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Rehabilitation Practice and Science

Translated Title

國人手部尺神經－正中神經吻合之電氣生理

Abstract

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 electrophysiologicexaminations, 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.

Language

Traditional Chinese

First Page

53

Last Page

59

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