Bipolar High-Voltage, Long-Duration Pulsed Radiofrequency Improves Pain Relief in Postherpetic Neuralgia

Background: Postherpetic neuralgia (PHN) is often refractory to existing treatments. Treatment of the dorsal root ganglion (DRG) using monopolar pulsed radiofrequency (PRF), which is a nonor minimally neurodestructive technique, is not efficacious in all patients. Objectives: This study aimed to determine the safety and clinical efficacy of bipolar highvoltage, long-duration PRF on the DRG in PHN patients. Study Design: Self before-after controlled clinical trial. Setting: Department of Pain Medicine, the First Affiliated Hospital of China Medical University. Methods: Ninety patients diagnosed with PHN for > 3months were included. Bipolar highvoltage, long-duration PRF at 42°C for 900 seconds was applied after the induction of paresthesias covered the regions of hyperalgesic skin. The therapeutic effects were evaluated using a visual analog scale (VAS) and the 36-item Short Form health survey (SF-36) before treatment and one, 4, 8, and 12 weeks after PRF. Results: The VAS scores at one, 4, 8, and 12 weeks after PRF treatment were significantly lower than before treatment (P < 0.001). The SF-36 scores, which included physical functioning, physical role, bodily pain, general health perceptions, vitality, social function, emotional role, and the mental health index, were significantly improved up to 12 weeks after PRF treatment (P < 0.001). No serious adverse effects were identified following treatment. The main adverse reactions included pain, tachycardia, and high blood pressure (especially when the field strength was enhanced). Limitations: Single center study, relatively small number of patients, lack of a control group. Conclusion: Bipolar high-voltage, long-duration PRF on the DRG is an effective and safe therapeutic alternative for PHN patients. This treatment could improve the quality of life of PHN patients. Clinical Trial Registration: NO ChiCTR-OCS-14005461 Key words: Pulsed radiofrequency, postherpetic neuralgia, VAS, SF-36