Visual and vestibular integration in Parkinson's disease while walking

Postural control requires effective sensory integration. People with Parkinson's disease (PD) are reported to have impaired visual and vestibular perception. While self-motion perception is a key aspect of locomotion, visual-vestibular integration has not been directly characterized in people with PD during gait. We compared the ability of people with PD and healthy older adults (OA) to integrate multi-sensory information during straight-line walking in response to visual and vestibular perturbations, using continuous translations of the visual surround and galvanic vestibular stimulation within a virtual reality environment. We measured their endpoint deviations from midline and changes in gait parameters. We found that people with PD deviated more than OA when walking in a dark environment but did not show differences in deviations when walking in a virtual room with visual information. With visual and vestibular perturbations, people with PD did not differ from OA in endpoint deviations nor variabilities. However, people with PD did not adopt a more cautious gait when GVS was applied in a virtual room, unlike OA. Overall, we showed that people with mild PD did not perform worse than OA but did show differences in gait patterns, suggesting that visual-vestibular integration is relatively preserved during gait in PD.