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Acute Flaccid Myelitis

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Acute Flaccid Myelitis

  • Epidemiology
  1. First reported in California, 2012
  2. Outbreaks have occured in late summer and early fall (2014, 2016, 2018)
  3. Median age: 9 years old (some patients have been over age 21 years old)
  • Pathophysiology
  1. Gray matter destruction typically related to viral infection
  • Symptoms
  1. Viral prodrome
    1. Fever
    2. Upper Respiratory Infection
  2. Meningeal symptoms may occur
    1. Headache
    2. Neck stiffness
    3. Myalgias
    4. Preserved mental status (no encephalopathy in most cases)
  3. Rapidly progressive and persistent weakness (follows fever by 3-7 days)
    1. Weakness peaks by 5 days after the weakness starts
    2. Bilateral in most cases
    3. Respiratory Failure may occur (requiring Mechanical Ventilation)
    4. Upper extremity involvement more common than lower extremity weakness
      1. Quadriplegia may occur
    5. Neurogenic bowel or Bladder
      1. Urine Incontinence
      2. Stool Incontinence
    6. Cranial Nerve Involvement may be present
      1. Facial weakness
      2. Extraocular Movement weakness (Ophthalmoplegia)
      3. Dysarthria
      4. Dysphagia
    7. Sensory deficits
      1. Focal Paresthesias
  • Causes
  1. See Transverse Myelitis
  2. Enterovirus D68 and A71
  3. Other non-polio viral infections
  • Labs
  1. Obtain labs to evaluate differential diagnosis (e.g. CBC, Chemistry panel)
  2. Enterovirus nasopharyngeal swabs
  3. Cerebrospinal Fluid
    1. Pleocytosis may be present
  • Imaging
  1. MRI Brain
    1. Brainstem lesions may be present (dorsal pontine tegmentum)
  2. MRI Spinal Cord with and without contrast
    1. Spinal cord gray matter changes, esp. in the anterior horns (T2-weight images)
  • Management
  1. Intravenous Immunoglobulin
  2. Other measures that have been used with variable efficacy
    1. Corticosteroids
  • Prognosis
  1. Complete recovery is uncommon
  2. Most patients will be left with residual deficits
  • References
  1. (2019) EM:Rap 19(2): 16-7
  2. (2019) Polio and other Infectious Causes of Acute Flaccid Paralysis, UpToDate, accessed 2/7/2019