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Congenital Spinal Stenosis


KEY FACTS

Terminology

  • Reduced AP canal diameter secondary to short, squat pedicles and laterally directed laminae

Imaging

  • Central canal diameter is smaller than normal

    • Cervical spine: Absolute AP diameter < 14 mm

    • Spinal stenosis present if AP canal diameter at L1 < 20 mm, L2 < 19 mm, L3 < 19 mm, L4 < 17 mm, L5 < 16 mm, S1 < 16 mm

      • –

        Lumbar spine: Critical stenosis at L4 < 14 mm, L5 < 14 mm, S1 < 12 mm

  • Short, thick pedicles

  • Trefoil-shaped lateral recesses

  • Laterally directed laminae

Top Differential Diagnoses

  • Acquired spinal stenosis

  • Inherited spinal stenosis

    • Achondroplasia

    • Mucopolysaccharidoses

Pathology

  • Torg ratio (AP canal diameter/AP vertebral body diameter) < 0.8

  • Idiopathic

Clinical Issues

  • Symptomatic cervical or lumbar stenosis symptoms at younger age than typical of degenerative stenosis

    • These patients typically lack complicating medical problems (diabetes or vascular insufficiency)

  • Athletes present with temporary neurological deficit following physical contact that subsequently resolves

  • Lumbar: Decompressive laminectomy, posterior foraminotomy at involved levels

  • Cervical: Posterior cervical laminectomy or laminoplasty

Sagittal graphic shows marked congenital anteroposterior narrowing of the central spinal canal.

Sagittal T2WI MR reveals moderate congenital AP canal narrowing exacerbated by C4-C5 disc herniation. The protrusion produces spinal cord T2 hyperintensity
corresponding to clinical myelopathy.

Axial graphic depicts congenital cervical AP spinal narrowing with generalized narrowing of the subarachnoid space. The pedicles
are short, thick, and laterally directed with resultant flattening of laminae
and compression of the spinal cord
.

Axial bone CT demonstrates marked AP canal reduction attributable to developmentally short pedicles
and laterally oriented laminae
.

TERMINOLOGY

Synonyms

  • Short pedicle syndrome, congenital short pedicles, developmental spinal stenosis

Definitions

  • Reduced AP canal diameter secondary to short, squat pedicles and laterally directed laminae

IMAGING

General Features

  • Best diagnostic clue

    • Short, thick pedicles producing narrowed anteroposterior spinal canal diameter

  • Location

    • Lumbar > cervical > thoracic spine

  • Size

    • Central bony canal diameter is smaller than normal

      • –

        Cervical spine: Absolute AP diameter < 14 mm

      • –

        Lumbar spine: Critical stenosis at L4 < 14 mm, L5 < 14 mm, S1 < 12 mm

  • Morphology

    • Short, thick pedicles

    • Trefoil-shaped lateral recesses

    • Laterally directed laminae

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