Long-term independence and quality of life after subthalamic stimulation in Parkinson's disease.

BACKGROUND Studies on long-term non-motor outcomes of subthalamic nucleus stimulation in Parkinson's disease are scarce. This study reports on very-long term non-motor and motor outcomes in one of the largest cohorts of people with advanced Parkinson's disease, treated for more than ten years with subthalamic nucleus stimulation. The main outcome was to document the evolution of independence in activities of daily living. The secondary outcomes were to measure the change in quality of life, as well as non-motor and motor outcomes. METHODS Patients were studied preoperatively, at one year, and beyond 10 years after subthalamic stimulation with an established protocol including motor, non-motor and neuropsychological assessments. RESULTS Eighty-five people with PD were included. Independence scores in the off-medication condition (measured with the Schwab & England activities of daily living scale), as well as quality of life (measured with the PDQ37) remained improved at longest follow-up compared to preoperatively (respectively p < 0.001, p = 0.015). Cognitive scores, measured with the MDRS, significantly worsened compared to before and one-year after surgery (p < 0.001), without significant change in depression, measured with the BDI. Motor fluctuations, dyskinesias and off dystonia remained improved at longest follow-up (p < 0.001), with a significant reduction in dopaminergic treatment (45%, p < 0.001). CONCLUSIONS This study highlights the long-term improvement of subthalamic stimulation on independence and quality of life, despite the progression of disease and the occurrence of levodopa-resistant symptoms