Comparing Three Epidural Steroid Injection Approaches for Lumbar Radicular Pain

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.

Inclusion Criteria: * Age 18 to 65 years. * Unilateral lumbosacral radicular pain consistent with a dermatomal distribution. * Magnetic resonance imaging-confirmed lumbar disc herniation (bulge, protrusion, or extrusion) at the corresponding clinical level. * Persistent symptoms despite at least 6 weeks of conservative management, including analgesics and physiotherapy. * Baseline Numerical Rating Scale pain score of 4 or greater. * American Society of Anesthesiologists physical status I to III. * Ability to understand and complete outcome assessments. * Written informed consent provided. Exclusion Criteria: * Previous lumbar spine surgery or failed back surgery syndrome. * Red-flag signs, including foot drop, urinary incontinence, or cauda equina syndrome. * Bilateral radicular symptoms or central canal stenosis requiring surgical intervention. * Coagulopathy or ongoing anticoagulant therapy. * Local or systemic infection or hepatic dysfunction. * Known allergy to contrast medium, local anesthetics, or corticosteroids. * Pregnancy. * Severe renal impairment contraindicating contrast use. * Chronic opioid use, defined as daily opioid use for more than 3 months before enrollment. * Uncontrolled systemic disease, including unstable diabetes or severe cardiopulmonary disease. * Inability to comply with follow-up.