Concordant Provocation as a Prognostic Indicator During Interlaminar Lumbosacral Epidural Steroid Injections

Background: Interlaminar epidural steroid injection is a well-established intervention for thetreatment 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 notwell known how this provocation pain relates to treatment outcomes.Objective: To determine the relationship between concordant versus discordant provocationduring interlaminar epidural steroid injection and its effects on pain reduction at follow-up.Study Design: Secondary analysis of a single center, prospective randomized double-blind study.Methods: Interlaminar epidural steroid injections under fluoroscopic guidance were performedon 48 patients with radicular lumbosacral pain. After injection with 80 mg methylprednisoloneand 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 outcomemeasure was self-rated percentage of pain reduction from baseline at 2-week follow-up. Secondaryoutcomes included improvement in activity level and decreased analgesic consumption.Results: Provocation was observed in 37 out of 48 patients (77%). This was further classifiedas concordant (22/37, 60%) or discordant (15/37, 40%) pain. The concordant group achieved asignificant decrease in self-reported pain as compared to the discordant group at 2-week followup (61%, t = 2.45, P < 0.01). There were also significantly more patients in the concordant groupwho 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 toimprovements in activity level (X = 2.56) and decreased analgesic use (X = 3.28).Limitations: The secondary analysis did not examine long-term outcomes.Conclusions: The concordant group demonstrated significantly higher pain reduction ascompared to the discordant group. There were no significant differences between the 2 groupsin terms of improved function or reduced analgesic requirements. Concordant provocation duringinterlaminar epidural injection may be a predictor of outcome.Key words: Lumbar epidural steroid injection, steroids, interlaminar injection, lumbar,lumbosacral, provocation, pressure paresthesia, low back pain