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Acute Inflammatory Demyelinating Polyneuropathy (AIDP)


  • Rapid onset polyneuropathy that manifests most often with ascending weakness and numbness that can involve the respiratory and facial musculature

  • Usually preceded by infectious illness a few weeks prior

  • Patients are much more likely to get AIDP from an infection than any vaccine, weak vaccine links to AIDP are an addition 1-2 cases per million flu vaccines.


  • Acute, progressive extremity weakness, weak or absent reflexes, and potentially subjective sensatory changes, especially back pain

    • There are a TON of variants of AIDP, with some having cranial nerve weakness early, proximal weakness, sensory ataxia, primarily sensory loss, or rapid muscle weakness; do not use lack of classic ascending weakness to dismiss the idea of AIDP

    • Sensory loss is common in an ascending pattern too


  • LP – albuminocytologic dissociation = high protein with normal cell count

    • One exception is HIV, which can cause AIDP but also have a high cell count and high protein count

    • Demyelinating pattern (temporal dispersion and decreased conduction velocities).

    • This can be normal in the first few days, and is most useful 2+ weeks out if the diagnosis is still unclear

  • Differential diagnosis: spinal cord lesions, LEMS, MG, acute HIV or HCV, viral myelitis (entero/West Nile)


  • ABCs! NIF at baseline then Q4-6 hours

    • NIF \< -30 with good effort generally warrants ICU monitoring
  • IVIG or PLEX

  • Can get worse with steroids