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Acute Disseminated Encephalomyelitis (ADEM)

Overview

Acute disseminated encephalomyelitis (ADEM) is an acquired condition in which the body’s immune system mistakenly attacks the brain and spinal cord. This leads to demyelination (damage to the protective covering called myelin around nerves), which disrupts how signals are sent in the nervous system. ADEM develops after an infection or immunisation. It generally affects the younger population and is usually monophasic (occurs once and does not recur).

Symptoms of ADEM often develop suddenly, usually a few days or weeks after an infection. These may include:

  • Fever
  • Headache
  • Meningism (neck stiffness and sensitivity to light, similar to meningitis)
  • Seizures (convulsions)
  • Altered mental state (confusion, drowsiness, or irritability)
  • Multiple neurological deficits (weakness, vision problems, imbalance, or difficulty speaking)

ADEM is not contagious; it occurs when the immune system overreacts and starts attacking the body’s own nervous system. The exact cause is not fully understood, but it often develops:

  • After an infection (such as viral flu, measles, or chickenpox)
  • Occasionally after vaccination (very rare)

Doctors perform several tests to diagnose ADEM and rule out other similar conditions:

  • CSF (cerebrospinal fluid) examination: to determine the number of white blood cells, protein levels, and abnormal immune proteins (oligoclonal bands).
  • MRI (Magnetic Resonance Imaging): to detect areas of demyelination (nerve covering damage), especially in both white and grey matter. Contrast dye may be used to check for active inflammation.
  • Differential diagnosis: Other diseases such as multiple sclerosis, myelin oligodendrocyte glycoprotein antibody disease (MOGAD), neuromyelitis optica, neurosarcoidosis, malignancy, and granulomas need to be ruled out.

Treatment aims to reduce inflammation and calm the immune response:

  • Intravenous steroids (first-line treatment): High steroid doses are given to quickly reduce inflammation.
  • Intravenous immunoglobulin: A 5-day course is used if steroids are not effective.

Seek immediate medical care if a child or adult develops:

  • Sudden confusion, seizures, or abnormal behaviour after an infection
  • Severe headache with fever and neck stiffness
  • Weakness, numbness, or balance problems that appear suddenly

There is no guaranteed way to prevent ADEM. However, treating infections early and maintaining good hygiene may reduce risk.

Patients with suspected ADEM should consult a Neurologist (specialist in brain and nerve disorders)

Disclaimer:

The information in this Health Library is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare professional with any questions about a medical condition or before starting any treatment. Use of this site and its content does not establish a doctor–patient relationship. In case of a medical emergency, call your local emergency number or visit the nearest emergency facility immediately.