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    Neuromuscular Weakness

    Cardinal Presentations / Presenting Problems, Neurological, Toxicology

    Last Updated Dec 15, 2023
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    First 5 Minutes

    • In patients presenting with weakness, determine whether or not the weakness represents true neuromuscular weakness or subjective weakness.
    • Avoid depolarizing neuromuscular blocking agents if intubation is required in true neuromuscular weakness.
    • Critical diagnoses include ischemic and hemorrhagic stroke, Guillain-Barré syndrome, myasthenic crisis and spinal cord compression.


    Causes of true neuromuscular weakness originate from disorders of the brain or spinal cord, nerves roots, plexus, or peripheral nerves, neuromuscular junctions or muscle fibers.

    Diagnostic Process

    Early recognition of signs of impending respiratory failure:

    Tachypnea, altered mentation, increased oral secretions, difficulty swallowing, inability to lift head from lying position, weak voice, difficulty speaking, dysarthria, shallow, weak and rapid breathing and accessory muscle use.

    Approach to true neuromuscular weakness in the emergency department. Adapted from various sources.


    • ECG
    • CBC, BMP, glucose, CK, LFTs, coagulation panel
    • +/- neuroimaging as indicated

    Recommended Treatment

    • Address respiratory failure and intubate as necessary:
      • GCS < 8
      • Inability to protect airways
      • Severe fatigue
      • Hypoxemia or hypercarbia
      • FVC <12 ml/kg
      • Negative inspiratory force <20 cm H20
    • Avoid succinylcholine if possible.
    • Involve neurology early.
    • Treat underlying cause.
    • Consult BC poison control if suspected exposure.

    Criteria For Hospital Admission

    • Decreased level of consciousness.
    • Respiratory distress.
    • Acute risk of aspiration or inability to protect airway.

    Criteria For Transfer To Another Facility

    Consult local institutional guidelines.

    Criteria For Safe Discharge Home

    If careful and thorough assessment has ruled out neurological emergency and rapidly progressive neuromuscular disease, patients may be discharged home with instructions to follow-up with family doctor or specialist as required.

    Quality Of Evidence?


    The diagnostic approach is recommended based on robust clinical guidelines and diagnostic features.


    Related Information


    Reference List

    1. Khamees D, Meurer W. Approach to Acute Weakness. Emerg Med Clin North Am. 2021;39(1):173-180.


    2. DynaMed. Acute Weakness in Adults – Approach to the Patient. DynaMed. Updated September 22, 2023. Accessed November 22, 2023.


    3. Casey KF. Assessment of Acute Motor Deficit. BMJ Best Practices. Updated June 2, 2023. Accessed November 22, 2023.



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