Myasthenic inspiratory vocal cord dysfunction: efficacy of nasal continuous positive airway pressure treatment.

Myasthenic vocal cord dysfunction (VCD), presenting with severe inspiratory stridor, was successfully treated with nasal continuous positive airway pressure (nCPAP), thus giving the medical staff time to make the diagnosis and avoiding intubation or tracheostomy. An important sign leading to diagnosis was the very high MEF(50)/MIF(50) ratio calculated from the flow-volume loop. nCPAP treatment induced prompt remission of stridor and a sharp reduction in the MEF(50)/MIF(50) ratio from 9.90 to 1.36. A review of the literature has shown that VCD with inspiratory stridor is an unusual onset symptom of myasthenia gravis and that nCPAP treatment may avoid emergency oral/tracheal intubation and tracheostomy. After diagnosis, the patient underwent thymectomy, and today, 3 years later, he is well without any further therapy.