Effects of Occlusion and Conductive Hearing Loss on Bone‐Conducted cVEMP

Abstract

Objective To evaluate the effects of conductive hearing loss and occlusion on bone-conducted cervical vestibular evoked myogenic potentials (cVEMPs). Study Design Prospective cohort study conducted in the year 2018. The right ear of each volunteer was evaluated under 3 conditions by using bone-conducted cVEMPs: normal (open external auditory canal), occluded (conductive hearing loss with occlusion effect), and closed (conductive hearing loss without the occlusion effect). Setting Single academic center. Subjects and Methods The study comprised 30 healthy volunteers aged 20 to 35 years (16 women, 14 men). All had normal hearing and no vestibular or auditory pathologies. The thresholds and amplitudes of cVEMP responses were recorded for the 3 conditions. The results of each condition for a particular participant were compared. Results As compared with the open condition, the conductive condition increased thresholds by 2.8 dB ( P = .01), and the occluded condition decreased thresholds by 3.8 dB ( P = .008). The amplitude in the occluded condition was larger than the normal condition and the conductive condition (mean difference: 20.64 [ P = .009] and 31.76 [ P < .001], respectively) Conclusion The occlusion effect is present in cVEMP responses. The mechanism is not due to the conductive hearing loss induced. Clinical implications include potentially altering vestibular function with sealed hearing aids and in the surgically modified ears (ie, obliterated ears and open cavity mastoidectomy).

Effects of External Auditory Meatus Occlusion on Ocular Vestibular Evoked Myogenic Potentials Induced by Bone Conducted Sound

“…The fact that occluding the external auditory meatus lowers the hearing threshold for BC sound has been known as the occlusion effect since the 19th century (7). The occlusion of the external auditory meatus improves hearing thresholds by 10-20 dB at frequencies of 250 and 500 Hz (7,9). As 500-Hz tone bursts are usually used for recording VEMP, occlusion of the external ear canal seems to be beneficial for inducing VEMP responses although it depends on the mechanism underlying the occlusion effect.…”

“…Rotem Betito et al (9) and Handzel and Himmelfarb (10) reported that external auditory meatus occlusion improved the BC cVEMP responses of healthy subjects. Rotem Betito et al also found that the effect of occlusion on BC cVEMP was not observed in ears filled with water, but was seen in ears that had been occluded using earplugs.…”

“…This is known as the occlusion effect (7,8). The occlusion of the external auditory meatus improves hearing thresholds by 10-20 dB at frequencies of 250 and 500 Hz (7,9). Therefore, occluding the external auditory meatus might improve VEMP responses.…”