Application of Pulsed Radiofrequency Currents to Rat Dorsal Root Ganglia Modulates Nerve Injury–Induced Tactile Allodynia

Abstract

Background Application of pulsed radiofrequency (PRF) currents to the dorsal root ganglia (DRG) has been reported to produce relief from certain pain states without causing thermal ablation. In this study, we examined the direct correlation between PRF application to DRG associated with spinal nerve injury and reversal of injury-induced behavioral hypersensitivity in a rat neuropathic pain model. Methods Neuropathic lesioning was performed via left L5 spinal nerve ligation on male adult Sprague-Dawley rats. Once the injured rats had developed tactile allodynia, one group was then assigned to PRF treatment of the L5 DRG and another group was assigned to the sham treatment to the DRG. Behavioral testing was performed on both the control and treated paws using the von Frey filament test before the surgery and at indicated days. The resulting data were analyzed using a linear mixed model to assess the overall difference between the treatment groups and the overall difference among the study days. Cohen’s d statistic was computed from paired difference-from-baseline scores for each of the 14 study days after treatment and these measures of effect-size were then used to descriptively compare the recovery patterns over time for each study group. Results Spinal nerve injury resulted in the development of behavioral hypersensitivity to von Frey filament stimulation (allodynia) in the hindpaw of the left (injury) side. Mixed Linear modeling showed a significant difference between the treatment groups (p = 0.0079) and a significant change of paw withdrawal threshold means over time (p = 0.0006) for all 12 animals. Evaluation of Cohen’s d (effect size) revealed that the PRF-treated animals exhibited better recovery and recorded larger effect-sizes than the sham-treated animals on 10 of the 14 post-PRF treatment days and exhibited moderate to strong effects posttreatment at days 8–10 and at and beyond day 32. Conclusions Findings from this study support that PRF of the DRG causes reversal of nerve injury (spinal nerve ligation)-induced tactile allodynia in rats. This allodynia reversal indicates that nonablative PRF acting via modulation of the DRG can speed recovery in nerve injury-induced pain.

Electrical Stimulation of Dorsal Root Ganglion in the Context of Pain: A Systematic Review of In Vitro and In Vivo Animal Model Studies

“…Main features of in vivo studies are shown in Table , divided by the type of stimulation in PRF stimulation group and EFS group . In all in vivo studies, SD rats weighing from 149 to 350 g were used.…”

Pulsed Radiofrequency Treatment Enhances Dorsal Root Ganglion Expression of Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels in a Rat Model of Neuropathic Pain

“…Four mammalian HCN channels have been cloned, HCN1-4, and subsequent studies have demonstrated widespread expression of all isoforms in both the PNS and CNS (Ludwig et al 1998). Changes in DRG neurons, the primary sensory neurons in peripheral pain processing, are crucial for the development of neuropathic pain (Chung et al 2002;Sluijter 2005;Wan 2008;Perret et al 2011). The present study revealed differential expression of HCN channel subtypes in DRG neurons, with HCN1 expressed mainly on the plasma membrane of large and medium-sized neurons, and HCN2 mainly in the cytoplasm of medium and small-sized neurons.…”

“…Moreover, PRF also reduces nociceptive responses in animal models. Tanaka et al demonstrated that PRF of the rat sciatic nerve significantly reduces mechano-allodynia induced by resiniferatoxin (Tanaka et al 2010), Aksu et al found that PRF significantly decreases mechanohyperalgesia in rabbits after tight ligation of the sciatic nerve (Aksu et al 2010), and Perret et al reported that PRF to the DRG decreases allodynia in rats with chronic constriction injury (CCI) to the L5 spinal nerve (Perret et al 2011). In rats with L5 spinal nerve ligation (SNL), Park et al found that PRF decreases mechanohypersensitivity (Park et al 2012).…”

Pulsed Radiofrequency

“…Various experimental neuropathic pain models show the pain-relieving effect of PRF on mechanical hypersensitivity, and sometimes on thermal allodynia [79][80][81][82][83][84] (Table 1). …”