The study was published in Thursday's issue of the New England Journal of Medicine.
In 2002 the Food and Drug Administration had approved the Activa deep brain stimulation therapy to treat Parkinson's. While earlier studies mainly looked at brain stimulation in treating motor functions, this study looked at quality of life as a main endpoint, in addition to motor functions.
Dr. Richard Kuntz, president of the neurological division of the Minneapolis medical-device company told that the results validate Activa's value by providing additional clinical evidence from this study that was more rigorous than past studies.
This six-month study was conducted on 156 patients below 75 years of age who have had Parkinson's for at least five years and suffer from impaired mobility despite medication. During the study all the patients received medication, and half received neurostimulation treatment with the Activa device.
Patients receiving neurostimulation saw a 25% improvement in quality of life and a 41% improvement in motor functions, compared with virtually no change in patients receiving only medication.
The study reports, "In carefully selected patients, neurostimulation of the subthalamic nucleus is a powerful treatment that alleviates the burden of advanced Parkinson's disease."
The Activa device includes electrodes surgically implanted in the brain and connected by an extension under the skin to a neurostimulator implanted near the collarbone. The electrical stimulation can be noninvasively adjusted.
The study was conducted by German and Austrian researchers. Medtronic has awarded some of the researchers including lead author Dr. Gunther Deuschl, with compensation and research grants.
Although the German government sponsored the study, Medtronic coordinated investigator meetings and payedfor supplemental insurance for the study's patients.
Dr. C. Warren Olanow, neurology department chairman at New York's Mount Sinai School of Medicine and leader of clinical research that led to Activa's FDA approval for Parkinson's, said the study achieved its endpoints and "further affirms this treatment is effective."
Of the 13 patients who reported severe adverse side effects, 10 received neurostimulation and three received only medication. Of the four deaths, three were in the neurostimulation group and one in the medication-only group.