Background: Lumbar transforaminal epidural injection (TFEI) effectively decreases low back pain and radicular pain in herniated intervertebral disc (HIVD) and spinal stenosis (SS). The precise delivery of drugs to the target is important for pain control and minimizing complications.
Objectives: We aimed to evaluate the efficacy and complications of the subpedicular (SP) and retrodiscal (RD) approaches by analysis of contrast spread patterns into the pathologic target on the basis of a newly established specific criterion. We also investigated whether the severity of patients' spinal disease influenced this pattern.
Study design: A prospective, randomized, observational study.
Setting: Interventional pain management center at a university-affiliated hospital.
Methods: Among patients who showed lumbar spinal stenosis or HIVD at the L4/5 level, participants were randomly assigned to undergo TFEI with the SP approach (SP group) or RD approach (RD group). Pain relief in terms of the visual analog scale (VAS) score and complications such as intravascular or intradiscal uptake were also analyzed. The contrast image was analyzed as the contrast media was injected, starting from 0.5 mL up to 3.0 mL. The spread patterns of contrast media were graded into 4 categories, which were newly defined in this study.
Results: Both groups demonstrated a significant decrease in pain relief (P value < 0.01) at 2 and 4 weeks after the procedures, but no significant difference was found between the 2 groups. In the intergroup analysis between the RD and SP groups, with a 1.5-mL contrast media injection, more patients in the RD group (17.2%) showed a grade 3 spread than those in the SP group (8.2%). In the subgroup analysis, the RD group showed superior spread (more grade 3 and 4) with 1.5-, 2-, and 2.5-mL contrast media injections (P values = 0.02, 0.03, and 0.04) in severe central stenosis, and 1.5- and 2-mL contrast media injections (P values = 0.01, 0.02) in severe foraminal stenosis.
Limitations: The follow-up period was only 4 weeks after TFESI, and higher contrast injection was used for procedures.
Conclusions: The RD approach for TFEI showed a better contrast spreading pattern than the SP approach, especially in patients with severe central and foraminal spinal stenosis. The RD approach might be more beneficial for patients with severe central and foraminal spinal stenosis in the short-term follow-up.
Keywords: epidural injection; epidural space; intervertebral disc herniation; radiating pain; spinal stenosis; Contrast media.