Effect of pulsed radiofrequency for postherpetic neuralgia

Background: Postherpetic neuralgia (PHN) is one of the most intractable pain disorders, particularly among elderly patients. Lesioning of dorsal root ganglion (DRG) using pulsed radiofrequency (PRF) has shown pain reduction for PHN. We assessed the efficacy of PRF lesioning of DRG for PHN via an open, nonrandomized study. Methods: Forty-nine patients with PHN refractory to conservative therapy were involved. After impedance and sensory electrical nerve stimulation thresholds were assessed, PRF was performed three times adjacent to the DRG of corresponding levels at 42 °C for 120 s under the fluoroscopic guidance. Pain ratings were conducted on a visual analogue scale at 4-, 8- and 12-week follow-up. The data were analyzed using the one-way ANOVA test. P<0.05 was considered to be statistically significant. Results: There was excellent pain relief (about 55%) at 4 weeks after PRF lesioning adjacent to the DRG and the effectiveness was maintained at the subsequent 12-week follow-up. The pain duration, age and stimulation level did not influence the outcome. There were no procedure-related complications. Conclusions: PRF lesioning of DRG showed significant pain relief compared with the conventional treatments in patients with intractable PHN. In order to elucidate the mode of action of PRF, further research is needed and the optimal electrical parameters of PRF have to be determined.