Interlaminar Versus Transforaminal Epidural Injections for the Treatment of Symptomatic Lumbar Intervertebral Disc Herniations

Background: Epidural steroid injections are commonly used for the treatment of radicular symptoms associated with symptomatic lumbar intervertebral disc herniations. Transforaminal epidural injections are believed to produce better clinical outcomes than interlaminar epidural injections.

Objective: To determine a difference in short-term pain improvement and longterm surgical rates between interlaminar and transforaminal injection techniques.

Design: Case Control Study.

Methods: For each technique, 20 patients were retrospectively identified who received their first fluoroscopically guided epidural steroid injection for radicular symptoms caused by a lumbar intravertebral disc herniation over an 18 months interval. All patients had corresponding MRI findings and failed previous non-invasive therapies. The Verbal Numerical Rating Scale (VNRS, 0-10 scale) before the treatment, within one hour after the treatment and upon follow-up (average 17.1 days) were analyzed, along with the need for repeat injections and surgical interventions over a 1-year follow-up interval. The patient groups were matched for symptom duration, MRI findings and pre-injection VNRS scores.

Results: In the transforaminal group, there was a statistically significant improvement in the VNRS scores from before the injection (VNRS mean 5.9) to immediately after the injection (VNRS mean 2.9, p<0.01), and upon follow-up (VNRS mean 3.2, p<0.01, mean 18.7 days). Nine patients (45%) required 1 or 2 repeated injections, 2 patients (10%) underwent surgery. In the interlaminar group, there was a statistically significant improvement in the VNRS scores from before the injection (VNRS mean 7.3) to immediately after the injection (VNRS mean 3.1, p<0.01), and upon follow-up (VNRS mean 5.9, p<0.01, mean 15.6 days). Eight patients (40%) required 1 or 2 repeated injection, 5 patients (25%) underwent surgery. Fourteen patients (70%) had an improvement of 2 points or more on the VNRS scale in the transforaminal group, compared to 9 (45%) in the interlaminar group.

Conclusions: In the current study, transforaminal epidural steroid injections for the treatment of symptomatic lumbar disc herniation resulted in better short-term pain improvement and fewer long-term surgical interventions than interlaminar epidural steroid injection.