应用电生理检测肌皮神经肱肌肌支在神经根的定位

An electrophysiologic study on the origination of brachialis branch of the nerve

目的探讨应用电生理检测肌皮神经肱肌肌支在神经根的定位，为肱肌肌支移位术的临床应用寻求理论依据。方法选择30例臂丛神经损伤行健侧C，移位的患者，年龄16～50岁，平均[（28．9±7．7）岁，^-x±s，下同]，术中暴露健侧正常的臂丛神经，运用意大利ESAOTE的Reporter四道程肌电诱发电位仪，分别刺激C5～T1神经根，在肱肌记录诱发电位的潜伏期及波幅。结果30例健侧C7移位者术中电生理检测，刺激臂丛神经根时，其中C5 29例、C6 30例、C7 28例记录到肱肌运动电位，而刺激C8、T1仅有6例记录到较小的肱肌运动电位。C5、6、7运动电位的潜伏期和波幅分别为（6．32±1．50）ms、（6．51±1．36）ms、（6．99±1．33）ms和（4．87±4．43）mV、（5．65±4．76）mV、（0．90±2．29）mV，其中以C6的波幅最大，C4次之，C7波幅较小，提示C5、6支配肱肌的神经纤维数可能最多。结论肱肌主要接受来自C5、6神经纤维的支配，该肌支移位至正中神经（骨间前神经）是可行及有效的，同时该方法为今后临床研究周围神经的定位提供了检测手段。

Objective To identify the origin of brachialis branch of musculocutaneous nerve （BBMCN） at root level using intraoperative electrophysiologic testing and provide theoretical basis for BBMCN transfer. Methods Thirty patients of brachial plexus injury who underwent contralateral C7 transfer were involved in the study. Patients＇ age ranged from 16 to 50 years with an average of （28.9 ±7.7） years. After exposure of the healthy side brachial plexus, C5 to T1 nerve roots were stimulated respectively to record compound muscle action potential （CMAP） in the brachialis muscle using Esaote 4 channel electrophysiological devise. Onset latency and amplitude of CMAPs were measured. Results Ample CMAP was recorded in the brachialis muscle in 29 cases upon C5 stimulation, in 30 cases upon C6 stimulation and in 28 cases upon C7 stimulation. Only subtle CMAP was recorded in the brachialis muscle of 6 cases while Cs and T1 were stimulated. The amplitude and latency of CAMAP were （4.87 ±4.43） mV and （6.32 ± 1.50） ms for C5, （5.65±4.76） mV and （6.51 ±1.36） ms for C6, and （0.90 ±2.29） mV and （6.99 ±1.33） ms for C7. CMAP amplitude from C5 and C6 was significantly higher than that from C7 , while there was no significant difference between C5 and C6 nerve root. Conclusion Analysis of CMAP suggested that BBMCN is mainly comprised of fibers from C5 and C6 nerve roots. Transfer of this muscle branch to the median nerve （ anterior interosseous nerve） is a feasible and effective procedure. The technique proposed here was a more direct and functional method to trace the origin of a specific nerve or of the nerve fibers innervating a given muscle.