Background: Pulsed radiofrequency (PRF) is increasingly used in clinical practice, especially in neuropathic pain disorders. Although PRF is not new to clinical use, there are significant gaps in knowledge regarding its effectiveness.
Objectives: The current study was conducted to evaluate the effect of duration of application of PRF on its analgesic efficacy in improvement of neuropathic pain.
Study design: A randomized experimental trial.
Setting: An animal research facility at the College of Veterinary Medicine at Mansoura University in Egypt.
Methods: Chronic constriction of the sciatic nerve of 36 male Sprague-Dawley rats was performed to induce neuropathic pain. The rats were divided into 6 groups (6 rats each) in which PRF was applied for 2, 4, 6, or 8 minutes or not at all. In one group, RF cannula was applied without performing PRF intervention. The pain was assessed through observation of resting paw posture (RPP) at 3, 10, and 21 days. Nerve damage was assessed by histopathological evaluation of the sciatic nerve. Immunohistochemical localization of proinflammatory cytokines (interleukin 6 [IL-6] and tumor necrosis factor alpha [TNF-alpha]) was also done.
Results: RPP was improved in rats treated with PRF. This improvement was significant only in rats treated for 8 minutes. Increased duration for PRF application was associated with a significant decrease in IL-6 and TNF-alpha contents in all groups when compared with the control group. Histopathological evaluation of the constricted sciatic nerve revealed no statistical significance among the different study groups.
Limitations: The study was limited by the lack of measurement of other inflammatory markers that may help elucidate other relevant mechanisms.
Conclusions: Increased duration of PRF application resulted in better analgesic efficacy without any increase in tissue injury in an animal model of neuropathic pain. This effect may be attributed to decreased production of pro-inflammatory cytokines.
Key words: Pulsed radiofrequency, analgesic, rats, sciatic nerve, duration, neuropathic pain.