Physiological and functional responses of water-cooled versus traditional radiofrequency ablation of peripheral nerves in rats

BACKGROUND AND OBJECTIVES: Several clinical studies have focused on assessing the effectiveness of different radiofrequency ablation (RFA) modalities in pain management. While a direct head-to-head clinical study is needed, results from independent studies suggest that water-cooled RFA (CRFA) may result in longer lasting pain relief than traditional RFA (TRFA). The primary purpose of this study was, therefore, to investigate in a preclinical model, head-to-head differences between the two RFA technologies. METHODS: RFA was performed in a rat sciatic nerve model (n=66) in two groups: (1) TRFA or (2) CRFA. The surgeon was not blinded to the treatment; however, all the physiological endpoints were assessed in a blinded fashion which include histological, MRI, and nerve function assessment via electromyography. RESULTS: The energy delivered by the generator for CRFA was significantly higher compared with TRFA. Histological staining of nerves harvested immediately following CRFA exhibited extended length and multiple zones of thermal damage compared with TRFA-treated nerves. MRI scans across 4 weeks following treatment showed edematous/inflammatory zones present for longer times following CRFA. Finally, there was greater attenuation and prolonged loss of nerve function measured via electromyography in the CRFA group. CONCLUSIONS: This study shows that CRFA has greater energy output, as well as more pronounced structural and functional changes elicited on the peripheral nerves compared with TRFA. While these preclinical data will need to be confirmed with a large clinical randomized controlled trial, we are encouraged by the direction that they may have set for those trials.