Among the in fl ammatory diseases of the central nervous system, with progressive demyelination is acute disseminated encephalomyelitis. This disease proceeds with the development of diverse neurological symptoms, the formation of foci of demyelination. The etiology of the disease is not known for certain, but there is a connection with viral diseases. The clinical case considered in this article shows the rapid development of the disease with extensive demyelination, with the formation of foci in almost all brain structures in a short period of time, and a progressive deterioration of the patient’s condition against the background of ongoing therapy.