The effect of real and virtual visual cues on walking in Parkinson's disease.
Patients with Parkinson's disease (PwPD) have a slow, shuffling gait, marked by sporadic freezing of gait (FoG) during which effective stepping ceases temporarily. As these gait problems are not commonly improved by medical and surgical treatments, alternative approaches to manage these problems have been adopted. The aim of this study was to evaluate the effect of real and virtual visual cues on walking in PD. We assessed 26 mid-stage PwPD, on and off medication, on a laboratory-based walking task which simulated real world challenges by incorporating FoG triggers and using appropriate placebo conditions. Cueing interventions were presented via virtual reality glasses (VRG rhythmic, visual flow and static placebo cues), and as transverse lines (TL) on the walkway. Objective measures of gait (task completion time; velocity, cadence, stride length; FoG frequency) and self-rated fear of falling (FoF) were recorded. Cueing intervention affected task completion time only off medication. Whereas placebo VRG cues provided no improvement in walking, visual flow VRG cues marginally reduced the task completion time. TL on the floor elicited more substantial improvements in gait with reduced cadence, increased stride length and reduced FoG frequency. VRG rhythmic cueing impaired overall walking. Notably, a final no-intervention condition yielded quicker task completion, greater walking velocity, increased stride length and less frequent FoG. Although the VRG produced modest improvements only in the visual flow condition, their flexibility is an advantage. These results endorse the use of TL and justify further testing and customisation of VRG cues for individual PwPD.