Acute disseminated encephalomyelitis (ADEM)

Acute disseminated encephalomyelitis (ADEM) Is a rare form of acquired demyelinating disorders of the central nervous system. Subforms are post-infectious and post-vaccinal encephalomyelitis. Despite the amount of case reports only few address diagnosis and prognosis. This review summarizes current knowledge on symptoms, signs, pathogenesis, diagnosis and therapy of ADEM and its distinguishing characteristics differentiating it from the more common multiple sclerosis (MS) including variants. In ADEM an unspecific infection or contact to allogenic protein weeks prior to the acute symptoms is followed by disseminated hyperintense and contrast-enhanced lesions on MRI. Therapy with high-dose methylprednisolon, cyclophosphamide, plasmaphereses or immunoglobulins, alternatively, are mostly successful. Young adults and children of both genders are more often affected than adults. Specific T-cell responses to immature myelin proteins support an infectious induction of ADEM based on genetic predisposition. Differential diagnosis includes inborn and acquired leukodystrophias in adults and viral encephalitis in children. Recent advances in prophylactic therapy of relapsing MS with beta-interferons amplifies the importance of accurate differentiation between ADEM and MS.