Long-Term Effects of Repeated Injections of Local Anesthetic With or Without Corticosteroid for Lumbar Spinal Stenosis: A Randomized Trial.

Objective: To determine the overall long-term effectiveness of treatment with epidural corticosteroid injections for lumbar central spinal stenosis and the effect of repeat injections, including crossover injections, on outcomes through 12 months.

Design: Multicenter, double-blind, randomized controlled trial comparing epidural injections of corticosteroid plus lidocaine versus lidocaine alone. Setting: Sixteen clinical sites. Participants: Participants with imaging-confirmed lumbar central spinal stenosis (N=400). Interventions: Participants were randomized to receive either epidural injections with corticosteroid plus lidocaine or lidocaine alone with the option of blinded crossover after 6 weeks to receive the alternate treatment. Participants could receive 1 to 2 injections from 0 to 6 weeks and up to 2 injections from 6 to 12 weeks. After 12 weeks, participants received usual care. Main outcome measures: Primary outcomes were the Roland-Morris Disability Questionnaire (RDQ) (range, 0-24, where higher scores indicate greater disability) and leg pain intensity (range, 0 [no pain] to 10 [pain as bad as you can imagine]). Secondary outcomes included opioid use, spine surgery, and crossover rates.

Results: At 12 months, both treatment groups maintained initial observed improvements, with no significant differences between groups on the RDQ (adjusted mean difference, -0.4; 95% confidence interval [CI], -1.6 to 0.9; P=.55), leg pain (adjusted mean difference, 0.1; 95% CI, -0.5 to 0.7; P=.75), opioid use (corticosteroid plus lidocaine: 41.4% vs lidocaine alone: 36.3%; P=.41), or spine surgery (corticosteroid plus lidocaine: 16.8% vs lidocaine alone: 11.8%; P=.22). Fewer participants randomized to corticosteroid plus lidocaine (30%, n=60) versus lidocaine alone (45%, n=90) crossed over after 6 weeks (P=.003). Among participants who crossed over at 6 weeks, the 6- to 12-week RDQ change did not differ between the 2 randomized treatment groups (adjusted mean difference, -1.0; 95% CI, -2.6 to 0.7; P=.24). In both groups, participants crossing over at 6 weeks had worse 12-month trajectories compared with participants who did not choose to crossover.

Conclusions: For lumbar spinal stenosis symptoms, epidural injections of corticosteroid plus lidocaine offered no benefits from 6 weeks to 12 months beyond that of injections of lidocaine alone in terms of self-reported pain and function or reduction in use of opioids and spine surgery. In patients with improved pain and function 6 weeks after initial injection, these outcomes were maintained at 12 months. However, the trajectories of pain and function outcomes after 3 weeks did not differ by injectate type. Repeated injections of either type offered no additional long-term benefit if injections in the first 6 weeks did not improve pain.