[Electrocochleography with an extratympanic tympanic membrane electrode : Age-dependent reference values for vertigo diagnostics].

Background Electrocochleography (ECochG) records electrical potentials of the inner ear and is used, among other applications, in the diagnostic work-up of Ménière's disease. For extratympanic recordings, age-dependent reference values are currently lacking, which limits clinical interpretation.Objective This study aims to establish age-stratified reference ranges for the summating potential (SP)/action potential (AP) amplitude and area ratios for noninvasive diagnostics in patients with suspected endolymphatic hydrops. Materials And Methods A total of 47 ears from 26 normal-hearing volunteers aged 20-70 years were examined using an extratympanic tympanic membrane electrode. The SP and AP potentials were recorded in a standardized manner. Amplitude and area ratios were calculated and analyzed with respect to age and laterality. Results The reference ranges (P5-P95) were 0.13-0.46 for the SP/AP amplitude ratio and 0.72-1.72 for the SP/AP area ratio. No significant side differences were observed. A slight age-related increase in both parameters was detected, without a clinically relevant impact. Conclusion Extratympanic ECochG enables a minimally invasive and reliable diagnostic approach with age-stratified reference values. It represents a practical adjunct to imaging in Ménière's disease and allows a more differentiated assessment of pathological inner ear function.