Imaging the intervertebral disk: age-related changes, herniations, and radicular pain.

The articulations of the spinal motion segment, the intervertebral disk, and the zygapophyseal joints, inevitably undergo age-related changes. This article focuses on the intervertebral disk, specifically when fissures sufficiently weaken the posterior annulus so as to allow herniation of nuclear material into the outer annular structure as a contained protrusion or breach the annulus and pass into the epidural space as an extrusion. This article examines the imaging of the age-related changes of the disk and disk herniation: nomenclature, the reliability and relative merits of imaging modalities, the imaging natural history of disk herniations, and, most importantly, the clinical significance.