Radiofrequency lumbar facet denervation: analysis of prognostic factors

Abstract

Percutaneous radiofrequency lumbar facet denervation has been in use as a treatment for intractable, mechanical low back pain for over 2 decades. A number of case series have been reported with high rates of success in selected patients; however, there has been limited objective outcome assessment, long-term follow-up, and analysis of prognostic factors. We have reviewed our experience with diagnostic lumbar facet blocks and percutaneous radiofrequency denervation at a mean follow-up interval of 3.2 years. Long-term outcome has been assessed by disinterested third party interview. Of 82 patients selected for these procedures, 56 had undergone prior low back surgery. Following diagnostic medial branch posterior primary ramus blocks, 42 reported at least 50% relief of pain and proceeded to radiofrequency denervation. Forty-five percent of patients undergoing denervation reported at least 50% relief of pain at long-term follow-up. Among the 40 patients who only underwent temporary blocks, 13% reported relief (i.e., spontaneous improvement or placebo effect) by at least 50% at long-term follow-up). By multivariate statistical analysis, patients undergoing bilateral blocks for bilateral or axial symptoms were significantly more likely to achieve temporary relief, and to proceed to permanent denervation. There was no difference, however, between the long-term results of bilateral denervation for bilateral or axial pain and those of unilateral denervation for unilateral pain. There was no significant difference in the rate of response between the 56 patients who had undergone prior lumbosacral spine surgery and the 26 who had not. There were no complications from the procedure. Percutaneous radiofrequency lumbar facet denervation has a moderate overall long-term yield, with no morbidity in our experience, and so remains a clinically useful technique in properly selected patients. Diagnostic blocks, used routinely in patient selection, may lack specificity in predicting long-term-response to denervation.