Videofluoroscopic assessment of swallowing function in patients with myasthenia gravis

Swallowing function in myasthenia gravis (MG) was investigated by videofluoroscopy (VF). A total of 23 VF examinations were performed on 11 MG patients at various time points over the exacerbation and remission stages of disease. The assessment parameters on VF examination are set as follows: bolus transport from the mouth to the pharynx, bolus holding in the oral cavity, velopharyngeal seal, tongue base movement, pharyngeal constriction, laryngeal elevation, upper esophageal sphincter (UES) opening, and bolus stasis at the pyriform sinus (PS). Aspiration was also assessed on VF examination. Aspiration was seen in 34.8%, and half of these cases involved silent aspiration. Three of four cases that showed silent aspiration went on to experience aspiration pneumonia during the follow-up term. By Spearman's rank correlation, disturbance of laryngeal elevation was significantly correlated with aspiration (p=0.001), and incomplete UES opening was not significantly, but tended to be, correlated with aspiration (p=0.067). Although other parameters in the oral and pharyngeal phase on VF examination, such as bolus transport from the oral cavity to the pharynx, pharyngeal constriction, or stasis at the PS, were remarkably disturbed (in more than 50% of the examinations), those parameters were not good indicators for aspiration. When a disturbance of laryngeal elevation is found at a bedside clinical test, we recommend performing precise swallowing evaluation, such as VF, Fiberoptic Endoscopic Evaluation of Swallowing (FEES), and/or scintigraphic assessment of swallowing, for MG patients, to detect silent aspiration.