Analysis of a series of cases with an initial diagnosis of acute disseminated encephalomyelitis over the period 2000-2010

Acute disseminated encephalomyelitis (ADEM) is a demyelinating disease that essentially affects the white matter of the central nervous system. The diagnosis is based on clinical-imaging and developmental findings. Magnetic resonance imaging of the brain is the most useful diagnostic tool. The disease course is usually monophasic and the preferred initial treatment is with corticoids. We conducted a retrospective study of 18 patients with a presumptive diagnosis of ADEM. Symptoms, imaging findings, progress and treatment were analysed. The definitive diagnosis was established in 12 patients, excluding one patient with positive polymerase chain reaction for herpes simplex virus in cerebrospinal fluid, one with a clinical picture that was consistent but normal magnetic resonance imaging of the brain, and four with an onset that was similar to ADEM whose definitive diagnoses were: Rassmusen's syndrome, haemophagocytic syndrome, brain tumour, and MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes). The median age was 31 months with no predominance of either sex. Infection of the upper respiratory tract was the most frequent cause in children over 2 years of age and of the gastrointestinal tract in those under the age of 2. All of them presented altered levels of consciousness and multifocal neurological deficits. The most frequent imaging finding was multifocal alteration of the white matter in both hemispheres. Corticoids were the preferred treatment in most cases. Progression was favourable in nearly all patients except for two, who were left with important sequelae. ADEM may present at any age, including in infants. There are a number of conditions that can mimic ADEM in the early stages.