Experimental Study On Repair Of Long Distance Facial Nerve Defect By Combined Bridge In Rabbits

[Objective]The present study was designed to investigate the nerve regeneration in the adult rabbit,which had been made a 1.5cm long gap in the continuity of facial nerve and the gap was repaired by combined bridge grafting which was made of rat sciatic nerves made acellular by chemical extraction and autogenous inside-out vein,to analysis the effect of FK506 when taken orally,at the same time,to explore the repair mechanism of bridge grafting that warrants further clinical investigation.[Methods]1.Scm long gap in the continuity of facial nerve were made surgically in 30 New Zealand adult rabbits,all the animals were divided into 3 groups randomly.The facial nerves of righe side were grafted with nothing as control,and the left side were grafted to repair the defect.The groupâ… of 10 rabbits each was grafted with autogenous facial nerve,the groupâ…¡of 10 rabbits each was grafted with autogenous facial nerve as same as the groupâ… ,and the take FK506 orally 1mg/kg.d^-1for 7 days,and the groupâ…¢of 10 rabbits each was grafted with combined bridge grafting which was made of rat sciatic nerves made acellular by chemical extraction and autogenous inside-out vein,and take FK506 orally 1mg/kg.d^-1for 7 days,too.All animals were sacrificed 16 weeks after surgery,before death,nerve conductive velocity(NCV)were measured,and then,the specimens were harvested and processed for histological examination.The amount of newly formed facial nerve was counted by image analysis,and the quality of newly formed facial nerve was also analyzed by using statistics software.[Results](1)The combined bridge was absorbed without severe inflammatory reaction and refrain the injured facial nerve from forming the neurofibroma,provide a better microenviroment for nerve regeneration.(2)The result of NCV measurement showed that the function of nerves were recovered well,there was no difference between the groupâ… ,â…¡,â…¢,but they all did not recovered to normal level.(3) Although there was no difference between the groupâ… ,â…¡,â…¢in NCV,there were difference between the groupâ… ,â…¡,â…¢in the maturity degree of myelinated axon, showed that FKS06 promoted facial nerve regeneration.[Conclusions](1)Acellular xenochthonous ECM(extracellular matrix)of nerve keeps the main structure of basal lamina tubes while remove the cells,axons and myelin sheath,can be a good material for nerve regeneration.(2)There was synergistic action between autogenous inside-out vein and acellular xenochthonous ECM of nerve,with a good microenviroment and lots of seed cells,the combined bridge grafting can promote facial nerve regeneration.(3)FK506 can suppress the systematical and local inflammatory reaction after facial nerve injury,and it is benefit the nerve regeneration.Apart from that,FK506 may has other mechanism to accelerate the regeneration of facial nerve and need more study.