End-to-side neurorrhaphies in a rodent model of peripheral nerve injury: a preliminary report of a novel technique

Object. The standard techniques for repair of peripheral nerve injuries with neuroma formation are typically suboptimal. To begin to explore alternative techniques, the authors used an established model in rodents by using end-to-side "terminolateral" neurorrhaphies (TLNs) to study alternative grafting techniques. The TLN "jump grafts" bypass a neuro-main-continuity, hypothetically maintaining functional units within the neuroma to facilitate functional regeneration. Evaluation of the extent and origin of the regenerating fibers within the grafts was also undertaken. Methods. The right tibial nerve in four adult Sprague-Dawley rats was injured using either a crush or transection technique and compared with four uninjured controls, The contralateral peroneal nerve was immediately harvested for microsurgical repair by using TLN jump grafts in all animals. Following a 3-month recovery, the repaired nerves were evaluated electrophysiologically by using evoked electromyography (EMG). Histological preparation was then performed using dual-fluorescent labeling to study axonal regeneration and origins. Evoked EMG evaluation confirmed healthy electrical conduction across the repair, which was unchanged after transection of the neuroma, but was abolished after transection of the jump graft, indicating functional neural regeneration across both the proximal and distal TLNs of the jump grafts. Fluorescent tracing analysis confirmed regeneration across both the proximal and distal portion of the jump grafts, demonstrated both motor and sensory neurons as the source of the regenerating fibers, and demonstrated significant numbers of double-labeled cell bodies, indicating that collateral sprouting was the primary source of regenerating fibers. Conclusions. The authors have preliminarily shown that regeneration occurs both electrophysiologically and histologically with a double-TLN jump graft. Clinically, this method could offer an alternative strategy for the technique and timing of neuroma repair.