Electrophysiological verification of ulnar-median neural communication in the hand : Inter-racial difference

• Published in: Japanese Journal of National Medical Services Vol. 41; no. 5; pp. 414 - 419
• Main Authors: KIMURA Itaru, SASAO Shunichi
• Format: Journal Article
• Language: Japanese
• Published: Japanese Society of National Medical Services 1987; 一般社団法人 国立医療学会
• Subjects: 尺骨神経; 正中神経; 神経線維吻合; 電気生理学的検索
• ISSN: 0021-1699; 1884-8729
• DOI: 10.11261/iryo1946.41.414

Electrophysiological verification of the neural communication between the deep branch of the ulnar nerve and recurrent branch of the median nerve (Riche-Cannieu anastomosis) in the hand was carried out. Two hundreds and twenty extremities of 110 healthy subjects (54 men and 56 women) including 25 Japanese, 30 American caucacian, 30 hispanic and 25 American black populations. Supramaximal nerve stimulation of the median and ulnar nerves at the wrist and elbow was used. The compound action potentials (CMAPs) were recorded from the abductor pollicis brevis (APB), first dorsal interosseus (FDI) and abductor digiti minimi (ADM) muscles. Detection of the ulnar-to-median nerve communication was evaluated with the ulnar innervation ratio (UNIR) in APB which was calculated as a ratio of CMAPs amplitude between on the ulnar and median nerve stimulation. The communication was detected in 82.5% of 220 extremities tested. The mean UNIR in APB was 27.6±16.4% (mean±SD). In American blacks, this mean value was statistically smaller than in Japanese, caucacian or hispanic population (p<0.05). The mean median nerve innervation ratio (MNIR) was also calculated in FDI and ADM. These were significantly smaller than UNIR in APB (p<0.01). This high percentage of the neural communication between ulnar and median nerves in the hand should be looked upon as a normal neural communication rather than it may signify one of a common anomalous innervation in the hand. We should always keep in mind this neural communication when we clinically or electrophysiologically examine the patients with carpal tunnel syndrome or with ulnar nerve entrapment at the Guyon canal. 手掌部での尺骨神経深枝と正中神経反回枝との線維連絡(Riche-Cannieu吻合)を正常者110名(220肢)について電気生理学的に検索した. (1) Riche-Cannieu吻合は正常肢の82.5%に検出され, その出現頻度はアメリカ黒人において他の日本人群, アメリカ白人, ラテン系群に比較して有意に低値であつた. (2) 80%以上の高頻度に認められたRiche-Cannieu吻合は手掌部での尺骨―正中両神経間一つの奇形としての線維結合と考えるよりはむしろ, 検索方法をより精密にすることによりほぼ全例に検出される可能性のある正常の線維連絡と考えられた. (3)この神経吻合は手根管症候群, Guyon管症候群の臨床的, 電気生理学的検索に必須の知識と考えられた.