Acute disseminated encephalomyelitis (ADEM)

Acute disseminated encephalomyelitis (ADEM) is a rare autoimmune inflammatory demyelinating disease of the central nervous system (brain, spinal cord, optic nerve). ADEM affects children more frequently than adults, and primarily children under the age of 10. It generally appears a few days or weeks after a viral or bacterial infection, or very rarely following vaccination.

What are the symptoms of ADEM?

ADEM manifests with many neurological symptoms such as motor weakness, sensory abnormalities, urinary or bowel dysfunction, balance and coordination problems, and vision loss. Patients affected by this disease may also experience behavioral, mood, memory, and/or concentration problems, as well as altered consciousness (encephalopathy, potentially leading to coma), headaches, and epileptic seizures. These symptoms worsen after 4 to 7 days and can last for several weeks. Children presenting with ADEM often have a fever.

Disease severity varies, and admission to an intensive care unit may be necessary.

How is ADEM diagnosed?

There is no specific biological marker for ADEM. Diagnosis is made by a specialist in inflammatory diseases of the central nervous system and is based on clinical examination and findings on brain and spinal cord magnetic resonance imaging (MRI). A lumbar puncture is also performed, along with blood tests, to rule out other diseases that may be responsible for similar symptoms (differential diagnosis).

Certain forms of the disease can be very severe, but around half of patients will have no sequelae.

In most cases, ADEM occurs as a single episode (monophasic disease), but relapses can occur. In adults, ADEM can also be the first manifestation of an inflammatory disease of the central nervous system with various neurological symptoms (such as neuromyelitis optica spectrum disorder [NMOSD; learn more here] or multiple sclerosis). Anti-myelin oligodendrocyte glycoprotein (MOG) antibodies are frequently found in children presenting with ADEM, and their continued presence after the initial episode indicates a risk of relapse in the form of ADEM or another inflammatory disease (e.g. optic neuritis, myelitis, etc.).

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