Comparison of volitional control and strength in elbow flexion after ipsilateral C7 transfer or double fascicular transfer in C5-6 brachial plexus injuries.

Abstract

Objective: Recovery of function after nerve injury requires strength, as well as plasticity, to allow independent control of the reinnervated muscle group. The aim of this study was to compare the recovery of strength and volitional control of elbow flexion in patients with C5-6 brachial plexus injuries who underwent reconstruction by either ipsilateral posterior division of C7 to anterior division of upper trunk nerve transfer (hereafter, ipsilateral C7 transfer) or double fascicular nerve transfer (DFT), in which fascicles of the ulnar nerve and fascicles of the median nerve are transferred to biceps and brachialis branches, respectively.

Methods: Patients with isolated C5-6 injuries from February 2003 to October 2022 at a single tertiary center underwent ipsilateral C7 transfer or DFT for elbow flexion. Additional shoulder abduction reconstruction was performed with intraplexus or extraplexus nerve transfers. Primary outcomes were strength (Medical Research Council [MRC] grade) and volitional control (Plasticity Grading Scale [PGS] score). Shoulder recovery was evaluated by the degree of abduction.

Results: Twelve patients received ipsilateral C7 transfer and 20 patients received DFT. There were no significant differences in the final MRC strength (100% vs 80%, p = 0.271) and the mean time to attain MRC grade M3 (17.1 ± 10.9 months vs 19.4 ± 24.4 months, p = 0.357) between the ipsilateral C7 and DFT groups, respectively. In the DFT group, volitional control was distributed as follows: PGS score 1 (no plasticity) (15%), PGS score 2 (30%), PGS score 3 (50%), and PGS score 4 (complete volitional control) (5%). All patients who received ipsilateral C7 transfers achieved a PGS score of 3. A higher rate of good to excellent plasticity (PGS score 3-4) occurred in the ipsilateral C7 group compared with the DFT group (100% vs 55%, p = 0.012). The mean shoulder abduction was 91.3° ± 52.2° in the ipsilateral C7 group and 82.8° ± 56.8° in the DFT group (p = 0.655).

Conclusions: Ipsilateral C7 transfer and DFT showed comparable strength recovery for elbow flexion. However, ipsilateral C7 transfer demonstrated better plasticity without compromise of hand grip. Ipsilateral C7 transfer should be considered as an alternative to DFT to improve hand function following reinnervation.