Conductive Hearing Loss Effect on Cervical Vestibular Evoked Myogenic Potential (cVEMP) Testing

Cervical Vestibular Myogenic Potential (cVEMP) is an important test evaluating the otholitic organs, especially the saccule. In response to air or bone conducted (AC or BC) sound the sternocleidomastoid muscle (SCM) contracts and relaxes. The main goal of this study was to assess the effect of conductive hearing loss (CHL) on BC cVEMPs.

A prospective and comparative study was conducted on 30 healthy volunteers. BC tone burst of 500 HZ was delivered in two conditions of CHL created in the external ear canal (EAC): closed with ear plugs (“occluded canal with occlusion effect”) and filled with water (“occluded canal without occlusion effect”). The thresholds and amplitude of the cVEMP tests were examined in each condition and compered to a normal, open, EAC.

As compared to the open EAC, CHL without occlusion effect increased thresholds from a mean of 43.5 dB to 46.3dB (p<0.01). The CHL with occlusion condition decreased thresholds to mean of 39.7dB (p<0.008). The amplitude in CHL with occlusion condition was amplified compared to normal condition and to CHL without occlusion condition (mean difference: 20.64 [p<0.09] and 31.76 [p<0.001], accordingly).

cVEMP responses decrease by CHL without occlusion effects and increase by CHL with occlusion effects. This effect is shown here for the first time. It has various clinical implications: fitting of sealed hearing aids, measuring VEMPs in surgically modified ears and more. The study points to the possibility of studying acoustic effects (such as tuning forks testing) in the ear by looking at vestibular rather than cochlear responses.