Deep brain stimulation benefits advanced Parkinson's disease

1 September 2006

Minneapolis, USA. A study carried out in Germany and Austria has found that Medtronic's (NYSE:MDT) Activa deep brain stimulation therapy combined with medication is significantly more effective than medication alone in treating motor symptoms of advanced Parkinson's disease. The results were published in the published in the Aug. 31 issue of The New England Journal of Medicine (NEJM).

Conducted at 10 academic medical centres in Germany and Austria, the study included 156 patients with severe motor symptoms of Parkinson's disease and rated improvements in motor function (among other outcomes) after six months of treatment. Patients were randomly assigned to one of two treatment groups: half were selected to receive medication plus bilateral DBS of the subthalamic nucleus (STN), a brain structure involved in regulating movement, using Medtronic's Kinetra(R) neurostimulation system; and the other half were selected to receive medication alone. At the time of enrollment in the trial, all patients were under 75 years old, had been diagnosed with Parkinson's disease at least five years previously, and suffered from impaired mobility despite optimal treatment with medication.

Compared to medication alone, DBS of the STN caused significantly greater improvements in motor function after six months. On average, patients who received DBS plus medication showed a 41 percent improvement in motor function (as measured by the motor examination component of the Unified Parkinson's Disease Rating Scale (UPDRS-III)). Medication-only patients showed no change on the same measure.

"In conclusion," the authors wrote, "this six-month study demonstrated that subthalamic neurostimulation resulted in a significantly and clinically meaningful improvement in ... patients under 75 years of age who had advanced Parkinson's disease with severe fluctuations in mobility and dyskinesia (involuntary movements caused by medication). The patients who received neurostimulation had longer periods and better quality of mobility with less dyskinesia."

Lead author Dr. Gunther Deuschl, professor of neurology and chairman of the Department of Neurology at the University of Kiel in Germany, explained the significance of the study's results: "DBS clearly provides important benefits to Parkinson's patients who suffer troubling motor symptoms despite optimal treatment with medication. It should therefore be offered to this group of patients as soon as mobility problems can no longer be managed sufficiently with medication."

While serious adverse events were more common with neurostimulation than with medication alone and included a fatal intracerebral hematoma, the total number of adverse events was higher among medication-only patients. The authors stated that all of the non-fatal adverse events "resolved without permanent complications" and that "most adverse events were well-known medical problems associated with advanced Parkinson's disease."

According to Dr. C. Warren Olanow, professor of neuroscience and chairman of the Department of Neurology at the Mount Sinai School of Medicine in New York, and former president of the Movement Disorder Society: "This study provides further evidence supporting the use of DBS as a therapy for advanced Parkinson's disease patients whose motor symptoms cannot be satisfactorily controlled with medication."

Dr. Olanow served as a lead investigator in the global clinical trial of DBS for Parkinson's disease that led to the therapy's approval by the U.S. Food and Drug Administration in January 2002.

"We welcome the results of this latest study, which represent an excellent addition to the clinical evidence for Activa DBS Therapy as a treatment for Parkinson's disease," said Dr. Richard E. Kuntz, president of Medtronic's Neurological division and senior vice president of Medtronic, Inc. "As the pioneer and leader of this therapeutic technology, Medtronic is committed to studying DBS for a variety of clinical applications. We are also committed to advancing the technology itself."

The study was supported by a grant from the German Federal Ministry of Education and Research. Medtronic coordinated several investigator meetings and covered the cost of supplemental patient insurance for study participants.

Affecting an estimated 1 million people in the United States alone, Parkinson's disease is a complex, progressive and degenerative neurological disorder that causes loss of control over body movements. Motor symptoms include rigidity (stiffness or inflexibility of the limbs and joints); bradykinesia/akinesia (slowness/absence of movement); and tremor (involuntary, rhythmic shaking of a limb; the head, mouth, or tongue; or the entire body).

Parkinson's disease has no known cause or cure. Symptoms arise when a small region of the brain called the substantia nigra, degenerates. As neurons (brain cells) in this region die, the brain becomes deprived of the chemical dopamine, a neurotransmitter that enables communication among brain cells involved in motor control. Reduced levels of dopamine lead to symptoms of Parkinson's disease. As it progresses, Parkinson's disease becomes increasingly disabling, making routine daily activities like bathing, dressing, and eating difficult or impossible without assistance.

Introduced more than 30 years ago, the drug levodopa remains the gold standard for the initial treatment of Parkinson's disease. After about five to seven years, however, treatment with levodopa typically causes motor complications such as dyskinesia and fluctuations in motor control that can lead to intolerable disability in many patients.

Activa DBS Therapy reduces some of the motor symptoms of advanced Parkinson's disease and the motor complications associated with levodopa by modulating abnormal neuronal activity in the brain's movement center. It involves the implantation of a medical device — the Kinetra or Soletra neurostimulation system — that delivers electrical pulses to precisely targeted areas of the brain involved in motor control. The stimulation can be adjusted non-invasively as the disease progresses to meet changing patient needs.

More than 30,000 people worldwide have received Activa DBS Therapy, which is approved for the treatment of the three most common movement disorders — Parkinson's disease, essential tremor, and dystonia.


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