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

Background: Lumbar facet joints are a well recognized source of low back pain and referredpain in the lower extremity in patients with chronic low back pain. Conventional clinical featuresand other non-invasive diagnostic modalities are unreliable in diagnosing lumbar zygapophysialjoint pain. Controlled diagnostic studies with at least 80% pain relief as the criterion standardhave shown the prevalence of lumbar facet joint pain to be 16% to 41% of patients with chroniclow 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 nerveblocks.Objective: To determine and update the diagnostic accuracy of lumbar facet joint nerve blocksin the assessment of chronic low back pain.Methods: A methodological quality assessment of included studies was performed usingQuality Appraisal of Reliability Studies (QAREL). Only diagnostic accuracy studies meeting atleast 50% of the designated inclusion criteria were utilized for analysis. Studies scoring less than50% are presented descriptively and analyzed critically.The level of evidence was classified as good, fair, and limited or poor based on the quality ofevidence developed by the United States Preventive Services Task Force (USPSTF).Data sources included relevant literature identified through searches of PubMed and EMBASEfrom 1966 to June 2012, and manual searches of the bibliographies of known primary andreview articles.Outcome Measures: Studies must have been performed utilizing controlled local anestheticblocks. Pain relief was categorized as at least 50% pain relief from baseline pain and the abilityto perform previously painful movements.Results: A total of 25 diagnostic accuracy studies were included. Of these, one study evaluated50% to 74% relief as criterion standard with a single block with prevalence of 48%, 4 studiesevaluated 75% to 100% relief as the criterion standard with a single block with a prevalence of31% to 61%, 5 studies evaluated 50% to 74% relief as the criterion standard with controlledblocks with a prevalence of 15% to 61%, and 13 studies evaluated 75% to 100% relief as thecriterion standard with controlled blocks with a prevalence of 25% to 45% in heterogenouspopulations. False-positive rates ranged from 17% to 66% in the 50% to 74% pain relief groupand 27% to 49% with at least 75% relief as the criterion standard. Based on this evaluation, theevidence showed that there is good evidence for diagnostic facet joint nerve blocks with 75% to100% 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 ispoor with single diagnostic blocks of 50% to 74%, and limited for 75% or more pain relief asthe criterion standard. Limitations: The shortcomings of this systematic review of the accuracy of diagnostic lumbar facet joint nerve blocks include apaucity 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 standardwith 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