[Spectral analysis of electrocochleogram in Menière's disease]

The power spectrum of electrocochleogram in Ménière's disease was analysed. Usually, the ratio -SP/AP was used to diagnose Ménière's disease. However, when -SP could not be discriminated exactly, we were dubious of using this method. With power spectrum, we can raise the rate of diagnosis and estimate the condition of endolymphatic hydrops. In power spectrogram it shows more components of low frequency (that is, the power peak moves to the left) when the amplitude of -SP goes higher. Extratympanic electrocochleography was performed on 34 ears diagnosed as having Ménière's disease (MD group) and on 8 normal ears (normal group). An obvious difference in power spectrogram was found between these two groups (P less than 0.01). The peak in spectrogram of normal group was mean = 594 Hz; S = +60 Hz; the peak in MD group was mean = 359 Hz; S = +161 Hz. In MD group there were 28 cases (82.4%) with power peak moved to the left and 18 cases (52.9%) with the ratio -SP/AP no less than 0.4. During remission, the spectrum resembled the normal ones.