Acute Disseminated Encephalomyelitis

Background

  • Autoimmune condition triggered by a viral infection (usually measles and chicken pox) or vaccination; more common in children
  • Causes antibody production causing demyelination of perivenous nerve tissue throughout the brain and spinal cord.

Presentation

  • Usually acute onset headache, vomiting, pyrexia, confusion and meningism
    • Focal brain/spinal cord signs/symptoms may also be present
      • e.g. optic neuritis, vertigo/balance problems, focal weakness, dysphasia, bladder/bowel problems, etc
  • Seizures/coma can occur

Investigations

  • MRI
    • Multiple high-signal areas similar to MS but with large confluent areas of abnormality (cf focal plaques in MS)
  • Lumbar puncture
    • May be normal
    • May show increase in protein and lymphocytes (can be significant: >100×10^6/l)
    • Can also show oligoclonal bands in the first instance but (unlike MS) these will resolve)
  • Blood cultures are often normal

Management

  • It can be fatal acutely- supportive measures and high-dose IV methylprednisolone are recommended
  • Antibiotics/antivirals are not required BUT if bacterial meningitis is suspected do not delay in administering antibiotics
  • Usually the disease is self-limiting after the acute phase.

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