國人手部尺神經－正中神經吻合之電氣生理

Electrophysiologic Study of the Hand Ulnar - Median Nerves Anastomosis in Taiwanese

姜義彬(Yi-Pin Chiang) ； 楊百嘉(Baii-Jia Yang) ； 蘇王麟(Wang-Lin Su) ； 吳俊明(Jiunn-Ming Wu)

《中華民國復健醫學會雜誌》 26卷2期 (1998/06) Pp. 53-59

摘要

手部尺神經與正中神經之間有數種不同的變異神經吻合存在，這些不同的神經吻合有時被泛稱為Riche-Cannieu神經吻合；在以往，針對此種神經吻合所做的電學檢查研究並不多，而這些變異神經吻合在解剖及臨床應用上的意義至今也尚未有明確的定論。但因為有這些神經吻合的存在，電流可能自尺神經，經由神經吻合傳到正中神經，而引發魚際肌的收縮。由於經由這些神經吻合所引發的收縮可能會造成檢查時的困擾，故設計此一研究探討國人在此種神經吻合之特性與發生率，以提供電學檢查者之參考。
本研究針對１００隻受測手進行研究，以電流分別刺激腕部的尺神經與正中神經，而以表面電極在外展拇短肌接收複合肌肉電位。結果發現，當刺激國人腕部的尺神經時，所有受測者皆可在外展拇短肌測得複合肌肉電位。但這些複合肌肉電位的波形幾乎都含初始正向波，而這些初始正向波的波幅大小不一。８７%受測手的複合肌肉電位，其初始正向波的波幅與負向波的波幅比值在２８%以下，因此推估國人手部尺神經與正中神經神經吻合的比例約在８７%左右；尺神經對激發外展拇短肌的貢獻比例平均為３１.７%±１４.１%，此比例與外國之研究結果相去不遠。刺激尺神經所得的複合肌肉電位，若其初始正向波佔整個波形的比例越小，則對於激發外展拇短肌的貢獻有越大的趨勢。學者在進行神經傳導檢查時，應多注意這些含初始正向波的複合肌肉電位，可對於檢查的判讀有所助益。

關鍵字

尺神經-正中神經神經吻合 ； 尺神經 ； 正中神經 ； 複合肌肉電位 ； 神經傳導檢查

並列摘要

There are several variations of nerve communications between the ulnar and the median nerves in the hand, which are referred as the Riche-Cannieu anastomoses. The anatomic and clinical significances of these anastomoses have not been clarified. Because of these variations, electric stimulation may travel from the ulnar nerve, through the communications, to the median nerve impulse and thus induces the contraction of thenar muscles. When performing electrophysiologic
examinations, additional attention should be paid to the variations to avoid misinterpretations.
In this study, one hundred hands of fifty normal persons were examined. The ulnar and the median nerves were stimulated, and the compound muscle action potential was recorded at the abductor pollicis brevis muscles with surface electrodes. We found that a compound muscle action potential could be detected in all of the tested thenar muscles when stimulating the ulnar nerve at the wrist. Almost all the potentials had the initial positive deflection, either large or small in amplitude. The ratio of the amplitude of the positive and negative deflection (PNR) was less than 28 % in 87 % of the tested hands. We conclude that the prevalence rate of hand ulnar-median nerve anastomosis is around 87%. The ulnar nerve innervation ratio (UNIR) to the thenar muscles was 31.7 %. Although there was no significant correlation between the PNR and the UNIR, there was an inverse relationship between the initial positive deflection and the contribution of the ulnar nerve to activate the thenar muscle. When performing nerve conduction studies, examiners should pay more attention to the initial positive deflection to avoid misinterpretations.

並列關鍵字

ulnar-median nerve anastomosis ； ulnar nerve ； median nerve ； compound muscle action potential ； nerve conduction study