Ultrasound-guided pulsed radiofrequency applied to intercostal nerves may be safe and effective for managing thoracic postherpetic neuralgia-associated pain, according to a study published in the Clinical Journal of Pain.
For this randomized, double-blind, placebo-controlled trial, 43 patients with postherpetic neuralgia for >6 months who attended an institutional pain clinic were enrolled. Investigators randomly assigned patients to receive ultrasound-guided pulsed radiofrequency (n=21) or a sham control (n=22) after 2 weeks of treatment with 150 mg pregabalin for 12 hours. Patients receiving radiofrequency underwent 2 cycles of the treatment at 42°C for 120 seconds over the intercostal nerves of the affected thoracic dermatome had been localized using ultrasound. Participants in the control group received a sham intervention that was of a similar duration.
Investigators assessed total analgesic consumption and pain scores using the Visual Analogue Scale at baseline, every 2 weeks for 6 months, and after 9 and 12 months. Quality-of-life outcomes were also evaluated with questionnaires at baseline and at 1, 3, 6, and 12 months after intervention.
Participants receiving radiofrequency treatment reported reduced pain scores from the second week after the start of treatment until the end of the study period (P <.001 for all).
Participants receiving radiofrequency treatment also consumed lower amounts of pregabalin and acetaminophen medications compared with patients in the control group, an effect that was sustained for 9 months (P <.001 for all). The general health perception, social function, mental health index, bodily pain index, vitality, and physical function domains of the Short-Form-36 questionnaire were also improved by the radiofrequency vs sham treatment at 1, 3, 6, and 12 months (P <.05 for all).
Limitations of the analysis include the small sample size and a reliance on self-evaluation of outcomes.
“[Pulsed radiofrequency] is a reproducible, non-destructive technique which has gained popularity among pain physician to induce long-term pain relief,” noted the study’s authors. “The mechanism by which [pulsed radiofrequency] causes pain relief is debatable. A popular theory is that the rapidly changing electric fields produced by [pulsed radiofrequency] alter the transmission of pain signals via a pathway involving c-Fos, a so-called immediate early gene,” they added.
Makharita MY, El Bendary HM, Sonbul ZM, Ahmed SES, Latif MA. Ultrasound-guided pulsed radiofrequency in the management of thoracic post-herpetic neuralgia: a randomized, double-blinded, controlled trial [published online May 11, 2018]. Clin J Pain. doi: 10.1097/AJP.0000000000000629