Acute Disseminated Encephalomyelitis (ADEM)

What is acute disseminated encephalomyelitis (ADEM)?

Acute disseminated encephalomyelitis (ADEM) is a neurological condition characterized by an episode (attack) of inflammation in your central nervous system. The attack often damages the protective covering around your nerve axon, called the myelin sheath, which helps transmit information between nerve cells.

Like the plastic cover around electrical wires, myelin surrounds your nerve fibers to help electrical signals move to other nerve cells in your body. If you have damage to your myelin, you may experience symptoms like vision loss and muscle weakness.

A healthcare provider may call ADEM a “demyelinating” condition. This condition is acute, meaning sudden. ADEM usually only occurs once but can sometimes happen again.

How common is ADEM?

ADEM is rare. Studies estimate that ADEM affects 1 in every 125,000 to 250,000 people in the United States.

What are the symptoms of ADEM?

Symptoms of ADEM usually follow a viral or bacterial infection. The symptoms vary based on where the inflammation occurs and could include:

• Fever.
• Headache.
• Nausea or vomiting.
• Confusion.
• Fatigue.

Neurological symptoms may include:

• Numbness or a tingling sensation in your arms and legs.
• Difficulty swallowing.
• Vision loss (optic neuritis).
• Muscle weakness.
• Difficulty walking.
• Seizures.

Your symptoms and the severity of your symptoms can vary widely.

What causes ADEM?

The exact cause of ADEM is unknown. Research suggests that an infection could trigger your immune system to respond to the threat abnormally, which causes symptoms of ADEM. When a viral or bacterial infection enters your body, your immune system works to get rid of the infection that makes you sick. If you have ADEM, your immune system can mistake certain parts of your central nervous system for the bacteria or virus and attack it. This results in inflammation (swelling), which then causes the symptoms of ADEM.

Approximately 70% to 80% of people diagnosed with ADEM experience an infection or illness before they experience symptoms of ADEM. Most cases of ADEM begin about seven to 14 days after the infection. Some common infections associated with ADEM include:

• Flu (influenza).
• Measles.
• Mumps.
• Rubella.
• Chickenpox.
• Epstein Barr virus.
• Cytomegalovirus.
• Herpes simplex virus.

While many different bacteria, viruses and other infections relate to ADEM, the cause doesn’t appear to be by any one infectious agent.

An increasingly recognized cause of ADEM, especially in children, is a condition known as myelin oligodendrocyte antibody-associated disease (MOGAD). This is thought to be an autoimmune condition that attacks the central nervous system and can sometimes cause ADEM.

What are the risk factors for ADEM?

Anyone can develop ADEM. It’s more common among children than adults. You’re more likely to get ADEM if you recently had an infection.

What are the complications of ADEM?

Complications of ADEM may include:

• Memory loss.
• Cognitive processing delays.
• Coma.

In very rare cases, symptoms of ADEM can be fatal.

Ongoing symptoms after treatment may include:

• Severe headaches.
• Numbness.
• Trouble with coordination.
• Blurry vision.

How is ADEM diagnosed?

A healthcare provider will take a detailed medical history and ask you questions about your symptoms. They’ll diagnose ADEM after a neurological examination, physical examination and testing.

Testing is necessary to look for underlying conditions that may cause the ADEM attack, such as MOGAD. Tests to diagnose ADEM usually include blood tests, as well as:

• An MRI.
• Spinal fluid testing.

ADEM on MRI

Magnetic resonance imaging (MRI) is a type of imaging test. It looks for changes deep within your brain. There are three areas in your central nervous system (brain, spinal cord, optic nerves) where a healthcare provider will look for changes, like lesions or spots, caused by ADEM:

• White matter: The white matter contains nerve fibers. Myelin covers your nerve fibers and appears white on the basic MRI sequences.
• Grey matter: The grey matter contains nerve cell bodies and no myelin. This gives it a darker appearance on basic MRI sequences.

Months after your first MRI, your healthcare provider may order another MRI to monitor how these areas of your central nervous system change over time.

Spinal fluid testing

A spinal tap or lumbar puncture is a diagnostic test that evaluates the cause of neurological symptoms. The lumbar puncture allows your neurological team to test your cerebrospinal fluid (CSF). CSF is a clear, colorless fluid that circulates around your brain and spinal cord, protecting it and providing it with nutrients.

In ADEM, your spinal fluid often shows an increase in white blood cells, predominantly lymphocytes. These cells are an active part of your immune system. A healthcare provider may remove a sample of CSF to test your cells’ reaction to certain bacteria or viruses thought to trigger ADEM. It can also check for other neuroinflammatory diseases.

How is ADEM treated?

Treatment for ADEM focuses on reducing inflammation in your brain and spinal cord. Treatment may include:

• Steroid medications: The first line of treatment for ADEM is usually intravenous (infusion through a vein) steroids. You may need more than one infusion followed by oral steroids (medications you take by mouth) to complete your treatment.
• Intravenous immune globulin (IVIG): This is an antibody treatment that comes from donor plasma, given via infusion into a vein.
• Plasma exchange: Plasma exchange or plasmapheresis circulates your blood through a machine that removes certain components to reduce your immune system’s activity. This treatment cycles blood from a vein into your arm into a machine and then back into a vein on your opposite arm. It can take a few hours to complete this treatment and you may need more than one session.

Research is ongoing to learn more about this condition and find new treatment options that can help you feel better.

Are there side effects of the treatment?

The side effects of short-term steroid therapy are usually temporary but may include:

• Increased blood glucose levels.
• Low potassium levels.
• Difficulty sleeping.
• Mood changes (irritability, crying, anxiety).
• Weight gain.
• Flushed cheeks.
• A metallic taste in your mouth.

The side effects and complications of IVIG may include:

• An allergic reaction.
• Infection.
• Shortness of breath.
• Blood clots.
• Kidney injury.
• Headaches.

The complications of plasmapheresis may include:

• Discomfort.
• Bleeding.
• Infection.
• Kidney injury.
• Ischemia (not enough blood supply to part of your body).

How soon after treatment will I feel better?

Most people who receive treatment for ADEM feel better a few days after they finish treatment. Depending on the severity of your symptoms, it may take up to six months to recover. In rare cases, some people aren’t able to fully recover.

Can ADEM be prevented?

There isn’t a way to prevent ADEM. You can reduce your risk by practicing good hygiene to avoid viral and bacterial infections.

What is the outlook for ADEM?

Most people diagnosed with ADEM make a full or nearly complete recovery after treatment. Very rare cases are life-threatening if inflammation is severe. Your healthcare provider will be able to give you a better idea about your prognosis.

What is the survival rate of ADEM?

The majority of people diagnosed with ADEM have a normal life expectancy. The condition is rarely life-threatening.

Is ADEM curable?

An attack of symptoms caused by ADEM usually only happens once but can recur (come back) depending on the underlying cause. With treatment, ADEM can go away, but there’s a chance your symptoms may happen again.

When should I see a healthcare provider?

Visit a healthcare provider if you experience symptoms of ADEM, especially after an infection.

What questions should I ask my healthcare provider?

• How do I prepare for diagnostic testing?
• What type of treatment do you recommend?
• Are there side effects of the treatment?
• Will my symptoms persist after treatment?