Analysis of the histologic effects of long-term pulsed radiofrequency application to rat sciatic nerve

Purpose: Radiofrequency treatments have been used in clinical practise for the treatment of variety pain syndromes for many years. The pain relief effect of conventional RF application is due to the high temperature which resulting coagulative necrosis within tissues. Recently RRF procedure has been developed which RF current is applied intermittently, in a pulsed fashion with a lower temperature. PRF procedure has been rapidly accepted for its clinically effectiveness and that does not cause extensive tissue injury. In our study, we aim to investigate the histopathologic effects of long duration PRF on rat sciatic nerve. Materials and Methods: After having our faculty?s Animal Studies Ethics Committee approval, 64 female Wistar Albino rats were divided into 6 groups. No procedure was applied to the rats in the control group (n:3). After all rats deeply anesthetised, RF electrode was placed within the sciatic nerve. In sham group electrode was placed but no current was passed. PRF was applied in group 3 (n:14) for 2 minutes, in group 4 (n:14) for 6 min., in group 5 (n:14) for 9 min., in group 6 (n:14) for 12 min. Sciatic nerves were removed from the half of the rats in each PRF treated groups (group 3,4,5,6) after the procedure, and those in the other half (n:7) were removed 2 day after the procedure in each PRF treated groups (group 3,4,5,6) for histological evaluation. The tissues were analyzed both with light microscopy and electron microscopy. Results: Rats treated with 2 min. showed no motor deficit. 4 rats in 6 min group, and 5 rats each 9 min. and 12 min. group showed footdrop. No pathology was evident in the control and sham groups. In 2 min. PRF group, there were no severe degeneration findings. There were mild endoneurial edema, enlarged endoplasmic reticulum cisterns in this group. Unmyelinated axons found to be normal ultrastructurally. Only a few myelinated axons showed only seperation in myelin configuration. There were similar findings in 6, 9 and 12 min PRF groups, no evident pathology was observed. Conclusion: Increasing duration time of PRF application did not cause significiant difference in pathology in tissue