Comparing Three Epidural Steroid Injection Approaches for Lumbar Radicular Pain

Overview

This study will compare three fluoroscopy-guided epidural steroid injection approaches for adults with unilateral lumbosacral radicular pain caused by lumbar disc herniation. The study will evaluate whether the pattern of contrast spread in the epidural space predicts meaningful pain relief. Ninety-nine participants will be randomly assigned in equal numbers to receive one of three treatments: high-volume parasagittal interlaminar injection, low-volume parasagittal interlaminar injection, or transforaminal epidural steroid injection. Participants will not be told which injection approach they receive. Pain and disability will be assessed before treatment and at 2 weeks, 1 month, 3 months, and 6 months after injection. The main outcome is the proportion of participants with clinically meaningful improvement in pain at 3 months.

Lumbar disc herniation may cause lumbosacral radicular pain through nerve-root compression and inflammation. Fluoroscopy-guided epidural steroid injections are commonly used when symptoms persist despite conservative treatment. Parasagittal interlaminar (PIL) and transforaminal epidural steroid injection (TFESI) approaches may produce different patterns of contrast distribution within the epidural space. It remains unclear whether contrast spread pattern independently predicts clinical response, apart from injection approach and injectate volume. This prospective, three-arm randomized clinical trial will enroll adults with unilateral lumbosacral radicular pain and magnetic resonance imaging-confirmed lumbar disc herniation. Participants will be allocated in a 1:1:1 ratio to high-volume PIL injection (10 mL), low-volume PIL injection (7 mL), or TFESI (3 mL). Before administration of the therapeutic injectate, 2 mL of non-ionic iodinated contrast medium will be injected under real-time fluoroscopy to confirm epidural placement, exclude intravascular or intrathecal injection, and document contrast distribution. Blinded assessors will classify contrast spread according to ventral epidural spread, laterality, foraminal or nerve-root spread, epidural distribution pattern, and cephalocaudal extent. Dynamic fluoroscopic assessment will measure time to first ventral opacification. Participants, radiographic assessors, and outcome assessors will be blinded to treatment allocation where feasible; the procedural physician cannot be blinded because of the procedural differences. The study will assess whether contrast spread variables independently predict responder status at 3 months, defined as a reduction of at least 2 points or 30% from baseline in Numerical Rating Scale pain score. Additional outcomes include changes in pain intensity and Oswestry Disability Index scores, procedural efficiency, duration of pain relief, and responder status during follow-up through 6 months.