Acute Disseminated Encephalomyelitis (ADEM)

Acute Disseminated Encephalomyelitis (ADEM) is a rare autoimmune condition that causes sudden inflammation in the brain and spinal cord. It typically follows a viral or bacterial infection (or sometimes a vaccination), and leads to damage of the protective myelin covering on nerve fibers, which disrupts nerve signals. ADEM is more common in children and young adults, and usually occurs only once (unlike multiple sclerosis, which is recurrent).

Sudden fever, headache, and confusion; Drowsiness or lethargy; Seizures (in some cases); Weakness or numbness (often on one side); Vision problems (blurred vision, eye pain, or double vision); Balance issues or trouble walking; Speech difficulties; Coma (in severe cases). Symptoms often develop rapidly over a few days.

Triggered by an immune system overreaction, usually after viral infections (e.g., measles, flu, COVID-19, Epstein-Barr), bacterial infections (rarely), or vaccinations (very rare). The immune system mistakenly attacks myelin in the central nervous system.

MRI scans to show inflammation and demyelination; Lumbar puncture (spinal tap) to check cerebrospinal fluid; Blood tests to rule out infections or other autoimmune diseases; Sometimes EEG. Doctors also rule out conditions like multiple sclerosis or autoimmune encephalitis.

High-dose corticosteroids (like IV methylprednisolone) are first-line. If steroids do not help: IVIG (intravenous immunoglobulin) or Plasmapheresis (plasma exchange). Supportive care (rehab, physical therapy, seizure control).

Most people recover fully, especially with early treatment. Some may have lingering symptoms (fatigue, concentration issues, or weakness). Rarely, ADEM can be fatal or evolve into multiphasic ADEM or MS. Prognosis is generally better in children than in adults.

Estimated 0.4 to 0.8 per 100,000 people per year. More common in children under age 10. Slightly more common in boys.