Beneficial Effects of Bilateral Subthalamic Stimulation on Non-Motor Symptoms in Parkinson's Disease

Background: STN-DBS is well established to improve motor symptoms and quality of life in patients with PD. While non-motor symptoms are crucial for quality of life in these patients, only neuropsychiatric and neuropsychological symptoms have been systematically studied in a longitudinal design so far. However, these are only a part of the non-motor symptoms spectrum. Hypothesis: We hypothesized that STN-DBS is associated with a beneficial effect on a range of non-motor symptoms. Methods: In this multicenter, open, prospective, international study (EuroInf-study, UKCRN10084/ DRKS00006735) we investigated non-motor effects of STN-DBS in real-life use. We evaluated Nonmotor Symptom Scale, and Questionnaire, PD Questionnaire-8, Scales for Outcomes of PD motor examination and complications, and activities of daily living preoperatively and at 6 months follow-up in 60 consecutive patients (35 male, mean age: 61.6 +/- 7.8 years, mean disease duration: 10.4 +/- 4.2 years). Results: All outcomes improved significantly at 6 months follow-up (PD Questionaire-8, p = 0.006; activities of daily living, p = 0.012; all others, p < 0.001; Wilcoxon signed-rank, respectively paired t-test; Bonferroni-correction). Post-hoc analyses of Non-motor Symptom Scale domains showed a significant reduction of sleep/fatigue and miscellaneous domains (p = 0.001), perceptual problems/hallucinations (p = 0.036), and urinary (p = 0.018) scores. Effect sizes were moderate for Non-motor Symptom Scale, and motor complications, large for motor examination, and small for other outcomes.