Acute Disseminated Encephalomyelitis

The inflammation usually occurs one to two weeks after a viral or bacterial infection, such as a sore throat or cough. ADEM very rarely occurs within three months after a child receives a vaccination for measles, mumps and rubella (MMR vaccine). The infection or vaccination triggers an autoimmune response, causing the body’s immune system to attack its own healthy myelin tissue.

The damaged myelin and resulting inflammation cause a variety of symptoms. Symptoms of acute disseminated encephalomyelitis include:

• Fever
• Weakness
• Numbness or tingling
• Headache
• Confusion
• Vomiting
• Blurry vision
• Changes in color perception
• Altered mental state

ADEM is typically a one-time event that most often affects children younger than 10 years old, although it can recur within a few months of the initial episode. The condition affects 1 in every 125,000 to 250,000 individuals each year. The condition occurs most often in winter and spring.

The symptoms of ADEM are similar to other conditions, including pediatric multiple sclerosis, optic neuritis (inflammation in the bundle of nerves that sends signals from the eye to the brain), transverse myelitis (inflammation in the spinal cord) and recurrent ADEM (acute disseminated encephalomyelitis that returns).

If your child shows signs of ADEM, a neurologist will perform specific tests to make an accurate diagnosis. Most children with ADEM make a complete and full recovery. Recovery time may take only a few days, but some cases may take up to a year to heal. Some children may continue to have some symptoms, such as blurred vision, numbness or weakness.

Diagnosis of Acute Disseminated Encephalomyelitis

Doctors at Riley at IU Health perform the following exams and tests to diagnose acute disseminated encephalomyelitis:

• Medical history. The neurologist will review your child’s medical history, especially any recent infections or vaccinations.
• Neurological exam. The doctor will check your child’s balance and look for signs of weakness in the limbs, numbness and changes in vision.
• Magnetic resonance imaging (MRI). The doctor will use MRI to look at the condition of the nerves in the brain and spinal cord.
• Lumbar puncture. A sample of spinal fluid is removed and checked for signs of central nervous system infections like meningitis or encephalitis, inflammation, cell count, protein and immune markers.
• Blood tests. A blood sample will be studied in the lab to check for infection triggers and other conditions similar to ADEM.

If repeated bouts of demyelinating symptoms occur, or if old and new lesions can be seen on an MRI exam, your child’s doctor may recommend further tests to check for other conditions, such as pediatric multiple sclerosis. The presence of older lesions on an MRI image may indicate multiple sclerosis, which can cause brain lesions before symptoms appear. A single episode of ADEM causes widespread myelin damage, while multiple sclerosis causes many attacks over time.