背阔肌电生理支配权重分析在同侧C_7神经根移位术中的临床意义

Latissimus dorsi muscle innervation by C_7:an electrophysiological dominance analysis and its clinical implication in ipsilateral C_7 transfer

目的通过比较健侧C_7移位术中背阔肌上、中、下份复合肌肉动作电位(compound muscle action potential,CMAP)波幅的差异,了解臂丛神经根对背阔肌的支配权重,从而为同侧C_7移位术的应用提供电生理依据。方法于健侧C_7移位术中依次刺激臂丛神经上、中、下干,分别于背阔肌上、中、下份记录CMAP,比较CMAP波幅差异,确定各臂丛神经对背阔肌的支配权重。术后4周随访背阔肌肌力。结果CMAP波幅提示背阔肌上份主要受臂丛中干和上中干支配占60%,受上干支配仅10%；中份受中干支配占70%,受上干支配占15%；下份受中、下干和中干支配占70%,无单独上干支配。综合背阔肌上中下份分析显示由上干主要支配仅占8%、由中干主要支配占33%、由下干主要支配占10%、中下干支配占23%、上中下干支配占8%。术后4周随访背阔肌功能无明显影响。结论通过术中对背阔肌所受臂丛神经支配的电生理权重的研究,证实了同侧C_7神经根移位术的安全性。

Objective Based on comparison of the amplitude differences of compound muscle action potential （CMAP） of the upper, middle and lower portions of the latissimus dorsi muscle （LDM） elicited by stimulating braehial plexus nerve roots in contralateral C7 transfer, the dominance of LDM innervation was analyzed to provide electrophysiological data for the application of ipsilateral C7 transfer. Methods The upper, middle and lower mink of the brachial plexus were stimulated respectively in the procedure of contralateral C7 transfer. Meanwhile CMAP was recorded at the upper, middle and lower portion of LDM. Dominance of LDM innervation by brachial plexus was determined by comparing the difference of CMAP amplitude. LDM muscle strength was evaluated after 4 weeks postoperatively. Results The upper part of LDM was mainly innervated by the middle and upper-middle trunks of brachial plexus （60%）, only 10% by the upper trunk. The middle part of LDM was mainly innervated by the middle trunk （70%）, only 15% by the upper trunk. The lower part of LDM was mainly innervated by the middle and middlelower trunks （70%）. Comprehensive analysis of different parts of LDM showed that LDM was mainly innervated by the upper trunk in 8%, by the middle trunk in 33%, by the lower trunk in 10%, by the middle-lower trtmks in 23% and by the upper-middle-lower thinks in 8%. Muscle strength of LDM was not impaired after C7 transection. Conclusion Eleetrophysiological dominance analysis on LDM innervation by brachial plexus provides objective proof that ipsilateral C7 transfer is safe.