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Acute Disseminated Encephalomyelitis (ADEM) is primarily a pediatric disease and can cause a wide variety of neurologic symptoms. As such, should always be in the differential for pediatric patient presenting with vague neurologic symptoms including altered mental status. It is an immune-mediated, demyelinating disease that can affect any part of the CNS; usually preceding a viral illness or rarely, immunizations.
The average age of onset is 5-8 years of age with no gender predilection. It usually has a prodromal. That includes headache, fever, malaise, back pain etc. Neurological symptoms can vary and may present with ataxia, altered mental status, seizures, focal symptoms, behavioral changes or coma.
MRI is the primary modality to diagnose this condition. Other possible indicators may be mild pleocytosis with lymphocyte predominance, and elevated inflammatory markers such as ESR, CRP. These findings, however, are neither sensitive nor specific.
First-line treatment for ADEM is systemic corticosteroids, typically 20-30 mg/kg of methylprednisolone for 2-5 days, followed by oral prednisone 1-2 mg/kg for 1-2 weeks then 3-6-week taper. For steroid refractory cases, IVIG and plasmapheresis may be considered.
ADEM usually has a favorable long-term prognosis in the majority of patients. However, some may experience residual neurological deficits including ataxia, blindness, clumsiness, etc.
Take home points:
- Always keep ADEM on the differential for any pediatric patient presenting with any neurologic symptoms
- MRI is the diagnostic modality of choice.
- If ADEM diagnosed, start treatment early in conjunction with pediatric neurology.
References
Gray, M.P. & Goralick, M.H. (2016). Acute disseminated encephalomyelitis (6th ed, volume 32). Milkwaukee, WI