Impending Myasthenic Crisis Before Thymectomy
34-year-old woman with a 6-month history of fluctuating ptosis, diplopia, and dysphagia that worsens in the evening. Anti-acetylcholine receptor antibody is positive, and chest CT shows a 4-cm anterior mediastinal mass. Thymectomy is scheduled in 3 weeks. Today she presents with fever, productive cough, and worsening dysphagia. Respiratory rate is 28/min, oxygen saturation 94% on room air, negative inspiratory force -20 cm H2O, and vital capacity 1.1 L. She takes pyridostigmine 60 mg every 6 hours and prednisone 10 mg daily. Chest radiograph shows a right lower lobe infiltrate; WBC is 15,000/µL. She is alert but cannot swallow her secretions and has nasal speech. She has no prior history of myasthenic crisis. The emergency department asks whether she can be admitted to the ward for intravenous antibiotics and observation.
1. Is she in impending myasthenic crisis, and where should she be managed?
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Yes. Fever, bulbar weakness, inability to handle secretions, nasal speech, tachypnea, oxygen saturation 94%, vital capacity 1.1 L, and negative inspiratory force -20 cm H2O indicate impending respiratory failure. A VC below about 15–20 mL/kg or an NIF weaker than -20 to -25 cm H2O is a threshold for ICU-level monitoring and often elective intubation before crash intubation.
Ward admission for antibiotics and observation is unsafe. She needs ICU or respiratory-monitored step-down care with frequent bedside vital capacity, NIF, and bulbar assessments. Do not rely on oxygen saturation alone, because myasthenic patients can maintain saturation until abrupt collapse. Establish advance planning for intubation and noninvasive ventilation, and involve neurology and critical care early.
2. How should her myasthenia medications and infection be managed in the first 24 hours?
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Start broad-spectrum antibiotics that cover community-acquired pneumonia, but avoid aminoglycosides, fluoroquinolones, macrolides, and other agents that worsen neuromuscular transmission when alternatives exist. Obtain blood and sputum cultures. Treat fever and hypoxemia.
Pyridostigmine may be held or reduced temporarily in crisis because it increases secretions and does not treat the underlying crisis; coordinate this with neurology and restart when bulbar and respiratory function improve. Continue prednisone 10 mg; do not start high-dose corticosteroids without caution, because they can transiently worsen weakness. For rapid immunotherapy, give IVIG 2 g/kg over 2–5 days or plasma exchange. Plasma exchange may be preferred with severe bulbar/respiratory involvement or infection, but access and stability determine choice. Do not delay respiratory support while awaiting immunotherapy.
3. What should be done about the scheduled thymectomy?
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Thymectomy should be postponed until she has recovered from the infection and is stable, off mechanical ventilation, and no longer in crisis. Operating during active myasthenic crisis and pneumonia would increase perioperative respiratory failure, mediastinitis, and prolonged ventilation risk.
After recovery, optimize immunotherapy, complete infection treatment, and reassess thymoma staging. Thymectomy is appropriate for a 4-cm anterior mediastinal mass with acetylcholine receptor antibody–positive myasthenia, but timing is elective after stabilization. Preoperative pulmonary function, bulbar status, and anesthetic planning should be reassessed, and she should receive preoperative immunotherapy optimization rather than urgent surgery.