Comparison of traditional stimuli versus novel stimulus-evoked masseteric vestibular-evoked myogenic potential in normal-hearing adults

Abstract

Background: Vestibular-evoked myogenic potentials (VEMPs) are the electromyographic (EMG) responses, widely used to assess the functional integrity of otolith organs, i.e., utricle recorded via ocular VEMPs at the level of inferior oblique muscle and saccule via cervical VEMPs at sternocleidomastoid muscle. In addition, VEMPs can also be recorded from other regions of the body as well that includes triceps muscle, trapezius muscle, gastrocnemius muscle, and masseter muscle. The short-latency inhibitory EMG responses recorded at the level of active masseter muscles with acoustic stimulation of vestibular end organ are referred to as masseteric VEMPs (mVEMPs). Aims and Objectives: The present study aimed at comparing various parameters of mVEMP responses such as latency, amplitude, and asymmetry gain across different stimuli. Materials and Methods: A total of 21 normal-hearing healthy individuals with a mean age of x̄ = 21.14 years and σ =1.7 participated in the study with a pure-tone average of 15 dBHL in air and bone conduction testing and normal immittance results for both ears. Results: Therefore, the median latency values for P11 were obtained as M = 11.84 ms, M = 14.67 ms, and M = 11.33 ms in the right ear and M = 11.83 ms, M = 14.83 ms, and M = 11.33 ms in the left ear for clicks, 500 Hz tone burst, and 500 Hz narrow band level specific (NBLS) chirp, respectively. Similarly, for N21, latency values were M = 20 ms, M = 25.16 ms, and M = 20.16 ms in the right ear and M = 19.67 ms, M = 24.67 ms, and M = 19.33 ms in the left ear for clicks, 500 Hz tone burst, and 500 Hz NBLS chirp, respectively. Conclusion: The study suggested mVEMP response to have significantly early latencies and largest amplitudes for 500 Hz NBLS chirp than clicks and 500 Hz tone burst stimuli. The NBLS chirp is an appropriate substitution for clicks and tone burst in assessing vestibulo-trigeminal pathway.