Synonyms:
a.k.a. Acute dissemniated leukoencephalitis a.k.a. Acute postinfectious/post-vaccinial perivenous encephalitis, a.k.a. acute demyelinating encephalomyelitis,
Diagnosis:
Clinical features plus MRI and supportive tests
Clinical features:
Encephalopathy, focal findings may occur. Often follows an infectious illness or exposure to new antigen to medication
Findings on Investigations:
MRI
- T2: preferred. High signal intensities (large patchy) in white matter in the brain (subcortical & deep, may extend to ventricles) +/-spinal cord and deep grey nuclei. May or may not enhance with gadolinium.
CT: some areas of hypoattenuation in the white matter and deep grey nuclei
CSF:
- Protein: mildly elevated 0.5-1.5 g/L (50-150 mg/dL)
- WCC: lymphocytic pleocytosis usually
- IgG index: usually normal
- Myelin basic protein: high
Pathology:
Gross: small lesions in the white matter
Microscopically: perivenous lymphocytes, macrophages & plasma cells. Perivenous demyelination, with relatively spared axons. Usually no inflammation around the arteries. Meningeal inflammatory infiltrates occur.
Acute hemorrhagic leukoencephalitis of Hurst a.k.a Acute hemorrhageic encephalomyelitis AHEM, variant:
Pathology; Grossly, disseminated foci of hemorrhage in the white matter of the cerebral hemispheres, corpus callosum, pons & cerebellum
Microscopically, fibrinoid necrosis of blood veins. Perivenous necrosis, surrounded by hemorrhages. Perivenous mononuclear cells and neutrophils. Some demyelination and axonal loss.
Investigations to consider:
MRI
LP for CSF analysis
Viral screen:
- Measles, paramyxovirus, varicella, rubella, and Epstein-Barr virus
- Mycoplasma pneumoniae serology & cold agglutinins
Treatment:
Consider:
- Corticosteroids
- IVIG
- Plasma exchange
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