An Update of the Systematic Assessment of the Diagnostic Accuracy of Lumbar Facet Joint Nerve Blocks

Abstract

Background: Lumbar facet joints are a well recognized source of low back pain and referred pain in the lower extremity in patients with chronic low back pain. Conventional clinical features and other non-invasive diagnostic modalities are unreliable in diagnosing lumbar zygapophysial joint pain. Controlled diagnostic studies with at least 80% pain relief as the criterion standard have shown the prevalence of lumbar facet joint pain to be 16% to 41% of patients with chronic low back pain without disc displacement or radiculitis, with a false-positive rate of 17% to 49% with a single diagnostic block. Study Design: A systematic review of the diagnostic accuracy of lumbar facet joint nerve blocks. Objective: To determine and update the diagnostic accuracy of lumbar facet joint nerve blocks in the assessment of chronic low back pain. Methods: A methodological quality assessment of included studies was performed using Quality Appraisal of Reliability Studies (QAREL). Only diagnostic accuracy studies meeting at least 50% of the designated inclusion criteria were utilized for analysis. Studies scoring less than 50% are presented descriptively and analyzed critically. The level of evidence was classified as good, fair, and limited or poor based on the quality of evidence developed by the United States Preventive Services Task Force (USPSTF). Data sources included relevant literature identified through searches of PubMed and EMBASE from 1966 to June 2012, and manual searches of the bibliographies of known primary and review articles. Outcome Measures: Studies must have been performed utilizing controlled local anesthetic blocks. Pain relief was categorized as at least 50% pain relief from baseline pain and the ability to perform previously painful movements. Results: A total of 25 diagnostic accuracy studies were included. Of these, one study evaluated 50% to 74% relief as criterion standard with a single block with prevalence of 48%, 4 studies evaluated 75% to 100% relief as the criterion standard with a single block with a prevalence of 31% to 61%, 5 studies evaluated 50% to 74% relief as the criterion standard with controlled blocks with a prevalence of 15% to 61%, and 13 studies evaluated 75% to 100% relief as the criterion standard with controlled blocks with a prevalence of 25% to 45% in heterogenous populations. False-positive rates ranged from 17% to 66% in the 50% to 74% pain relief group and 27% to 49% with at least 75% relief as the criterion standard. Based on this evaluation, the evidence showed that there is good evidence for diagnostic facet joint nerve blocks with 75% to 100% pain relief as the criterion standard with dual blocks and fair evidence with 50% to 74% pain relief as the criterion standard with controlled diagnostic blocks; however, the evidence is poor with single diagnostic blocks of 50% to 74%, and limited for 75% or more pain relief as the criterion standard. Limitations: The shortcomings of this systematic review of the accuracy of diagnostic lumbar facet joint nerve blocks include a paucity of literature and continued debate on an appropriate gold standard. Conclusion: There is good evidence for diagnostic facet joint nerve blocks with 75% to 100% pain relief as the criterion standard with dual blocks, with fair evidence with 50% to 74% pain relief. Key words: Chronic low back pain, lumbar facet or zygapophysial joint pain, facet joint nerve blocks, medial branch blocks, controlled comparative local anesthetic blocks