Longitudinal Effects of Bilateral Subthalamic Nucleus Deep Brain Stimulation Versus Best Medical Therapy on Static and Dynamic Balance and Gait in Advanced Parkinson’s Disease: A 36-Month Comparative Study

Objective: To evaluate the long-term impact of bilateral subthalamic nucleus deep brain stimulation (STN-DBS) versus best medical therapy (BMT) on static and dynamic balance as well as gait disturbances in patients with advanced Parkinson’s disease (PD). Methods: In this prospective study, 50 patients with advanced PD were randomly assigned to receive either bilateral STN-DBS (n = 28) or BMT (n = 22). Comprehensive evaluations were performed at baseline and during four consecutive visits over 36 months. Static balance was assessed using posturographic measurements (COP velocity, perimeter, ellipse area), and dynamic balance and gait were evaluated using tandem gait tasks and pivoting maneuvers. Statistical analyses included repeated measures ANOVA-Friedman and Dunn-Bonferroni post hoc tests. Results: DBS-treated patients demonstrated stable dynamic balance and gait performance over 36 months with no significant decline in tandem gait and pivot tests. Conversely, the BMT group showed a significant deterioration in dynamic balance (Walking Tandem Test; χ2 = 10.63, p = 0.014) and gait function, particularly in the medication OFF state. Static balance in the DBS group worsened notably under sensory-deprived conditions (eyes closed, OFF state; χ2 = 10.13, p = 0.017), whereas BMT maintained static balance stability without significant changes. Conclusions: STN-DBS effectively preserves dynamic balance and gait functions in patients with advanced PD over 36 months, but exhibits limited efficacy in maintaining static balance under sensory-deprived conditions. These findings highlight the need for individualized therapeutic approaches that emphasize combined neuromodulation and multidisciplinary rehabilitation strategies.