An electromyographic study of parkinsonian swallowing and its response to levodopa

Few studies have investigated the effect of levodopa on parkinsonian swallowing with findings thus far being equivocal.

We used surface electromyography and accelerometry to investigate submental and laryngeal muscle activation during swallowing in 14 parkinsonian subjects before and after levodopa and in 22 age-matched controls. Our aims were (1) to demonstrate the clinical utility of noninvasive electromyography, (2) to identify electromyographic features of parkinsonian swallowing, and (3) to investigate the effect of levodopa on parkinsonian swallowing.

The parkinsonian group showed increased burst amplitudes and durations and increased swallow duration, clearing activity and latency between submental and laryngeal bursts (P < .05) and used more swallows than did controls to consume water boluses (P < .001). Levodopa decreased the latency between submental and laryngeal bursts (P < .05) but did not produce effects on individual muscle bursts.

The clinical utility of electrophysiological and biomechanical methods of swallowing assessment was demonstrated. Levodopa tended to normalize the timing of the combined swallow response but not the activity of individual muscles.