上腕二頭筋腱膜の絞扼による前骨間神経麻痺の1例

Anterior Interosseous Nerve Palsy Entrapped by Lacertus Fibrosus. Case Report

　上腕二頭筋腱膜による絞扼が発症の要因となった前骨間神経麻痺の1例を報告する．患者は43歳の女性で，左上肢の運動の際に上肢の激痛が出現した．数日で疼痛は軽快したが，母指，示指の屈曲障害が出現した．前骨間神経麻痺の診断で保存的に加療していたが症状の改善を認めなかったため，発症4カ月後に手術を行った．上腕二頭筋腱膜の一部が索状に硬化しており前骨間神経の神経束を圧迫していたため，この腱膜を切離した．術後3カ月で筋力は正常に回復した．前骨間神経麻痺の要因として上腕二頭筋腱膜が関与していた症例は稀である．

　We report the case of a 43-year-old female who experienced severe pain in her upper limb while flexing her elbow.　The pain subsided in a few days；however, muscle weakness developed in the flexor pollicis longus and flexor digitorum profundus of the index finger.　She was diagnosed with anterior interosseous nerve (AIN) palsy, and conservative treatment was selected.　Because no improvement was observed, surgery was performed 4 months after the onset of symptoms.　Entrapment of AIN by the hardening and thinning lacertus fibrosus was observed.　This aponeurosis was resected.　Normal muscle strength was recovered 3 month after surgery.　The AIN palsy caused by extrinsic compression, especially by the lacertus fibrosus, is relatively rare.