不同治疗方法对坐骨神经卡压损伤大鼠疼痛阈值和电生理学变化的影响

Effects of different treatments on pain threshold and electrophysiological changes in rats after chronic compression injury of the sciatic nerve

目的:探讨坐骨神经卡压损伤后4种治疗方法对疼痛缩腿阈值和电生理指标恢复的影响。方法:将32只SD大鼠(180～220g)制备成慢性坐骨神经卡压模型(CCI模型),随机分为4组,每组8只,1周后去卡压,即刻在损伤的神经外膜周围分别给予以下药物:对照组:生理盐水0.05mL,利多卡因组:20g/L利多卡因0.05mL,得宝松组:得宝松0.05mL,联合用药组:利多卡因0.05mL+得宝松0.05mL,分别于去卡压后即刻、给药后1,2,4,6,8周定期测定大鼠足爪的疼痛缩腿阈值,并观察损伤神经各种电生理指标及电镜的变化。结果:去卡压一至两周,各组检测指标均有恢复,去卡压后第2周,联合用药组疼痛阈值、运动神经传导速度、动作电位波幅明显优于其他3组(P<0.05),电镜显示各组坐骨神经髓鞘板层结构均较松散,但联合用药组出现增生肥大的雪旺氏细胞;去卡压后4～8周,联合用药组各项指标的恢复较其他3组明显增快(P<0.05),电镜显示各组均出现明显的“洋葱球”改变;联合用药组电镜变化尤为明显。结论:慢性卡压神经损伤应及早去除卡压,单纯给予利多卡因或得宝松效果欠佳,同时加局麻药有助于神经源性疼痛的缓解和功能的恢复。

AIM: To investigate the effects of four therapeutic methods on mechanical paw withdrawal thresholds(PAWs) and electrophysiological index recovery after the chronic compression injury(CCI) of the sciatic nerve. METHODS:Thirty two SD rats(180-220 g) were made into the models of CCI of the sciatic nerve, and were randomly divided into four groups with eight rats in each group.The decompression was done after one week, and the following drugs were injected around the injured epineurium instantly: control group: sodium chloride 0.05 mL; lidocaine group: 20 g/L lidocaine 0.05 mL; diprospan group: diprospan 0.05 mL; associated drug group: 20 g/L lidocaine 0.05 mL plus diprospan 0.05 mL. The changes of PAWs in rats, electrophysiological indexes and electron microscope were monitored regularly after decompression immediately and 1, 2, 4, 6, and 8 weeks after administration. RESULTS: The indexes were gradually recovered in all groups after decompression of 1-2 weeks.The PAWs, the speed of motor nerve conduction, action potential amplitude of wave in associated drug group were obviously superior to those in the other three groups after decompression two weeks(P< 0.05). There were loose structure of layers in myelin sheath in all groups, but the proliferative and hypertrophic Schwann cells were found under electron microscope in the associated drug group. After decompression of 4-8 weeks, the recovery of indexes in the associated drug group increased faster than that in the other three groups(P< 0.05). The obvious“onion bulbs' changes were found under electron microscope in all groups, and the change of electron microscope in the associated drug group was the most obvious. CONCLUSION: The CCI should be decompressed as soon as possible. The therapeutic effect of the decompression was not good if only given lidocaine or diprospan, and adding local anesthetic simultaneously will be helpful for remission of neurogenic pain and functional recovery.