What Is Acute Disseminated Encephalomyelitis?
Acute disseminated encephalomyelitis (ADEM) is a rare kind of inflammation that affects the brain and spinal cord, usually in children. It damages the coating that protects nerve fibers, called myelin.
Symptoms may be severe, but they can be treated. Most people make a full recovery and don't have another attack.
ADEM comes on suddenly and gets worse fast. Symptoms include:
ADEM Causes and Risk Factors
Doctors think ADEM is an autoimmune disease. That means your immune system attacks your body's own cells and tissues as if they were bacteria or viruses.
Experts don't know exactly what triggers it, but it could be a reaction to an infection. Most of the time, the attack happens when a child is getting over a common illness, like a cold or stomach bug.
Other times, symptoms seem to come out of nowhere.
ADEM risk factors include:
- Age. More than 80% of cases are in children younger than 10. Most of the rest are in older kids.
- Sex. Boys are slightly more likely to get it than girls.
- Time of year. Cases in North America peak during winter and spring.
How Is ADEM Different From MS?
ADEM has a lot in common with multiple sclerosis (MS) and other diseases that damage myelin. They share some symptoms, like muscle weakness, numbness, loss of vision, and loss of balance.
The differences include:
- MS is rare in children. ADEM is more common.
- Kids with ADEM may have a fever, a headache, seizures, or trouble thinking clearly. These symptoms are rare with MS.
- The disease usually appears soon after a viral illness. There's no such link with MS.
- An ADEM attack usually happens once, but multiple sclerosis involves many episodes over time.
ADEM Diagnosis and Tests
No one test can spot ADEM. Doctors most often diagnose it with MRI (pictures of your brain made with a large magnet and radio waves) and a lumbar puncture (fluid drawn from around the spinal cord and then tested).
Your doctor will try to rule out conditions with similar symptoms. ADEM and MS look different on tests:
- Tests of spinal fluid usually show certain proteins when you have MS, but not ADEM.
- With ADEM, spinal fluid usually has more white blood cells than usual.
- Damage to the brain from ADEM and damage caused by MS look different on an MRI. It's more widespread with ADEM.
The doctor will also rule out infections of the brain and spinal cord, such as meningitis.
The goal is to get the inflammation down quickly and stop the immune system attack. This will probably take a week or two in the hospital.
Most people start with high doses of a strong corticosteroid put into a vein (intravenous, or IV) for a few days. Your child may feel better within hours. They'll keeping taking a steroid (as a pill or a liquid) for several weeks, in smaller and smaller doses.
If your child can't have steroids or if they don't work, some procedures can calm the immune system. The doctor may filter their blood through a machine to take out the antibodies that their immune system is sending to attack their brain. This is called plasmapheresis. Or they could get shots of antibodies from a healthy person, which is called intravenous immunoglobulin treatment.
After the hospital, they may need physical, occupational, or speech therapy. They may have to stay in a rehab hospital for a while, or they might be able to go home and work with a therapist.
Your child will probably have a follow-up MRI to make sure the inflammation is gone and no new scars have formed.
Most children who get ADEM will recover fully. It’s usually a slow process, over 4 to 6 weeks. It could be up to a year before they're totally well.
Sometimes, kids don't get over all of their symptoms. They may have lasting vision damage or muscle weakness. They might have trouble in school if they've missed a lot of time or as a long-term effect of the inflammation.
About 8 times out of 10, ADEM happens only once. But sometimes, you can get it again within a few months, especially if you don't take steroids for long enough. Rarely, children who have ADEM get MS later on.
In less than 2% of cases, ADEM can be deadly.