An updated systematic review of the diagnostic utility of selective nerve root blocks.

BACKGROUND Selective nerve root blocks or transforaminal epidural injections are used for diagnosis and treatment of different spinal disorders. A clear consensus on the use of selective nerve root injections as a diagnostic tool does not currently exist. Additionally, the effectiveness of this procedure as a diagnostic tool is not clear. A systematic review of diagnostic utility of selective nerve root blocks was performed and published in January 2005, which concluded that selective nerve root injections may be helpful as a diagnostic tool in evaluating spinal pain with radicular features, but its role needs to be further clarified. OBJECTIVE To evaluate and update the accuracy of selective nerve root injections in diagnosing spinal disorders. STUDY DESIGN A systematic review of selective nerve root blocks for the diagnosis of spinal pain. METHODS A systematic review of the literature for clinical studies was performed to assess the accuracy of selective nerve root injections in diagnosing spinal pain. Methodologic quality evaluation was performed utilizing Agency for Healthcare Research and Quality (AHRQ) and Quality Assessment Studies of Diagnostic Accuracy (QUADAS) criteria. Studies were graded and evidence classified into 5 levels: conclusive, strong, moderate, limited, or indeterminate. An extensive literature search was performed utilizing resources from the library at Vanderbilt University Medical Center, PubMed, EMBASE, BioMed, and Cochrane Reviews. Manual searches of bibliographies of known primary and review articles, and abstracts from scientific meetings within the last 2 years were also reviewed. RESULTS There is limited evidence on the effectiveness of selective nerve root injections as a diagnostic tool for spinal pain. There is insufficient research for stronger support, but the available literature is supportive of selective nerve root injections as a diagnostic test for equivocal radicular pain. There is moderate evidence for use in the preoperative evaluation of patients with negative or inconclusive imaging studies. The positive predictive value of diagnostic selective nerve 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 evaluating spinal pain with radicular features. However, their role needs to be further clarified by additional research and consensus.