# Duration Dependent Outcomes of Combined Dorsal Root Ganglion Pulsed Radiofrequency and Epidural Steroid Injection in Chronic Lumbosacral Radicular Pain

## TL;DR

A study found that a longer 8-minute PRF treatment combined with an epidural steroid injection provided better pain relief and function for chronic lower back pain compared to a 4-minute treatment.

## Contribution

This study provides clinical evidence that prolonged PRF duration improves outcomes in chronic lumbosacral radicular pain.

## Key findings

- 8-minute PRF showed better pain reduction and functional improvement than 4-minute PRF at 6 months.
- Functional benefits were observed as early as 3 months with the 8-minute protocol.
- The 8-minute treatment had higher patient satisfaction and no increased adverse events.

## Abstract

Background/Objectives: The optimal duration of pulsed radiofrequency (PRF) applied to the dorsal root ganglion (DRG) remains unclear, particularly in patients with chronic lumbosacral radicular pain (LRP) who are unresponsive to conservative therapy. Although preclinical data suggest duration-dependent neuromodulatory effects, comparative clinical evidence for specific exposure times is limited. This study aimed to evaluate the outcomes of 4 min and 8 min DRG-targeted PRF applications performed in combination with transforaminal epidural steroid injection (TFESI) in patients with chronic LRP unresponsive to conservative treatment, to determine whether prolonged exposure provides superior analgesic and functional outcomes. Methods: In this prospective, single-center, observational comparative study, 72 patients with chronic lumbar radicular pain (LRP) refractory to conservative management received DRG-targeted PRF using standardized parameters (45 V, 20 ms, 2 Hz, ≤42 °C). Participants underwent either 4 min (n = 36) or 8 min (n = 36) PRF, assigned according to clinical discretion. All procedures were followed by transforaminal epidural injection of dexamethasone and bupivacaine. The primary endpoint was Numeric Rating Scale (NRS) pain intensity at 6 months. Secondary endpoints included Oswestry Disability Index (ODI), patient satisfaction, responder rates, and analgesic use across 1-, 3-, and 6-month follow-up. Results: Both groups achieved significant improvements from baseline at all time points. Linear mixed-effects analysis demonstrated a significant overall association favoring the 8 min protocol for pain (estimate: −0.81, 95% CI: −1.52 to −0.10, p = 0.025) and functional disability (estimate: −12.84, 95% CI: −19.36 to −6.32, p < 0.001). Functional benefits emerged by 3 months (p = 0.006), while pain reduction reached borderline statistical significance at 6 months (p = 0.048). The 8 min group showed numerically higher responder rates and patient satisfaction without increased adverse events. Conclusions: In this study evaluating a combined PRF and corticosteroid injection protocol, 8 min PRF exposure was associated with superior pain and functional outcomes compared to 4 min, without compromising safety. However, the observational design and concurrent medication administration limits causal inference. Randomized controlled trials are needed to confirm these findings and isolate the independent effect of PRF duration.