Effects of interlaminar epidural steroid injection in patients with moderate to severe lumbar central spinal stenosis: a prospective study.

Background: In this study, we evaluated the outcome of interlaminar epidural steroid injection ( ESI) in patients with chronic pain induced by moderate or severe lumbar central spinal stenosis (LCSS), and compared the effects of interlaminar ESI according to the severity of LCSS. Methods: Sixty patients with chronic lower extremity pain due to LCSS were included and received interlaminar ESI. Two patients were lost to follow-up. On the basis of sagittal lumbar magnetic resonance imaging findings, 30 patients had moderate LCSS (group A) and 28 patients had severe LCSS (group B). Pain intensity was evaluated using a numeric rating scale (NRS) before treatment and at 1, 2, and 3 months after treatment. Results: In all the recruited patients, pain intensity was significantly lower at each evaluation time point compared to that before treatment. Intragroup analysis revealed that patients in each group showed a significant decrease in pain intensity at 1, 2, and 3 months after treatment. However, at 3 months after treatment, only 9 patients (30.0%) in group A and 5 patients (17.9%) in group B reported successful pain relief (pain relief of =50%). Pain intensity was significantly lower in group A than in group B at each evaluation time point. Conclusions: Interlaminar ESI might be effective for alleviating pain induced by moderate or severe LCSS, but its effectiveness appears to be limited. Patients with severe LCSS showed worse treatment outcome compared to patients with moderate LCSS.