感音難聴と蝸電図

概要

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Three kinds of electrical phenomena-auditory nerve action potential (AP), cochlear microphonics (CM) and summating potential (SP) were recorded from patients with sensorineural deafness. The reversibility of hearing impairment can be predicted in cases showing both lower detection threshold of CM and greater AP response at high sound stimulus levels. AP showing a dominant negative SP can also indicate reversibility of hearing impairment, except for noiseinduced deafness where the organ of Corti is damaged. Conversely, cases showing both a low AP response and a high detection threshold of CM are likely to have an irreversible hearing loss. The site of lesion or pathophysiology of the inner ear can be estimated. Ménière's disease and syphilitic labyrinthitis showing increased negative SP may be related to endolymphatic hydrops. In cases of sudden deafness, this methodology is very helpful not only in predicting prognosis, but also in estimating the extent of hair cell damage or damage of the eighth nerve. The recruitment phenomenon can be studied objectively. Recruitment is reflected in a super-normal AP response at high stimulus levels or a dominant negative SP. The increased negative SP itself may play an important role in the super-normal AP recorded from type 1 Ménière's showing a normal CM.
耳鼻と臨床会の論文