Understanding Vascular Risks in Lumbar Transforaminal Epidural Injections: Insights From Anatomy and Clinical Evidence

Transforaminal epidural steroid injections (TFESIs) are frequently used to treat lumbar and radicular pain. Although ischemic complications are extremely rare, their severity-often resulting in irreversible paraplegia-necessitates a thorough understanding of the anatomical and procedural risk factors. This review carefully examines the vascular anatomy of the lumbar intervertebral foramen, the distribution and risks associated with radiculomedullary arteries, and reported cases of severe complications related to lumbar TFESIs. Anatomical and radiological data indicate that radicular arteries are particularly rare below the L2-L3 level and are more common on the left side. The upper third of the intervertebral foramen, especially at T12-L3, is the most likely site of arterial involvement, raising concerns about the safety of traditional subpedicular approaches. Kambin's triangle appears to be a safer alternative, reducing arterial contact while still enabling effective drug delivery. The use of particulate corticosteroids, especially methylprednisolone and triamcinolone, is strongly associated with ischemic events owing to their larger particle sizes. Non-particulate options such as dexamethasone are preferred, particularly at higher spinal levels. Although rare, venous punctures and hematomas require vigilance and careful steroid selection. Test doses of local anesthetics remain controversial and do not provide clear protective benefits. Current evidence indicates that adjusting techniques-including needle placement, imaging guidance, and corticosteroid choice-can help reduce risks while maintaining the effectiveness of lumbar TFESIs.