Oropharyngeal dysphagia in polymyositis/dermatomyositis.

The nature of the oropharyngeal dysphagia in polymyositis/dermatomyositis (PM/DM) has been investigated by EMG methods. Nineteen patients with PM/DM were studied. The oropharyngeal phase of swallowing was evaluated by the electrophysiological methods measuring the laryngeal relocation time, pharyngeal transit time and the triggering of the pharyngeal phase of swallowing reflex. The EMG of cricopharyngeal muscle of the upper esophageal sphincter was also recorded in 10 patients. The patients have been compared with a group of 22 healthy controls matched with age and gender. Dysphagia limit was also measured for all patients and control subjects. Fourteen out of 19 patients could not swallow 20 ml or less amount of water at one go and divided the bolus into two or more pieces (piecemeal deglutition) in comparison to normal subjects. In PM/DM patients, the triggering of the swallowing reflex for the voluntarily initiated swallow was normal while the pharyngeal phase of swallowing was significantly prolonged. The cricopharyngeal sphincter muscle EMG demonstrated severe abnormalities in halves of the patients investigated. These findings demonstrated the weakness of the striated oropharyngeal muscles. Cricopharyngeal sphincter muscle was affected less frequently and showed either hyperreflexic or hyporeflexic states during swallowing. It is concluded that the pharyngeal stage of oropharyngeal swallowing is mainly involved in patients with PM/DM.