兔坐骨神经急性挤压伤的MRI与病理学对比初步研究

Acute sciatic nerve crush injuries in rabbits:MRI and pathological comparative study

目的 模拟人类外周神经损伤机制 ,制作坐骨神经急性挤压伤模型 ,探讨其MRI表现与病理学之间的关系 ,为临床诊治外周神经损伤及选择手术时机提供客观依据。方法 32只新西兰兔按钳夹力的不同随机分为A、B 2组 ,钳夹力分别为 3 6 1、10 5 0kg ,每组有 16只 ,左下肢为损伤侧 ,右下肢为对照侧 ,建立坐骨神经急性挤压伤模型 ,每组又将 4只分在 1、2、4、8周的不同时间观察段中 ,于伤后不同时间段分别行双侧坐骨神经MR扫描 ,扫描后分别取材进行病理学检查。结果 损伤侧坐骨神经除T1W 1上无明显变化外 ,三维T2 WI、T2 WI的质子频谱预饱和反转恢复序列 (SPIR)、平衡快速梯度回波序列 (B FFE)、T2 WI的短反转时间恢复序列 (STIR)均显示挤压伤远段神经增粗、扭曲、T2 WI信号增高。 32条损伤神经 30条MRI显示异常 ,诊断正确率 93 75 %,假阴性率为6 2 5 %。损伤侧远段神经 /肌肉信号强度比 (SIR)明显高于对照侧远段 (P <0 0 0 1) ;A、B 2组间SIR差异无显著意义 (P >0 0 5 )。损伤侧SIR 1周明显升高 ,展趾功能丧失 ,2周SIR达高峰 ,病理学检查见髓鞘大部分崩解、轴突消失 ;4～ 8周SIR下降 ,病理见大量雪旺细胞明显增生 ,髓鞘崩解产物吸收 ,此时展趾功能逐渐恢复。对照侧坐骨神经MRI及病理学检查未见异常。结论?

Objective Simulating injury mechanism in human peripheral nerve, acute sciatic nerve crush injuries model was produced in rabbits to investigate the relationship between the manifestations of MRI and pathology in order to provide the information for clinical therapy and operative plan . Methods Thirty-two adult rabbits were randomly divided into two groups: group A (n=16) and B (n=16).In group A, the left sciatic nerves were crushed with a stress of 3.61 kg;In group B, with a stress of 10.50 kg.4 time intervals in each group were observed in 1, 2, 4, and 8 weeks, respectively, and each time interval contained 4 rabbits.Left sciatic nerves were served as injured sides, right sciatic nerves were regarded as control sides.MRI was performed at different time interval after crush injury.Then the nerves were examined pathologically.Results There were no obvious changes on T_1WI in injured sides, but the injured distal segment of sciatic nerve thickened and twisted, showing high signal intensity on 3D T_2WI, T_2WI/SPIR, B-FFE, and T_2WI/STIR.MRI could show abnormality of 30 sciatic nerves, the correct diagnostic rate was 93.75% and false negative rate was 6.25%.The distal sciatic nerve/muscle signal intensity ratio (SIR) of the injured sides was significantly higher than that of the control sides (P<0.001).However, there was no difference in SIR between group A and group B (P>0.05).SIR in injured side increased at 1 week, reached the peak at 2 weeks, at this time, nerve axons disappeared and lots of myelin degenerated, abduction function disappeared.SIR decreased during 4～8 weeks, the myelin sheath breakdown and Schwann cell proliferated obviously, and abduction functions were observed.The control sciatic nerves showed no abnormality in MRI and pathology. Conclusion MRI can make the diagnosis of crush injury of sciatic nerve, and dynamic SIR measurement of nerve injury correlates well with the pathological and functional recovery process.MRI is an effective method to monitor degeneration, regeneration, and prognosis after injuries.