Fig 1. Insufficient infiltration and insufficient passage. A, Insufficient infiltration of the root, compressed by the herniated L4–5 disk. Contrast leakage lateral to the neural foramen (arrowheads) is observed. B, Insufficient passage of the injectate from a blockade by a huge herniated disk. A filling defect of contrast media by an inferiorly migrated huge paracentral disk herniation at L4–5 is observed (arrowheads).