[Acute disseminated encephalomyelitis].

Background: Acute disseminated encephalomyelitis (ADEM) is a rare demyelinating disease that occurs predominantly in children. According to the guidelines, ADEM belongs to the myelin oligodendrocyte glycoprotein (MOG)-associated diseases and usually manifests after febrile infections (also after SARS-CoV-2) or postvaccinally.

Objectives: Incidence, course and clinical, and as well, as radiological features and new developments and treatment of ADEM.

Methods: Analysis and review of the literature on ADEM and of notable cases and guidelines.

Results: The first signs of ADEM include fever, nausea and vomiting, headache and meningism as well as, by definition, encephalopathy, which usually manifests as drowsiness and confusion. The radiological diagnosis is made by magnetic resonance imaging (MRI). Here, the asymmetrically distributed, diffuse and tumefactive lesions can be located supra- and infratentorially. In the acute phase, the lesions usually show contrast enhancement and restricted diffusion. Spinal involvement of the gray matter with the typical H‑pattern with myelitis transversa is not uncommon. ADEM has mostly a monophasic course, with a recurrent form ("relapsing ADEM") in 1-20% of cases. For treatment, steroids and in severe cases immunosuppressive drugs are used.

Conclusions: ADEM is generally a monophasic disease whose symptoms usually last for a few weeks or months. It is crucial to differentiate ADEM from other demyelinating diseases, like for example multiple sclerosis, in order not to delay the proper treatment.