晩発性放射線腰仙部神経叢障害の1例

A CASE OF DELAYED RADIATION LUMBO-SACRAL PLEXOPATHY

　症例は47歳女性で，昭和52年右卵巣癌のため両側卵巣摘出術と放射線照射（総線量70Gy）を施行された。その後再発は認められず経過良好であったが，8年後に両下腿の筋力低下と感覚障害が出現し，徐々に進行した。神経学的には両下肢の軽度筋力低下，深部腱反射消失および両下腿前面，足背，足底の全感覚低下を認めた。腹部・骨盤CTでは癌の再発は認められなかったが，腸管壁，膀胱壁の肥厚・癒着，両側尿管の狭窄と水腎症，著明な後腹膜の線維化を認めた。これらの所見は放射線照射野に一致し，晩発性放射線障害と考えられた。下肢の神経症状より第2腰髄から第2仙髄の障害が考えられ，照射後の神経周囲組織の線維化による絞拒性の腰仙部神経叢障害が推察された。

We report a 47-year-old woman who developed a slowly progressive lumbosacral plexopathy withmixed sensorimotor losses in the lower extremi-ties. The symptoms were apparent 8 years after x-ray irradiation for an ovarian carcinoma.

Neurological examination showed mild weakness and absent deep tendon reflexes of bilateral lower extremities, and hypesthesia to all modalities in anterior aspects of bilateral lower thighs, in dor-sum pedis and soles.

Extensive investigations regarding the possibi-lity of tumor recurrence were negative. Computed tomography of pelvis showed abnormal soft tissue densities around the lumbosacral plexus. Intra-venous pyelography showed bilateral hydrone-phrosis and narrowed ureters at the first sacral vertebra level. These findings are consistent with radiation-induced fibrosis rather than tumor in-filtration. The results suggest the entrapment lumbosacral plexopathy due to surrounding fibrosis after irradiation. We speculated the sensorimotor losses caused by entrapment of the lumbosacral plexus.