Total brachial plexus injury： contralateral C7 root transfer to the lower trunk versus the median nerve

Contralateral C7（cC7） root transfer to the healthy side is the main method for the treatment of brachial plexus root injury. A relatively new modification of this method involves cC7 root transfer to the lower trunk via the prespinal route. In the current study, we examined the effectiveness of this method using electrophysiological and histological analyses. To this end, we used a rat model of total brachial plexus injury, and cC7 root transfer was performed to either the lower trunk via the prespinal route or the median nerve via a subcutaneous tunnel to repair the injury. At 4, 8 and 12 weeks, the grasping test was used to measure the changes in grasp strength of the injured forepaw. Electrophysiological changes were examined in the flexor digitorum superficialis muscle. The change in the wet weight of the forearm flexor was also measured. Atrophy of the flexor digitorum superficialis muscle was assessed by hematoxylin-eosin staining. Toluidine blue staining was used to count the number of myelinated nerve fibers in the injured nerves. Compared with the traditional method, cC7 root transfer to the lower trunk via the prespinal route increased grasp strength of the injured forepaw, increased the compound muscle action potential maximum amplitude, shortened latency, substantially restored tetanic contraction of the forearm flexor muscles, increased the wet weight of the muscle, reduced atrophy of the flexor digitorum superficialis muscle, and increased the number of myelinated nerve fibers. These findings demonstrate that for finger flexion functional recovery in rats with total brachial plexus injury, transfer of the cC7 root to the lower trunk via the prespinal route is more effective than transfer to the median nerve via subcutaneous tunnel.

Is it necessary to use the entire root as a donor when transferring contralateral C7 nerve to repair median nerve？

If a partial contralateral C7 nerve is transferred to a recipient injured nerve, results are not satisfactory. However, if an entire contralateral C7 nerve is used to repair two nerves, both recipient nerves show good recovery. These findings seem contradictory, as the above two methods use the same donor nerve, only the cutting method of the contralateral C7 nerve is different. To verify whether this can actually result in different repair effects, we divided rats with right total brachial plexus injury into three groups. In the entire root group, the entire contralateral C7 root was transected and transferred to the median nerve of the affected limb. In the posterior division group, only the posterior division of the contralateral C7 root was transected and transferred to the median nerve. In the entire root ＋ posterior division group, the entire contralateral C7 root was transected but only the posterior division was transferred to the median nerve. After neurectomy,the median nerve was repaired on the affected side in the three groups. At 8, 12, and 16 weeks postoperatively, electrophysiological examination showed that maximum amplitude, latency, muscle tetanic contraction force, and muscle fiber cross-sectional area of the flexor digitorum superficialis muscle were significantly better in the entire root and entire root ＋ posterior division groups than in the posterior division group. No significant difference was found between the entire root and entire root ＋ posterior division groups. Counts of myelinated axons in the median nerve were greater in the entire root group than in the entire root ＋ posterior division group, which were greater than the posterior division group. We conclude that for the same recipient nerve, harvesting of the entire contralateral C7 root achieved significantly better recovery than partial harvesting, even if only part of the entire root was used for transfer. This result indicates that the entire root should be used as a donor when transferring contralateral C7 nerve.

Contralateral C7 Nerve Root Transfer for Function Recovery in Adults： A Meta-analysis

Background：Root avulsion to all 5 roots of the brachial plexus is a common presentation and keeps a major reconstructive challenge.The contralateral C7 （CC7） nerve transfer has been used in treating brachial plexus avulsion injury （BPAI） since 1986.However,the effectiveness of the procedure remains a subject of controversy.The aim of this meta-analysis was to study surgical outcomes regarding motor and sensory recovery after CC7 nerve transfer.Methods：Chinese or English （i.e.,＂contralateral c-7＂,＂contralateral c7＂,＂c7 nerve root＂,and ＂seventh cervical nerve root＂） keywords were used for a literature search for articles related to CC7 nerve transfer in several databases （i.e.,PubMed,Cochrane,Embase,CNKI,CQVIP,and Wanfang Data）.Clinical research articles were screened,and animal studies as well as duplicate publications were excluded.Muscle strength and sensory recovery were considered to be effective only when the scores on the United Kingdom Medical Research Council scale were equal to or higher than M3 and S3,respectively.Results：The overall ipsilateral recipient nerve recovery rates were as follows：the efficiency rate for muscle strength recovery after CC7 nerve transfer was 0.57 （95% confidence interval [CI]：0.48-0.66） and for sensory recovery was 0.52 （95% CI：0.46-0.58）.When the recipient nerve was the median nerve,the efficiency rate for muscle strength recovery was 0.50 （95% CI：0.39-0.61） and for sensory was 0.56 （95% CI：0.50-0.63）.When the recipient nerve was the musculocutaneous nerve and the radial nerve,the efficiency rate for muscle strength recovery was 0.74 （95% CI：0.65-0.82） and 0.50 （95% CI：0.31-0.70）,respectively.Conclusions：Transfer of CC7 nerves to musculocutaneous nerves leads to the best results.CC7 is a reliable donor nerve,which can be safely used for upper limb function reconstruction,especially for entirely BPAI.When modifying procedures,musculocutaneous nerves and median nerve can be combined as recipient nerves.

Outcome of contralateral C7 nerve transferring to median nerve

Background Contralateral C7 （cC7） transfer had been widely used in many organizations in the world, but the outcomes were significantly different. So the purpose of the study was to evaluate the outcome of patients treated with cC7 transferring to median nerve and to determine the factors affecting the outcome of this procedure.

Evaluation of nerve transfer options for treating total brachial plexus avulsion injury： a retrospective study of 73 participants

Despite recent great progress in diagnosis and microsurgical repair, the prognosis in total brachial plexus-avulsion injury remains unfavorable.Insufficient number of donors and unreasonable use of donor nerves might be key factors. To identify an optimal treatment strategy for this condition, we conducted a retrospective review. Seventy-three patients with total brachial plexus avulsion injury were followed up for an average of 7.3 years. Our analysis demonstrated no significant difference in elbow-flexion recovery between phrenic nerve-transfer （25 cases）, phrenic nerve-graft （19 cases）, intercostal nerve （17 cases）, or contralateral C7-transfer （12 cases） groups. Restoration of shoulder function was attempted through anterior accessory nerve （27 cases）, posterior accessory nerve （10 cases）, intercostal nerve （5 cases）, or accessory ＋ intercostal nerve transfer （31 cases）. Accessory nerve ＋ intercostal nerve transfer was the most effective method. A significantly greater amount of elbow extension was observed in patients with intercostal nerve transfer （25 cases） than in those with contralateral C7 transfer （10 cases）. Recovery of median nerve function was noticeably better for those who received entire contralateral C7 transfer （33 cases） than for those who received partial contralateral C7 transfer （40 cases）. Wrist and finger extension were reconstructed by intercostal nerve transfer （31 cases）. Overall, the recommended surgical treatment for total brachial plexus-avulsion injury is phrenic nerve transfer for elbow flexion, accessory nerve ＋ intercostal nerve transfer for shoulder function, intercostal nerves transfer for elbow extension, entire contralateral C7 transfer for median nerve function, and intercostal nerve transfer for finger extension. The trial was registered at Clinical-Trials.gov （identifier： NCT03166033）.