Investigation of hearing-balance interaction in normal individuals at the level of vestibulo-ocular reflex

Objective: This study aims to demonstrate the sensor integration capability of the vestibulo-ocular reflex (VOR) mechanism by evaluating the hearing-balance interaction at the VOR level and to introduce a new video head impulse test (vHIT) modality into the literature. Method: 40 healthy young adults (Age: 21.56±1.10) were included in the study. All subjects underwent ocular and cervical VEMP (Vestibular Evoked Myogenic Potential) tests. vHIT was performed in a silent environment at the beginning and end of the study. Additionally, vHIT was repeated with different auditory stimuli delivered to each ear separately, first at 60 dB SL and then at the higher of the VEMP thresholds. VOR gains and asymmetries were compared between silent and auditory conditions. Results: No significant differences were found in vHIT results between the beginning and end of the study in a silent environment (p>0.05). No significant differences in VOR gains were observed between silent and 60 dB SL conditions (p>0.05). However, significant differences in VOR gains were found in bilateral anterior and lateral semicircular canals (SCCs) between silent and VEMP threshold conditions (p<0.05), while no differences were observed in bilateral posterior SCCs (p>0.05). Monaural auditory stimuli at VEMP threshold increased horizontal asymmetry and decreased vertical asymmetry (p<0.05), with no changes in anterior and posterior SCC axes (p>0.05). Tone burst stimuli had the most significant effect on VOR gains. Conclusion: The study demonstrates significant effects of auditory stimuli on SCC-related VOR, indicating an interaction between hearing and balance systems at the VOR level. The developed vHIT protocol may allow rapid and effective measurement of superior vestibular nerve activity, suggesting potential innovative approaches for clinical vestibular function assessment and treatment.