An investigation of the effects of various proprioceptive inputs on vestibuloocular reflex and otolith organs

The vestibular system is crucial for balance and gaze stability. Proprioceptive inputs from the musculoskeletal system significantly contribute to vestibular processing, especially under postural challenge. To examine how proprioceptive inputs in various body positions affect the vestibulo-ocular reflex (VOR) and otolith organ function. Thirty healthy adults (18-40 years, no vertiginous symptoms) underwent cervical and ocular vestibular evoked myogenic potentials (c-VEMP, o-VEMP) and video head impulse testing (v-HIT) in four positions: sitting, standing, one-leg standing, and on a balance disk. Primary outcomes included latency, amplitude, and asymmetry for VEMPs; gain and asymmetry for semicircular canals (SCCs) via v-HIT. c-VEMP latencies and amplitudes did not differ significantly across positions; however, amplitude asymmetry was significantly different between sitting and other conditions (p = .041). o-VEMP results remained consistent (p > .05). v-HIT revealed progressively reduced SCC gain from sitting to disk stance, with significant decreases in lateral SCCs (p < .05) and vertical SCCs (p < .001); asymmetry remained stable. Increased proprioceptive demand reduced VOR gain and modified c-VEMP asymmetry, reflecting enhanced vestibulospinal engagement. These outcomes likely arise from multisensory interactions rather than proprioceptive input alone, underscoring integrated sensory contributions to postural control.