Interlaminar versus Transforaminal Epidural Steroid Injections for the Treatment of Symptomatic Lumbar Spinal Stenosis

Background. Lumbar spinal stenosis is a common condition that causes axial low back pain, radicular pain, and neurogenic claudication. Epidural steroid injections are commonly used for the treatment of radicular symptoms and neurogenic claudication associated with symptomatic lumbar spinal stenosis. No prior study has evaluated whether transforaminal or interlaminar epidural steroid injections produce better clinical outcomes. Design. Retrospective case control study. Methods. For each technique, 19 patients were retrospectively identified who received their first fluoroscopically guided epidural steroid injection for radicular and neurogenic claudication symptoms caused by lumbar spinal stenosis over a 12-month interval. All patients had corresponding MRI findings and had failed previous non-invasive therapies. Outcomes included the visual analog scale (VAS, 0-10 scale) immediately before the injection, immediately after the injection, and upon follow up at 4-6 weeks. Surgery rates and number of repeat injections over a 3 year period were also analyzed. The patient groups were matched for age and level of stenosis on MRI. Results. There was no statistically significant difference between the two groups in pre injection to follow up VAS scores (P = 0.919). The difference between number of repeat injections between the interlaminar and transforaminal groups was not statistically significant (0.91-mean 2.47 and 2.58, respectively). Both the interlaminar and transforaminal groups experienced statistically significant improvement in VAS scores from before the injection to after the injection, and on follow up. Low numbers underwent surgery (11% in the interlaminar group vs 15% in the transforaminal group, not significant, P = 0.63). Conclusions. In the current study, neither transforaminal nor interlaminar steroid injections resulted in superior short term pain improvement or fewer long term surgical interventions or repeat injections when compared with each other.