Pain outcomes and safety of dorsal root ganglion-targeted transforaminal injection for postherpetic neuralgia: a retrospective single-center cohort study.

backgroundPostherpetic neuralgia (PHN) is a refractory neuropathic pain syndrome after herpes zoster and is often complicated by medication intolerance in older adults. The dorsal root ganglion (DRG) is a biologically plausible target for interventional analgesia.

methodsWe conducted a retrospective, observational single-arm cohort study including consecutive adults with PHN, who underwent DRG-targeted transforaminal injection (DRG-TFI; local anesthetic with or without corticosteroid) between January 2022 and June 2024. Time zero was the first DRG-TFI during the study period. The primary endpoint was within-patient change in 0-10 numeric rating scale (NRS) pain from baseline to 4 weeks. We report observed pain outcomes and responder rates with confidence intervals (CIs). A linear mixed-effects model is presented to summarize repeated NRS assessments with incomplete follow-up. Exploratory summaries added sleep-disturbance NRS, absolute pain-reduction thresholds, analgesic co-medication trajectories, and calibration of the short-term responder model.

resultsAmong 298 included patients (mean age 65.7 ± 10.9 years; 58.1% female), baseline NRS was 7.3 ± 1.1 and a 4-week assessment was available for 279 (93.6%). In the mixed-effects model, mean NRS decreased by - 3.1 points at 4 weeks (95% CI - 3.4 to - 2.8; P < 0.001), with an observed 4-week NRS of 4.1 ± 1.9. At 4 weeks, 191/279 (68.5%, 95% CI 62.7-73.9%) achieved ≥ 30% pain reduction and 118/279 (42.3%, 95% CI 36.4-48.3%) achieved ≥ 50% reduction. Procedure-related adverse events were documented in 26/298 (8.7%), with no documented persistent neurologic deficits or infections. At 4 weeks, 232/279 (83.2%, 95% CI 78.2-87.4%) achieved a ≥ 2-point NRS reduction and 145/279 (52.0%, 95% CI 45.9-58.0%) achieved a ≥ 4-point reduction; mean sleep-disturbance NRS decreased from 6.5 ± 1.8 at baseline to 4.2 ± 2.1 at 4 weeks.

conclusionsIn this single-center retrospective cohort, DRG-TFI was associated with clinically meaningful short-term pain reduction and no documented persistent neurologic deficit or procedure-related infection. However, chart-based adverse-event ascertainment and historical particulate-steroid exposure preclude definitive safety conclusions. Longer-term outcomes should be interpreted as observed outcomes under routine care because rescue interventions occurred during follow-up.