Change in the summating potential and action potential during the fluctuation of hearing in Ménière's disease.

Summating potential (SP) and action potential (AP) were monitored by extratympanic electrocochleography (ECoG) during the fluctuation of hearing in 8 patients with Ménière's disease. The relationship of SP and AP parameters to pure-tone hearing threshold level was examined. The correlational analysis revealed the following: AP amplitude decreases with increase in the hearing threshold level at higher frequencies (2-8 kHz), whereas it alters independently of the change in the hearing threshold level at lower frequencies (0.25-1 kHz). -SP amplitude is unchanged irrespective of changes in the hearing threshold level at any frequency. The ratio of -SP to AP amplitude increases with increase in the hearing threshold level at higher frequencies (2-8 kHz), whereas it alters independently of the change in the hearing threshold level at lower frequencies (0.25-1 kHz).