a.k.a. Acute dissemniated leukoencephalitis a.k.a. Acute postinfectious/post-vaccinial perivenous encephalitis, a.k.a. acute demyelinating encephalomyelitis,
Clinical features plus MRI and supportive tests
Encephalopathy, focal findings may occur. Often follows an infectious illness or exposure to new antigen to medication
Findings on Investigations:
- 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
- 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
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:
LP for CSF analysis
- Measles, paramyxovirus, varicella, rubella, and Epstein-Barr virus
- Mycoplasma pneumoniae serology & cold agglutinins
- Plasma exchange