Empirical Study Of High-frequency Ultrasound Observing Sciatic Nerve Injection Injury

Objective: We want to provide image data about ultrasound diagnosing peripheral nerve injection injury, provide more proof for clinician diagnosing peripheral nerve injection injury, verification the possibility and exactly of ultrasound diagnosing peripheral nerve disease, by high-frequency ultrasound observing the rabbits'injection injured sciatic nerve and contrasting with pathology.Methods: 22 rabbits were enrolled in this study, anesthetized by injected phenobarbital sodium through the ear edge vein. The rabbits were epilated and sterilized before ultrasound guided left sciatic nerve cidomycin injection and their general condition was observed after the operation. Ultrasound examination on the left sciatic nerve was performed before the injection, after the injection at once,1day, 3 days, 1week, 2 weeks, 3 weeks and 4 weeks after the injection, observing the sciatic nerve's internal echo, stiffness, demarcation with surrounding tissue, demarcation between nerve-tract and epineurium, the level of epineurium's rough, blood supply of the nerve by using Color Doppler Flow Imaging, measuring outer diameter and inner diameter, computing thickness and proportion of epineurium.After each examination 2 rabbits were killed and dissected the affected limb. The sciatic nerve was observed by eyes, then imbedded with paraffin, common sliced, stained with haematoxylin and eosin, observed under microscope.Results: After injection, the rabbits appeared gradually inability of affected limbs, disfunction of toes expanding, weakness of both extensor and flexor myodynamia. Autophagy phenomenon was found on some of the rabbits . The sciatic nerves'outer diameter, inner diameter, thickness of the epineurium, the proportion of epineurium was increased(p<0.05), internal echo of the nerves was reduced(p<0.05), epineurium became rough(p<0.05), demarcation with surrounding tissue became gradually fuzzy (p<0.05), the nerves became rigid(p<0.05). There was no obvious change on blood supply and demarcation between nerve-tract and epineurium(p>0.05). After the limbs were dissected, the normal sciatic nerves'surface was smooth, glossy, no hyperemia and hemorrhage, easy dissection, no adhesion with the surrounding tissue , courser of the nerve was natural. While the injected nerves'surface was dim, hyperemia and hemorrhage, courser of the nerve was not natural, adhesion with the surrounding tissue. Observed by microcrope, the normal sciatic nerves'nerve fibers'courser were natural and axons, tunica vaginalis, nucleus of schwann cell, node of Ranvier were clearly seen After injection, hyperemia and hemorrhage of endoneurium and epineurium, inflammatory cell infiltration, damaged nerve fiber structures, desmoplasia inside and outside nerve can be seen.Conclusions: Sciatic nerve of rabbit can be seen clearly with high-frequency ultrasonogram. We can diagnose rabbit's sciatic nerve's injection injury in nonage by sonography. The sonogram of injection injured nerve vary in different periods, and related with pathological changes. High-frequency ultrasound is a reliable imaging method of diagnosing sciatic nerve injection injury.