Axial symptoms as main predictors of short-term subthalamic stimulation outcome in Parkinson's disease

Deep brain stimulation (DBS) is an established therapeutic option for Parkinson's disease (PD) patients; however, a clear-cut definition of subthalamic (STN) DBS predictors in PD is lacking. We analyzed a cohort of 181 STN-treated PD patients and compared pre- vs. 1-year post-surgical motor, dyskinesia, Off time, and daily-life activities (ADL) scores. A multivariate linear regression analysis was used to evaluate the association between clinical/demographic characteristics and the extent of STN-DBS response for outcomes proving a significant change after surgery. After STN-DBS, we observed a significant improvement of motor symptoms (P < 0.001), dyskinesia (P < 0.001), and daily Off time (P < 0.001). Sex, PD duration, cognitive status, and the motor and axial response to levodopa significantly explained the motor improvement (R = 0.360, P = 0.002), with presurgical response of axial symptoms (Beta = 0.203, P = 0.025) and disease duration (Beta = 0.205, P = 0.013) being the strongest predictors. Considering the daily Off time improvement, motor and axial response at the levodopa challenge test and disease duration explained 10.6% of variance (R = 0.326, p < 0.001), with disease duration being the strongest predictor of improvement (Beta = 0.253, p: 0.001) and axial levodopa response showing a trend of significance in explaining the change (Beta = 0.173, p: 0.056). Dyskinesia improvement was not significantly explained by the model. Our findings highlight the emerging role of axial symptoms in PD and their response to levodopa as potentially pivotal also in the DBS selection process.