Electromyography and Therapeutic Response to Lumbosacral Epidural Steroid Injections: A Systematic Review

The association between electromyography (EMG)-confirmed lumbosacral (LS) radiculopathy and pain outcomes following epidural steroid injection (ESI) has not been systematically summarized. The primary objective of this systematic review was to summarize the effects of EMG-confirmed LS radiculopathy on pain intensity following ESI. A secondary objective was to summarize the effects of EMG-confirmed LS radiculopathy on physical functioning following ESI. An a priori protocol was registered and a database search conducted by a reference librarian from January 2000 through December 2020. The search was date-limited to ensure the results of the systematic review represented contemporary clinical practice. Study-inclusion criteria included randomized trials, prospective and retrospective studies, cross-sectional studies, case series, and case reports, age ≥18 years, and use of EMG as a prognostic tool prior to an ESI. Two independent reviewers screened all titles, abstracts, and full texts. Data were extracted using a templated electronic database. The risk of bias was assessed using the Risk of Bias in Nonrandomized Studies of Interventions tool and certainty in evidence assessed using the Grading of Recommendations, Assessment, Development, and Evaluation approach. Due to clinical heterogeneity in study characteristics, a meta-analysis was not performed. A total of 454 studies were screened, and eight nonrandomized studies met the inclusion criteria. Five studies had a moderate risk of bias, two serious risks, and one a critical risk. The key findings included four of eight nonrandomized studies reporting a significant association between EMG-confirmed radiculopathy and ESI response and four of eight nonrandomized studies reporting no significant association. Important sources of bias limited interpretation of individual study findings, and multiple sources of clinical heterogeneity limited between-study comparisons. The findings of this systematic review demonstrate that associations existed between EMG-confirmed LS radiculopathy and pain outcomes after ESI in some, but not all studies. These results should be carefully interpreted with full understanding of the risk of bias and very low certainty in evidence that characterize the nonrandomized studies comprising this systematic review.