A Randomized, Double-Blind Controlled Trial of Lumbar Interlaminar Epidural Injections in Central Spinal Stenosis: 2-Year Follow-Up

Background: While low back pain is the number one cause of disability in the United States, lumbar spinal stenosis along with intervertebral disc herniation and degenerative spondylolisthesis is one of the 3 most common diagnosis of low back and leg pain for which surgery is performed. Numerous modalities of treatments including drug therapy and complex surgical fusions have been recommended for treatment of central spinal stenosis. Epidural injections are one of the commonly performed nonsurgical interventions in managing central spinal stenosis; however, there has been paucity of literature in reference to efficacy of epidural injections in managing central spinal stenosis with lumbar interlaminar epidural injections. Study Design: A randomized, double-blind, active controlled trial. Setting: Private interventional pain management practice and specialty referral center in the United States. Objective: To assess the effectiveness of lumbar interlaminar epidural injections with or without steroids in providing effective and long-lasting pain relief with improvement in functional status for the management of chronic low back and lower extremity pain related to lumbar central spinal stenosis. Methods: A randomized, double-blind, active-control trial was designed with the inclusion of 120 patients assigned to 2 groups. Group I patients received lumbar interlaminar epidural injections of local anesthetic (lidocaine 0.5%) 6 mL, whereas Group II received lumbar interlaminar epidural injections with local anesthetic (lidocaine 0.5%) 5 mL mixed with 1 mL of steroids and 6 mg of betamethasone. Outcomes Assessment: Outcomes were assessed utilizing the numeric pain rating scale (NRS) and Oswestry Disability Index (ODI) at 3, 6, 12, 18, and 24 months post treatment. The primary outcome measure was significant improvement, defined as 50% improvement in pain and disability scores. Results: Significant relief and functional status improvement was seen in 72% and 73% of patients in Groups I and II at the end of 2 years considering all participants; however, this was 84% and 85% in the successful group. Overall significant improvement was achieved for 65.7 +/- 37.3 weeks in Group 1 and 68.9 +/- 37.7 weeks in Group II at the end of 2 years when all participants were considered; whereas, this was 77 +/- 27.8 weeks and 77.9 +/- 30.2 weeks when they were separated into successful categories. The average number of procedures per patient was 5 to 6 in both groups. Limitations: Limitations of this trial include lack of placebo control group and treatment of patients with multiple procedures over a period of 2 years. Conclusion: Lumbar interlaminar epidural injections of local anesthetic with or without steroids provide relief in a significant proportion of patients with lumbar central spinal stenosis.