Postinfectious Encephalomyelitis
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What is Acute Disseminated Encephalomyelitis?Is there any treatment?What is the prognosis?What research is being done?OrganizationsWhat is Acute Disseminated Encephalomyelitis?
Acute disseminated encephalomyelitis (ADEM) is characterized by a brief but intense attack of inflammation in the brain and
spinal cord that damages myelin – the protective covering of nerve fibers. It often follows viral infection, or less often,
vaccination for measles, mumps, or rubella. The symptoms of ADEM come on quickly, beginning with encephalitis-like symptoms
such as fever, fatigue, headache, nausea and vomiting, and in severe cases, seizures and coma. It may also damage white matter
(brain tissue that takes its name from the white color of myelin), leading to neurological symptoms such as visual loss (due
to inflammation of the optic nerve) in one or both eyes, weakness even to the point of paralysis, and difficulty coordinating
voluntary muscle movements (such as those used in walking). ADEM is sometimes misdiagnosed as a severe first attack of multiple
sclerosis (MS), since some of the symptoms of the two disorders, particularly those caused by white matter injury, may be
similar. However, ADEM usually has symptoms of encephalitis (such as fever or coma), as well as symptoms of myelin damage
(visual loss, paralysis), as opposed to MS, which doesn’t have encephalitis symptoms. In addition, ADEM usually consists
of a single episode or attack, while MS features many attacks over the course of time. Doctors will often use imaging techniques,
such as MRI (magnetic resonance imaging), to search for old and new lesions (areas of damage) on the brain. Old “inactive”
brain lesions on MRI suggest that the condition may be MS rather than ADEM, since MS often causes brain lesions before symptoms
become obvious. In rare situations, brain biopsy may show findings that allow differentiation between ADEM and severe, acute
forms of MS. Children are more likely than adults to have ADEM.
Is there any treatment?
Treatment for ADEM is targeted at suppressing inflammation in the brain using anti-inflammatory drugs. Most individuals respond
to intravenous corticosteroids such as methylprednisolone. When corticosteroids fail to work, plasmapheresis or intravenous
immunoglobulin therapy has been shown to produce improvement. Additional treatment is symptomatic and supportive.
What is the prognosis?
Corticosteroid therapy can shorten the duration of neurological symptoms and halt further progression of the disease in the
short term, but the long term prognosis for individuals with ADEM varies. For most, recovery begins within days, and half
will recover completely. Others may have mild to moderate lifelong impairment. Severe cases of ADEM can be fatal. Some
individuals who initially diagnosed as having ADEM will later be reclassified as MS, but there is currently no method to determine
whom those individuals will be.
What research is being done?
The National Institute of Neurological Disorders and Stroke (NINDS) and other institutes of the National Institutes of Health
(NIH) conduct research related to ADEM in laboratories at the NIH, and also support additional research through grants to
major medical institutions across the country. Much of this research focuses on finding better ways to prevent, treat, and
ultimately cure demyelinating disorders such as ADEM.
Select this link
to view a list of studies currently seeking patients.
Organizations
Prepared by:
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National Institute of Neurological Disorders and Stroke
National Institutes of Health
Bethesda, MD 20892
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or an official position of the National Institute of Neurological Disorders and Stroke or any other Federal agency. Advice
on the treatment or care of an individual patient should be obtained through consultation with a physician who has examined
that patient or is familiar with that patient's medical history.
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Last updated January 23, 2006
