Can sensory protection improve the functional outcome in delay repaired rat brachial plexus injury?

Background: Reconstruction of brachial plexus injuries (BPIs) at a delayed time point may prolong the denervation of target muscles and jeopardize the outcome. Sensory protection has been hailed as a promising technique that may help preserve muscle mass and restore functional outcome. We utilize the rat brachial plexus model to investigate the difference between early and delay repair, and evaluate if sensory protection of distal nerves can assist in delayed repair. Materials and Methods: Forty-eight Lewis rats were randomly assigned to four groups (n = 12 in each group, including one positive control group). All the rats were transected at the upper, middle, and lower trunk levels with a 2-cm gap. Group I underwent immediate reconstruction from the upper trunk to the median; Group II underwent the same reconstruction but at 4 months after the initial transection; Group III was same as Group II and additional sensory protection to the median nerve via a nerve graft from the lower trunk. The final outcome was studied and analyzed 16 weeks postoperatively. Results: Group I (immediate repair) showed the best functional results in muscle contraction force, muscle action potential, and muscle weight, in addition to higher axon counts. Groups II and III (delayed repair) both showed inferior results to Group I, and sensory protection did not show any significant improvements in outcome. Conclusion: Delayed repair still shows inferior outcomes to acute repair in BPIs. There is no sufficient evidence to support the use of sensory protection in delayed repair.