Degenerative Disc Disease


KEY FACTS

Terminology

  • Generalized and multifactorial process affecting discovertebral unit leading to biomechanical/morphologic alterations

Imaging

  • Loss of disc space height, vacuum phenomenon seen as low signal within disc

  • Degenerative endplate changes I → III

    • Type I: Replacement with fibrovascular marrow

    • Type II: Replacement by fatty marrow

    • Type III: Bony sclerosis with little residual marrow

  • T2 shows loss of signal from nucleus, loss of horizontal nuclear cleft

  • Disc may show linear enhancement with degenerative disc disease, enhancement within Schmorl nodes

Top Differential Diagnoses

  • Disc space infection

  • Hemodialysis spondyloarthropathy

  • Seronegative spondyloarthropathy

Pathology

  • Etiology of disc degeneration multifactorial

  • Individuals involved in manual materials handling, with repeated heavy lifting, at increased risk

  • Some studies show strong familial predisposition to discogenic back pain

Clinical Issues

  • Asymptomatic or associated with back/neck pain ± radiculopathy

  • Lifetime incidence of back pain (all causes) in United States 50-80%

  • Prevalence among adults ranges from 15-30%

  • Back pain most common cause of disability in persons younger than 45 years

  • Of patients complaining of chronic pain (> 3 months), 1/3 have disabling symptoms

Sagittal graphic shows degeneration of L4-5 and L5-S1 intervertebral discs with loss of disc height, associated type II fatty endplate change
, and osteophyte formation
.

Sagittal NECT reformat shows multilevel severe loss of disc height and vacuum phenomenon, which appears as black pockets of gas in the disc
. Endplate eburnation (sclerosis) is most obvious at L3-4
. Osteophytes are present at several levels
.

Sagittal T2WI MR shows degenerated disc as low signal at L4-5, L5-S1 compared to normal disc signal intensity at L3-4. Degenerative disc disease is also seen as loss of disc height at L4-5, disc herniation at L5-S1
, and anular tear at L4-5
.

Axial T2WI MR shows protrusion
compressing the exiting root. Degenerated disc shows low signal centrally with disrupted internal disc contents pointing toward the herniation
.

TERMINOLOGY

Synonyms

  • Degenerative disc disease (DDD), disc degeneration, spondylosis

Definitions

  • Generalized and multifactorial process affecting discovertebral unit leading to biomechanical/morphologic alterations

  • Asymptomatic or associated with back/neck pain ± radiculopathy

IMAGING

General Features

  • Best diagnostic clue

    • Decreased signal of intervertebral disc on T2WI

  • Location

    • Intervertebral disc, adjacent endplates

  • Size

    • Normal disc height with mild signal loss to marked loss of disc height

  • Morphology

    • Nucleus/anulus alteration, with adjacent facet/foramina osteoarthritic degenerative change

Radiographic Findings

  • Radiography

    • Late disease shows loss of disc space height, osteophyte formation, bony endplate eburnation “discogenic sclerosis,” vacuum phenomenon

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