CVEMP Testing in Patients with a Third Mobile Window

Abstract

Objective To determine the usefulness of cervical vestibular-evoked auditory potential (cVEMP) testing for the evaluation of patients with and without a third mobile window (superior canal dehiscence or large vestibular aqueduct). Methods A retrospective review of charts from patients who underwent cVEMP testing at a single tertiary referral center was performed. The cVEMP is a vestibular reflex generated by an air-conducted stimuli, causing an inhibitory potential in the ipsilateral sternocleidomastoid muscle measured by external electrodes. cVEMP results were correlated with demographic characteristics, hearing testing, diagnosis, and imaging. Mean cVEMP thresholds (at 500 Hz) and amplitudes (@ 95dB nHL and 500 Hz) were compared between ears and between patients with and without a third mobile window (TMW). Unequal variance t-Test was used to determine significance. Patients were excluded if they had a history of Meniere's disease, middle ear disease or otologic surgery. Results 63 patients received cVEMP testing, of which 8 had either unilateral or bilateral TMW. 114 non-TMW ears were compared to 10 ears with TMW. Ears with TMW had a lower mean threshold (68 dB nHL) vs. non-TMW (83 dB nHL) (p<0.003) and a higher mean amplitude (321?V) vs. non-TMW (78?V)(p<0.009). Conclusions Patients with TMW have lower thresholds and higher amplitudes on cVEMP testing. This study supports the use of cVEMPs to diagnose TMW in patients who present with an unexplained air-bone gap, autophony, aural fullness, or dizziness.