Long‐term evaluation of rabbit peripheral nerve repair with end‐to‐side neurorrhaphy in rabbits

Abstract

This study was designed to quantitatively assess long-term end-to-side neurorrhaphy in rabbits. The cut right ulnar nerve was repaired and sutured to the median nerve, in which a perineurial window was created in an end-to-side fashion 3 cm above the elbow joint. Both the extent of the reinnervation and the integrity of the intact donor nerve were evaluated in 36 rabbits randomly treated with fresh or delayed nerve repair. Evaluations included motor nerve conduction velocity (MNCV), dry muscle weight (DMW), and histological examinations at 9 and 12 months postoperatively. The recovery rates of MNCV were 90.1% and 92.8% for the ulnar nerve, and 95.7% and 96.8% for the median nerve, compared to intact contralateral nerves at 9 and 12 months, respectively. MNCV was not detectable for the ulnar nerve in control animals, while it was normal for the median nerve. Recoveries of flexor carpi ulnaris dry muscle weight of about 90.7% and 94.5% were observed at 9 and 12 months postoperatively, respectively. However, muscle mass measurements revealed a recovery of only 31.3% and 27% for control groups at 9 and 12 months postoperatively. The differences between experimental groups and control groups were statistically significant (P < 0.01). Neurofilament and silver stains showed numerous sprouting axons originating from the median nerve to the ulnar nerve. The results indicate that end-to-side neurorrhaphy could induce axonal sprouting from the main nerve trunk of upper limbs in rabbits, leading to useful functional recovery.

Collateral sprouting axons of end-to-side nerve coaptation in the avulsion of ventral branches of the C5-C6 spinal nerves in the brachial plexus

“…After these factors are released from Schwann cells by diffusion, they penetrate through the epineurium into the perineurium. In this way, directed collateral sprouting from the region closest to the injury site occurs at the Ranvier nodes of the donor nerve [61].…”

“…Schwann cells stimulate axonal regeneration from both the distal nerve stump and the nodes of Ranvier of the donor nerve [54,56]. This mechanism is indirectly controlled by neurotropic factors [61]. After these factors are released from Schwann cells by diffusion, they penetrate through the epineurium into the perineurium.…”

“…In the case of end-to-side coaptation, regenerated axons appear from the Ranvier nodes of the donor nerve most proximal to the coaptation site, and it is guided into the epineurium of the donor nerve [27,61]. Before axonal development, Schwann cells are organized into columns at the coaptation site [52].…”

“…It is widely accepted that resection of a small part of the epineurium improves the efficacy of end-to-side coaptation. Other research has demonstrated that resection of the deeper connective layers of the nerve (the perineurium) further increases the efficacy of terminolateral reconstruction [25,35,61].…”

Terminolateral Neurorrhaphy between Somatic Nerve and Autonomic Nerve

“…In fact, when there is no injury to the donor nerve, nerve regeneration can occur following endto-side anastomosis, but several experimental studies have shown that when the donor nerve had a fenestration, the effect of nerve regeneration was better [71][72][73][74]. Although there are still controversies over whether fenestration can damage the donor nerve, many studies have confirmed that the fenestration of the epineurium can cause a slight damage to the donor nerve, but does not affect the donor nerve function [75][76][77]. this approach does not cost the donor function when nerve grafting.…”