L5-S1 Disk Extrusion
33 y/o male with a history of radicular pain on the right.
A focal extrusion of the disk is seen at the L5-S1 level on sagittal and axial images.
Disk extrusions are characterized by a relatively narrow base compared to a broad base for disk protrusions. In extrusions, the nucleus has ruptured completely through the annulus. In protrusions, some annular fibers remain. Asymptomatic disk protrusions are not infrequent, unlike extrusions.