Acute disseminated encephalomyelitis

The advent of magnetic resonance imaging (MRI) has contributed to increase the interest and awareness in childhood white matter disorders. Pediatric inflammatory demyelinating diseases of the central nervous system (CNS) are clinically heterogeneous with respect to their mode of presentation, clinical severity, rate of progression, and prognosis. Acute disseminated encephalomyelitis (ADEM) is an immune-mediated inflammatory disorder of the CNS, typically transitory and self-limiting. The highest incidence of ADEM is observed during childhood. It is characterized by an acute encephalopathy with polyfocal neurological deficits. In the absence of specific biological markers the diagnosis of ADEM is still based on clinical features and MRI evidence of widespread demyelination, after ruling out other possible explanations for an acute encephalopathy. Over the past decade, many retrospective patient studies have focused on clinical and neuroimaging features, in an attempt to define specific diagnostic criteria. The occurrence of relapses in children with ADEM poses diagnostic difficulties in its differentiation from multiple sclerosis (MS) and neuromyelitis optica (NMO). With the widespread use of high-dose steroids, the long-term prognosis of ADEM with regard to functional and cognitive recovery is favorable. This chapter summarizes the available literature on ADEM in children, including the proposed consensus definitions for its monophasic and relapsing variants.