The Short-Term Outcome of Transforaminal Epidural Steroid Injection in Patients with Radicular Pain Due to Foraminal Stenosis from Lumbar Isthmic Spondylolisthesis.

Purpose: In this study, we evaluated the therapeutic outcomes of transforaminal epidural steroid injection (TFESI) in managing chronic radicular pain due to foraminal stenosis. Furthermore, we evaluated its effectiveness according to isthmic spondylolisthesis (IS) severity. Patients and Methods: We included 40 patients with radicular pain due to IS-derived foraminal stenosis in our study and treated them with TFESI. Two patients were lost during follow-up. Based on the lateral lumbar radiograph findings, we allocated the recruited patients with < 25% slippage by IS to Group 1 (n = 23) and those having 25-50% slippage to Group 2 (n = 15). The degree of pain was measured using a numeric rating scale (NRS) at pre-treatment and 1 and 2 months after TFESI. Results: In 38 patients who completed the study, the NRS at pre-treatment was significantly reduced at the 1- and 2-month follow-ups. In the Group analysis, the NRS scores were significantly reduced after TFESI in both Groups 1 and 2, regardless of IS severity. However, the reduction in NRS scores 1 month after TFESI was significantly greater in Group 1 than in Group 2. Moreover, the rate of successful treatment outcomes was significantly higher (65.2%) in Group 1 than in Group 2 (26.7%). Conclusion: After TFESI, chronic radicular pain was significantly reduced regardless of IS severity, and its effect persisted for at least 2 months. However, its effect was superior when the vertebra slippage by IS was less than 25% compared to patients with 25%-50%.