二分内耳道低形成

Double Barreled Hypoplasia of Internal Auditory Canal

I．はじめに

　外耳道閉鎖症を伴わない一側性の先天性幌は言語習得などには影響を及ぼさないため就学時の健診などで発見されることが多い。その原因の一つである先天性内耳および内耳道奇形についてはすでに種々の報告^1〜5）があるが，二分内耳道低形成の報告は少ない。われわれはこの2年間に同奇形を3例経験したので報告する。

　Double barreled hypoplasia of internal auditory canal is a rare congenital anomaly and causes unilateral deafness.

　We presented 3 cases of this anomaly and also reviewed the other 3 cases previously reported.

　The right internal auditory canal was affected in all cases and all but one case were girls. The vestibular function was preserved in 2 cases out of 6 cases.

　Radiographically the right internal auditory canals were narrow and its superior and inferior compartments were separated by a long crista falciformis. These findings were obtained by transorbital view of IAC and confirmed bytomography. All girls with deafness of the right ear should be examined radiographically.