Randomized trial of deep brain stimulation for Parkinson disease: Thirty-six-month outcomes

Objectives: Our objective was to compare long-term outcomes of deep brain stimulation(DBS) of the globus pallidusinterna (GPi) and subthalamic nucleus(STN) for patients with Parkinson disease (PD) in a multicenter randomized controlled trial. Methods: Patients randomly assigned to GPi (n = 89) or STN DBS (n = 70) were followed for 36 months. The primary outcome was motor function on stimulation/off medication using the Unified Parkinson9s Disease Rating Scale motor subscale. Secondary outcomes included quality of life and neurocognitivefunction. Results: Motor function improved between baseline and 36 months for GPi (41.1 to 27.1; 95% confidence interval [CI] −16.4 to −10.8; p p p = 0.59). Health-related quality of life improved at 6 months on all subscales (all p values significant), but improvement diminished over time. Mattis Dementia Rating Scale scores declined faster for STN than GPi patients ( p = 0.01); other neurocognitivemeasures showed gradual decline overall. Conclusions: The beneficial effect of DBS on motor function was stable and comparable by target over 36 months. Slight declines in quality of life following initial gains and gradual decline in neurocognitivefunction likely reflect underlying disease progression and highlight the importance of nonmotor symptoms in determining quality of life. Classification of Evidence: This study provides Class III evidence that improvement of motor symptoms of PD by DBS remains stable over 3 years and does not differ by surgical target. Neurology ® 2012;79:55–65