Myasthenic Crisis

Definition:
Myasthenic crisis is a life-threatening exacerbation of myasthenia gravis (MG) characterized by worsening of myasthenic weakness that requires intubation or noninvasive ventilation. While the primary cause of respiratory failure is weakness of respiratory muscles, severe bulbar muscle weakness (especially oropharyngeal muscles) often accompanies it or may even be the predominant feature in some patients. When this leads to upper airway obstruction or severe dysphagia with aspiration, intubation and mechanical ventilation become necessary. It requires management in an intensive care setting.

Evaluation and Treatment:

• Chest X-ray to exclude other lung diseases.
• Monitor electrolytes, and obtain a CBC with differential.
• Consider forced vital capacity (FVC) measurements.
• Respiratory support: Early use of **HFNC** or **BiPAP** if mild-moderate respiratory distress.
• Intubation only if clinically indicated.
• Pyridostigmine: Initiate at 60 mg PO q6hr for new MG diagnosis.
• Plasma exchange (PLEX, plasmapheresis) is preferred for stabilizing disease; if contraindicated, use intravenous immunoglobulins (IVIG).
• Avoid certain medications: Aminoglycosides, fluoroquinolones, beta-blockers, and others.

Source: 
(1) Myasthenic crisis – UpToDate. https://www.uptodate.com/contents/myasthenic-crisis.
(2) Frontiers | A Practical Approach to Managing Patients With Myasthenia …. https://www.frontiersin.org/journals/neurology/articles/10.3389/fneur.2020.00604/full.
(3) Myasthenia gravis & myasthenic crisis – EMCrit Project. https://emcrit.org/ibcc/myasthenia/.
(4) SOP myasthenic crisis – Neurological Research and Practice. https://neurolrespract.biomedcentral.com/articles/10.1186/s42466-019-0023-3.
(5) Neurocritical Care of Myasthenic Crisis | SpringerLink. https://link.springer.com/chapter/10.1007/978-3-319-73585-6_12.
(6) undefined. https://www.wolterskluwer.com/en/know/clinical-effectiveness-terms.