Experimental And Clinical Study Of The Location Of The Deep Branch Of The Radial Nerve In The Main Trunk In The Upper Arm

[Objective] (1)To observe the radial nerve in the upper arm and locatethe deep branch of the radial nerve in the main trunk and bring up theanatomic basis for the selective nerve transfer for repairing the deepbranch of the radial nerve in clinic; (2)To compare the anatomicalstructure of the radial nerve between the SD rats and human being; tocompare the motor fibers in the medial portion with those in the lateralportion of the antebrachial branch of the radial nerve at the level oflatissimus dorsi insertion; to evaluate the effect of repairing the deepbranch of the radial nerve at the level of the latissimus dorsi insertionby using different donor nerves; (3)To evaluate the short-period effectof repairing the deep branch of the radial nerve at the level of latissimusdorsi insertion by using intercostal nerves in 3 cases. [Methods] (1)Usinggross and micro anatomical methods to observe the radial nerve in the upperarm, the proximal micro-dissectible point between the deep branch andsuperficial branch of the radial nerve and the location of theantebrachial branch of the radial nerve at the level of the latissimusdorsi insertion; (2)Using the micro-anatomical and histochemical methodsto compare the SD rat's radial nerve with the human's radial nerve andto compare the numbers of the motor fibers in medial portion of theantebrachial branch of the radial nerve with those in the lateral portionat the level of the latissimus dorsi insertion. Thirty SD rats wererandomly divided into 3 groups: medial group, lateral group, and directcoaptation group, with 10 each. In the medial group full length phrenicnerve was harvested through open chest surgery and transferred to themedial portion of antebrachial branch of radial nerve at the level of thelatissimus dorsi insertion. In the lateral group full length phrenic nervewas harvested through open chest surgery and transferred to the lateralportion of antebrachial branch of radial nerve at the level of the latissimus dorsi insertion. In the direct coaptation group (the controlgroup) the radial nerve was cut at that level and sutured directly. Grossobservation, electrophysiological and histochemical testings wereperformed 4 months after operation. Sixty SD rats were randomly dividedinto 3 groups: phrenic nerve group, contralateral C7 group, and directcoaptation group, with 20 each. In the phrenic nerve group full lengthphrenic nerve was harvested through open chest surgery and transferredto the medial portion of antebrachial branch of radial nerve at the levelof the latissimus dorsi insertion. In the contralateral C7 groupcontralateral C7 nerve root was transferred to the antebrachial branchof radial nerve at the level of the latissimus dorsi insertion by usingulnar nerve grafting. In the direct coaptation group (the control group)the radial nerve was cut at that level and sutured directly. Grossobservation, electrophysiological and histochemical testings wereperformed 4 and 6 months after operation. (3)In 3 brachial plexus injurycases we transferred the intercostal nerves to the medial portion of theantebrachial branch of the radial nerve at the level of the latissimusdorsi insertion. [Results] (1)The antebrachial branch of the radial nervecontains two big fascicles which have both motor fibers and sensory fibers.The medial fascicle continues to form the deep branch of the radial nerve.We can locate the antebrachial branch and the triceps' branches in themain trunk at the level of the latissimus dorsi insertion. The proximalmicro-dissectible point between the deep branch and superficial branchof the radial nerve is at the level of the lower 3/10 of the antebrachialbranch of radial nerve. (2)The anatomical structure of the radial nerveis similar between SD rat and human being. The medial portion of theantebrachial branch of the radial nerve contains more motor fibers. Inthe experiment of transferring the full length of the phrenic nerve todifferent portion of the antebrachial branch of the radial nerve,extension of wrist with ulnar deviation or in central position andextension of toes appeared in the medial group.However extension of wristwith radial deviation appeared in the lateral group. Extensor carpiulnaris recovered better in the medial group thanin the lateral groupand there were no differences in the extensor carpi radialis and extensor digitorum communis' recoveries between these two groups. In theexperiment of using different donor nerves to transfer to the antebrachialbranch of the radial nerve, the recovery rate of muscle weight, musclecross-sectional areas, cross-sectional areas of myelinated nerve andmaximum amplitude of CMAP in the direct coaptation group were the best.The recovery rates in the contralateral C7 group were superior to thosein phrenic nerve group. (3)in 3 patients who underwent the operation oftransferring intercostal nerves to the medial portion of the antebrachialbranch of radial nerve at the level of the latissimus dorsi insertion,one recovered the extension of wrist in 2 years follow-up, however theother two patients did not recover the extension function in 2 yearsfollow-up. But EMG test showed that the intercostal nerves hadreinnervated the extensors in one of this two patients. [Conclusion](1)The antebrachial branch of the radial nerve can be located in the maintrunk at the level of the latissimus dorsi insertion and it contains twobig fascicles which both have the motor fibers and sensory fibers. Themedial portion continues to form the deep branch of radial nerve. Theproximal micro-dissectible point between the deep branch and superficialbranch of the radial nerve is at the level of the lower 3/10 of theantebrachial branch of radial nerve;(2) the anatomical structure of theradial nerve is similar between SD rats and human being. The medial portionof the antebrachial branch of the radial nerve contains more motor fibersof the deep branch of the radial nerve. The treatment outcome of transferof contralateral C7 to the antebrachial branch of the radial nerve issuperior to that of full-length phrenic nerve. (3)The short-periodoutcome of transferring of the intercostal nerves to the medial portionof antebrachial branch of the radial nerve at the level of the latissimusdorsi insertion is fair. Long-period follow-up is necessary to observethe final outcome.