Electrocochleographic findings in patients with Ménière's disease: associations with hearing thresholds and endolymphatic hydrops.

OBJECTIVE: To evaluate the associations of extratympanic electrocochleography (ECochG) parameters with hearing thresholds and gadolinium-enhanced magnetic resonance imaging (MRI)-confirmed endolymphatic hydrops (EH) in patients with Ménière's disease (MD). METHODS: In this prospective cross-sectional study, patients with definite MD were enrolled between March and June 2024. All underwent pure-tone audiometry, extratympanic ECochG, and intravenous gadolinium-enhanced 3D-real inversion recovery MRI. The summating potential/action potential (SP/AP) ratio and the area of summating potential/area of action potential (ASP/AAP) ratio were measured. Ears were classified as EH or non-EH based on MRI findings. Correlations between ECochG parameters and frequency-specific hearing thresholds and EH severity were analyzed, and receiver operating characteristic analyses were performed to assess diagnostic accuracy. RESULTS: A total of 98 ears were analyzed, and MRI-confirmed EH was identified in 59 (60.2%). Both SP/AP and ASP/AAP ratios were significantly higher in the EH group than in the non-EH group (0.42 vs. 0.24, P<.001; 1.55 vs. 1.33, P=.003, respectively). Both parameters correlated more strongly with hearing thresholds (r = .28-0.44) than with EH severity (r = .23-0.33). Diagnostic performance was modest, with area under the curve values of 0.62-0.72 for EH detection. Machine learning models based on pure-tone audiometric features showed higher area under the curve values (0.92-0.95). CONCLUSION: In patients with MD, ECochG parameters were associated with both hearing thresholds and MRI-confirmed EH. Their stronger associations with hearing thresholds than with hydrops severity suggest that ECochG abnormalities may be more closely related to cochlear functional status than to the anatomical extent of hydrops. Given their modest diagnostic performance, ECochG parameters may have limited value as standalone markers for EH detection.