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Acute flaccid myelitis
Other Resources UpToDate PubMed

Acute flaccid myelitis

Contributors: Bo Hoon Lee MD, Jamie Adams MD, Eric Ingerowski MD, FAAP, Richard L. Barbano MD, PhD
Other Resources UpToDate PubMed


Acute flaccid myelitis (AFM) is a rare neurologic disease presenting as rapid-onset flaccid weakness due to selective inflammation of the central gray matter of the spinal cord.

AFM predominantly affects children, with a median age of 8 years. Neurologic symptoms may be preceded by a febrile respiratory illness and sometimes pain in the extremities. This is followed by sudden-onset flaccid paralysis in a single limb or in multiple limbs with areflexia. Progression is rapid, with nadir of weakness within hours to days. Cranial nerve involvement may result in facial weakness, ophthalmoplegia, dysphagia, dysarthria, and difficulty breathing. Respiratory failure can result in the need for mechanical ventilation. Typically, there are no sensory or cognitive changes. Bowel and bladder involvement are rare. Severity of the disease can range from mild weakness in one limb to complete paralysis and inability to breathe. There is currently no established treatment. Prognosis is variable, but the disease can result in permanent paralysis.

This clinical syndrome has been associated with several pathogens, including enteroviruses (EV; eg, EV-D68), flaviviruses (eg, West Nile virus), and herpes virus, among others, but causation has not been established.

On September 9, 2022, the Centers for Disease Control and Prevention (CDC) Health Alert Network urged health care providers to consider EV-D68 as a possible cause of acute, severe respiratory illness (with or without fever) in children and the potential for an increase in acute flaccid myelitis cases in the upcoming weeks.


G83.89 – Other specified paralytic syndromes

41370002 – Myelitis

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Diagnostic Pearls

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Differential Diagnosis & Pitfalls

  • Transverse myelitis
  • Acute demyelinating encephalomyelitis
  • Acute inflammatory demyelinating polyneuropathy – cytoalbuminologic dissociation in cerebrospinal fluid (CSF)
  • Poliomyelitis
  • Spinal cord injury or Spinal cord compression
  • Spinal cord tumor or abscess
  • Botulism / Infant botulism
  • Tick paralysis
  • Peripheral neuropathy (eg, compressive neuropathy, Acute motor axonal neuropathy)
  • Stroke (Cerebral stroke, Cerebellar stroke) / Transient ischemic attacks
  • Myasthenia gravis

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Last Reviewed:10/31/2018
Last Updated:10/10/2022
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Acute flaccid myelitis
A medical illustration showing key findings of Acute flaccid myelitis : Dysarthria, Eyelid ptosis, Dysphagia, Hyporeflexia, Facial weakness, Limb weakness
Copyright © 2024 VisualDx®. All rights reserved.