Comparing Three Epidural Steroid Injection Approaches for Lumbar Radicular Pain

Lumbar disc herniation may cause lumbosacral radicular pain through nerve‐rootcompression and inflammation. Fluoroscopy‐guided epidural steroid injections are commonlyused when symptoms persist despite conservative treatment. Parasagittal interlaminar(PIL) and transforaminal epidural steroid injection (TFESI) approaches may producedifferent patterns of contrast distribution within the epidural space. It remains unclearwhether contrast spread pattern independently predicts clinical response, apart frominjection approach and injectate volume.This prospective, three‐arm randomized clinical trial will enroll adults with unilaterallumbosacral radicular pain and magnetic resonance imaging‐confirmed lumbar discherniation. 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 thetherapeutic injectate, 2 mL of non‐ionic iodinated contrast medium will be injected underreal‐time fluoroscopy to confirm epidural placement, exclude intravascular or intrathecalinjection, and document contrast distribution.Blinded assessors will classify contrast spread according to ventral epidural spread,laterality, foraminal or nerve‐root spread, epidural distribution pattern, andcephalocaudal extent. Dynamic fluoroscopic assessment will measure time to first ventralopacification. Participants, radiographic assessors, and outcome assessors will beblinded to treatment allocation where feasible; the procedural physician cannot beblinded because of the procedural differences.The study will assess whether contrast spread variables independently predict responderstatus at 3 months, defined as a reduction of at least 2 points or 30% from baseline inNumerical Rating Scale pain score. Additional outcomes include changes in pain intensityand Oswestry Disability Index scores, procedural efficiency, duration of pain relief, andresponder status during follow‐up through 6 months.