Diagnostic Utility of Selective Nerve Root Blocks in the Diagnosis of Lumbosacral Radicular Pain: Systematic Review and Update of Current Evidence

Abstract

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. Key words: Low back pain, lower extremity pain, selective nerve root block, transforaminal epidural injection, discogenic pain, radiculitis, sciatica radiculopathy, nerve root pain

Spinal Injections: A Narrative Review from a Surgeon’s Perspective

“…Diagnostic selective nerve root blocks can be useful when the findings for preoperative imaging studies and clinical presentations are inconsistent, or when there are symptoms without particular findings on images [ 54 ]. When a diagnostic selective nerve root block is performed to identify an area that is the cause of pain, it is important to use a low volume injectate to increase the specificity of the diagnosis (recommended local anesthetic volume, 0.5 cc (without steroids)) [ 55 ]. It has been reported that the accuracy can be improved if the analgesic effect is simultaneously tested while determining whether a patient’s usual pain is evoked during the diagnostic selective nerve root block [ 56 ].…”

Clinical Outcomes of Percutaneous Transforaminal Endoscopic Discectomy Assisted with Selective Nerve Root Block for Treating Radicular Pain with Diagnostic Uncertainty in the Elderly

“…[4][5][6] However, it is not easy for the elderly population with multilevel lumbar spine degeneration or atypical pain, increasing diagnostic uncertainty. 6,7 Selective nerve root block (SNRB) was first described by Macnab et al in 1971 to treat lower leg radicular pain and remains a popular therapeutic and diagnostic option for radicular pain. 3,4,[6][7][8][9] Despite the fact that many studies have demonstrated that SNRB is a viable diagnostic tool for determining the responsible segment, only a few studies have focused on elderly patients with multilevel lumbar spine degeneration.…”

“…6,7 Selective nerve root block (SNRB) was first described by Macnab et al in 1971 to treat lower leg radicular pain and remains a popular therapeutic and diagnostic option for radicular pain. 3,4,[6][7][8][9] Despite the fact that many studies have demonstrated that SNRB is a viable diagnostic tool for determining the responsible segment, only a few studies have focused on elderly patients with multilevel lumbar spine degeneration. 7 Hence, this retrospective study included a group of elderly patients with radicular pain as the primary complaint but a doubtful diagnosis, to investigate the clinical outcomes of selective nerve root block combined with percutaneous transforaminal endoscopic discectomy.…”

Pain Relief After Selective Nerve Root Block as a Predictor of Postoperative Functional Outcome in Patients with Degenerative Lumbar Spinal Stenosis Patients Undergoing Decompressive Surgery

“…[6][7][8][9] Several reports have indicated the accuracy of SNRB for the prediction of affected nerve roots contributing to LLRP to be approximately 31% to 100%. 8,[10][11][12] In addition, SNRB is among the most effective nonsurgical treatment options for intractable sciatica. 13 As reported by Pfirmmann et al, 14 therapeutic SNRB is not a curative therapy; that is, it does not eliminate the pathological factors contributing to LLRP but rather provides temporary relief of peak pain as required for spontaneous resolution.…”

“…The use of SNRB to identify the most problematic spinal nerve root has been reported for patients with multilevel lumbar spinal stenosis or for those suffering from LLRP with ambiguous radiographic findings 6–9 . Several reports have indicated the accuracy of SNRB for the prediction of affected nerve roots contributing to LLRP to be approximately 31% to 100% 8,10–12 . In addition, SNRB is among the most effective nonsurgical treatment options for intractable sciatica 13 .…”