A Study on Masking Cervical Vestibular Evoked Myogenic Potentials Elicited by Vertical-Axis Vibrations through Speech Noises or Random Interstimulus-Interval Tone-Bursts.

Abstract

Objective: Vestibular evoked myogenic potential (VEMP) can be elicited using bone-conducted vibration (BCV) and air-conducted sound, with BCV VEMP typically associated with bilateral vestibular pathways. We employed a new acoustic masking method to obscure BCV VEMP, aiming to explore the feasibility of unilateral BCV VEMP testing.

Materials and methods: Twenty healthy adults (20-37 years old; 10 males and 10 females) participated in the study. Vertical-axis vibrations (VAVs) of 500-Hz short-tone bursts (STB500) and 750-Hz short-tone bursts (STB750) were used to induce cervical VEMP. These stimuli were delivered through a Mini-Shaker placed at the vertex under three conditions: without acoustic masking (no masking [NOM]), with 100 decibels sound pressure level (dB SPL) speech noise masking (SNM), and with random interstimulus-interval tone bursts (rISITB), applied binaurally during VEMP testing.

Results: The response rates for STB500 were less affected by SNM or rISITB (92.5% for NOM, 85.0% for SNM, and 75.0% for rISITB), whereas the response rates for STB750 were significantly reduced from 90.0% (NOM) to 17.5% (SNM) and 45.0% (rISITB) (p < 0.05, Fisher's exact test). The response amplitude and p13 latency of STB750 also differed significantly from those of STB500 (p < 0.05, two-way repeated measures analysis of variance). The VAVs of STB750 elicited a >90% response rate for cervical VEMP but showed an 80% decrease in response rate under SNM.

Conclusion: SNM proved more effective than rISITB in masking the VEMP response evoked by BCVs. This approach offers the potential for conducting VEMP tests on individual ears or targeting specific vestibular organs using BCV VEMP.