Effect of deep brain stimulation of the subthalamic nucleus on non-motor fluctuations in Parkinson's disease: Two-year' follow-up

Background: Deep brain stimulation of the subthalamic nucleus (STN-DBS) reduces motor fluctuations in Parkinson's disease (PD) but its effect on non-motor fluctuations (NMF) is not well known. In this study we assess the efficacy of STN-DBS on NMF two years after surgery. Methods: Autonomic, cognitive, psychiatric and sensory NMF in 20 patients were evaluated using a questionnaire designed to assess the frequency and severity of the NMF preoperatively and after two years of follow-up. The UPDRS scale was used for assessing the motor state. Results: Compared with the preoperative situation, STN-DBS at 2 years of follow-up was associated with a significant reduction in the number and severity of autonomic and psychiatric NMF in the off state (without medication), and in the severity of sensory NMF, which were not observed in the on state (with medication). A cross-sectional analysis at the two-year time-point of the four possible motor conditions (combining medication and stimulation) showed a reduction in the total number of NMF and in the severity of autonomic and sensory NMF after switching on the stimulation in the on state. Improvement of the UPDRS-motor score was correlated with a reduction in the severity but not in the frequency of NMF. A worsening of motor function after suppressing stimulation in the off state was not paralleled by a worsening of NMF. Conclusion: After two years of follow-up, STN-DBS in the off medication was associated with a reduction in the frequency and severity of NMF. These results will need to be confirmed in controlled studies. (C) 2013 Elsevier Ltd. All rights reserved.