Acute disseminated encephalomyelitis in children: differential diagnosis from multiple sclerosis on the basis of clinical course

Lee, Yun Jin

Diagnostic criteria for ADEM in children have been proposed by the International Pediatric Multiple Sclerosis Study Group (Table 3) 23) . The major criteria are a clinical attack of CNS demyelinating disease with acute or subacute onset, polysymptomatic neurologic features, and encephalopathy. Encephalopathy as a presenting symptom is essential for a diagnosis of ADEM, according to the Study Group criteria 23) . Encephalopathy is defined as including either behavioral changes, such as lethargy or irritability, or more severe alterations in the level of consciousness, such as coma. The onset of occurring within three months of the inciting ADEM episode are considered part of the same acute event. In addition, ADEM relapses that occur during a steroid taper or within four weeks of completing a steroid taper are considered part of the initial inciting ADEM episode. Lesion Characteristics on MRI FLAIR and T2 weighted images Large (>1 to 2 cm in size) multifocal, hyperintense, bilateral, asymmetric lesions in the supratentorial or infratentorial white matter. Rarely, brain MRI shows a single large (≥1 to 2 cm) lesion predominantly affecting white matter. Gray matter, especially basal ganglia and thalamus, may be involved Spinal cord MRI may show confluent intramedullary lesion(s) with variable enhancement, in addition to the abnormalities on brain MRI No radiologic evidence of previous destructive white matter changes Encephalopathy is a required feature for the diagnosis of ADEM, but is not a typical feature of multiple sclerosis. In addition, a cerebrospinal fluid pleocytosis ≥50 white blood cells/mm can be observed in ADEM, whereas this finding is highly atypical for multiple sclerosis. CNS, central nervous system; MRI, magnetic resonance imaging; FLAIR, fluid-attenuated inversion recovery. encephalopathy almost directly corresponds to the occurrence of the disease state. This feature helps to differentiate ADEM from other clinically isolated syndromes that are related to recurrence of MS and will lead to a subsequent MS diagnosis. Brain MRI criteria for ADEM diagnosis include focal or multifocal lesions predominantly involving the white matter, without evidence of previous white-matter changes.