Background: Pulsed radiofrequency (PRF) on the dorsal root ganglion (DRG) is a common minimally invasive surgery for herpes zoster (HZ)-related pain, including acute zoster pain and postherpetic neuralgia (PHN); however, some patients still have no obvious pain relief, a high recurrence rate, and short-term recurrence. Radiofrequency thermocoagulation (RF-TC) has a higher temperature; however, it is still unknown whether the degree of complete damage will affect the recurrence rate and if there is any difference compared with the effect of PRF.
Objectives: This study mainly aimed to explore whether there was a difference in the recurrence rate following CT-guided PRF and RF-TC for HZ-related pain. This is also a preliminary exploration of RF-TC for treatment of HZ-related pain.
Study design: A retrospective cohort study.
Setting: The study was carried out in the Affiliated Hospital of Jiaxing University in Jiaxing, China.
Methods: We included a total of 134 patients who underwent CT-guided PRF or RF-TC for HZ-related pain in the pain department. Medical records related to relapse, numerical rating scale scores (NRSs), Pittsburgh sleep quality index (PSQI), adverse events, and satisfaction were reviewed. The Kaplan-Meier analysis was used to estimate the cumulative survival rates of the surgical procedures. After controlling for related confounders, the relationship of surgical procedure and recurrence rate was analyzed by interval-censored multivariable Cox regression. A time-independent receiver operating characteristic (ROC) curve analysis confirmed the signature's predictive capacity. A nomogram was used to predict postoperative recurrence. Multiple imputations was used to deal with the randomly missing data. Repeated-measures analysis of variance (ANOVA) was applied to analyze NRSs and PSQI at each time interval, and multiple comparisons were made.
Results: In 134 patients with HZ-related pain, the ratio of patients receiving PRF to those receiving RF-TC was 1:1. Interval-censored multivariable Cox regression analysis demonstrated that lesion space (1-2% / ref: adjusted hazard ratio (HR), 2.075; 95% confidence intervals (CI), 1.002-4.210; > 2% / ref: adjusted HR, 3.406; 95% CI, 1.670 - 6.950), pain grade (adjusted HR, 2.249; 95% CI, 1.221 - 4.143) and surgical procedure (adjusted HR, 2.392; 95% CI, 1.308 - 4.375) were significantly associated with a higher risk of the primary outcome. There were 20 cases of recurrence in RF-TC group, while there were 30 cases in PRF group. The short-term (within 3 months) postoperative recurrence rate was 14.93% in the RF-TC group and 37.31% in the PRF group. The differences in PSQI and NRSs between 2 groups were also statistically significant.
Limitations: The study uses a small sample size from a single center. The model built is not validated internally or externally. The conclusions of randomized controlled trials will be more convincing. Subgroup analysis of the disease course was not performed.
Conclusion: In the treatment of HZ-related pain, the use of PRF is significantly associated with a high short-term recurrence rate. However, compared with RF-TC, PRF results in milder numbness and less intraoperative pain. RF-TC may be a feasible procedure if patients can accept pain relief at the cost of long periods of numbness, whether RF-TC has the value of clinical promotion still needs to be further explored.
Keywords: postherpetic neuralgia; pulsed radiofrequency; thermocoagulation; Herpes zoster.