Acute demyelinating encephalomyelitis

Synonyms

ADEM, acute disseminated encephalomyelitis, multiphasic ADEM, relapsing ADEM, Balo's concentric sclerosis (pathological finding of alternating bands of demyelination and remyelination characteristic of ADEM).

Definition

Acute disseminated encephalomyelitis (ADEM) is an acute, demyelinating disease of the brain that typically develops in the weeks to months after an infection or vaccination. Children are affected more commonly than adults. Clinically, patients may present with a wide variety of signs and symptoms including ataxia, psychosis, motor dysfunction, sensory loss, or blindness. Since the disease usually causes multi-focal white matter lesions, patients often have a plethora of clinical manifestations. MRI features usually include multiple hyperintense lesions that can involve structures in the cortex, subcortical white matter, basal ganglia, brain stem, and optic nerve (see Figure 1); however, some patients will develop solitary, enlarging, tumor-like areas of...