Riche-Cannieu吻合に両側手根管症候群・右肘部管症候群を合併した1例

Riche-Cannieu Anastomosis and a Paradoxical Preservation of Thenar Muscles in Carpal Tunnel Syndrome : A Case Report

　要旨　症例は72歳女性。3年前より左母指から中指にかけての異常知覚が，1年前より右薬指・小指の異常知覚が出現した。 神経学的所見では，左正中神経領域・右尺骨神経領域の感覚異常，右手内在筋筋力低下・右小指球筋萎縮・右母指球筋萎縮を認めたが，左母指球筋の萎縮は明らかではなかった。 神経伝導検査では，両側手根管症候群と右肘部管症候群を認めた。左短母指外転筋に探査電極を置いて左尺骨神経を刺激してしたところ，陰性の立ち上がりで始まる活動電位が記録され，手掌内での正中-尺骨神経吻合（Riche-Cannieu吻合）の存在が示された。 Riche-Cannieu吻合に正中神経あるいは尺骨神経損傷が合併した場合，臨床的に説明困難な手内在筋の筋萎縮・筋力低下をきたすことがあり，この解剖学的破格も念頭において詳細に電気生理学的評価を行う必要がある。

　A 72-year old woman had been suffered from a dysesthesia in the left median nerve distribution, followed by a dysesthesia in the right ulnar distribution. Neurological examination revealed weakness in the right intrinsic hand muscles with the ipsilateral thenar and hyothenar atrophy. Paradoxical preservation of the left thenar muscles was a clinical challenge. Nerve conduction studies disclosed bilateral carpal tunnel syndrome and the right cubital tunnel syndrome. In needle electromyography, however, the left abductor pollicis brevis and opponens pollicis muscles had normal motor unit potentials without denervation activity. The needle recording of the left abductor pollicis brevis muscle showed a good motor response with a negative deflection by the left ulnar nerve stimulation, indicating an ulnar to median nerve innervation, i.e., Riche-Cannieu anastomosis. A Riche-Cannieu anastomosis in a setting of a median or ulnar nerve injury can produce confusing clinical and electrodiagnostic findings. We reviewed clinical findings, electrophysiological data, and the impact of a Riche-Cannieu anastomosis in median nerve injury.

（Received : August 26, 2003）