中耳奇形の術前診断と手術についての検討

Abstract

We retrospectively analyzed 26 ears of 21 subjects having auditory ossicular malformation and who had undergone auditory reconstruction between April 2004 and December 2010 at our clinic. We checked preoperative condition, pathological classification, surgical procedure, and hearing improvement. We could predict pathological conditions precisely from preoperative computed tomography (CT), including incudostapedial disconnection (9/12, 75%) and malleus and/or incus fixation (7/12, 58%), which tended to be present in external ear malformation, and stapes footplate fixation (0/12, 0%). We could not, however, predict complex malformation (0/8, 0%). Overall success was 90% (18/20) in the 20 ears observed for at least 1 year. In the 2 ears without improved hearing, the first had congenital cholesteatoma and no stapes superstructure, was treated with type IV tympanoplasty. The second had malleus, incus, and stapes fixation and discontinuity between the incus and stapes, and was treated with type III tympanoplasty and stapes mobilization. Preoperative diagnosis is difficult in mixed congenital auditory ossicular malformation, especially stapes footplate fixation, possibly requiring unexpected procedures, with a poor hearing outcome. Preoperative status must thus be evaluated precisely using hearing, tympanometry, acoustic reflex test, and CT. Temporal bone CT and external ear findings are useful in diagnosing middle-ear malformation. Subjects' informed consent should also be obtained due to the possible need for changing procedure based on findings during surgery.