The addition of subthalamic stimulation to medication therapy improved the quality of life and reduced subsequent motor disability in patients with early Parkinson's disease and mild levodopa-induced motor complications, according to a study published in the February 14 New England Journal of Medicine. The findings suggest that "neurostimulation may be a therapeutic option for patients at an earlier stage than current recommendations suggest," said lead author W.M.M. Schuepbach, MD, a researcher at the National Institute of Health and Medical Research in Paris.
Dr. Schuepbach and his colleagues randomized 127 patients with early motor complications to best-practices drug therapy and 124 patients to drug therapy and subthalamic neurostimulation. There were no significant between-group differences at baseline. The average age for patients in both groups was about 52. The average disease duration was 7.5 years, and patients had taken levodopa for about five years. Subjects had levodopa-induced motor complications for an average of about 18 months.
Neurostimulation patients underwent bilateral stereotactic surgery for the implantation of electrodes and a pulse generator. Stimulation was similar in both hemispheres, with a mean strength of 2.8 V, mean stimulation frequency of 142 Hz, and mean pulse duration of 66 µs. Stimulation took about five months to reach its maximum benefit.
At the end of two years, the combination group had a 7.8-point quality-of-life improvement on the 100-point Parkinson’s Disease Questionnaire (PDQ-39) summary index, the study’s primary outcome. Patients who received medication only had a 0.2-point drop in quality of life.
The neurostimulation group had less motor disability than the medication group. The between-group difference on the 70-point Unified Parkinson’s Disease Rating Scale (UPDRS), Part III was 16.4 points in favor of neurostimulation. Neurostimulation was also modestly superior on activities of daily living and levodopa-induced motor complications, both also assessed by UPDRS. The neurostimulation group also had longer times with good mobility and no dyskinesia, as reported in patient diaries. Stimulation patients had a 39% reduction in their levodopa-equivalent daily dosages, while drug-only patients had an increase of about 21%.
Because motor symptoms and quality of life remained relatively constant in the drug-only group, “the improvement among patients who underwent surgical implantation can be attributed to neurostimulation,” said Dr. Schuepbach.
Schuepbach WM, Rau J, Knudsen K, et al. Neurostimulation for Parkinson’s disease with early motor complications. N Engl J Med. 2013;368(7):610-622.