Impact of temperature on the magnitude and duration of relief after lumbar facets medial branch nerves radiofrequency ablation: a randomized double-blinded study

Introduction: There are numerous studies appraising the variables that may influence the clinical outcomes after lumbar thermal radiofrequency ablation (RFA). Expanding the lesion size may increase the likelihood of capturing the target nerves in the lesion, thereby increasing the technical success rate of RFA. However, our literature search has failed to identify a consensus on the optimal target temperature. A retrospective study demonstrated that there seems to be significant functional improvement associated with the temperature of 90°C compared with 80°C. The authors prospectively studied the subject in a double-blinded randomized fashion.

Methods: Patients undergoing RFA for lumbar facetogenic pain were randomized in two cohorts (80°C and 90°C). Physicians and patients were blinded to the temperature used. The primary outcome was self-reported pain scores up to 12 months. Secondary outcomes included: self-reported functional improvement, duration of relief as measured by the time before repeat ablation of the same medial branches nerves, opioids' consumption, and patient satisfaction.

Results: Both groups reported pain improvement in all follow-up time points. Overall, both groups achieved statistically significant pain reduction (p<0.05). The median time to repeat RFA in the 80°C group was 112 (49-252) days, while it was 217 (198-348) days in the 90°C group (p<0.04). The univariate analysis emphasized that the RFA temperature is a statistically significant factor for pain improvement of more than 50%, OR 2.7 (1.1 to 6.6) p value=0.031.

Conclusion: RFA has been demonstrated as an effective therapeutic modality for lumbar facetogenic back pain. Yet, the several factors involved in determining a favorable outcome of this procedure require further research and optimization. This prospective double-blinded randomized trial demonstrated that RFA at both temperatures (80°C, 90°C) provided significance at all the time periods examined. However, RFA at 90°C was superior to 80°C in regard to the duration of relief.