• Jae Ni Jang, Soyoon Park, Ji-Hoon Park, Yumin Song, Young Uk Kim, Dong Seong Kim, Jeong Eun Sohn, and Sukhee Park.
• Department of Anesthesiology and Pain Medicine, International St. Mary's Hospital, Catholic Kwandong University School of Medicine, Incheon, Republic of Korea.
• Pain Physician. 2023 Nov 1; 26 (7): E797E804E797-E804.

BackgroundLumbar radicular pain (LRP) is a common but challenging clinical symptom. Pulsed radiofrequency (PRF), a neuromodulation technique that uses short pulses of radiofrequency current, is effective in treating various pain disorders. However, few studies have been conducted on the effects of PRF and its modifying parameters.ObjectivesOur study aimed to determine the intraoperative parameters of PRF of the lumbar dorsal root ganglion (DRG) that are related to clinical effects in patients with LRP unresponsive to transforaminal epidural steroid injections (TFESI).Study DesignProspective double-blind randomized controlled trial, pilot study.SettingSingle medical center in the Republic of Korea.MethodsPatients were allocated to one of 2 groups, high-voltage (60 V) or standard-voltage (45 V), according to the preset maximum voltage at which the active tip temperature does not exceed 42°C. Intraoperative parameters, such as output current, sensory threshold, and impedance, were measured. The primary outcomes were radicular pain intensity, physical functioning, global improvement and satisfaction with treatment, and adverse events. The assessments were performed up to 3 months postprocedure.ResultsThe patients in the standard-voltage group showed significant improvements in the Numeric Rating Scale pain score (P = 0.007) and Oswestry Disability Index (ODI) (P = 0.008) scores at 3 months post-PRF; however, no difference was observed in the high-voltage group. Among the intraoperative parameters, the output current showed a significant negative linear relationship with analgesic efficacy. The output current also showed a significant association with pain intensity (P = 0.005, R2 = 0.422) and ODI score (P = 0.004, R2 = 0.427) at 3 months postprocedure in a multiple regression analysis. The optimal cut-off value of the output current to lower pain intensity after 3 months was 163.5 mA with a sensitivity of 87.5%, specificity of 100%, and an area under the receiver operating characteristic curve value of 0.92 (95% CI. 0.76 - 1.00).LimitationsLimitations of our study include an imbalance of baseline characteristics, small sample sizes, and short follow-up periods.ConclusionsLower output currents during PRF application to the lumbar DRG were associated with greater analgesic effects in patients who did not respond to therapeutic TFESI.

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