Application of pulsed radiofrequency currents to rat dorsal root ganglia modulates nerve injury-induced tactile allodynia.

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 to 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.

Side effects and adverse events related to intraligamentous injection of sclerosing solutions (prolotherapy) for back and neck pain: A survey of practitioners.

OBJECTIVE: To study the side effects and adverse events related to intraligamentous injection of sclerosing solutions (prolotherapy) for back and neck pain. DESIGN: Practitioner postal survey. SETTING: Postal survey of practitioners of prolotherapy for back and neck pain in the United States and Canada. PARTICIPANTS: A sample of prolotherapy practitioners from 2 professional organizations were surveyed about their training and experience, use of specific treatment procedures, estimated prevalence of side effects, and adverse events related to prolotherapy for back and neck pain. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Prevalence of side effects and adverse events. RESULTS: Surveys were completed by 171 practitioners (response rate, 50%). Ninety-eight percent held medical degrees, and 83% were board certified in various disciplines. Respondents had a median of 10 years of experience, during which they had treated a median of 500 patients and given a median of 2000 treatments. Side effects with the highest median estimated prevalence were pain (70%), stiffness (25%), and bruising (5%). There were 472 reports of adverse events, including 69 that required hospitalization and 5 that resulted in permanent injury secondary to nerve injury. The vast majority (80%) were related to needle injuries such as spinal headache (n = 164), pneumothorax (n=123), temporary systemic reactions (n = 73), nerve damage (n = 54), hemorrhage (n = 27), nonsevere spinal cord insult (ie, meningitis, paralysis, spinal cord injury) (n = 9), and disk injury (n = 2). CONCLUSIONS: Side effects related to prolotherapy for back and neck pain, such as temporary postinjection pain, stiffness, and bruising, are common and benign. Adverse events related to prolotherapy for back and neck pain are similar in nature to other widely used spinal injection procedures. Further study is needed to fully describe the adverse event profile of prolotherapy for back and neck pain.