手根管症候群におけるAPB-CMAP導出不能例の長期術後成績

Long-term Postoperative Follow-up of Carpal Tunnel Syndrome with Undetectable APB-CMAP

要旨：透析例などを除く特発性手根管症候群で短母指外転筋の複合筋活動電位（APBC-MAP）が導出不能であった症例の手根管開放術後1年以上経過後の治療成績について検討を加え，母指対立障害の改善が術前に予測可能かどうかについて考察した．術後1年以上経過観察し得たのは33例37手であり，平均年齢59.8歳，平均経過観察期間3年3カ月であった．筋萎縮が消失していたものは21手57％で全手でAPB-CMAPが導出可能であった．筋萎縮が残存していたのは16手43％であり，筋萎縮残存手でAPB-CMAP導出可能であったのは7手，導出不能のままであったのは9手であった．術前罹病期間では筋萎縮消失手と残存手に有意差を認めなかった．年齢別では50歳未満の7手では全手で筋萎縮が消失しており，原則として手根管開放術のみで良好な回復が期待できると考えられたが，50歳以上では術前に筋萎縮改善を予測することは困難であった．

Abstract : This study assessed the predictability of postoperative recovery of thumb opposition in patients with carpal tunnel syndrome and undetectable compound muscle action potential of the abductor pollicis brevis (APB-CMAP). Thirty-seven hands of 33 patients with a mean age of 59.8 years old were reviewed one year or longer after carpal tunnel release surgery, with a mean follow-up period of 39 months. Thenar muscle atrophy had disappeared in 21 hands (57％), all of which had detectable APB-CMAPs. Thenar muscle atrophy persisted in 16 hands (43％), among which APB-CMAPs were detectable in 7 hands and remained undetectable in 9 hands. Disease duration preceding surgery did not differ significantly between the hands in which muscle atrophy disappeared and the hands in which muscle atrophy persisted. Thenar atrophy disappeared in all seven patients under 50 years of age at the time of carpal tunnel release, but persisted in 16 of the 30 (53％) patients over 50 years of age. These findings indicate that good recovery of thumb opposition can be expected without opponensplasty in patients less than 50 years of age. However, recovery was not predictable in patients over 50 years of age.