Myasthenic Crisis

Myasthenic crisis is the most severe complication of myasthenia gravis, defined as worsening of weakness sufficient to require mechanical ventilation or, in patients with bulbar involvement, intubation to protect the airway. It occurs in 15 to 20 percent of myasthenia gravis patients during the course of their disease.

Triggers include infections, surgery, certain medications such as aminoglycosides, fluoroquinolones, beta blockers and magnesium, pregnancy, thymectomy, sudden tapering of immunosuppressants and emotional stress. Patients show rapidly worsening bulbar symptoms, neck flexor weakness, weak cough, decreased forced vital capacity and negative inspiratory force.

Management requires intensive care monitoring with serial vital capacity and inspiratory force measurements, early elective intubation when respiratory parameters deteriorate, treatment of triggering factors and aggressive immunomodulation with plasmapheresis or intravenous immunoglobulin. Pyridostigmine is often paused during mechanical ventilation to reduce secretions. Long-term management includes optimization of immunosuppression and patient education on warning symptoms.