Comparison of VHIT and FHIT in Individuals with Auditory Neuropathy Spectrum Disorder (ANSD) and Healthy Individuals

Abstract

Several studies have reported vestibular dysfunction in individuals with Auditory Neuropathy Spectrum Disorder (ANSD), indicating that the underlying pathology may extend beyond the auditory nerve to also involve the vestibular system. The present study aimed to compare the outcome parameters of the video head impulse test and functional head impulse test between individuals with ANSD and Healthy individuals, and to correlate the test findings of vHIT and fHIT in individuals with ANSD and Healthy individuals. The study consisted of thirty participants, fifteen individuals diagnosed with ANSD and fifteen age-matched healthy controls with an age range of 18-55 years, who underwent the assessment. vHIT was used to assess vestibulo-ocular reflex (VOR) gain and identify refixation saccades, while fHIT assessed the functional integrity of VOR through the percentage of correct visual responses during rapid head movements. Results showed a significantly reduced VOR gain and a higher presence of refixation saccades in the ANSD group, particularly in the lateral and posterior canals. fHIT scores were also significantly lower in individuals with ANSD, indicating reduced functional VOR performance. A significant positive correlation between vHIT VOR gain and fHIT responses was observed in the right posterior and left anterior canals. These findings support the presence of vestibular involvement in ANSD and highlight the complementary diagnostic value of combining vHIT and fHIT. The study provides the first known application of fHIT in ANSD and suggests its potential clinical utility in assessing both physiological and functional aspects of vestibular deficits in this population, and may augment rehabilitation.