Subthalamic Nucleus Stimulation in Parkinson's Disease: 5‐Year Extension Study of a Randomized Trial

BACKGROUND: In Parkinson's disease (PD) long‐term motor outcomes of subthalamic nucleus deep brain stimulation (STN‐DBS) are well documented, while comprehensive reports on non‐motor outcomes are fewer and less consistent. OBJECTIVE: To report motor and non‐motor symptoms after 5‐years of STN‐DBS. METHODS: We performed an open 5‐year extension study of a randomized trial that compared intraoperative verification versus mapping of STN using microelectrode recordings. Changes from preoperative to 5‐years of STN‐DBS were evaluated for motor and non‐motor symptoms (MDS‐UPDRS I‐IV), sleep disturbances (PDSS), autonomic symptoms (Scopa‐Aut), quality of life (PDQ‐39) and cognition through a neuropsychological test battery. We evaluated whether any differences between the two randomization groups were still present, and assessed preoperative predictors of physical dependence after 5 years of treatment using logistic regression. RESULTS: We found lasting improvement of off‐medication motor symptoms (total MDS‐UPDRS III, bradykinetic‐rigid symptoms and tremor), on‐medication tremor, motor fluctuations, and sleep disturbances, but reduced performance across all cognitive domains, except verbal memory. Reduction of verbal fluency and executive function was most pronounced the first year and may thus be more directly related to the surgery than worsening in other domains. The group mapped with multiple microelectrode recordings had more improvement of bradykinetic‐rigid symptoms and of PDQ‐39 bodily discomfort sub‐score, but also more reduction in word fluency. Older age was the most important factor associated with physical dependence after 5 years. CONCLUSION: STN‐DBS offers good long‐term effects, including improved sleep, despite disease progression. STN‐DBS surgery may negatively impact verbal fluency and executive function.