Influences of VR-Based Optokinetic Stimulation on Head and Trunk Instability on a Sinusoidal Moving Platform

Optokinetic stimulation (OKS) induces visual-vestibular conflict, influencing postural stability. Virtual reality (VR)-based OKS provides an immersive alternative to conventional screen-based OKS, potentially enhancing vestibular rehabilitation. This study investigated the effects of VR-based OKS on head and trunk instability while standing on a continuous sinusoidal moving platform. Sixteen healthy adult males participated. Six experimental conditions combined three visual conditions (eyes open, eyes closed, VR-based OKS) with two platform frequencies (0.5 Hz, 1.0 Hz). Head and trunk accelerations were recorded using inertial measurement units, and root mean square values were analyzed. Cross-correlation between head and trunk sway was assessed. VR-based OKS induced significantly greater lateral trunk sway compared to the eyes-open condition (p = 0.003). Cross-correlation analysis showed a significant association between lateral head and trunk sway under OKS, with a moderate correlation at 0.5 Hz (r = 0.540, p < 0.05) and a strong correlation at 1.0 Hz (r = 0.793, p < 0.01). VR-based OKS dynamically alters sensory reweighting, inducing synchronized head-trunk movements. These findings highlight the potential use of VR-based OKS in vestibular rehabilitation and underscore the importance of adjusting stimulus intensity to suit individual needs. Further research should explore long-term adaptation effects.