Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Date of Graduation

5-12-2022

Document Type

Dissertation

Degree Name

Doctor of Audiology (AuD)

Department

Department of Communication Sciences and Disorders

Advisor(s)

Christopher Clinard

Erin Piker

Lincoln Gray

Abstract

Cervical vestibular evoked myogenic potentials (cVEMPs) elicited by steady-state amplitude-modulated (AM) tones yield different information than conventional cVEMPs elicited by transient tonebursts, such as signal-to-noise ratio (SNR) and phase coherence (PC). This study systematically examined the effects of tonic EMG activation on AMcVEMP response properties versus conventional transient cVEMPs. Thirty five young, healthy adults (ages 19–23) with normal audiograms and no known vestibular lesions participated in this study. AMcVEMPs were elicited with bone-conducted tones with a carrier frequency of 500 Hz and an amplitude modulation frequency of 37 Hz, and transient cVEMPs were elicited by 4-0-4 Blackman-gated 500 Hz tonebursts with 8 ms duration. Both cVEMP types were recorded for five different EMG target levels ranging from 10 to 90 μV. For both cVEMP types, amplitude increased linearly with increased tonic EMG activation. Corrected amplitude, SNR, and PC values were minimal at 10 μV, but were robust and virtually plateaued in value from 30 to 90 μV. Interaural asymmetry ratios (IARs) for SNR and phase coherence were substantially lower than either raw or corrected amplitude measures. SNR, PC, and EMG-corrected amplitudes reached essentially maximum values at relatively low levels of EMG activation and did not require higher levels of EMG activation to be adequately elicited. Lower IARs for SNR and PC could have clinical implications about their ability to detect unilateral saccular and/or inferior vestibular nerve lesions versus conventionally used amplitude measures. Findings of this study largely replicated those of Clinard et al (2020).

Available for download on Thursday, April 11, 2024

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