Comparative study of positive predictive value of diagnostic single versus dual median branch block for radiofrequency neurotomy in lumbar facet joint syndrome

Abstract

Background: Almost 60%–85% of people suffer from low back pain once in their lifetime. Due to a large number of pain generators, many a times lower back pain pose as enigma. Many clinical trials have shown validity of median branch block (MBB) in the management of chronic low back pain arising from facet joint pathology. Single blocks result in 27%–63% false positives, whereas double controlled blocks significantly decrease the false positives and increases the sensitivity to 54% and specificity to 88%. The aim of our study was to determine positive predictive value of diagnostic single and dual MBB for radiofrequency (RF) neurotomy in patients with facet joint arthropathy in Indian population. Subjects and Methods: Thirty patients allocated into two groups (n = 15), Group S - Single diagnostic MBB and Group D - Dual diagnostic MBB. Numerical Rating Score (NRS) and Roland Morris Disability Questionnaire (RMDQ) were recorded in all patients in both the groups at multiple times. Pre and postprocedure NRS and RMDQ score in both the groups were statistically compared. Results: NRS in Group D was lower as compared to Group S 1 month after neurotomy (P = 0.034). RMDQ in Group D 1 month after RF neurotomy was lower as compared to Group S (P = 0.045). The positive predictive value in Group S with single MBB is 66.6%, whereas the positive predictive value in Group D with dual MBB is 86.6% at the end of 1 month post-RF ablation. Conclusions: Single MBB injection for diagnosis of facet joint syndrome yields many false positives results and the positive predictive value for the same is lower as compared to Dual MBB.