Acute Disseminated Encephalomyelitis (ADEM)

Figure 1: Sagittal STIR (top row left), sagittal T1 post-contrast fat-saturated (FS) (top row right), and axial T2 images of the thoracic spine demonstrate an expansile, T2/STIR hyperintense, intramedullary lesion with patchy enhancement in the thoracic spinal cord. The features are non-specific and the differential diagnosis includes both intramedullary neoplasm and demyelinating disease. However, with the given history of recent viral illness and clinical resolution following the treatment with steroids, the findings were most compatible with ADEM. 

Clinical Features

  • Peak Age: Childhood (5-8)
  • Gender: M > F (1:0.6-0.8)
  • Etiology: Post-infectious or post-vaccination immune-mediated demyelination

Imaging

  • General:
    • Location:
      • Brain/Brain stem: Multifocal subcortical/juxtracortical white matter lesions (commonly involves gray matter too), less common periventricular and callososeptal white matter lesions. Commonly basal ganglia and thalami involved (symmetric)
      • Spinal Cord:
        • Dorsal cord white matter
        • +/- gray matter
      • Nerves: +/- cranial nerve involvement
    • General Appearance:
      • Flame-shaped lesions in spinal cord
  • Modality-Specific (Spinal Cord Only):
    • CT Myelography:
      • Spinal cord not well evaluated. May see spinal cord swelling in acute phase (mimics intramedullary tumor)
    • MRI:
      • T1: Isointense or hypointense
      • T1 + Contrast: +/- Enhancement. Patchy, ring, nodular, or cloud-like/fluffy
      • T2: Flam...
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