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Acute disseminated encephalomyelitis ADEM* - Coggle Diagram
Acute disseminated encephalomyelitis ADEM*
UpToDate 2022 jun
clinical features
classic ADEM
antecedent viral/febrile illness 75%
neurologic symptoms appear 4-13 day after infection/vaccination
presentation: fever, headache, vomiting, meningismus
encephalopathy: irritability, confusion, sleepiness - coma, seizures 1/3rd of patients
progression to maximum deficits 4-7 days
multifocal neurologic signs: pyramidal signs, acute hemiparesis, cerebellar ataxia, cranial neuropathies - optic neuritis, myelopathy - transverse myelitis. Aphasia, movement disorders, sensory deficits less common
clinical course: severe phase 2-4 weeks, hospitalization 13-27 days, ICU admission severe enephalopathy, seizures, paralysis of diaphragm 25%
inflammatory haemorrhagic demyelination of CNS
acute hemorrhagic leukoencephalitis
acute hemorrhagic leukoencepathy
acute hemorrhagic encephalomyelitis
acute necrotizing hemorrhagic leukoencephalitis of Weston Hurst
more progressive and more severe, worse prognosis
evaluation
when to suspect ADEM: multifocal neurologic abnormalities with encephalopathy, particularly 2 weeks after viral infection
MRI
brain+spine T2, FLAIR and gadolinium-enhanced
lesions bilateral, asymmetric, poorly marginated
multiple
deep and subcortical white matter
demyelination
periventricular white matter often spared
hypointense lesions on T1 (black holes) are unusual and indicate MS
gray matter: thalami, basal ganglia - often symmetrical; supratentorial lesions are asymmetrical
hemorrhagic demyelination: diffuse white matter lesions within 72 hours of first symtoms, susceptibility weiihted sequences
brainstem and spinal cord abnormalities are common - LETM
contrast enhancement variable - acute lesions
sequential MRI: required to confirm diagnosis of ADEM; monophasic ADEM no new lesions and relapses ->alternate diagnosis
LP
ruling out infection: cell counts, protein, glucose, culture, viral studies: influenza, EBV, HSV, VZV, mycoplasma, chlamydia, rubella
CSF+serum: oligoclonal IgG bands - isoelectric focusinf, IgG index - local IgG synthesis - 0-20%
WBC<100/ul, but may be 600/ul, hemorrhagic lesions - red blood cells
rule out infection: blood count, blood cultures, viral cultures of throat, stool, serologic testing influenza, EBV, HSV, VZV, mycoplasma, CMV, rubella
serum autoantibodies
anti-MOG IgG: MOGAD
anti-AQP4 IgG: NMOSD
diagnosis
no confirmatory test, clinical and radiological features, diagnosis of exclusion
diagnostic criteria
International Pediatric Multiple Sclerosis Group 2007 and 2012 (all required)
A first polyfocal, clinical central nervous system event with presumed inflammatory demyelinating cause
Encephalopathy that cannot be explained by fever, systemic illness, or postictal symptoms
No new clinical and MRI findings emerge three months or more after the onset
Brain MRI is abnormal during the acute (three-month) phase
MRI
Diffuse, poorly demarcated, large (>1 to 2 cm) lesions involving predominantly the cerebral white matter
Deep gray matter lesions (eg, involving the basal ganglia or thalamus) can be present
T1 hypointense lesions in the white matter are rare
differential diagnosis
hacterial and viral CNS infections
other inflammatory/demyelinating CNS disorder: NMOSD, MOGAD, MS,
vasculitis, small vessel childhood primary angiitiis of the CNS - PACNS
CNS malignancy
hemophagocytic lymphohistiocystosis HLH: cytopenia, multiple organ involvement, liver abnormalities, high ferritin
pathophysiology
autoimmunity
triggered by environmental stimulus in genetically susceptible individuals
myelin autoantigens: myelin basic protein MBP, proteolipid protein, myelin oligodendrocyte glycoprotein MOG. EBNA similar to MBP
associated pathogens: coronacirus, coxsackie, EBV, HSV, HAV, HIV, influenza, measles, rubella, VZV, West Nile, Borrelia burgdorferi, chlamydia, Leptospira, Mycoplasma pneumoniae, rickettsia, beta hemolytic Streptococcus
=postinfectiosus encephalomyelitis
immunopathological phases
priming and activation of Tcells
recruitment and effector phase
repair and remyelination
epidemiology
incidence 0.2-0.5/100.000/year
3-7 year
postinfectious - antecedent fever 75%
winter, spring
postvaccinal: little/no connection