Reinnervation of the biceps in C5-7 brachial plexus avulsion injuries: results after distal bypass surgery.

Abstract

The authors report various techniques, and their results, after performing median and ulnar nerve transfers to reanimate the biceps muscle in C5-7 avulsion-related brachial plexus injuries (BPIs). Forty-three adult patients with BPIs of the upper-middle plexus underwent reinnervation of the biceps muscle; neurotization of the musculocutaneous nerve was performed using fascicles from the ulnar nerve (39 cases) and the median nerve (four cases). The different techniques included sectioning, rerouting, and direct suturing of the entire musculocutaneous nerve (35 cases); direct reinnervation of the motor branches of the musculocutaneous nerve (three cases); and reinnervation using small grafts to the motor fascicles that enter the biceps muscle (five cases). Elbow flexion recovery ranged from M2 to M4, according to the patient's age and the level of integrity of the hand. No surgery-related failure occurred. No significant difference in outcome was related to any of the technical variants. In patients younger than age 45 years and exhibiting a normal hand function a score of M4 or better was always achieved. On average, reinnervation occurred 6 months after surgery. There was no clinical evidence of donor nerve dysfunction. When accurate selection criteria are met, the results after this type of neurotization have proved excellent.