CT and MR of lateral disc herniation: typical appearance and pitfalls of interpretation

Lateral disc herniation is a relatively uncommon manifestation of intervertebral disc disease, defined as herniation of disc material lateral to or into the vertebral foramen. Failure to recognize this lesion preoperatively may lead to unsuccessful surgical exploration. We describe here the radiologic findings in seven patients with lateral disc herniation. Three were evaluated with magnetic resonance imaging alone, three with computed tomography alone, and one with both modalities. Example of three entities which may mimic lateral disc herniation (pseudodisc protrusion of scoliosis, paravertebral masses, and volume averaging artifacts) are illustrated.