ADEM and MS

Disseminated encephalomyelitis and Multiple sclerosis

• A proportion of children with DEM will develop MS. The proportion of children with DEM who will develop MS is unclear.
• According to the International Paediatric MS Study Group a diagnosis of Multiple Sclerosis in children needs multiple episodes of demyelination separated in time and space

	Acute Disseminating Encephalomyelitis	Multiple Sclerosis
Demographics	Monophasic ADEM is more common in children	MS is more common in Adults
incidence	Peak incidence in children of 3–10 years with mild male predominance. Multiphasic ADEM have a much older mean age at onset (6th decade or after)	Female predominance
symptoms and signs	more likely to present with encephalopathy and may be initially diagnosed as having viral encephalitis commonly have headache, vomiting, drowsiness, and meningism	These symptoms are uncommon in MS
Infections and seasonality	may be precipitated by infections ( eg measles, Epstein-nBarr virus, mycoplasma, and group A streptococcus )	association with infections seasonality less clear
Seizures	incidence of seizures is about 13-35% [1, 2, 3, 4, 5]	Incidence of seizures is rare[1]
symptoms	Encephalopathy with depressed consciousness and altered sensorium is more common in ADEM (45–75%)[1, 2, 3, 4, 5, 6]	less common 13-15%
Optic neuritis	Optic neuritis when present is commonly bilateral	Optic neuritis when present is typically unilateral
Symptoms and signs	Symptoms and signs are usually multiple In multiphasic ADEM relapses often occur in the form of myelitis and there would be neurophysiological (50%) and clinical (30%) evidence of Peripheral nervous system involvement [7]	symptoms and signs are usually isolated
Biochemistry	Inflammatory markers are usually raised common occurrence of pleocytosis and blood-brain barrier damage in the CSF different cytokine-chemokine profile [8] CSF Oligoclonal bands are seen in only 0–29% of ADEM patients. Even when present they are only transitory (Tawazzi 2008).	oligoclonal bands (oligoclonal IgG in CSF but not in serum), occurs in 40–95% of MS patients
MRI	The lesions on MRI in ADEM often have poorlydefined margins deeper white matter withperiventricular sparing (only 29–60% of ADEM patients have periventricular lesions) When the spinal cord is involved in ADEM, the lesion is typically large, swollen, and thoracic the grey matter (both cortical and deep grey/basal ganglia) is frequently involved in ADEM new lesions should not occur in ADEM on followup MRI (0–9% of ADEM patients have new lesions on follow up) demyelination is sparse and restricted to narrow perivenous sleeves [9]	well defined "plaque-like" margins Characteristic lesion sites include Periaqueductal, corpus callosum, and periventricular white matter lesions Spinal cord lesions are typically smaller,more discrete, and cervical. The white matter is classically involved new lesions in MS are anticipated focal confluent plaques of primary demyelination showing variable degrees of axonal injury and loss
Prognosis	The outcome in ADEM is often good with 57–81% of patients making a complete recovery. In children who havesuffered one episode of inflammatory demyelination, adverseprognostic factors for irreversible disability include: sequelae after the first episode, a polysymptomatic presentation, progressiveevolution, and the number of relapses in the first two years [2, 3, 4, 10]

References

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Further reading [12, 13, 14]

12. Dale RC and Branson JA. Acute disseminated encephalomyelitis or multiple sclerosis: can the initial presentation help in establishing a correct diagnosis?. Arch Dis Child 2005 Jun; 90(6) 636-9. doi:10.1136/adc.2004.062935 pmid:15908633.
13. Tenembaum SN. Disseminated encephalomyelitis in children. Clin Neurol Neurosurg 2008 Nov; 110(9) 928-38. doi:10.1016/j.clineuro.2007.12.018 pmid:18272282.
14. Tenembaum S, Chitnis T, Ness J, and Hahn JS. Acute disseminated encephalomyelitis. Neurology 2007 Apr 17; 68(16 Suppl 2) S23-36. doi:10.1212/01.wnl.0000259404.51352.7f pmid:17438235.

Links

1. see icnapedia article on Disseminated encephalomyelitis

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