Comparison of epidural space contrast flow and clinical outcomes in parasagittal versus transforaminal epidural steroid injection

Epidural steroid injections (ESI) are frequently used to treat lumbosacral radicular pain, but the solute spread in the epidural space needs further investigation. This semi-blind, randomized study assessed clinical outcomes and contrast spread patterns between the parasagittal interlaminar (PIL) and transforaminal (TF) approaches in 79 adults with low back pain. Participants were randomly assigned to receive either TF-ESI (3 ml) or high-volume PIL-ESI (10 ml). All procedures were performed under fluoroscopic guidance. Contrast spread was evaluated by a blinded pain specialist, and clinical outcomes, including analgesia, patient satisfaction, and quality of life, were measured at two weeks, one month, two months, and six months post-treatment. Results showed no differences in baseline characteristics between groups. There were no statistically significant differences between the two groups in mean pain intensity at baseline and six months after treatment (p = 0.590 and 0.484, respectively). Pain relief, satisfaction, quality of life, and contrast spread to the anterior epidural space did not differ over six months. However, the TF group required significantly more fluoroscopic images (p < 0.001). High-volume PIL-ESI provides clinical efficacy and anterior contrast distribution equivalent to TF-ESI, with fewer fluoroscopic images needed.