Efficacy of pulsed radiofrequency treatment duration to the lumbar dorsal root ganglion in lumbar radicular pain: a double-blind randomized controlled trial.

Background: Pulsed radiofrequency (PRF) of the dorsal root ganglion (DRG) is a minimally invasive treatment for lumbar radicular pain (LRP), but the optimal stimulation duration remains uncertain. Preclinical evidence suggests that extended PRF may enhance neuromodulation, yet comparative clinical data are limited. This randomized, double-blind controlled trial aimed to compare the efficacy according to duration of PRF of DRG in patients with LRP.

Methods: A total of 60 patients with chronic unilateral LRP were allocated to receive PRF of the DRG for 4 min (group A), 6 min (group B) or 8 min (group C). The primary outcome was pain intensity, measured by the Numeric Rating Scale (NRS) assessed at 1 week, 2 weeks, 1 month, 3 months, and 6 months. Secondary outcomes included functional disability (Oswestry Disability Index, ODI) and patient satisfaction (Global Perceived Effect, GPE) assessed at 1 month, 3 months and 6 months. The primary analysis followed an intention-to-treat (ITT) approach with the last observation carried forward. A per-protocol (PP) analysis was also conducted to validate results.

Results: All groups demonstrated significant improvement in NRS and ODI over time (p<0.001). At 6 months, group B showed significantly greater pain reduction compared with group A (mean difference=-1.35, SE=0.69, p=0.031). Group C also showed improved NRS and the lowest ODI scores, though not statistically significant in the ITT analysis. However, PP analysis revealed statistically significant NRS reduction in both groups B and C compared with group A. Group C was the only group to demonstrate significant within-group improvement in GPE over time.

Conclusions: A 6 min PRF duration provided the most consistent and statistically significant improvement in pain and function, supporting its use as a clinical standard. The 8 min duration may yield additional subjective and functional benefits in selected patients. PRF was safe and well tolerated across all groups.