Abstract: Objectives This study was designed to evaluate the diagnostic value of extra-tympanic electrocochleography(ET-ECochG)in definite Ménières disease(MD)patients. Methods Fifty-eight definite MD patients(60 ears)underwent ET-ECochG using bronze foil electrodes. The medical history, as well as pure tone audiometry, ET-ECochG, and 3D FLAIR MRI data of each patient were collected. Meanwhile, forty healthy volunteers were enrolled as controls. The amplitudes, latencies, and durations of SP and AP, the SP/AP amplitude ratio(SP/AP), and the area ratio of SP/AP(Asp/Aap)were collected. An adjusted calculation method for Asp/Aap was proposed. The differences among the ET-ECochG results of the definite MD ears, contralateral asymptomatic ears, and normal ears were analyzed using the t-test and the Mann-Whitney U test. The associations of Asp/Aap of ET-ECochG with the clinical history, pure tone audiometry, and endolymphatic hydrops evaluated via MRI were analyzed. Results ET-ECochG was identified in 46 of 60 ears(76.67%). Using the receiver operating characteristic(ROC)curve, the optimal cutoff points of SP/AP and Asp/Aap were 0.38 and 2.42, respectively. The area under the ROC curve(AUC)of Asp/Aap(0.985)was higher than the AUC of SP/AP(0.920). The ET-ECochG results of the definite MD ears, including SP/AP, Asp/Aap, and SP duration, were significantly higher than those of the contralateral asymptomatic ears and normal ears(p<0.05). The duration and disease stages of MD were significantly associated with SP/AP. The degree of endolymphatic hydrops of the cochlea was correlated with SP/AP and Asp/Aap, whereas the degree of vestibular hydrops only correlated with Asp/Aap. Conclusion SP/AP and Asp/Aap may be indicative of the degree of endolymphatic hydrops. Thus, ET-ECochG is useful for the clinical diagnosis of MD.

Key words: Extra-tympanic electrocochleography, Amplitude ratio, Area ratio, Menieres disease, Endolymphatic hydrops