The mechanism of action of pulsed radiofrequency in reducing pain: a narrative review

Abstract

Pain from nervous or musculoskeletal disorders is one of the most common complaints in clinical practice. Corticosteroids have a high pain-reducing effect, and their injection is generally used to control various types of pain. However, they have various adverse effects including flushing, hyperglycemia, allergic reactions, menstrual changes, immunosuppression, and adrenal suppression. Pulsed radiofrequency (PRF) is known to have a pain-reducing effect similar to that of corticosteroid injection, with nearly no major side effects. Therefore, it has been widely used to treat various types of pain, such as neuropathic, joint, discogenic, and muscle pain. In the current review, we outlined the pain-reducing mechanisms of PRF by reviewing previous studies. When PRF was first introduced, it was supposed to reduce pain by long-term depression of pain signaling from the peripheral nerve to the central nervous system. In addition, deactivation of microglia at the level of the spinal dorsal horn, reduction of proinflammatory cytokines, increased endogenous opioid precursor messenger ribonucleic acid, enhancement of noradrenergic and serotonergic descending pain inhibitory pathways, suppression of excitation of C-afferent fibers, and microscopic damage of nociceptive C- and A-delta fibers have been found to contribute to pain reduction after PRF application. However, the pain-reducing mechanism of PRF has not been clearly and definitely elucidated. Further studies are warranted to clarify the pain-reducing mechanism of PRF.

A narrative review of pulsed radiofrequency for the treatment of carpal tunnel syndrome

“…23 This could possibly be mediated via microscopic changes of the mitochondria, microfilaments, and microtubules in Aδ and C-type fibers. 24 Nonetheless, histologic murine studies have demonstrated only transient changes in the sciatic nerve with PRF, suggesting there may also be non-structural changes in gene expression or cytokine upregulation that are eliciting positive effects. 25 Indeed, PRF has been shown to be associated with downstream changes in gene and molecular expression, such as lower levels of proinflammatory cytokines IL-6 and TNFα, lower levels of intracellular proteins such as β-catenin that are correlated with neuropathic pain, and internalization of glutamate receptor subunits.…”

Progress in Clinical Application of Pulsed Radiofrequency for Chronic Pain

“…Its mechanism of action is not clear. Current studies have shown that pulsed radiofrequency can exert analgesic effects through long-term inhibition of pain signals transmitted from peripheral nerves to the central nervous system, inactivation of microglia, reduction of pro-inflammatory cytokines, increase of endogenous opioid precursor mRNA, enhancement of descending pain inhibition pathways, inhibition and damage of nociceptive nerve fibers [3].…”

Comparison of two distinct needle tip positions in pulsed radiofrequency for herpes zoster‐related pain

“…PRF occurs through RF generators which can produce transient pulsed RF current 8,9 . The RF generator uses alternatively repeated electrical stimulation, maintaining the temperature of the neural tissue below 42°C 10 . In PRF, the short duration and resting phase between pulses can avoid apoptosis and necrosis of histocytes 11 …”