Comparison of Air Conduction and Bone Conduction Masseter Vestibular Evoked Myogenic Potential Between Neurotypical Young Adults and Individuals With Conductive Hearing Loss.

Introduction Masseter vestibular evoked myogenic potential (mVEMP) is an acoustically evoked potential recorded from the masseter muscle. It is a recent tool in the vestibular assessment battery that checks the integrity of the vestibulomasseteric reflex pathway, specifically for saccular function. Need of the study There is a small pool of subjects with cervical spondylitis and anomalies in the eye muscle where cervical vestibular evoked myogenic potential (cVEMP) and ocular vestibular evoked myogenic potential (oVEMP) tests cannot be performed. In such conditions, mVEMP is considered an appropriate tool to assess the vestibular function. Bone conduction (BC) mVEMP assesses vestibular function in individuals with conductive hearing loss having a significant air-bone gap (ABG). Hence, it is essential to establish a comparative normal range of values for air conduction (AC) and BC mVEMP. Aim of the study The study aimed to evaluate the vestibulomasseteric reflex pathway using AC and BC mVEMP for click and 500 Hz tone burst stimuli in neurotypical young adults and compare it to individuals with conductive hearing loss. Method Ten neurotypical (20 ears) young adults and five (10 ears) individuals with conductive hearing loss in the age range of 15-40 years without vestibular complaints were recruited for the study. The AC and BC mVEMP were recorded monaurally using click and 500 Hz tone burst stimuli for all the participants. Results For neurotypical young adults, the mean latencies of P1 and N1 for AC and BC mVEMP using click were 13.87±1.86 ms and 19.78±2.14 ms and 13.79±2.06 ms and 21.30±1.48 ms, respectively. The P1 and N1 mean latencies for AC and BC mVEMP using 500 Hz tone burst were 14.90±1.50 ms and 21.03±1.30 ms and 14.18±0.95 ms and 19.75±1.71 ms, respectively. For individuals with conductive hearing loss, the P1 and N1 mean latencies for AC and BC mVEMP using click were 15.37±1.46 ms and 20.65±2.65 ms and 15.41±0.68 ms and 21.07±1.45 ms, respectively. AC mVEMP responses were absent for 500 Hz tone burst stimuli. The P1 and N1 mean latencies for BC mVEMP using 500 Hz tone burst stimuli were 14.96±0.6 ms and 22.72±1.42 ms, respectively. Conclusion AC mVEMP was absent for 500 Hz tone burst stimulus but present for click stimulus in individuals with conductive hearing loss as there was a larger ABG at the low frequencies than at the mid-high frequencies. BC mVEMP was present for click and 500 Hz tone burst stimuli in all individuals with conductive hearing loss and latencies of P1 and N1 were similar to results obtained for neurotypical young adults and no significant difference was seen.