Lateralized Subthalamic Stimulation for Axial Dysfunction in Parkinson's Disease: Exploratory Outcomes and Open‐Label Extension

Abstract

AbstractBackgroundA randomized trial suggested that reducing left‐sided subthalamic stimulation amplitude could improve axial dysfunction.ObjectivesTo explore open‐label tolerability and associations between trial outcomes and asymmetry data.MethodsWe collected adverse events in trial participants treated with open‐label lateralized settings for ≥3 months. We explored associations between trial outcomes, location of stimulation and motor asymmetry.Results14/17 participants tolerated unilateral amplitude reduction (left‐sided = 10, right‐sided = 4). Two hundred eighty‐four left‐sided and 1113 right‐sided stimulated voxels were associated with faster gait velocity, 81 left‐sided and 22 right‐sided stimulated voxels were associated with slower gait velocity. Amplitude reduction contralateral to shorter step length was associated with 2.4‐point reduction in axial MDS‐UPDRS. Reduction contralateral to longer step length was associated with 10‐point increase in MDS‐UPDRS.ConclusionsLeft‐sided amplitude reduction is potentially more tolerable than right‐sided amplitude reduction. Right‐sided more than left‐sided stimulation could be associated with faster gait velocity. Shortened step length might reflect contralateral overstimulation.