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Nov. 12, 2008 -- Electrodes implanted deep in the brain reduce severe obsessive-compulsive disorder symptoms, but it's a risky procedure, a French study shows.
It's called deep brain stimulation. The technique already helps relieve movement disorders in people with Parkinson's disease. Early studies suggest it can also help people with severe obsessive-compulsive disorder that does not respond to other treatments.
A team led by Luc Mallet, MD, PhD, of INSERM, the French national research institute, focused on a specific brain region called the subthalamic nucleus. This area of the brain is thought to help people coordinate different behaviors.
Mallet's team enrolled 16 patients with severe obsessive-compulsive disorder. On a 0 to 40 scale called the Y-BOCS, the patients' average score was 30 (at the high end of the "severe" range, close to the "extreme" scores of 32 to 40).
All of the patients had persistent symptoms despite previous treatment with several different drugs and with cognitive-behavioral therapy.
The researchers implanted an electrode into the subthalamic nucleus of each patient. They used electric stimulation to pinpoint the spot that seemed to offer the most benefit and fewest adverse effects.
After placement, the electrode was connected to an implanted pulse generator. The generator was turned on for a three-month period in eight patients (active treatment) and left off in the remaining eight patients (sham treatment).
After a one-month pause, the device was turned off in the eight patients who had received active treatment and turned on in the patients who initially received sham treatment.
Active deep brain stimulation reduced patients' average Y-BOCS scores from 30 to 19 -- well within the range of "moderate" obsessive-compulsive symptoms.
However, there were risks. One patient suffered a cerebral hemorrhage during the operation, which left him with a palsy in his fingers. It affected the hand most involved in his compulsive symptoms and increased his anxiety.
Two other patients suffered infections and had to have their electrodes removed. Overall, there were serious side effects in 11 of the 17 patients who received implants. (One of the patients had an infection and the electrode had to be removed before treatment began).
Mallet and colleagues note that patients received a low-dose current to keep side effects at a minimum. This was done so that study investigators would not know which patients were receiving active treatment and which were receiving sham treatment.
A higher current might have been more effective, but it would also have caused more side effects.
"Stimulation of the subthalamic nucleus may reduce the symptoms of severe forms of obsessive-compulsive disorder but is associated with a substantial risk of serious adverse events," Mallet and colleagues conclude.
Studies of deep brain stimulation are under way in the U.S.
Mallet and colleagues report their findings in the Nov. 13 issue of TheNew England Journal of Medicine.