Pitfalls in the Evaluation of Respiratory Failure in Myasthenia Gravis Patients: A Case Series.

Objectives: To highlight the importance of recognizing different presentations of respiratory failure due to myasthenic and non-myasthenic etiologies in myasthenia gravis (MG) patients.

Methods: We describe 3 patients with different presentations of respiratory failure in MG.

Cases: Patient 1 is a 49-year-old female with longstanding MG who presented with lethargy and neck weakness without notable respiratory distress. She was found to be in hypercarbic respiratory failure, which improved with plasmapheresis treatment. Patient 2 is a 58-year-old female who presented with ptosis, dysphagia, and dyspnea requiring intubation. Her hypophonia and dyspnea persisted despite escalation in MG treatment, and further workup revealed glottal stenosis secondary to granulomatosis with polyangiitis. Patient 3 is an 85-year-old female with MG presenting with refractory hypoxia, which was secondary to a large patent foramen ovale resulting in right-to-left shunting.

Discussion: All 3 cases emphasize the role of clinical reasoning and careful analysis based on thorough history taking, detailed neurologic exam and comprehensive laboratory findings to determine the etiologies for respiratory dysfunction in MG and provide appropriate treatment.

Conclusion: A lack of overt signs of respiratory distress in MG does not rule out the presence of respiratory failure due to the sedating effect of hypercapnia. There is a need to consider alternative etiologies of hypoxia in MG patients if typical symptoms or signs of MG exacerbations are absent.