Background Studies have found that diffuse pain, indicative of central sensitization, portends poor interventional outcomes. Multiple chemical sensitivities are associated with signs of central sensitization. We sought to prospectively determine whether hypersensitivity reactions (HR) were associated with epidural steroid injection (ESI) outcomes.
Methods HR were classified as immune-related or non-immune-related and categorized by number (0=low, 1 or 2=intermediate, ≥3=high). The primary outcome measure was mean reduction in average leg pain score 1 month post-procedure. A positive outcome was defined as a two-point or greater decrease in average leg pain accompanied by satisfaction 1 month post-procedure.
Results The mean number of immune-mediated and non-immune-mediated HR were 0.6±1.2 and 0.8±1.4, respectively. Individuals in the high (n=24) total HR group had a mean reduction in average leg pain of 0.1±2.7, compared with those in the low (n=61; 1.8±2.1, p=0.025) and intermediate groups (n=52; 1.6±3.1, p=0.060). For back pain and categorical successful outcome, those with fewer HR experienced greater benefit. There were no differences in outcomes when patients were stratified by immune-related HR. Among participants in the low, intermediate and high non-immune-mediated HR groups, the mean reductions in average leg pain scores were 1.7±2.5, 1.6±3.0, and −0.2±2.3, respectively (p = 0.002). 51%, 35%, and 12% of people with low, intermediate and high numbers of non-immune-mediated HR experienced a positive categorical outcome, respectively (p=0.007).
Conclusions Non-immune-related HR were inversely correlated with some ESI outcome measures.
- neuraxial blocks: epidural
- interventional pain management
- spinal/epidural injection
- chronic pain: back pain
- chronic pain: central pain syndromes, fibromyalgia
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Contributors SPC contributed to the concept design. TLD contributed to the statistical analysis. SPC, TCD, SD, AJV, SRG, MS and CK contributed to the data collection. SPC and CK did the planning. SPC, TCD, AG, OCC, MBJ and CK contributed to the administrative requirements. SPC, TCD, AG, OCC, MBJ, SD, AJV, SRG, MS and CK were responsible for the patient enrolment and treatment. TCD, AG, OCC, MBJ, SD, AJV, SRG, MS and CK contributed to the critical review of manuscript. SPC and TLD contributed to the interpretation of data. SPC, TLD and TCD drafted the tables and figures. SPC and TLD drafted the manuscript.
Funding Funded in part by a grant from the Centers for Rehabilitation Sciences Research, US Department of Defense.
Competing interests SPC serves as a consultant to Semnur Pharmaceuticals, which is developing a steroid approved by the US FDA for epidural administration.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
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