A pacemaker-like brain implant has been cleared by the Food and Drug Administration (FDA) for marketing as a treatment for severe and chronic obsessive-compulsive disorder (OCD), the agency announced on February 19.

Surgically implanted deep brain stimulation (DBS) devices are already on the market for treating tremor, dystonia, and movement disorder associated with Parkinson's disease. In recent years scientists in Europe and North America have been conducting clinical research on its effectiveness in the treatment of OCD and depression by applying electrical pulses to different brain circuits (Psychiatric News, December 19, 2008). Some of the studies, although small, produced encouraging results for patients who are severely disabled and have failed to respond to conventional treatments.

The device, manufactured by Medtronic Inc., is the first to be approved for treating severe OCD. The FDA said that it granted the approval based on the humanitarian device exemption regulation authorized by the federal Food, Drug, and Cosmetic Act, which applies to devices "intended to treat or diagnose a disease or condition affecting fewer than 4,000 people per year in the United States."

The FDA reviewed clinical data from four centers at which 26 patients with severe, treatment-resistant OCD received the implant and at least 12 months of stimulation. The patients experienced on average a 40 percent reduction in symptoms at the end of one year. Two-thirds of the patients had "marked functional improvements" in psychological, social, and occupational" areas, according to the company's announcement about the study results. The pooled results of the multisite clinical trials were published in Molecular Psychiatry online on May 20, 2008.

The device consists of a four-electrode stimulator to be implanted in the brain, which is connected to a small battery that is surgically embedded under the skin near the collar bone or the abdomen. The stimulator is implanted on one side or both sides of the brain.

Adverse effects seen in the clinical trials were mostly related to the brain surgery or resolved after postsurgery adjustments to the device setting, such as altering the intensity and frequency of the electrical pulses. In the clinical trials, all patients were required to have regular checkups after the surgery, and some needed to have the device's battery replaced after a period of time.

Medtronic said in the press release that it was going to conduct clinical trials on DBS for treatment-resistant severe depression at five medical centers in the United States. ▪