Efficacy of Pulsed Radiofrequency in the Treatment of Thoracic Postherpetic Neuralgia from the Angulus Costae: A Randomized, Double-Blinded, Controlled Trial

Background: Postherpetic neuralgia (PHN) is often refractory to existing treatments. Pulsed radiofrequency(PRF) is known to be effective for treating neuropathic pain. In common, the targets of PRF treatment werethe segmental dorsal root ganglion (DRG) neurons responsible for the pain. A potential complication thatcan occasionally occur with PRF treatment is damage to the adjacent tissue and organ. The effectiveness ofthe angulus costae as a puncture site for PRF has not been tested in thoracic PHN treatment.Objective: The goal of this study was to investigate the therapeutic efficacy and safety of PRF fortreating thoracic PHN through the puncture of the angulus costae.Study Design: Prospective, randomized, double-blinded study.Setting: Department of Anesthesiology, Xinhua Hospital, Shanghai Jiaotong University School ofMedicine.Methods: Ninety-six patients with thoracic (T2-11) PHN were equally randomized assigned into 2groups. The electrode needle punctured through the angulus costae of each patient guided by x-ray; PRFat 42°C for 120 seconds was applied after inducing paresthesia involving the affected dermatome area.PRF was applied in the PRF group (n = 48) twice. It was also applied in the sham group (n = 48) twicewithout radiofrequency energy output. The treatment was done once a week for 3 weeks. Tramadol wasused for flare pain when the visual analog scale (VAS) ≥ 3.Outcomes Assessment: The therapeutic effect was evaluated by VAS, SF-36 health surveyquestionnaire, side effects (type, frequency, and onset time) before treatment, at days 3, 7, and 14,and at months one, 2, 3 and 6 after PRF. The average of tramadol (mg/d) administrated within the firstmonth after treatment was also recorded.Results: The postprocedure VAS scores in the PRF group were significantly lower than those in the shamgroup and lasted for 6 months after treatment (P < 0.05). The SF-36 score, such as physical functioning,physical role, bodily pain, general health perceptions, social function, emotional role, and mental health indexwere significantly improved until 6 months after treatment in the PRF group compared to the sham group (P <0.01-0.05). The average dosage of tramadol administered (mg/d) within the first month after treatment wasalso significantly reduced in the PRF group compared to the sham group (P < 0.05). There were no obvioussigns of pneumothorax, bleeding, infection, or other severe side effects in either group (P > 0.05).Limitations: Single center study, relatively small number of patients.Conclusions: The strategy that the angulus costae be used as the PRF puncture point of an electrodeneedle and the final localization of the needle tip as determined by sensory testing is an effective andsafe therapeutic alternative for thoracic PHN treatment. Benefits include that the procedure is minimallyinvasive, provides short-term pain relief, and improves quality of life.Clinical Trial Registration: NO ISRCTN25588650.Key words: Thoracic, postherpetic neuralgia, pulsed radiofrequency, angulus costae