真珠腫の耳管上陥凹への進展に対するCT診断の価値について

The Role of High-resolution CT in Cholesteatoma Involving the Supratubal Recess

I．はじめに

　耳管陥凹は上鼓室前力に位置しShcehyによってcogと呼称された骨隔壁^1）で上鼓室と分けられている（図1）。弛緩部型真珠腫はキヌタ骨体の外側を後方に向かうことが多く耳管上陥凹への進展頻度は少ない。しかし耳管上陥凹は鼓室蓋，顔面神経膝神経節，蝸牛，前半規管など重要組織と隣接する^2）。もし真珠腫が耳管上陥凹に進展すると，種々の合併症を起こす危険があり，それゆえこの部位の術前診断はきわめて重要である。

　近年高分解能CTの進歩とともに側頭骨各部位に対する画像診断能力が向上し，その診断価値が確認されつつある。

　Operative findings of the supratubal recess were examined in the 30 patients with acquired cholesteatoma. They were compared with findings of high-resolution CTs (HRCTs) obtained preoperatively. Thus the role of HRCT in cholesteatoma involving the supratubal recess were evaluated.

　HRCTs of 172 cars without otitis media and 65 ears with tubotympanic type otitis media were analyzed as control.

　The HRCT has proved to provide excellent informations regarding the presence of cholesteatoma in the supratubal recess. Diagnostic points were as follows.

　(1) Destruction of the "cog". (2) Erosion or destruction of surrounding bony structures, for example, facial canal, tympanic tegmen. (3) Soft tissue density in the supratubal recess.