Preliminary Study On Peripheral Nerve Regeneration Chamber Constructed By Scissoring And Sleeve Jointing Autologous Epineurium Small Gap Anastomosis

Clinically,the traditional nerve anastomosis, such as the epineurium or perineurium neurorrhaphy, is the most used repair method for peripheral nerve rupture, especially proximal nerve injury. However, it often induces the misorientated docking of the nerve bundle, neuroma formation, and axonal outgrowth from the coaptation sites, which seriously affects neural function recovery. The"peripheral nerve selective regeneration theory"provides a basis for small gap anastomosis to repair peripheral nerve repair rupture. Many scholars have centered on the small gap sleeve bridging fields including natural and synthetic conduits. But they have many complications and disadvantages, such as the limited resource of the grafts and functional defects at the donor site. And many investigators have used the epineurial sheath as a conduit to span the short nerve gaps. However, the epineurium anastomotic stoma, located in the small gap, can lead to neuroma formation and axonal outgrowth from the coaptation sites, and poor recovery of nerve function. The turnover of the sliding epineurial sheath tube can expose part of the normal nerve bundle, which can destroy the blood supply of the epineurium, and this can affect nerve regeneration and recovery of nerve function.Objcctive:The experiment was designed to investigate the feasibility and benefits of the nerve regeneration chamber constructed by scissoring and sleeve jointing autologous epineurium small gap anastomosis.Methods:Animal experiment: A total of 40 Sprague Dawley (SD) rats ,aged 3 months and weighing 250g-350 g, were randomly divided into two groups with 20 rats in each group. sciatic nerve injury models were constructed by cuting at a breakpoint located 10 mm above the sciatic nerve crotch. Experimental group: small gap anastomosis bridging the sciatic nerve by scissoring and sleeve jointing the epineurium (with 2 mm gap between the two stumps); and the control group: epineurium neurorrhaphy was applied in situ after sciatic cutoff. At postoperative 2, 4, 6, 8, 10, 12, 14 and 16 weeks, 2 SD rats from each group were deeply anesthetized. Then we generally observed autonomic activities, the ulcer healing situation, the appearance of the regeneration chamber and anastomotic place with the microscope. The structural changes of sciatic nerve were observed by hematoxylin-eosin(HE) staining and transmission electron microscopy.Results:1. Postoperative paralysis appeared in SD rats after the bilateral sciatic nerves were cut off. The experimental rats recovered automomic activities quicker than control group, and experimental rats ulcer healing is faster than control group.2. Observation under operative microscope showed the epineurium of the small gaps did not collapse, and there was no evidence of neuroma formation and axonal outgrowth from the coaptation sites at the epineurium anastomotic stoma, and there were minimal adhesions at the outer surface of the epineurial tube to the surrounding tissue in the experimental group. While there were serious adhesions at the epineurial anastomotic stoma to the surrounding tissue and neuroma formed at the epineurial anastomotic stoma in control group.3. Optical microscope showed that the connective tissue hyperplasia was significantly reduced, and myelinated nerve fibers are arranged orderly in experimental group. The nerve fibers are arranged disorderly and the connective tissue hyperplasia is significant in control group.4. Transmission electron microscope showed that the layers of myelin sheath were arranged in concentric circles, compacted and regular, without differences from the normal nerve structure, and schwann cell hyperplasia was obvious in experimental group. While the layers of myelin sheath were arranged irregularly and sparsely , and the myelin sheath was obviously tortuous and blurry in control group.5. Statistical analysis showed that myelinated nerve fibers count in experimental group is more than control groupin each units vision and the regenerated nerve fibers recovery rate is higher than the control group, which the difference is significant meaning (P < 0.05).Conclusion:1. The neural regeneration chamber constructed by scissoring and sleeve jointing autologous epineurium small gap anastomosis was feasible and superior and the anastomosis is a new small gap anastomosis to repair nerve rupture.2. The neural regeneration chamber constructed by the new method was feasible and superior, considering that the epineurium originates from the native tissue, it eliminates the use of a donor nerve, reduces donor site morbidity, and minimizes foreign body reaction.. This neural regeneration chamber constructed by the new method is a relatively airtight and complete, keeps the retroposed epineurium anastomotic stoma outside of the small gap, and not in the same level with nerve stumps, which provides a favorable microenvironment for neural axons to selectively regenerate and avoids the misorientation docking of nerve bundle, neuroma formation and axonal outgrowth from the coaptation sites.