Lumbar epidural steroid injections for lumbosacral radicular pain in patients with normal imaging: A propensity-matched study.

Background: Epidural steroid injections are indicated for radicular pain, with a pre-injection MRI not mandated in guidelines. There is conflicting evidence that MRI findings correlate with outcomes. Methods: Fourteen patients with near-normal imaging (i.e., no evidence of nerve root compression and minor degenerative changes if present) who underwent ESI for lumbosacral radicular pain and were followed for up to 12 weeks were propensity matched against 14 patients with radicular pain secondary to concordant MRI pathology. The primary outcome measure was mean reduction in average leg pain relief at 4 and 12 weeks. Secondary outcome measures included average back pain, function, analgesic reduction, satisfaction, and a categorical measure of success predesignated as a ≥2-point decrease in average leg pain score coupled with a positive global perceived effect and not requiring any additional intervening interventions. Results: For mean reduction in average leg pain at 4 weeks, there were no significant differences between those with near-normal MRIs and those with abnormal imaging (2.36 (SD 2.55) vs. 2.61 (SD 2.15); P = 0.72). For average back pain reduction at the same time point, the mean reduction was 0.75 (1.73) among cases vs. 1.07 (2.01) in control patients (P = 0.57). There were also no differences observed in pain reduction outcomes at 12 weeks. The average reduction in Oswestry Disability Index at 12 weeks favored the near-normal imaging group (8.64 % (SD 11.36) vs. 0 % (7.69); P = 0.047). A trend was noted wherein more patients with abnormal imaging experienced a positive outcome at 4 weeks (50 % vs. 28.57 %; P = 0.22) but not 12 weeks (28.57 % in both groups). Conclusions: There were no significant differences in pain outcomes compared to control patients, though patients with near-normal imaging fared worse than historical controls and the larger cohort from which propensity-matched patients were selected. The possibility of poorer outcomes should be considered when selecting patients with normal imaging and radiculopathy for ESI.