"Reverse Looping for Nerve Repair: An Experimental Study on Retrograde Axonal Regeneration".

Abstract

Peripheral nerve injuries with segmental loss present significant reconstructive challenges. While autologous nerve grafting is considered the gold standard, it requires two coaptation sites, increasing the risk of axonal misdirection and hindering functional recovery. Emerging evidence suggests that retrograde axonal regeneration is possible. Based on this potential, our study evaluates reverse nerve looping, a technique in which the distal median nerve is pivoted proximally and coapted to the proximal stump using a single suture. We compared this approach with conventional nerve graft repair. Fifty-four female Wistar rats underwent 15-mm median and ulnar nerve excision in the arm. The median nerve defect was reconstructed using: (1) Nerve Graft Group (n=22), where an autologous nerve graft was interposed, requiring two coaptations; and (2) Reverse Nerve Loop Group (n=22), where the distal median nerve was pivoted and coapted to the proximal stump, creating a single coaptation site. Additionally, 10 rats (Sham Group) underwent nerve dissection without transection. Functional recovery was assessed via grasp strength testing (20 and 30 weeks), electrophysiology, muscle weight analysis, and immunohistochemistry. At 30 weeks, grasp strength recovery reached 61% in the Nerve Graft Group and 66% in the Reverse Nerve Loop Group (p > 0.05). Electrophysiology and muscle weight analysis showed similar recovery between groups. Histological analysis confirmed comparable axonal regeneration. Reverse nerve looping provided functional and histological outcomes comparable to autologous nerve grafting, while reducing coaptation sites. This technique may offer an alternative for selected cases of peripheral nerve reconstruction.