Improving gait performance in Parkinson´s disease by interpersonal synchrony-based dynamic stabilization

Previously, research on gait control has mainly focused on interpersonal synchrony and locomotor control. However their intersection, the interpersonal synchronization of stepping rhythms which is widely observed in our daily life, remains relatively unexplored, despite being a common phenomenon that has considerable rehabilitation potential. Therefore, from the perspective of mutual entrainment of gait rhythms, we have constructed an interpersonal synchrony emulation system between a human subject and a biped virtual robot that generates pacing signal cues using nonlinear oscillators. This system synchronizes the stride interval times of a human and the robot in a cross-feedback manner; by presenting auditory stimulation that indicates the timing of the partner´s foot contacting the ground. Here, we evaluated the effectiveness of the system in gait stabilization of twenty-one Parkinson´s disease (PD) patients, who previously displayed disturbances in rhythm formation and festinating gait (accelerating steps). The results showed that the festinating gait, as measured as stride time reduction rate, significantly stabilized and accelerated less with the system compared to unassisted walking. Additionally, significant carry-over effects were observed. After termination of the auditory stimulation, the gait remained stabilized. Our previous pilot study suggested that the gait of PD patients was dynamically stabilized by applying the inter personal synchrony process between the timing of human´s gait and of external auditory cues. In this paper, we showed significant improvement for the festinating gait in twenty one PD patients.