Elbow Flexion Reconstruction in Brachial Plexus Avulsion Injuries - Results with Intercostal Nerve and Distal Nerve Transfers

Background: The neural surgical options for reconstruction of elbow flexion in brachial plexus injuries depend on the availability of nerve donors. In upper-type avulsion injuries, the ulnar or median nerves, when intact, are reliable intra-plexal donor nerves for transfers to the biceps muscle. In complete avulsion injuries, donors are limited to extra-plexal sources, such as intercostal nerves (ICNs). Methods: We reviewed our results of ICN and partial distal nerve (ulnar or median) transfers for elbow flexion reconstruction in patients with brachial plexus avulsion injuries. The time taken for recovery of elbow flexion strength to M3 and the final motor outcome at 2 years were compared between both groups. Results: 38 patients were included in this study. 27 had ICN transfers to the musculocutaneous nerve (MCN), 8 had partial ulnar nerve transfers and 3 had partial median nerve transfers to the MCN's biceps motor branch. The mean time interval from injury to surgery was 3.6 months. Recovery of elbow flexion was observed earlier in the distal nerve transfer group (p < 0.05). Overall, success rates were higher in patients with distal nerve transfers (100%), compared to ICN transfers (63%) at 2 years (p = 0.018). Patients with distal nerve transfers achieved a higher final median strength of M4.0 [Interquartile range (IQR) 3.5-4.5], compared to M3.5 (IQR 2.0-4.0) in the ICN group (p = 0.031). In the subgroup of patients with upper-type brachial plexus injuries, there were no significant differences in motor outcomes between the ICN versus distal nerve transfers group. Conclusions: In our entire cohort, patients with distal nerve transfers had faster motor recovery and better elbow flexion power than patients with ICN transfers. In patients with partial brachial plexus injuries, outcomes of ICN transfers were not inferior to distal nerve transfers.