Acute disseminated encephalomyelitis and other inflammatory demyelinating variants.

Acute disseminated encephalomyelitis (ADEM) is an immune-mediated inflammatory central nervous system disorder characterized by acute or subacute onset of multifocal neurologic deficits with headache and impaired conscious level. Acute haemorrhagic leuoko-encephalitis (AHEM) is a more sever, often fatal variant. These disorders often follows a viral illness or vaccination, and are usually monophasic, though (probably more commonly in childhood) a multiphasic variant of ADEM is recognized. Because of the relative non-specificity of the clinical presentation (a sub-acute encephalopathy with focal signs), the differential diagnosis is wide; and distinction from the first episode of relapsing-remitting multiple sclerosis can occasionally be difficult. Here the clinical and investigational features of these disorders and their treatment are discussed.