Differential effects of dopaminergic medication and subthalamic deep brain stimulation on gait in Parkinson's disease: A two-case report

Introduction

In Parkinson's disease (PD), interactions between medication (Med) and deep brain stimulation (DBS) across gait domains and in individuals with distinct clinical profiles remain incompletely understood. This study conducted detailed within-subject gait analyses in two individuals with PD across four conditions: (1) DBS ON/Med ON, (2) DBS OFF/Med ON, (3) DBS ON/Med OFF, and (4) DBS OFF/Med OFF, comparing results with healthy reference data. Case 1 Due to fluctuations in effectiveness that could no longer be treated with oral medication, accompanied by pronounced dyskinesia and insufficient tremor control, decision for subthalamic nucleus (STN) stimulator implantation was made. The patient continued to receive medication. STN-DBS primarily optimized axial control and intersegmental coordination, substantially increasing walking speed, while dopaminergic medication provided limited additional benefit. Case 2 The patient noticed increasing bradykinesia of the left leg, later accompanied by rigidity and resting tremor, and subsequently on the right side. He suffered from severe freezing episodes. Under dopamine agonists, he experienced nightmares and pseudohallucinations. Thus, STN stimulator implantation was performed. The patient continued to receive medication. STN-DBS improved posture and alignment, bringing kinematics closer to those of healthy controls, while the effects of combined STN-DBS and medication appeared more complementary than in Case 1 .