Diagnostic utility of selective nerve root blocks in the diagnosis of lumbosacral radicular pain: systematic review and update of current evidence.

BACKGROUND   Lumbosacral selective nerve root blocks and/ or transforaminal epidural injections are used for diagnosis and treatment of different disorders causing low back and lower extremity pain. A clear consensus on the use of selective nerve root injections as a diagnostic tool does not currently exist. Additionally, the validity of this procedure as a diagnostic tool is not clear. OBJECTIVE To evaluate and update the accuracy of selective nerve root injections in diagnosing lumbar spinal disorders. STUDY DESIGN A systematic review of selective nerve root blocks for the diagnosis of low back and lower extremity pain. METHODS Methodological quality assessment of included studies was performed using the Quality Appraisal of Reliability Studies (QAREL) checklist. 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, or limited or poor based on the quality of evidence grading scale 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 September 2012, and manual searches of the bibliographies of known primary and review articles. OUTCOME MEASURES In this review, we evaluated studies in which controlled local anesthetic blocks were performed using at least 50% pain relief as the reference standard. RESULTS There is limited evidence for the accuracy of selective nerve root injections as a diagnostic tool for lumbosacral disorders. There is limited evidence for their use in the preoperative evaluation of patients with negative or inconclusive imaging studies. LIMITATIONS The limitations of this systematic review include a paucity of literature, variations in technique, and variable criterion standards for the diagnosis of lumbar radicular pain. CONCLUSIONS There is limited evidence for selective nerve root injections as a diagnostic tool in evaluating low back pain with radicular features. However, their role needs to be further clarified by additional research and consensus.