Long-term follow-up indicates that deep brain stimulation is potentially effective for patients with treatment resistant major depression, according to a presentation at the annual meeting of the American Association of Neurological Surgeons.

Researchers from the Cleveland Clinic, Brown University, and Massachusetts General Hospital presented results of a long-term outcome study that built on previous promising research. The surgical procedure involves placement of tiny implantable electrodes into specific parts of the brain that were functioning abnormally. The electrodes emit tiny pulses of electrical stimulation to block the abnormal activity associated with symptoms such as pain, tremors, and movement problems in patients with movement disorders and obsessions, moods and anxieties in patients with psychiatric disorders.

The success of the procedure is dependent on the surgical team's ability to precisely pinpoint the specific brain area for stimulation. The advantage of deep brain stimulation is that it is reversible, nondestructive, and can be modified by adjustment of the stimulator settings after implantation.

Fifteen chronic and severely depressed patients were enrolled: All had failed multiple medication trials, as well as psychotherapy and electroconvulsive therapy. These highly intractable and often suicidal patients underwent bilateral electrode implantation in the ventral internal capsule/ventral striatum at three institutions.

The Montgomery-Asberg Depression Rating Scale (MADRAS) was the primary outcome scale, among many scales, including those assessing overall quality of life, functioning and cognitive status.

Outcome raters were blinded to the status of each patient. Follow-up ranged from six to 48 months, with durations of one year or longer in 11 of the 15 patients. Responder criteria were defined as a 50-percent decrease in MADRAS scores.

Responses were seen in 7 (47 percent) of 15 patients at six months, 5 (45.5 percent) of 11 at 12 months, and 8 (53.3 percent) of 15 at their last follow-up. Long-term improvement in depression severity, function, and quality of life were all noted. In addition, patients who responded had improvement in measures of short-term memory.

There were no hemorrhages, infections or other neurological deficits.

Ali R. Rezai, MD, director of Cleveland Clinic's Center for Neurological Restoration, and a multi-center team of investigators were inspired to conduct the pilot study based on the success of deep brain stimulation in treating tremors associated with Parkinson's and movement disorders such as dystonia and essential tremor.

"Starting in 2001, we began treating patients with obsessive compulsive disorder (OCD) with promising outcomes. These findings resulted in the initiation of a subsequent trial for patients with severe and medication intractable major depression, starting in 2003," stated Rezai.

"The preliminary results of research undertaken between 2003 and 2005 indicated that bilateral deep brain stimulation of the anterior limb of the internal capsule holds promise for the treatment of intractable major depression, which led to the more extensive research results being presented today," added Dr. Rezai.

The multidisciplinary research team consists of neurosurgeons, psychiatrists and psychologists from each participating institution.

"This research substantiates our earlier findings, which indicate that bilateral deep brain stimulation of the anterior limb of the internal capsule holds promise and hope for select patients suffering from severe and treatment resistant major depression, stated Rezai.

"While about half of this patient group responded to treatment, I feel that as we learn more about this rather new technology, efficacy will continue to improve. It is important to understand that this treatment is not for everyone with major depression and only for those that have tried various medications, psychotherapy and electroconvulsive therapy. But, nevertheless, it is very promising news for the many suffering patients and their family members that have virtually given up hope."