ELECTRODIAGNOSTIC METHODS FOR NEUROGENIC DYSPHAGIA

Objective: Swallowing mechanisms and neurogenic dysphagia have not bee n systematically studied by the EMG technique. It is desirable to eval uate neurogenic dysphagia for diagnostic and possibly for therapeutic purposes using electrophysiological methods. Results: The following me thods were described: mechanical upward/downward movements of the lary nx were detected using a piezoelectric sensor, while submental integra ted EMG activity was recorded during dry and wet swallowing. The EMG a ctivity of cricopharyngeal muscle of the upper oesophageal sphincter w as also recorded in some normal subjects and patients. Piecemeal deglu tition and the dysphagia limit were determined in all patients to dete ct dysphagia objectively. In this study 75 normal subjects and 177 neu rological patients with various degrees of dysphagia were investigated . Results: Voluntarily triggered oropharyngeal swallowing was commonly pathological in the majority of patients, with or without overt dysph agia. The dysphagia limit appeared to be an objective measure of the d egree of dysphagia in more than 90% of patients. Pathophysiological me chanisms were different in at least three groups of patients with neur ogenic dysphagia. In the group of patients with muscular disorders, la ryngeal elevators were involved while the CP-sphincter was intact. The second group included patients with the clinical signs of corticobulb ar fibre involvement such as amyotrophic lateral sclerosis and pseudob ulbar palsy. In these patients, there was incoordination between paret ic laryngeal elevators and hyperreflexic CP-sphincter. In the third gr oup (patients with Parkinson's disease), the swallowing reflex was del ayed and prolonged. Conclusions: EMG methods described in the present study are very useful for the diagnosis of neurogenic dysphagia, objec tively and quickly. They are important to understand the physiological mechanisms for deglutition and its disorders. (C) 1998 Elsevier Scien ce Ireland Ltd. All rights reserved.