聴力正常の内耳奇形

A Study of Inner Ear Malformation with Normal Hearing

I．緒言

　内耳の形態異常のなかで生前に診断が可能なものは，一般に機能的にろう，あるいは高度の難聴を有するものに対して行われたX線写真によるものであり，しかもそれは骨迷路に著しい異常のある例に限られている。しかしなんらかの理由で断層X線撮影が行われた聴力正常の耳のX線写真を検討していると，聴力が正常であるにもかかわらず内耳に明らかな骨迷路の形態異常を見出すことが稀にある。今回われわれはこの点に注目して若年性一側性高度難聴（いわゆる一側ろう）の難聴側および正常側のX線所見について検討を加えた。

　1) 126 patients with unilateral deafness of unknown cause were studied by tomography (fronto-posterior projection). and 10 ( 7.9%) were found to have inner ear deformity in the side of hearing loss.

　2) Of these 10 patients, three (2.1%) were found to have bilateral deformity.

　3) Inner ear deformity in the side with normal hearing was enlargement of the semicircular canalsand vestibules in these three cases. One of these, in addition. had the unclear shape of the cochlea.

　4) Though Schuknecht considered that the complete deformity of inner ear structure was always accompanied by a loss of auditory and vestibular function, in the cases of the incomplete deformity, they may not be accompanied with such losses.

　This suggested that there might be bilateral deformities, although a loss of hearing was unilateral.