Schmorl Node


KEY FACTS

Terminology

  • Definition: Node within vertebral body due to vertical disc extension (intravertebral disc herniation) through vertebral endplate

    • Any level, although thoracic, thoracolumbar > cervical

Imaging

  • Focal invagination of endplate by disc material surrounded by sclerotic (old) or edematous (acute) bone

  • Plain films

    • Contour defect within endplate, extending from disc space into vertebral body spongiosa with well-corticated margins

  • CT

    • Island of low density surrounded by condensed bone on axial slice through vertebral body

  • MR

    • Focal defect in endplate filled by disc ± adjacent marrow edema, fatty marrow conversion

Top Differential Diagnoses

  • Acute compression fracture

  • Degenerative endplate change

  • Discitis

    • Both endplates show defect

  • Limbus vertebrae

    • Seen at vertebral body corners

  • Bone island (sclerotic nodule)

  • Focal metastasis

    • No contiguity with parent disc

  • Scheuermann disease

    • Thoracic, with anterior wedging

Clinical Issues

  • Seen in up to 75% of all normal spines

  • Conservative management

Diagnostic Checklist

  • Schmorl node is always contiguous with parent disc

Sagittal CT shows multiple Schmorl nodes (SN) of varying size
. There is variable sclerosis adjacent to nodes. Wedging at T12
is a normal anatomic variant often seen at T11-L1. It is distinguished from compression fracture by normal contour and equal involvement of both endplates.

Lateral fluoroscopy image (different patient) during discography reveals a superior endplate SN
. Contrast injected into the contiguous intervertebral disc fills the herniated disc within the vertebral SN defect.

Sagittal T2WI MR demonstrates the typical pattern of fatty marrow
outlining chronic endplate herniation (SN)
.

Axial T2WI MR (same patient) shows a well-defined focus of low signal
in the superior S1 endplate representing an SN. There is a thin concentric rind of fatty marrow conversion
surrounding the SN.

TERMINOLOGY

Abbreviations

  • Schmorl node (SN)

Synonyms

  • Intravertebral disc herniation

Definitions

  • Node within vertebral body due to vertical disc extension through weakened vertebral body endplate

IMAGING

General Features

  • Best diagnostic clue

    • Focal invagination of endplate by disc material surrounded by either sclerotic (old) or edematous (acute) bone

  • Location

    • T-8 to L1 region most common

  • Size

    • Varies from several millimeters to “giant”

  • Morphology

    • Typically upwardly round or cone-shaped defect contiguous with disc space

Radiographic Findings

  • Radiography

    • Contour defect within endplate, extending from disc space into vertebral body spongiosa with well-corticated margins

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