耳小骨直接加振による蝸牛マイクロホン電位（CM）を用いた中耳伝音特性評価

抄録

Cochlear microphonic (CM) is known to faithfully correspond to the frequency and level of sound pressure applied to the cochlea. If the CM is measured and compared before and after the treatment during middle ear surgery, the improvement of the efficiency of the middle-ear sound transmission can be evaluated, and the risk of reoperation can be decreased. However, the sound transmission efficiency cannot be evaluated by applying sound to the middle ear with a speaker because the sound transmission mechanism of the middle ear is temporarily disabled in some operative procedure. In this study, an evaluation system of the middle-ear sound transmission efficiency by measuring the CM during surgery was constructed. The system consists of a vibration probe, electrodes, amplifier, and controller. The ossicles are vibrated by the vibration probe instead of sound from a speaker, and the CM signals generated by the vibration are measured. In most cases, the CM amplitude increased in proportion to the input voltage applied to the vibration probe as is the case in sound stimulation. This result suggests that the intraoperative assessment of improvement of middle-ear sound transmission efficiency is possible by using the vibration probe.