Asthma as a cause of persistent dyspnea in treated myasthenia gravis patients

摘要

Aims: The aim of this study was to evaluate the proportion of patients with treated myasthenia gravis (MG) who present with dyspnea not related to MG. Methods: We analyzed the files of 63 consecutive adult patients with treated MG and persistent dyspnea who had been referred to our Pulmonary Function Test (PFT) Department between 2000 and 2010. Results: We observed that asthma was the first cause of MG-unrelated dyspnea in MG patients, with 9 patients (14) presenting with asthma-related PFT abnormalities. Six patients had asthma for several years before developing MG, and 3 patients (4) developed asthma a few months after MG was diagnosed, suggesting a non-coincidental association between the two conditions. In all 3 cases, asthma appeared in elderly patients with severe late-onset AchR-Ab-positive MG, treated with pyridostigmine and corticosteroids and/or intravenous immunoglobulins. In all 3 patients, β2-adrenergic agonist treatment allowed only partial control of dyspnea. In one case, respiratory symptoms were alleviated when pyridostigmine dosage was reduced. Conclusions: Patients with treated MG and persistent dyspnea should be investigated for asthma using PFT before being diagnosed with refractory MG. If asthma is diagnosed, a bronchodilator treatment should be instituted and a reduction in pyridostigmine dosage should be proposed.