Ten-year outcome of subthalamic stimulation in Parkinson disease: a blinded evaluation.

OBJECTIVE: To assess the 10-year motor outcome of deep brain stimulation of the subthalamic nucleus (STN-DBS) in patients with Parkinson disease (PD).

DESIGN: Patients with PD with bilateral STN-DBS were assessed according to the Core Assessment Program for Surgical Interventional Therapies in Parkinson's Disease protocol and videotaped at baseline and 1, 5, and 10 years after surgery. An independent rater blinded to stimulation and medication condition scored the 10-year video assessments.

SETTING: Movement Disorders Centre, Toronto Western Hospital, University Health Network, University of Toronto.

PATIENTS: Eighteen patients with advanced PD and 10-year follow-up of STN-DBS.

INTERVENTION: Bilateral STN-DBS surgery.

MAIN OUTCOME MEASURES: The primary outcome was the change in blinded Unified Parkinson's Disease Rating Scale (UPDRS) motor scores/subscores between the no medication/stimulation condition vs the no medication/no stimulation condition at 10 years. Secondary outcomes were the changes in blinded UPDRS motor scores between the medication/no stimulation and medication/stimulation conditions, UPDRS II scores, UPDRS IV dyskinesia and motor fluctuations scores, and anti-PD medication dose (levodopa equivalent daily dose) at different points.

RESULTS: In the 18 patients available for follow-up at 10 years, STN-DBS still significantly improved the UPDRS total motor score (P = .007) and resting and action tremor (P < .01 and P = .02, respectively) and bradykinesia (P = .01) subscores. The UPDRS II scores in the medication and no medication conditions, UPDRS IV dyskinesia and motor fluctuations scores, and the levodopa equivalent daily dose were also significantly reduced compared with baseline. Axial signs showed the most progressive decline in stimulation and levodopa response over the years.

CONCLUSION: This class III study provides evidence that stimulation-induced motor improvement was sustained overall at 10 years, although part of the initial benefit wore off mainly because of progressive loss of benefit on axial signs over time.