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Acute disseminated encephalomyelitis (ADEM)

Overview

Acute disseminated encephalomyelitis (ADEM) is an immune-mediated condition that causes widespread inflammation and damage to myelin in the brain and spinal cord. It most often occurs following an infection, particularly in children, although the exact cause is not always known.

ADEM is thought to result from an abnormal immune response in which the body mistakenly targets components of the central nervous system. Proposed mechanisms include molecular mimicry, disruption of the blood–brain barrier, and broader neuroinflammatory processes.

ADEM is typically described as a monophasic condition, meaning it occurs as a single episode. However, multiphasic forms have been reported, and distinguishing ADEM from other demyelinating diseases such as multiple sclerosis can be challenging.

Common Symptoms

Fever, headaches, irritability, fatigue, lethargy, malaise, unintended weight loss, nausea, and vomiting, vision loss in one or both eyes, muscle weakness even to the point of paralysis, difficulty coordinating voluntary muscle movements, confusion, stupor, delirium, and potentially coma.

Coexisting Diseases and Conditions

In some cases, distinguishing ADEM from other demyelinating conditions such as multiple sclerosis or MOG antibody-associated disease can be difficult, particularly early in the disease course.

Risk Factors and Prevalence

ADEM most commonly occurs after an infection, often developing within one to two weeks. While many cases follow viral illness, other triggers have been reported, and individual susceptibility, potentially influenced by genetic factors, may also play a role.

Additional encephalitis resources can be found at https://www.encephalitis411.org/

 

Recent Research

Sources

  1. Sources

    1. Rose, N. R., & Mackay, I. R. (2020). The Autoimmune Diseases (6th ed., pp. 1086-1087). Academic Press.

    2. U.S. Department of Health and Human Services. (n.d.). Acute Disseminated Encephalomyelitis Information Page. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/All-Disorders/Acute-Disseminated-Encephalomyelitis-Information-Page. 

    3. NORD – National Organization for Rare Disorders, Inc. (2016, June 28). Acute Disseminated Encephalomyelitis. NORD (National Organization for Rare Disorders). https://rarediseases.org/rare-diseases/acute-disseminated-encephalomyelitis/#:~:text=Acute%20disseminated%20encephalomyelitis%20(ADEM)%20is,and%20proteins%20known%20as%20myelin.  

    4. The National Multiple Sclerosis Society. (n.d.). Acute Disseminated Encephalomyelitis (ADEM). National Multiple Sclerosis Society. https://www.nationalmssociety.org/What-is-MS/Related-Conditions/Acute-Disseminated-Encephalomyelitis-(ADEM). 

    5. Tenembaum, S., Chitnis, T., Ness, J., & Hahn, J. S. (2007, April 17). Acute disseminated encephalomyelitis. Neurology. https://n.neurology.org/content/68/16_suppl_2/S23. 

    6. Siegel Rare Neuroimmune Association. (2020, June 26). Acute Disseminated Encephalomyelitis (ADEM): Diagnosis. SRNA. https://wearesrna.org/living-with-myelitis/disease-information/acute-disseminated-encephalomyelitis/diagnosis/. 

    7. Anilkumar, A. C., Foris, L. A., & Tadi, P. (2024). Acute Disseminated Encephalomyelitis. In StatPearls. StatPearls Publishing.

    8. Ferenc, K., Semik, P., & Paprocka, J. (2026). Acute Disseminated Encephalomyelitis (ADEM): Current View into Etiopathogenesis and Clinical Features. Brain sciences, 16(2), 201. https://doi.org/10.3390/brainsci16020201

    9. Kazzi, C., Alpitsis, R., O’Brien, T. J., Malpas, C., & Monif, M. (2024). Cognitive and psychopathological outcomes in acute disseminated encephalomyelitis. BMJ neurology open, 6(1), e000640. https://doi.org/10.1136/bmjno-2024-000640

    10. Nabizadeh, F., Noori, M., Rahmani, S., & Hosseini, H. (2023). Acute disseminated encephalomyelitis (ADEM) following COVID-19 vaccination: A systematic review. Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia, 111, 57–70. https://doi.org/10.1016/j.jocn.2023.03.008

    11. Mahapure, K. S., Prabhune, A. S., & Chouvhan, A. V. (2021). COVID-19-Associated Acute Disseminated Encephalomyelitis: A Systematic Review. Asian journal of neurosurgery, 16(3), 457–469. https://doi.org/10.4103/ajns.AJNS_406_20