Pulsed radiofrequency treatment of the dorsal root ganglion in patients with chronic neuropathic pain: A narrative review

Background: Chronic neuropathic pain (CNP) is a complex condition that has profound impacts on quality of life. Pulsed radiofrequency (PRF) on the dorsal root ganglia (DRGs) is a novel treatment that has shown clinical efficacy in pain relief, however, its mechanism remains unknown. Objectives: The objective of this review is to synthesize the literature on inflammatory markers and clinical pain outcomes in CNP patients treated with PRF. Study Design: A narrative review was conducted. Setting: Eligibility criteria included human trials on adults diagnosed with CNP. Monopolar and bipolar PRF treatments on the DRG were included. Methods: Four peer reviewed electronic databases (Medline, EMBASE, PubMed, and Cochrane) were systematically searched for studies on PRF on the DRG to treat CNP. The primary outcome measures included pain scores and cerebrospinal fluid samples taken pre- and posttreatment measuring inflammatory markers. Results: Thirty-three articles were identified in the database searches. Titles, abstracts, and full-text articles were evaluated, and eight articles met the inclusion criteria. The study designs included five randomized-controlled trials and three quasi-experimental studies. Patients: There were 311 patients pooled with an age range of 35–76 years. Types of CNP included chronic radicular pain, postmastectomy pain syndrome, chronic lumbosacral pain, and postherpetic neuralgia. Intervention: Treatments in included studies included monopolar and bipolar PRF stimulation ranging from 120 s at 2 Hz to 360 s with 5 Hz pulses. Measurement: The main findings revealed that PRF treatment provided significant pain relief (P < 0.05), with the greatest pain reduction at 3 months. Pro-inflammatory markers were found to decrease, whereas anti-inflammatory markers increased post-PRF intervention. Limitations: There were differing PRF procedure standards, and it is uncertain whether a higher frequency or duration is correlated with better outcomes. Studies had small sample sizes increasing the margin of error. Longer duration randomized-controlled trials are needed to understand the optimal therapeutic duration using PRF.