Epidural steroid injections (ESI) are the most commonly performed pain procedures. Despite numerous studies, controversy continues to surround their effectiveness. The purpose of this study is to determine whether a standard, clinical local anesthetic injection can predict outcomes for ESI.Study Design.
In this multicenter study, 103 patients received two ESI 2 weeks apart. Prior to their first injection, subjects rated the pain intensity of a standardized subcutaneous (SQ) injection of lidocaine prior to the full dose. Numerical rating scale pain scores were correlated with leg and back pain relief, and functional improvement, through 3-month follow-up.Outcome Measures.
A composite successful outcome was predetermined to be a ≥2-point decrease in leg pain score, coupled with a positive global perceived effect.Results.
A small but significant relationship was found between SQ pain score and reduction in leg (r= −0.21, 95% CI −0.38 to −0.04;P= 0.03) and back pain (r= −0.22, 95% CI −0.36 to −0.07;P= 0.03). Subjects with a positive outcome at 1 month had a mean SQ pain score of 2.5 (SD 1.9) vs 4.1 (SD 2.7) in those with a negative outcome (P= 0.04). Subjects with SQ pain scores <4/10 had lower leg and back pain scores than those with pain scores ≥4 at 1-month (mean 3.2, SD 2.6 vs 5.1, SD 2.7 for leg,P< 0.01; mean 3.7, SD 2.6 vs 5.0, SD 3.0 for back,P= 0.02) and 3-month (mean 3.8, SD 2.7 vs 5.2, SD 3.1 for leg,P= 0.01; mean 4.0, SD 2.6 vs 4.9, SD 3.1 for back;P= 0.14) follow-up.Conclusions.
The results of this study found a weak positive correlation between SQ pain scores and treatment results. Further research should consider whether pain perception in conjunction with other variables might prove to be a reliable predictor for ESI and other procedural outcomes.