結果的にstapedectomyとなった耳硬化症症例—あぶみ骨手術に対する考察

Evaluation of Postoperative Hearing in Stapedecotomy and Inadvertent Stapedectomy

I．はじめに

　耳硬化症に対するあぶみ骨手術は聴力に対する良好な結果から現在手術手技として確立されたものとみなされているが，あぶみ骨底の取扱い，あるいはprosthesisの選択などに術者それぞれの工夫がみられる。

　当教室では昭和54年以来stapedectomyに代わってstapedotomyを行っている。そのなかで当初stapedotomyを予定して手術を進め，あぶみ骨の上部構造を除去するさいに底板も一緒に摘出され，結果的にstapedectomyとなった症例がある。これらの症例と他のstapedotomy症例との術後経過，とくに聴力の変化について検討し，あぶみ骨手術に対する若干の考察を加えた。

　Postoperative hearing was evaluated in patients with otosclerosis who underwent stapedotomy or inadvertent stapedectomy. In stapedotomy 0.6mm × 4 mm piston was introduced into the vestibule through a O.8 mm hole which was created at the center of the footplate. The same prosthesis was used for those whose footplate of the stapes was removed with the superstructure inadvertently.

　The average preoperative and postoperative hearing level of the patients of stapedotomy group (26 ears) was 58.0 dB and 25.7 dB and that of inadvertent stapedectomy group (8 ears) was 59.0 dB and 20.3 dB. No significant difference was observed in these two groups. The average AB gap was 8.85 dB in stapedotomy group and 5.31 dB in stapedectomy group. Improvement rate was 83.4% in stapedotomy group and 97.0% in stapedectomy group.