An Updated Systematic Review of the Diagnostic Utility of Selective Nerve Root Blocks

Background: Selective nerve root blocks or transforaminal epidural injections are used fordiagnosis and treatment of different spinal disorders. A clear consensus on the use of selectivenerve root injections as a diagnostic tool does not currently exist. Additionally, the effectivenessof this procedure as a diagnostic tool is not clear. A systematic review of diagnostic utility ofselective nerve root blocks was performed and published in January 2005, which concluded thatselective nerve root injections may be helpful as a diagnostic tool in evaluating spinal pain withradicular features, but its role needs to be further clarified.Objective: To evaluate and update the accuracy of selective nerve root injections in diagnosingspinal disorders.Study Design: A systematic review of selective nerve root blocks for the diagnosis of spinalpain.Methods: A systematic review of the literature for clinical studies was performed to assessthe accuracy of selective nerve root injections in diagnosing spinal pain. Methodologic qualityevaluation was performed utilizing Agency for Healthcare Research and Quality (AHRQ) and QualityAssessment Studies of Diagnostic Accuracy (QUADAS) criteria. Studies were graded and evidenceclassified into 5 levels: conclusive, strong, moderate, limited, or indeterminate. An extensiveliterature search was performed utilizing resources from the library at Vanderbilt University MedicalCenter, PubMed, EMBASE, BioMed, and Cochrane Reviews. Manual searches of bibliographies ofknown primary and review articles, and abstracts from scientific meetings within the last 2 yearswere also reviewed.Results: There is limited evidence on the effectiveness of selective nerve root injections asa diagnostic tool for spinal pain. There is insufficient research for stronger support, but theavailable literature is supportive of selective nerve root injections as a diagnostic test for equivocalradicular pain. There is moderate evidence for use in the preoperative evaluation of patients withnegative or inconclusive imaging studies. The positive predictive value of diagnostic selectivenerve root blocks is low, but they have a useful negative predictive value.Conclusion: Selective nerve root injections may be helpful as a diagnostic tool in evaluatingspinal pain with radicular features. However, their role needs to be further clarified by additionalresearch and consensus.Keywords: Selective nerve root block, transforaminal epidural injection, spinal pain, discogenicpain, radiculopathy, nerve root pain