Phrenic nerve transfer for two different targets in adult brachial plexus injuries: Results of function and brain plasticity in a multi-center study

Abstract

This study compares two cohorts of patients who underwent phrenic nerve transfer following a traumatic brachial plexus injury at two tertiary centers on different continents, each utilizing different targets for reinnervation. The aim was to determine whether statistical differences existed in: (1) shoulder abduction versus elbow flexion results, (2) brain plasticity at the final outcome, and (3) factors influencing outcomes in both populations. A retrospective review was conducted involving assessment of shoulder range of motion (ROM) and elbow flexion strength, while brain plasticity was evaluated using the Plasticity Grading Scale (PGS). A total of 104 patients were included, with 59 receiving phrenic nerve transfers to restore shoulder abduction (Ph-shoulder group), and 45 transfers aimed at elbow flexion (Ph-Ef group). Of these, 40 patients were assessed using the Plasticity Grading Scale (PGS). The shoulder group achieved an average ROM of 75.8°, with 61 % regaining ≥ 60° abduction within 16.8 months. The elbow group achieved an average MRC grade of 3.3 strength, with 80 % reaching ≥M3 flexion in 18.6 months. The mean PGS for the Ph-shoulder group was 2.8 (n = 18), while for the Ph-Ef group (n = 22), it was 2.6. Younger age and lower BMI were significant predictors of improved shoulder outcomes, while shorter intervals between shorter injury-tosurgery intervals enhanced elbow recovery. As both groups exhibited similar functional results and brain plasticity scores, we can conclude that the outcomes after a phrenic nerve transfer are comparable between them, demonstrating the predictability, adaptability, and consistency of this nerve transfer.