Acute Fulminant Demyelinating Disease

Abstract

Traditionally, acute demyelinating encephalomyelitis (ADEM) is characterized by a severe inflammatory attack, frequently secondary to infectious events or vaccinations.^1,2 Although the pathophysiologic mechanism of ADEM remains unknown, an autoimmune response to myelin basic protein triggered by infection or immunization is considered to be a possible etiologic factor.^3,4 In most cases ADEM is monophasic, but in some patients it may be recurrent and relapses may occur immediately after the onset of the disease.^5,6 If these relapses are considered to represent part of the same acute monophasic immune process, including symptoms similar to those in the first episode, the term multiphasic disseminated encephalomyelitis (MDEM) can be used.⁶ In approximately 30% of cases, a first episode of ADEM subsequently evolves to typical multiple sclerosis (MS), with a clear dissemination in time and space.^6,7 The ability to determine which patients with ADEM will subsequently develop MS after a single clinical episode has prognostic and therapeutic implications because early treatment of MS may be advantageous.^8,9 The recently proposed criteria for MS include dissemination in time, defined as new brain lesions observed on magnetic resonance imaging (MRI) performed during the months after the first demyelinating episode.^10,11 Furthermore, previous studies^1,6,7 reported that new gadolinium-enhanced lesions could appear several months after a first episode of ADEM in adults without any new clinical relapse. This fact could be a limitation for the application of the new criteria for MS in cases of ADEM.