Abstract
Effects of treadmill walking on Parkinson’s disease (PD) patients’ spatiotemporal gait parameters and stride duration variability, in terms of magnitude [coefficient of variation (CV)] and temporal organization [long range autocorrelations (LRA)], are known. Conversely, effects on PD gait of adding an optic flow during treadmill walking using a virtual reality headset, to get closer to an ecological walk, is unknown. This pilot study aimed to compare PD gait during three conditions: Overground Walking (OW), Treadmill Walking (TW), and immersive Virtual Reality on Treadmill Walking (iVRTW). Ten PD patients completed the three conditions at a comfortable speed. iVRTW consisted in walking at the same speed as TW while wearing a virtual reality headset reproducing an optic flow. Gait parameters assessed were: speed, step length, cadence, magnitude (CV) and temporal organization (evenly spaced averaged Detrended Fluctuation Analysis, α exponent) of stride duration variability. Motion sickness was assessed after TW and iVRTW using the Simulator Sickness Questionnaire (SSQ). Step length was greater (p = 0.008) and cadence lower (p = 0.009) during iVRTW compared to TW while CV was similar (p = 0.177). α exponent was similar during OW (0.77 ± 0.07) and iVRTW (0.76 ± 0.09) (p = 0.553). During TW, α exponent (0.85 ± 0.07) was higher than during OW (p = 0.039) and iVRTW (p = 0.016). SSQ was similar between TW and iVRTW (p = 0.809). iVRTW is tolerable, could optimize TW effects on spatiotemporal parameters while not increasing CV in PD. Furthermore, iVRTW could help to capture the natural LRA of PD gait in laboratory settings and could potentially be a challenging second step in PD gait rehabilitation.
Highlights
Parkinson’s disease (PD) results from dopamine-producing neurons degeneration in the basal ganglia and is clinically characterized by classical motor triad combining rest tremor, plastic rigidity, and bradykinesia (Jankovic, 2008)
The added optic flow during immersive Virtual Reality on Treadmill Walking (iVRTW) induced a positive effect on the spatiotemporal gait parameters with higher step length and reduced cadence compared to Treadmill Walking (TW)
Regarding magnitude of stride duration variability, the coefficient of variation (CV) was similar between TW and iVRTW (p = 0.177) which shows that the added optic flow had no significant effect on this parameter (Table 3 and Figure 1)
Summary
Parkinson’s disease (PD) results from dopamine-producing neurons degeneration in the basal ganglia and is clinically characterized by classical motor triad combining rest tremor, plastic rigidity, and bradykinesia (Jankovic, 2008). 2D displays and projection systems were used to study the impact of optic flow during treadmill walking on healthy subjects’ gait (Prokop et al, 1997; Mohler et al, 2007; Katsavelis et al, 2010; Mukherjee et al, 2011; Chien et al, 2014, 2016) and PD gait (Schubert et al, 2005; van Wegen et al, 2006b) These devices are still used in recent studies, some of their technical characteristics do not make it possible to realistically produce an optic flow. Considering visual dependence of PD gait, the lack of optic flow on TW and recent technological advances, we put forward the hypothesis that the addition of an optic flow in iVR during treadmill walking will allow to more ecologically and accurately capture PD patients’ natural LRA in stride duration variability, similar to overground walking
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