Contribution of Vestibular Evoked Myogenic Potentials (VEMP Test) to the Evaluation of Patients with Idiopathic Sudden Hearing Loss

Abstract: Objective: To evaluate Vestibular Evoked Myogenic Potentials (VEMP) testing results in patients with unilateral Idiopathic Sudden Hearing Loss (ISHL) and to correlate them with the findings of caloric testing, the clinical appearance of vertigo, the influence of age, the grade and type of initial hearing loss and finally, the early recovery of subjects.Materials andMethods: One hundred and four (104) patients with unilateral ISHL and 35 healthy controls were subjected to a standard protocol of neurotological evaluation. VEMP responses were measured and compared to caloric responses, to epidemiological and clinical parameters and to the initial and final audiograms of each subject. Results: Overall, abnormal VEMP responses were observed on the affected side in 28.8% of patients whereas abnormal Caloric findings occurred in 50% of the subjects studied. A significant relationship was found between the results of the two tests, meaning that the highest probability is either of the lesion to spare both otoliths and semicircular canals or, to involve both labyrinthic structures at the same time. A significant relationship was found between the type of vestibular lesion and subjective vertigo. Advancing age correlated statistically with more extended labyrinthic lesion, mostly including both semicircular canals and otolithic organs. Moreover, a statistically significant relationship was found between the type of inner ear lesion and the incidence of profound hearing loss. The type of vestibular lesion did not correlate with the occurrence of high frequency hearing loss, and the audiogram type had no significant effect on the likelihood of hearing recovery. Finally, a negative correlation was found between the extent of inner ear lesion and the likelihood of early recovery.Conclusions: The combination of VEMP and ENG testing has proven vestibular involvement in many ISHL patients. Both tests are necessary in order to obtain a more thorough and deep knowledge of the pathophysiology of ISHL. The extent of inner-ear lesion tends to correlate with the severity of cochlear damage in ISHL. Vestibular assessment can be extremely valuable in prediction of the final outcome.