OBJECTIVE: Before the advanced evaluation of deglutition and selection of a treatment method, objective screening methods are necessary for patients with dysphagia. In this study a new electroclinical test was established to evaluate patients with dysphagia. METHODS: This test is based on determining piecemeal deglutition; which is a physiological phenomenon occurring when a bolus of a large volume is divided into two or more parts which are swallowed successively. The combined electrophysiological and mechanical method used to record laryngeal movements detected by a piezoelectric transducer, and activities of the related submental integrated EMG (SM-EMG)-and sometimes the cricopharyngeal muscle of the upper oesophageal sphincter (CP-EMG)-were performed during swallowing. Thirty normal subjects and 66 patients with overt dysphagia of neurogenic origin were investigated after detailed clinical evaluation. Twenty patients with a potential risk of dysphagia, but who were normal clinically at the time of investigation, were also evaluated to determine the specificity of the test. All subjects were instructed to swallow doses of water, gradually increasing in quantity from 1 ml to 20 ml, and any recurrence of the signals related to swallowing within the eight seconds was accepted as a sign of dysphagia limit. RESULTS: In normal subjects as well as in the patients without dysphagia, piecemeal deglutition was never seen with less than 20 ml water. This volume was therefore accepted as the lower limit of piecemeal deglutition. In patients with dysphagia, dysphagia limits were significantly lower than those of normal subjects. CONCLUSION: The method is a highly specific and sensitive test for the objective evaluation of oropharyngeal dysphagia even in patients with suspected dysphagia of neurogenic origin. It can also be safely and simply applied in any EMG laboratory.

We investigated the pathophysiological mechanisms of dysphagia in amyotrophic lateral sclerosis. Forty-three patients with sporadic amyotrophic lateral sclerosis were examined by clinical and electrophysiological methods that objectively measured the oropharyngeal phase of voluntarily initiated swallowing, and these results were compared with those obtained from 50 age-matched control subjects. Laryngeal movements were detected by a piezoelectric sensor and EMG of submental muscles, and needle EMG of the cricopharyngeal muscle of the upper oesophageal sphincter of both the amyotrophic lateral sclerosis and control groups was recorded during swallowing. Amyotrophic lateral sclerosis patients with dysphagia displayed the following abnormal findings. (i) Submental muscle activity of the laryngeal elevators, which produce reflex upward deflection of the larynx during wet swallowing, was significantly prolonged whereas the laryngeal relocation time of the swallowing reflex remained within normal limits. (ii) The cricopharyngeal sphincter muscle EMG demonstrated severe abnormalities during voluntarily initiated swallows. The opening of the sphincter was delayed and/or the closure occurred prematurely, the total duration of opening was shortened and, at times, unexpected motor unit bursts appeared during this period. (iii) During voluntarily initiated swallows there was significant lack of co-ordination between the laryngeal elevator muscles and the cricopharyngeal sphincter muscle. These results point to two pathophysiological mechanisms that operate to cause dysphagia in amyotrophic lateral sclerosis patients. (i) The triggering of the swallowing reflex for the voluntarily initiated swallow is delayed and eventually abolished, whereas the spontaneous reflexive swallows are preserved until the preterminal stage of amyotrophic lateral sclerosis. (ii) The cricopharyngeal sphincter muscle of the upper oesophageal sphincter becomes hyper-reflexic and hypertonic. As a result, the laryngeal protective system and the bolus transport system of deglutition lose their co-ordination during voluntarily initiated swallowing. We conclude that these pathophysiological changes are related mainly to the progressive degeneration of the excitatory and inhibitory corticobulbar pyramidal fibres.