内耳疾患におけるＳＰ／ＡＰ比の診断学的評価

Abstract

Electrocochleograms were recorded in response to tone burst stimuli with a transtympanic technique from 22 normal ears, 28 ears of patients with a clinical diagnosis of Ménière's disease and 27 ears affected by sensorineural hearing loss (subtractive loss type). We correlated the SP/AP ratio and stimulus frequency, stimulus intensity, and inter-stimulus interval in normal ears and evaluated the diagnostic efficiency of the SP/AP ratio in comparison with that of the SP amplitude in inner ear disease.1) The SP/AP ratio changed as a fUnction of stimulus frequency, stimulus intensity and inter-stimulus interval. The SP/AP ratio to 4kHz tone burst stimulus showed characteristically the largest value with the smallest standard deviation on the average.2) It may safely be said that the SP/AP ratio can serve at present as the most useful indicator in the electrocochleographic diagnosis of Meniere's disease.3) It was clear that the SP amplitude was more effective than the SP/AP ratio in the diagnosis of sensorineural hearing loss.It was concluded that the diagnostic significance of the SP/AP ratio is to catch important phenomena in the electrocochleogram, such as the dominant negative SP or the abnormal increase in negative SP. In addition, we emphasize that the mechanism of generation and the pathophysiological significance of this phenomenon should be made clear in order to complete the electro-pathophysiological diagnosis of Meniere's disease.