周围神经损伤后不同时间的修复比较

背景:大量实验证明,Bungner带-许旺细胞-基底膜结构是神经再生理想的微环境.这一结构在神经损伤两三周后形成.而在神经损伤数小时后,近断端的神经纤维就开始发芽再生神经纤维开始再生与所需微环境的形成并不同步.目的:观察周围神经损伤后不同时间进行修复的最佳效果.设计、时间及地点:随机对照动物实验,于2007-06/2008-06在哈尔滨医科大学动物实验中心完成.材料:新西兰大白兔20只,随机数字表法分为4组:2周后神经修复组、4周后神经修复组、3个月后神经修复组、即时神经修复组.方法:建立成年新西兰大白兔周围神经损伤模型,即时修复组立即缝合伤口,2周后神经修复组、4周后神经修复组、3个月后神经修复组采用神经两断端分别固定于肌膜上,逐层缝合伤口,2周,4周,3个月后重新打开伤口,在手术显微镜下用10-0无损伤尼龙针线进行外膜缝合修复坐骨神经,缝合伤口.主要观察指标:各组缝合神经段的神经电生理、轴突数、光镜及电镜观察结果.结果:2周后神经修复组神经传导速度慢于4周后神经修复组、3个月后神经修复组(P＜0.01);即时神经修复组与2周后神经修复组差异无显著性意义(P＞0.05).2周后神经修复组效果最好,神经纤维走行正常、排列完好,神经纤维可见血管增生,髓鞘结构较好,许旺细胞功能活跃,新生轴突内微缝密集排列.4周后神经修复组最差,神经纤维数量少、排列紊乱,髓鞘轴突变性明显,大部分神经纤维脱髓鞘崩解,轴突消失,未见再生神经纤维.3个月后神经修复组效果较差,可见较多神经纤维结构破坏,捧列略紊乱,髓鞘和轴突变性较明显,仅见少量再生神经纤维,许旺细胞略少,胞质不发达.即时进行神经修复组效果较好,神经纤维结构破坏不明显,排列整齐,髓鞘和轴突变性轻,神经纤维内见有大量再生髓鞘,许旺细胞明显增多,胞质较发达.2周后神经修复组轴突计数优于其他3组(P＜0.05),4周后神经修复组最少.结论:神经损伤2周后进行神经修复效果优于其他时间点,是周围神经损伤后修复的最佳时机.

Comparative study on repairing effects at different time points after peripheral nerve injury

BACKGROUND:It is proved by a number of experiments that such a structure as Bungner band-Schwann cell-basilar membrane,which is formed at 2 or 3 weeks after nerve injury,is the ideal microenvironment for neural regeneration. However,the sprouting of nerve fiber close to broken ends takes place at several hours after nerve injury,which shows that the regeneration of nerve fiber and the formation of required microenvironment don't occurred at the same time.OBJECTIVE:To investigate the best repairing time for peripheral nerve injury.DESIGN,TIME AND SETTING:A randomized control animal experiment was performed in the Animal Experiment Centre,Harbin Medical University from June 2007 to June 2008.MATERIALS:A total of 20 New Zealand rabbits were randomly divided into four groups,namely,an immediate repairing group and the other three groups that were repaired respectively at week 2,week 4 and month 3 after injury.METHODS:Peripheral nerve injury models of New Zealand rabbits were established. The immediate repairing group received suture immediately after injury;For the other three groups,the two broken ends of their nerves were fixed on sarcoiemmas temporarily and their wounds were sutured layer by layer. Then they were opened respectively at week 2,week 4 and month 3 after injury,to receive epineural suture with non traumatic 10-0 nylon suture under operating microscope,after which wounds were sutured again.MAIN OUTCOME MEASURES:Nerve electrophysiological observation,axon number,light microscope and electron microscope observation of sutured nerve segments in each group.RESULTS:Nerves repaired at week 2 after injury had a slower nerve conduction velocity than those at week 4 and month 3 after injury (P＜0.01);There was no difference of significance between the immediate repairing group and the group repaired at week 2 after injury (P＞0.05). According to the comparison among the four groups:it had the best repairing effect to repair nerve at week 2 after injury,with normal course and neat arrangement of nerve fibers,vascular proliferation in nerve fibers,myelin sheaths with better structure,Schwann ceils with active function,as well as regenerated axons with intensively arranged microfilaments;Repairing at week 4 after injury had the worst effect,with rare nerve fivers disorderly arranged,myelin sheath and axons significantly degenerated,most nerve fibers demyelinated with axons disappeared,and no regenerated nerve fibers seen;Repairing at month 3 saw the worse repairing effect,with more nerve fiber damaged and disorderly arranged,myelin sheath and axons significantly degenerated,nerve fibers rarely regenerated,less Schwann cells,as well as cytoplasm did not well develope;The effect of immediate repairing after injury was better,with nerve fibers unobviously damaged and well arranged,myelin sheath and axons lightly degenerated,large amounts of myelin sheaths regenerated in nerve fibers,Schwann cells increased obviously,as well as cytoplasms better-developed. Axon counting result was better in the group repaired at week 2 after injury than the otherthree groups,with the minimum in the group repaired at week 4 after injury.CONCLUSION:Repairing at week 2 after injury can get a better result than at any other time points,accordingly two weeks after nerve injury is the best time for repairing peripheral nerve injury.