Assessment of Vestibular Function in Patients with Congenital Bilateral Sensorineural Hearing Loss: A Case-Control...

Background/Objectives: The cochlea and vestibular organs develop concurrently during embryogenesis and share anatomical and functional pathways. As a result, congenital factors affecting the vestibulocochlear system may impair both hearing and vestibular function. Despite this, the relationship between congenital bilateral sensorineural hearing loss (SNHL) and vestibular dysfunction remains insufficiently defined. This study evaluated vestibular function in patients with congenital bilateral SNHL and investigated the association between hearing loss severity and vestibular function. Methods: A total of 202 participants aged 7-31 years were enrolled, including 102 patients with congenital bilateral SNHL and 100 healthy controls. Vestibular function was assessed using videonystagmography (VNG) during sinusoidal harmonic acceleration (SHA) rotational testing and caloric testing performed according to the Fitzgerald-Hallpike protocol, as well as with the video head impulse test (vHIT). Statistical analyses compared vestibular parameters between groups and assessed correlations with hearing loss severity. Results: Patients with congenital bilateral SNHL exhibited significantly lower vestibulo-ocular reflex (VOR) values in the SHA test compared to controls. Greater hearing loss severity was associated with lower VOR gain values. No statistically significant differences were observed between groups in caloric test results or vHIT VOR gain values. However, corrective saccades during vHIT were identified exclusively in patients with hearing loss and occurred in approximately 15% of cases. Furthermore, the age of independent walking was significantly delayed in the study group compared to controls. Conclusions: Congenital bilateral SNHL is associated with vestibular dysfunction, as evidenced by abnormal SHA test results and the presence of corrective saccades in vHIT. These patients may also experience delayed motor development. These findings suggest that vestibular dysfunction may be present in patients with congenital sensorineural hearing loss and may have functional implications.