On-Demand Cueing Sensitive to Step Variability: Understanding Its Impact on Gait of Individuals With Parkinson’s Disease

Parkinson’s disease (PD) is characterized by gait disturbances with freezing of gait (FoG) being one of the most disabling symptoms. The FoG episode is often preceded by an increase in variability in Step Time. As the disease progresses, such gait impairment may become resistant to pharmacotherapy. Use of external cues is an alternative. Existing solutions deliver external cues in a continuous manner that might cause habituation effects, thereby emphasizing the need for on-demand cueing. Manual on-demand cueing upon freezing has been shown to be powerful in bringing an individual out of a freezing state. This can be achieved if one’s proneness to freeze before entering into freezing state can be sensed, and in-turn triggering an external cue on-demand. Motivated by this, we have developed a wearable device (SmartWalk<inf>VC</inf>) that can sense such proneness based on variability in Step Time to offer a visual cue on-demand. We conducted a study involving 20 age-matched healthy individuals and those with PD who walked overground while wearing SmartWalk<inf>VC</inf> operated in three modes with regard to offering visual cue, namely (a) On-demand cueing, (b) Continuous cueing and (c) No cueing. The results of our study showed that with on-demand cueing, those with PD had minimum variability of Step Time among all the three modes unlike healthy individuals whose gait remained majorly unaffected by different cueing modes. Also, walking speed increased along with a reduction in FoG episodes for those with PD in the on-demand cueing mode compared with the other two modes.