Acute Disseminated Encephalomyelitis (ADEM)
A sudden, brief inflammation of the brain and spinal cord, often after infection
Quick Facts
- Type: Inflammatory brain and spinal cord condition
- Common trigger: A recent infection or, rarely, vaccination
- Most affected: Children, though adults can be affected
- Urgency: Medical emergency; seek immediate care
Overview
Acute disseminated encephalomyelitis (ADEM) is a sudden, widespread bout of inflammation affecting the brain and spinal cord. The inflammation damages myelin, the protective coating that surrounds nerve fibers, which disrupts the signals the nervous system relies on. ADEM usually develops within days to a few weeks after an infection and, less commonly, after a vaccination.
ADEM is most common in children but can occur at any age. Although the rapid onset of neurological symptoms can be alarming, ADEM is typically a single (monophasic) event, and many people, especially children, recover well with prompt treatment. Because the symptoms can be serious and progress quickly, ADEM is a medical emergency that needs urgent evaluation.
Symptoms
Symptoms come on quickly and can affect many parts of the nervous system at once. They often follow a recent illness and may include:
- Headache, fever, and feeling generally unwell
- Confusion, drowsiness, irritability, or in severe cases reduced consciousness
- Weakness or numbness, sometimes on one or both sides of the body
- Unsteadiness, difficulty walking, or loss of coordination
- Vision changes, such as blurred or double vision
- In some cases, seizures
Seek emergency care immediately for sudden confusion, severe drowsiness, seizures, weakness, or vision loss, especially after a recent infection.
Causes
ADEM is thought to result from an abnormal immune response that mistakenly attacks the myelin coating of nerves in the brain and spinal cord. Triggers include:
- Recent infection: Many cases follow a viral or, less often, bacterial infection by days to weeks.
- Post-vaccination immune reaction: Rarely, ADEM has been reported after vaccination, though this is uncommon.
- Idiopathic cases: In some people, no clear trigger is identified.
The immune system's reaction, rather than direct infection of the brain, causes the inflammation. ADEM is not contagious and is not inherited.
Risk Factors
- A recent infection, especially a viral illness
- Childhood, as ADEM is more common in children
- It can affect people of any age and is generally rare
- No strong lifestyle risk factors are established
Diagnosis
Prompt evaluation is needed to diagnose ADEM and rule out other serious conditions such as infection of the brain:
- MRI of the brain and spinal cord: Shows the characteristic areas of inflammation affecting myelin.
- Lumbar puncture (spinal tap): Examining the fluid around the brain and spinal cord helps detect inflammation and exclude infection.
- Blood tests: Look for signs of infection and other conditions.
- Neurological examination: Assessing the pattern and severity of symptoms.
Treatment
Treatment focuses on calming the immune attack and supporting the body during recovery:
- Corticosteroids: High-dose anti-inflammatory steroids, usually given by vein, are the main treatment to reduce inflammation.
- Other immune therapies: If steroids are not enough, treatments such as intravenous immunoglobulin (IVIG) or plasma exchange may be used.
- Supportive care: Managing fever, seizures, and other symptoms, sometimes in intensive care for severe cases.
- Rehabilitation: Physical, occupational, and other therapies aid recovery of function.
Many people, particularly children, recover well, though some have lasting effects. ADEM is usually a single episode, but a small number of people have further attacks and need ongoing follow-up.
Prevention
- There is no specific way to prevent ADEM
- General hygiene may reduce some of the infections that can trigger it
- Seeking prompt care for sudden neurological symptoms supports the best outcome
- Following up after recovery helps monitor for any further episodes
When to See a Doctor
Seek emergency care immediately if you or your child develops, especially after a recent infection:
- Sudden confusion, severe drowsiness, or reduced consciousness
- Seizures
- Weakness, numbness, or trouble walking
- Sudden vision changes or loss
- Severe headache with fever and a stiff neck
These symptoms need urgent evaluation, both to treat ADEM early and to rule out other serious conditions.
Frequently Asked Questions
What is ADEM?
ADEM, or acute disseminated encephalomyelitis, is a sudden, widespread inflammation of the brain and spinal cord that damages the protective myelin coating of nerves. It usually develops within days to weeks after an infection and causes neurological symptoms such as weakness, confusion, and vision changes.
Is ADEM the same as multiple sclerosis?
No, though both involve damage to myelin. ADEM is typically a single episode of widespread inflammation, often after an infection and most common in children, whereas multiple sclerosis is a chronic condition with repeated attacks over time. Doctors monitor for any further episodes to make this distinction.
What causes ADEM?
ADEM is thought to be caused by an abnormal immune response that attacks myelin after a trigger, most often a recent viral infection and, rarely, a vaccination. In some cases no clear trigger is found. It is not contagious or inherited.
Can people recover from ADEM?
Yes. Many people, especially children, recover well with prompt treatment, though some have lasting effects. ADEM is usually a single event, but a small number of people have further attacks and need ongoing follow-up.
When is ADEM an emergency?
ADEM is a medical emergency. Seek immediate care for sudden confusion, severe drowsiness, seizures, weakness, numbness, or vision loss, especially after a recent infection, as early treatment and ruling out other serious conditions are important.
References
- National Institute of Neurological Disorders and Stroke (NINDS). Acute Disseminated Encephalomyelitis.
- MedlinePlus, U.S. National Library of Medicine. Encephalitis.
- National Multiple Sclerosis Society.
- Mayo Clinic. Encephalitis — Symptoms and causes.