高强度超声对兔坐骨神经急性损伤的观察

Observation on the acute injury of rabbit sciatic nerve by high intensity ultrasound

目的:观察高强度超声(HighIntensityUltrasound,HIU)作用于兔坐骨神经干后,胫神经、腓浅神经动作电位幅度、神经传导速度的变化,为HIU用于顽固性疼痛的治疗提供实验基础。方法:以不同的HIU剂量辐照兔坐骨神经干,然后分别观察从辐照点近端到远端踝部胫神经、腓浅神经电生理指标变化及辐照处组织形态变化。结果:动作电位的峰值下降幅度随HIU剂量的增加而增加:辐照15s,胫神经下降9.0%,腓浅神经下降40.3%;辐照35s,胫神经下降81.1%,腓浅神经下降87.0%。传导速度:辐照15,20,25s前后变化不大,而辐照35s后,胫神经传导速度下降77.5%,腓浅神经下降66.8%。组织学变化:光镜下,辐照15s,坐骨神经轻微脱髓鞘改变;35s则出现轴突断裂,髓鞘裂解。电镜下,辐照15s,髓鞘变形,分层;35s轴突变性,髓鞘脱失。结论:HIU剂量越大,兔坐骨神经损伤越重,动作电位峰值下降越明显。在相同剂量HIU辐照下,腓浅神经动作电位峰值下降幅度大于胫神经。HIU可以部分或完全阻滞兔坐骨神经。

AIM:To determine the changes of the action potential value and nerve conduction velocity(NCV) of the rabbit tibial nerve and superficial peroneal nerve after the exposure of high intensity ultrasound(HIU) so as to provide the experimental basis for treating refractory pain with HIU. METHODS:The rabbit sciatic nerve trunk was exposed to different doses of HIU.The electrophysiological index changes of rabbit ankle tibial nverve and superficial peroneal nerve from the short to the long distance of exposed points,and the corresponding histological changes of the nerve exposed were observed,too. RESULTS:The larger dose of the HIU was,the greater decrease of the action potential peak value was.After 15 s and 35 s exposure to HIU,the action potential peak value of tibial nerve decreased by 9.0%and 81.1%respectively,and that of superficial peroneal nerve decreased by 40.3%and 87.0%respectively.There were no significant changes of maximal NCV after 15 s,20 s, 25 s exposure to HIU for both nerves,while the NCV of tibial nerve decreased by 77.5%,and 66.8%of superficial peroneal nerve respectively after 35 s exposure to HIU.Slight deformation of the myelin sheath at 15 s,and axonotmesis and myelin sheath burst at 35 s were observed under slight microscope.Myelin sheath deformation and delamination at 15 s,axonal degeneration and myelin sheath breakdown and loss at 35 s were observed under electron microscope. CONCLUSION:The larger dose of HIU is,the higher degree of the injury of the sciatic nerve is,and the more obvious decreases of action potential peak value are.Exposed to the same dose of HIU,the action potential peak value of superficial peroneal nerve is larger than that of tibial nerve.Sciatic nerve may be blocked by HIU partially or completely.