Vestibular Evoked Myogenic Potentials in Sudden Hearing Loss

Aims: Vestibular evoked myogenic potentials (VEMPs) are short-latency electromyograms recorded from the ipsilateral tonically contracting sternocleidomastoid muscle in response to loud clicks or tone-bursts. It is reported that this reflex is generated via a disynaptic pathway, beginning in the saccule. The purpose of the study is to investigate the VEMPs in cases of sudden hearing loss.

Materials and Methods: Twelve patients with unilateral idiopathic sudden hearing loss were subjected to pure tone audiometry, acoustic immittance testing, caloric testing, auditory brainstem responses, and VEMP testing. A group of healthy volunteers was also enrolled. VEMP responses were measured and compared to caloric responses.

Results: VEMPs were present in all normal subjects and ipsilaterally normal on the unaffected side in all patients with sudden hearing loss. Five out of 12 patients displayed abnormal VEMPs (41.6%) on the affected side (in 4 cases were absent, in 1 case delayed) and 4 of them demonstrated decreased canal paresis, while the fifth had normal caloric responses. In 5 patients both electronystagmographic findings and VEMPs were normal, while the remaining 2 patients showed normal VEMP test results but abnormal caloric responses.

Conclusion: Most of the patients displayed normal VEMPs. However, in a considerable number of cases they were abnormal. Also, in the majority of patients, VEMPs correlated to the caloric responses, although in 3 patients either the superior or the inferior vestibular nerve was involved.