内反肘に伴う遅発性尺骨神経麻痺の2例

Delayed Ulnar Nerve Palsy Secondary to Cubitus Varus Deformity. Report of Two Cases

　小児期肘関節周辺骨折後の内反肘に伴う遅発性尺骨神経麻痺の2例を報告する．2例とも初診時に左尺骨神経支配領域の知覚低下，患側の筋力低下を認め，肘外偏角は内反30°と内反20°であった．術前inching法運動神経伝導速度検査で肘部管相当部に障害があることが予測された．術中尺骨神経のfibrous bandによる絞扼を認め2例ともにfibrous bandの切離を行い，1例に内反肘矯正骨切り術を併用し良好な結果が得られた．今回の症例ではfibrous bandによる絞扼が原因であると考えられる．

　It is well known that cubitus varus deformity often causes late ulnar nerve palsy. We encountered two rare cases of delayed ulnar nerve palsy secondary to cubitus varus deformity carsed by a supracondylar fracture of the humerus. Both patients had an ulnar sensory impairment and intrinsic muscle atrophy. Their carrying angle was 30 degrees and 20 degrees, respectively, of varus. Preoperative measurement of motor nerve conduction velocity by the “inching” technique revealed localized impaired conduction around the cubital tunnel in both cases. At surgery a fibrous band was observed to have compressed the ulnar nerve. Surgical treatment consisted of release of the fibrous band in both patients and corrective osteotomy in one of them. Satisfactory results were obtained in both cases. We concluded that the main etiologic factor in the ulnar nerve palsy in both cases was compression of the ulnar nerve by a fibrous band.