Effects Of Pulsed Radiofrequency With Different Voltages On Pain Threshold And Nerve Structure Of Rat CCI Model

Objective:To observe the effects of thermal withdrawal latency(TWL),mechanical withdrawal threshold(MWT)and structure of sciatic nerve in the rat model with chronic constriction injury(CCI)after the treatment by pulsed radiofrequency(PRF)in difference voltage.Methods:Seventy-two adult male SD rats were randomly divided into 4 groups: sham group,PRF-45 V group,PRF-55 V group and PRF-65 V group,18 rats in each group.The rats in sham group were only placed RF needle 120 s without pulse intervention,while other groups were treated with 45 V,55 V and 65 V voltage of the PRF intervention(2 Hz,120s)after CCI model successfully established.Thermal withdrawal latency(TWL)and mechanical withdrawal threshold(MWT)were determined before the model,model establishment time(7 d after the model),and 1,4,7,10,14 d after PRF.The sciatic nerves of CCI rats were taken at 14 d after PRF.The structural changes were observed under electron microscope.Results:TWL and MWT were significantly lower at different times than those before establishment of the model(P <0.05);No differences of TWL and MWT were found among all groups before the model and model establishment time(P >0.05);At each time point after PRF,TWL and MWT of PRF-45 V,PRF-55 V and PRF-65 V groups weresignificantly higher than those in sham group(P <0.05);There were no differences in TWL and MWT between PRF-55 V group and PRF-65 V group at 14 days after PRF(P >0.05),which were significantly higher than those in PRF-45 V group(P <0.05).Under the electron microscope,there was no obvious injury of sciatic nerve in all groups,only a large number of irregular myelin sheaths appeared in PRF-65 V group was higher than that in PRF-55 V group and PRF-45 V group.Conclusion:1.The early pain threshold of CCI rats was obviously restored after PRF intervention.The effects of PRF with the high-voltage of 55 V and 65 V are clearly higher than the low-voltage of 45 V,while there is little difference between the high-voltage of 55 V and65 V.2.The voltage PRF established in this experiment only caused minor damage to the sciatic nerve,and the degree of edema of myelinated nerve fibers in PRF-65 V group was higher than that in PRF-55 V group and PRF-45 V group.