Action Potential Latency in Individuals with Endolymphatic Hydrops

Abstract

Meniere 's disease has one of the highest prevalence among those that affect the peripheral vestibular system. Various tests have been employed for the diagnosis of Endolymphatic hydrops. These include Glycerol test, OAE, VEMP. CHAMP, and ECochG in addition to the conventional routine audiological evaluations. Howeve1; the reports in the literature are suggestive of inaccurate and inadequate performance of these tests in the diagnosis of Meniere 's disease. The present study aimed at checking the utility of latency difference between. condensation and rarefaction polarities of AP and ABR in the diagnosis of Meniere's disease. The study also aimed at comparing these two techniques with the more established SP/AP amplitude ratio. In the present study, the conventional ABR and extratympanic ECochG were recorded from 21 ears of individuals with Meniere 's disease with pure tone average less than 55 dB, 25 ears of individuals with sensorineural hearing loss other than sloping configuration and pure tone average less than 55 dB, and also 48 ears of healthy individuals. The latency of AP and wave J of ABR for rarefaction and condensation, and SP/AP ratio were measured for all the group of participants. There was a significant correlation for the latency difference between AP polarities and wave I of ABR. There was no correlation between SP/AP ratio and latency difference between AP polarities and also between SP/AP ratio and wave I of ABR. The AP latency difference and wave I latency difference produced higher positive results in Meniere's disease than the SP/AP ratio. A combination of the AP latency difference and SP/AP ratio could identify Meniere 's disease in 85% of individuals and hence the combination would be a better choice.