Concordant provocation as a prognostic indicator during interlaminar lumbosacral epidural steroid injections

Interlaminar epidural steroid injection is a well-established intervention for the treatment of radicular pain. Pain is commonly reported during the injection into the epidural space; this provocation is typically either concordant or discordant with the patient's baseline pain. It is not well known how this provocation pain relates to treatment outcomes. To determine the relationship between concordant versus discordant provocation during interlaminar epidural steroid injection and its effects on pain reduction at follow-up. Secondary analysis of a single center, prospective randomized double-blind study. Interlaminar epidural steroid injections under fluoroscopic guidance were performed on 48 patients with radicular lumbosacral pain. After injection with 80 mg methylprednisolone and 2 mL of normal saline at a single level, patients were asked to report if pain was provoked, and whether the pain was concordant or discordant with their baseline pain. The primary outcome measure was self-rated percentage of pain reduction from baseline at 2-week follow-up. Secondary outcomes included improvement in activity level and decreased analgesic consumption. Provocation was observed in 37 out of 48 patients (77%). This was further classified as concordant (22/37, 60%) or discordant (15/37, 40%) pain. The concordant group achieved a significant decrease in self-reported pain as compared to the discordant group at 2-week follow-up (61%, t = 2.45, P < 0.01). There were also significantly more patients in the concordant group who reported 75% pain reduction as compared to the discordant group (X = 6.44, df(1), P < 0.05). There were no significant differences between concordant and discordant groups in regard to improvements in activity level (X = 2.56) and decreased analgesic use (X = 3.28). The secondary analysis did not examine long-term outcomes. The concordant group demonstrated significantly higher pain reduction as compared to the discordant group. There were no significant differences between the 2 groups in terms of improved function or reduced analgesic requirements. Concordant provocation during interlaminar epidural injection may be a predictor of outcome.