Myasthenic crisis revealed by severe hypoxemic pneumonia and diagnosed after extubation failure: A case report

Background: Myasthenic crisis is an acute worsening of bulbar and respiratory weakness in myasthenia gravis and may require mechanical ventilation. Initial presentation during severe pneumonia is uncommon and may represent a major diagnostic challenge in the intensive care unit.
Case presentation: An 18-year-old man with no relevant medical history was admitted for acute hypoxemic respiratory failure due to severe pneumonia with septic shock. After intubation and anti-infective therapy, an extubation attempt on ICU Day 3 failed because of delayed hypercapnic hypoventilation, ineffective cough, dysphagia, and diffuse weakness, with no pulmonary, cardiac, or metabolic explanation. A neuromuscular disorder was then suspected. Electromyography demonstrated a postsynaptic neuromuscular transmission defect consistent with myasthenia gravis, while cerebrospinal fluid examination was normal. Early tracheostomy was performed, followed by intravenous immunoglobulin at 0.4 g/kg/day for 5 days, with progressive respiratory recovery and subsequent decannulation.
Conclusion: Unexplained extubation failure in a young adult should prompt consideration of neuromuscular disease, particularly myasthenia gravis [3-5]. Early electrophysiological evaluation, avoidance of aggravating medications, rescue immunotherapy with intravenous immunoglobulin, and timely tracheostomy may facilitate ventilator weaning and functional recovery.