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Many patients initially diagnosed with ADEM subsequently develop clinically definite MS upon long-term follow-up.
Introduction
- Relevant as a stroke mimic and so should be identifiable
- Acute disseminated encephalomyelitis mainly affects children but can affect adults
- Inflammatory condition of brain and spinal cord that damages myelin
- May follow a viral illness or have another precipitant
Aetiology
- Classically acute and monophasic but not always
- Usually affects young adults and children
- Pathological hallmark of ADEM is perivenular inflammation with limited "sleeves of demyelination"
- CSF elevated IFN-gamma, IL-6, and IL-8
Precipitants
- Bacterial infections: mycoplasma, Gram negative organisms, salmonella typhi
- Vaccination for measles, mumps, or rubella.
- Post viral: Measles, varicella, rubella, Herpes-zoster, Infectious mononucleosis
- Cerebral malaria
Clinical
- Fever, meningism, seizures, coma, usually monophasic but not always
- Weakness, hemianopia, neglect
Investigations
- CT: may show cerebral oedema
- MRI scan: large symmetrical lesions with basal ganglia and thalamus involved.
- LP: raised protein and slight increase in WCC in 80%.Protein > 100mg/dl. No oligoclonal bands
- Brain biopsy: consistent with demyelination.
Differentials
- Multiple sclerosis
- Susac syndrome
- Progressive multifocal leukoencephalopathy
Management
- Mortality is up to 30%
- Treat with high dose IV Methylprednisolone
- Alternatives include Plasmapheresis, IVIG and Rituximab
References and further reading