一側聾・他側CPの両側内耳奇形

A Case Report of Bilateral Inner Ear Anomaly Associated with Unilateral Deafness and Contralateral Vestibular Dysfunction

I．はじめに

　一側聾を主訴に来院した7歳男児にCTを含む検索の結果，聾耳の蝸牛・前庭・半規管形成不全を見出すと同時に，聴力正常耳にも前庭・半規管の形成不全を発見した。興味深いことには，聴力正常耳の温度性眼振は4℃（20ml）でも全く解発されず，反対に聾耳は温度刺激に正常に反応した。

　症例を報告するとともに，蝸牛・前庭・半規管機能と形態異常（X線学的）の関係などにつき考察した。

　A 7-year-old-boy, born as a premature twin, was diagnosed as having bilateral inner ear anomaly. The high resolution computed tomography (CT) revealed that the vestibules in both sides were markedly enlarged and his left cochlea was poorly developed. The right cochlea appeared normal. No other anomaly was found in either side of the middle and external ear nor in other part of his body.

　The most interesting feature of the case is thatwhile the normal hearing ear lacked caloric response, the deaf ear showed normal caloric response. The ENG testing revealed spontaneous nystagmus directed to the deaf ear (i.e. the ear withnormal caloric response).

　The correlation between the morphological anomaly and the inner ear function was discussed, and the literature was reviewed.