with severe obsessive compulsive disorder who have not responded to conventional therapy," FDA official Dr. Daniel Schultz said in a news release.

"However, Reclaim is not a cure for OCD. Individual results will vary and patients implanted with the device are likely to continue to have some mild to moderate impairment in functioning and continue to require medications."

The device, which Medtronic compares to a pacemaker, uses a small electrical pulse generator that blocks abnormal nerve signals in the brain. A battery-powered unit implanted near the abdomen or the collar bone is connected to electrodes implanted in the brain.

May aid those whom drugs have not helped

Medtronic is starting a multi-centre, randomized clinical trial of the Reclaim system. While an estimated two per cent of the U.S. population suffer from OCD, the system is only appropriate for a tiny subset of that group, well below the 4,000 patient limit set by the FDA, the company said in a release.

The people who might benefit from Reclaim are OCD sufferers who struggle with social activities "or even daily tasks," said Dr. Donald Malone, a psychiatrist at the Cleveland Clinic and co-lead investigator of Medtronic's trial.

European and U.S. research shows deep-brain stimulation has potential for OCD patients "who have remained very ill and debilitated despite aggressive use of medications and cognitive behavioral therapy," said principal investigator Dr. Benjamin D. Greenberg, professor of psychiatry at Butler Hospital and the Alpert Medical School of Brown University, both in Rhode Island.

Four institutions in Europe and the U.S. have studied deep-brain stimulation therapy in 26 patients. The results, published recently in the journal Molecular Psychiatry, show "clinically meaningful symptom reductions and functional improvement in about two-thirds of patients," Medtronic said.

However, the process and device have drawbacks. Eleven patients — 42 per cent of the sample — suffered a combined total of 23 "serious adverse events," with 15 of the events associated with the surgical implant procedure, the device, or therapy. All of the events were resolved without consequences, Medtronic said.