Palatal prolapse during nasal expiration in patients with myasthenia gravis

Introduction/Aims We have encountered patients with myasthenia gravis (MG) who exhibited palatal prolapse (PP) during nasal expiration in the supine position while awake. This may be an overlooked cause of dyspnea in MG patients. This study aimed to examine and describe the characteristics of MG patients with PP. Methods We reviewed the medical records of 183 consecutive patients who were diagnosed with MG in our hospital from 2012 to 2021. Thirty‐two patients underwent laryngoscopy because of bulbar symptoms. Eight of these patients (25%) exhibited PP on laryngoscopy. Clinical features of these eight patients were retrospectively characterized. Results Median age of the eight patients with PP was 70 years. Six were men. Median body mass index was 21.6 kg/m2. All patients exhibited PP in the supine position but not the sitting position. Although no patient had abnormal findings on spirometry nor chest computed tomography, six reported dyspnea or difficulty with nasal expiration only in the supine position. PP improved in all four patients who underwent edrophonium testing. All eight patients eventually improved after immunotherapy. Discussion PP during nasal expiration may be a cause of dyspnea in MG patients, along with respiratory muscle impairment, lung disease, and vocal cord paralysis. Laryngoscopy in the supine position is required to confirm. Palatal prolapse in myasthenia gravis. (A) In the supine position, the palate ballooned and completely obstructed the velopharynx with nasal expiration. (B) In the left decubitus position, the palate deviated to the left and nasal expiration was possible (arrow). (C) After injection of edrophonium, palatal prolapse disappeared.