Lumbar Spine Definitions and Diagnostic Criteria: Degeneration, Herniation and Stenosis

Disc Degeneration: Spondylosis (Spondylosis Deformans) is a general term used for age-related changes to the disc. This includes disc dessication, bulging and marginal osteophyte. Disc degeneration (Intervertebral osteochondrosis) (Resnick) is characterized by disorganization and dessication of the nucleus pulposis and by disc space narrowing. With loss of disc space height there is annular bulging/laxity and mechanical failure of the disc (Herzog). It generally represents the sequel of disc injury and may be symptomatic or asymptomatic (Fardon, Herzog). We use disc space narrowing as our primary parameter to grade disc degeneration: Mild-Desiccation with < 25% disc space narrowing Moderate-Desiccation with 25-75% disc space narrowing Severe-Desiccation with > 75% disc space narrowing Some radiologists will use moderately severe for 75-90% disc space narrowing and severe for complete collapse. While disc desiccation is also a feature of disc degeneration, it is difficult to use this parameter for grading. First, disc desiccation can be seen with normal aging. Second, the signal intensity of a degenerated disc can vary with MRI field strength and pulse sequence selection. Finally, this parameter does not facilitate comparison with CT findings.