Detection of Electrophysiologic Conduction After Polyethylene Glycol-Fusion Repair of Peripheral Nerve Injuries in a Porcine Model

INTRODUCTION: Peripheral nerve injuries (PNIs) are associated with significant morbidity, and traditional repair techniques often result in incomplete functional recovery. Polyethylene glycol (PEG) fusion has been proposed as a technique to promote rapid axonal continuity and facilitate electrophysiologic conduction. This study evaluates PEG fusion in a porcine median nerve injury model, with a focus on detectable electrophysiologic conduction following repair. MATERIALS AND METHODS: Thirty-one Yucatan pigs underwent creation of single-cut or 2 cm segmental PNIs. Twenty-nine animals had analyzable immediate electrophysiologic data, and 27 underwent end-of-study (EOS) evaluation. Repairs were performed using standard repair (SR) or neurorrhaphy augmented with PEG fusion. Segmental defects were reconstructed using ulnar nerve autograft with or without adjunctive Tisseel and Tacrolimus. Electrophysiologic outcomes were assessed using compound action potentials and compound motor action potentials immediately post-repair and up to 90 days postoperatively. Outcomes were recorded as binary presence or absence of detectable electrophysiologic conduction. RESULTS: PEG fusion was associated with detectable electrophysiologic conduction immediately following repair in both single-cut and segmental injury models, whereas no immediate conduction was observed following standard repair in segmental injuries. At EOS, both PEG-treated and standard repair single-cut injuries demonstrated persistence of detectable electrophysiologic conduction in 5 of 7 animals (71%). In segmental injuries, no animals treated with standard repair (0/4) or PEG alone (0/3) demonstrated detectable conduction at EOS. In contrast, PEG-treated autografts with Tisseel demonstrated detectable conduction in 1 of 4 animals (25%), while PEG-treated autografts with Tisseel and Tacrolimus demonstrated detectable conduction in 2 of 2 animals (100%), although subgroup sizes were small. CONCLUSIONS: PEG fusion was associated with detectable electrophysiologic conduction following peripheral nerve repair in this porcine model. Although no difference was observed between PEG and standard repair in single-cut injuries at EOS, PEG-enabled immediate conduction and adjunctive augmentation strategies were associated with detectable conduction in a subset of segmental injuries. Because outcomes were limited to qualitative electrophysiologic measures without functional or histologic correlation, conclusions regarding functional recovery cannot be made. Further investigation in larger studies incorporating quantitative electrophysiologic, histologic, and functional outcome measures is required to define its clinical relevance.