Subthalamic neural entropy is a feature of freezing of gait in freely moving people with Parkinson's disease

Abstract The goal of this study was to investigate subthalamic (STN) neural features of Freezers and Non-Freezers with Parkinson's disease (PD), while freely walking without freezing of gait (FOG) and during periods of FOG, which were better elicited during a novel turning and barrier gait task than during forward walking. Methods: Synchronous STN local field potentials (LFPs), shank angular velocities, and ground reaction forces were measured in fourteen PD subjects (eight Freezers) off medication, OFF deep brain stimulation (DBS), using an investigative, implanted, sensing neurostimulator (Activa® PC + S, Medtronic, Inc.). Tasks included standing still, instrumented forward walking, stepping in place on dual forceplates, and instrumented walking through a turning and barrier course. Results: During locomotion without FOG, Freezers showed lower beta (13–30 Hz) power (P = 0.036) and greater beta Sample Entropy (P = 0.032), than Non-Freezers, as well as greater gait asymmetry and arrhythmicity (P