The acute lumbar disc herniation: imaging diagnosis.

The acute lumbar herniated nucleus pulposus (HNP) can often be diagnosed on good quality MRI or CT examination. Myelography, discography, and postmyelography/postdiscography CT ordinarily are reserved for equivocal and protracted cases. MRI is recommended as the initial study of choice except for older patients for whom CT may be more valuable because of the high incidence of osteophytosis. Patients with acute herniated nucleus pulposus (HNP) may have varied clinical symptoms depending on the level of the HNP, extent of the annulus tear/depth of penetration of nuclear material, and the direction of the disc herniation. HNP does not necessarily produce radiculopathy and may cause vague low back pain. This article reviews and analyzes the clinical symptoms and problems associated with HNP, as well as the pitfalls and differential diagnostic possibilities in interpretation.