Acute Disseminated Encephalomyelitis (ADEM) is a neurological immune-mediated disorder. It damages white matter tissue and causes widespread inflammation of the central nervous system (the brain and spinal cord).
White matter is made up of nerve fibers that are covered by fats and proteins known as myelin or the myelin sheath. Myelin acts as an insulator and accelerates the rate of transmission of nerve signals. When the myelin sheath is damaged, it affects the nerves’ ability to transmit information. This can potentially cause a large range of neurological symptoms, including vision loss, numbness, tingling, seizures, changes in mental status, and weakness in the arms and legs.
What causes ADEM?
The specific cause of ADEM is unknown, although it is thought to be associated with an autoimmune response that could be activated by an infection or, in extremely rare cases, vaccination.
What are the symptoms of ADEM?
Symptoms are typically neurological and include seizures, numbness of the body, cranial nerve dysfunction, slurred speech, weakness in the arms and/or legs, and the inability to coordinate voluntary movements. Seizures are more common in young children. The average age of onset for children is between 5 and 8 years old, but it has been diagnosed in babies as young as 7 months old.
When ADEM is considered to have been caused by an infection, initial symptoms typically appear within a few days or weeks of the start of the infection. The severity and progression of ADEM symptoms depend on the location of the brain lesions at the time of onset. Typically, someone who experiences ADEM will not experience it again, but a few people are reported to have experienced it more than once.
Are treatments available for ADEM?
Treatments may include targeted immune system therapies and rehabilitation therapy.