Comparison between direct repair and human acellular nerve allografting during contralateral C7 transfer to the upper trunk for restoration of shoulder abduction and elbow flexion

Abstract

Direct coaptation of contralateral C7 to the upper trunk could avoid the interposition of nerve grafts. We have successfully shortened the gap and graft lengths, and even achieved direct coaptation. However, direct repair can only be performed in some selected cases, and partial procedures still require autografts, which are the gold standard for repairing neurologic defects. As symptoms often occur after autografting, human acellular nerve allografts have been used to avoid concomitant symptoms. This study investigated the quality of shoulder abduction and elbow flexion following direct repair and acellular allografting to evaluate issues requiring attention for brachial plexus injury repair. Fifty-one brachial plexus injury patients in the surgical database were eligible for this retrospective study. Patients were divided into two groups according to different surgical methods. Direct repair was performed in 27 patients, while acellular nerve allografts were used to bridge the gap between the contralateral C7 nerve root and upper trunk in 24 patients. The length of the harvested contralateral C7 nerve root was measured intraoperatively. Deltoid and biceps muscle strength, and degrees of shoulder abduction and elbow flexion were examined according to the British Medical Research Council scoring system; meaningful recovery was defined as M3-M5. Lengths of anterior and posterior divisions of the contralateral C7 in the direct repair group were 7.64 ± 0.69 mm and 7.55 ± 0.69 mm, respectively, and in the acellular nerve allografts group were 6.46 ± 0.58 mm and 6.43 ± 0.59 mm, respectively. After a minimum of 4-year follow-up, meaningful recoveries of deltoid and biceps muscles in the direct repair group were 88.89% and 85.19%, respectively, while they were 70.83% and 66.67% in the acellular nerve allografts group. Time to C5/C6 reinnervation was shorter in the direct repair group compared with the acellular nerve allografts group. Direct repair facilitated the restoration of shoulder abduction and elbow flexion. Thus, if direct coaptation is not possible, use of acellular nerve allografts is a suitable option. This study was approved by the Medical Ethical Committee of the First Affiliated Hospital of Sun Yat-sen University, China (Application ID: [2017] 290) on November 14, 2017.

Keywords: accessary nerve; brachial plexus avulsion injury; contralateral C7 nerve root transfer; direct repair; elbow function; human acellular nerve allograft; nerve graft; nerve regeneration; nerve transfer; neural regeneration; phrenic nerve; shoulder function.

Figure 1

Flow chart of the study. hANAs: Human acellular nerve allografts.

Figure 2

An 18-year-old male with an injury to the right C5–8 nerve roots. The patient underwent direct coaptation of CC7 nerve transfer to the ipsilateral upper trunk via the prespinal route with additional suprascapular nerve innervation 90 days after brachial plexus avulsion injury. (A) Preoperative view of the right upper limb, which lost the functions of shoulder abduction, elbow flexion, and partial finger flexion and extension. (B) The patient showed excellent right shoulder external rotation. (C) The patient showed excellent right shoulder abduction at the 48-month follow-up. Muscle strength in the deltoid was M4. (D) The patient had excellent right elbow flexion independent of synchronous shoulder adduction and contralateral shoulder adduction at the 48-month follow-up. Muscle strength in the biceps was M4. CC7: Contralateral cervical 7 nerve root.

Figure 3

A 35-year-old male with an injury to the left C5–8 nerve roots. The patient underwent CC7 nerve transfer combined with human acellular nerve allograft reconstruction to reinnervate the injured upper trunk via the prespinal route with additional suprascapular nerve innervation 60 days after injury. (A, B) Preoperative view of the left upper limb, which lost the functions of shoulder abduction, elbow flexion, and partial finger flexion and extension. (C) The patient showed excellent left shoulder abduction during the 52-month follow-up. Muscle strength in the deltoid was M4. (D) The patient had excellent left elbow flexion independent of synchronous shoulder adduction and contralateral shoulder adduction during the 52-month follow-up. Muscle strength in the biceps was M4. CC7: Contralateral cervical 7 nerve root.

Figure 4

Surgical procedure in the two groups. (A–C) Direct repair group: (A) The CC7 nerve root (black arrow) was identified and transected as distally as possible, and then the length of the harvested CC7 nerve root was measured. (B) The reach appeared adequate between CC7 and C5/C6 nerve roots (white arrow). (C) Direct repair (black arrow) was performed without tension to avoid interposing the graft. (D–F) Surgical procedure in the hANAs group: (D) The CC7 nerve root (black arrow) was identified and transected as distally as possible, and then the length of the harvested CC7 nerve root was measured. (E) Measurement of the length of the gap (white arrow) between the CC7 nerve root and upper trunk. (F) hANAs (black arrow) were applied to bridge the gap between the end of the CC7 nerve root and the upper trunk, and end-to-end coaptation was adopted with 8-0 Prolene sutures. Additional suprascapular nerve (white arrow) reinnervation was simultaneously undertaken. CC7: Contralateral cervical 7 nerve root; hANAs: human acellular nerve allografts.

Figure 5

An 18-year-old male with an injury to the right C5–8 nerve roots. The patient underwent direct coaptation of CC7 nerve transfer to the ipsilateral upper trunk via the prespinal route with additional suprascapular nerve innervation 90 days after brachial plexus avulsion injury. In the follow-up period, Tinel’s sign assessment was performed monthly. (A) The 12 critical location areas on the recipient-side upper extremity for Tinel’s sign assessment: 1, greater supraclavicular fossa; 2, subclavian fossa; 3, clavicular part of the pectoralis major; 4, proximal upper arm (deltoid); 5, middle upper arm; 6, distal upper arm; 7, elbow; 8, proximal forearm; 9, middle forearm; 10, distal forearm; 11, wrist; and 12, palm. Comparisons were performed using Student’s t-test. (B) Comparison of C5/C6 reinnervation times in the two groups. Plots are evenly distributed on both sides of the regression line. CC7: Contralateral cervical 7 nerve root; hANAs: human acellular nerve allografts.