Evaluating Bilateral Symptom Relief Following Parasagittal Interlaminar Epidural Steroid Injections.

Introduction: Interlaminar epidural steroid injections (ILESIs) using a parasagittal approach are frequently employed to manage lumbar radicular pain. The degree of contralateral symptom relief achieved with parasagittal ILESIs remains underexplored. This study aims to evaluate the short-term effectiveness of parasagittal ILESIs in providing ipsilateral and contralateral symptom relief in patients with bilateral lumbar radiculopathy and unilateral contrast spread. Methods: A retrospective review was conducted on 12 patients with bilateral lumbar radicular symptoms who underwent parasagittal ILESIs under fluoroscopic guidance. Patient-reported symptom relief was assessed for both ipsilateral and contralateral sides at a two-week follow-up visit or phone call. Descriptive statistics were used to evaluate patterns in symptom relief across the cohort. Results: All patients experienced significant relief on the ipsilateral side, with reported improvement ranging from 60% to 100% (mean: 84.6%). Contralateral relief was more variable, ranging from 0% to 90% (mean: 37.5%). No complications were reported. Conclusion: Parasagittal ILESIs provide more consistent and substantial relief of ipsilateral lumbar radicular symptoms. Contralateral relief is less predictable and may be limited by needle placement and the spread of medication. These findings support the use of parasagittal ILESIs in cases of unilateral or dominant-side radicular pain. For patients with significant bilateral symptoms, midline ILESIs or bilateral transforaminal injections may be more effective. Further prospective studies are warranted to identify predictors of bilateral relief and optimize procedural technique.