Management of Acute Non-Traumatic Weakness

Immediate Life-Threatening Assessment

Assess respiratory function immediately by measuring negative inspiratory force (NIF) and vital capacity (VC), as respiratory failure is the defining feature of myasthenic crisis and can occur with Guillain-Barré syndrome, according to the Journal of Clinical Oncology 1
Monitor for bulbar symptoms (dysphagia, dysarthria, facial weakness) which indicate impending respiratory compromise, as recommended by the Journal of Clinical Oncology 1
Obtain pulse oximetry, continuous ECG, blood pressure, and respiratory rate within minutes of patient contact, as suggested by the European Journal of Heart Failure 3
Consider ICU-level monitoring for patients with rapidly progressive symptoms, any dysphagia, facial weakness, or respiratory muscle weakness, according to the Journal of Clinical Oncology 1

Perform detailed neurological examination to localize the lesion (central vs peripheral nervous system, neuromuscular junction, or muscle), and consider cranial nerve involvement, particularly ocular, bulbar, and facial muscles, as recommended by the Journal of Clinical Oncology 1
Evaluate the pattern of weakness: Proximal, distal, ascending, descending, or fluctuating, as suggested by Praxis Medical Insights 2

Obtain immediate laboratory testing including creatine kinase (CK), aldolase, troponin, complete metabolic panel, and inflammatory markers (ESR, CRP), as recommended by the Journal of Clinical Oncology 1
Check for elevated CK/aldolase with weakness, which suggests myositis or rhabdomyolysis, according to the Journal of Clinical Oncology 1
Evaluate troponin and ECG to assess for myocardial involvement, which can be life-threatening, as suggested by the Journal of Clinical Oncology 1

Immediately review and stop medications that worsen myasthenia gravis, such as beta-blockers, IV magnesium, fluoroquinolones, aminoglycosides, and macrolide antibiotics, as recommended by the Journal of Clinical Oncology 1

For myasthenia gravis, the American College of Physicians recommends holding immune checkpoint inhibitors if applicable, starting pyridostigmine, and administering prednisone, as suggested by the Journal of Clinical Oncology 1
For Guillain-Barré syndrome, the American Academy of Neurology recommends discontinuing immune checkpoint inhibitors, obtaining neurology consultation, and starting IVIG or plasmapheresis, as suggested by the Journal of Clinical Oncology 1
For inflammatory myositis, the European League Against Rheumatism recommends offering prednisone, using acetaminophen or NSAIDs for pain, and performing autoimmune myositis panel, EMG, and MRI of affected muscles, as suggested by Praxis Medical Insights 4

Do not overlook myocardial involvement by failing to check troponin and ECG, as this can be life-threatening, as warned by Praxis Medical Insights 4
Do not delay specialist (neurology) referral, particularly in moderate to severe cases, as recommended by the Journal of Clinical Oncology 1
Do not use clinical decision rules alone to exclude serious causes of weakness; clinical judgment is essential, as suggested by the Annals of Emergency Medicine 6