Long-term Effects of Bilateral Subthalamic Deep Brain Stimulation on Postural Instability and Gait Difficulty in Patients with Parkinson's Disease

Objective The long-term effects of bilateral subthalamic nucleus deep brain stimulation (STN-DBS) on postural instability and gait difficulty (PIGD) in patients with Parkinson's disease (PD) remain unclear. In this study, we aimed to evaluate the long-term effects of STN-DBS surgery on PIGD symptoms in patients with advanced-stage PD. Methods This study included 49 consecutively included patients with PD who underwent bilateral STN-DBS. The Unified Parkinson's Disease Rating Scale (UPDRS) scores and subscores for PIGD were assessed at baseline and at 1, 3, and 5 years post-operatively. The PIGD subscore was divided into PIGD-motor and PIGD-activities of daily living (ADL) scores according to parts III and II of the UPDRS, respectively. Results The PIGD-motor and PIGD-ADL scores at the "medication-off" state improved at 3 and 5 years, respectively. Overall, the UPDRS III and II scores at "medication-off" improved at 5 years. The UPDRS IV score also significantly improved and the levodopa equivalent daily dosage decreased at all follow-ups. Finally, the PIGD-motor score at baseline was able to predict long-term improvement in the PIGD-motor score at the 5-year follow-up. Conclusion The STN-DBS has both short- and long-term effects on PIGD, as well as overall motor function, in patients with advanced PD. The degree of PIGD at the preoperative evaluation can be used to predict long-term outcomes after STN-DBS surgery.