Patient Outcomes Following Parasagittal Interlaminar Epidural Steroid Injections for Bilateral Lumbar Radicular Symptoms: Correlation of Contrast Spread With Symptom Relief

Introduction Bilateral lumbar radicular symptoms are commonly treated with interlaminar epidural steroid injections (ILESIs). The parasagittal approach often results in unilateral contrast spread, which may influence the degree of bilateral symptom relief. This study evaluates whether unilateral contrast spread correlates with symptom improvement in both ipsilateral and contralateral symptoms. Methods A retrospective review of six patients with bilateral lumbar radiculopathy secondary to lumbar degenerative disc disease, spondylosis, or disc herniation was conducted. All patients underwent ILESIs using a parasagittal approach. The injectate consisted of bupivacaine, preservative-free normal saline, and triamcinolone. Contrast spread was assessed fluoroscopically, and symptom relief was evaluated at a two-week follow-up using patient-reported outcome measures. Results Ipsilateral symptom relief ranged from 75% to 100% (mean: 89.2%), while contralateral relief ranged from 0% to 90% (mean: 35.8%). Notably, two patients experienced substantial bilateral relief (80-90%) despite unilateral contrast spread. These findings suggest that while ipsilateral relief is typically achieved, contralateral relief is variable. Conclusion The side of contrast spread strongly correlates with ipsilateral symptom improvement at short-term follow-up, while bilateral symptom relief is less predictable. Understanding the relationship between unilateral contrast spread and bilateral symptom relief is critical in optimizing injection techniques for patients with lumbar radiculopathy. Future research should focus on larger cohorts, randomized controlled trials, and direct comparisons between the parasagittal approach and midline or bilateral transforaminal techniques to optimize bilateral symptom relief strategies.