Myasthenic Crisis as the First Presentation of Myasthenia Gravis: A Case Report

BACKGROUND Myasthenic crisis is a condition characterized by the sudden onset of myasthenic weakness involving the respiratory muscles and requires ventilatory support to prevent death. This is a case report of respiratory failure in a 43-year-old man as the first presentation of myasthenia gravis. CASE REPORT A 43-year-old man with underlying hypertension and a lacunar stroke with good muscle-power recovery presented with severe community-acquired pneumonia, complicated with respiratory failure requiring invasive ventilatory support. He responded well to the intravenous antibiotic therapy and after 1 week of treatment, he was hemodynamically stable and his septic parameters improved. However, he persistently failed to maintain adequate spontaneous respiratory effort after the removal of the ventilatory support and had to be reintubated multiple times. There was no other identifiable cause for the worsening respiratory failure. He had no clinical features or muscle weakness suggestive of myasthenia gravis. However, his blood test was positive for serum anti-acetylcholine receptor antibodies and repetitive nerve stimulation tests showed the characteristic decremental response of compound muscle action potential amplitude, in keeping with the diagnosis of myasthenia gravis. He responded well to intravenous immunoglobulin and was discharged with anticholinesterase inhibitors and long-term immunosuppression therapy. CONCLUSIONS This report demonstrates that when patients are admitted to the hospital with acute respiratory failure without any underlying pulmonary disease and with weakness of the respiratory muscles, the diagnosis of myasthenia gravis presenting with a myasthenic crisis should be considered.