An electrophysiological study of the sequential water swallowing

Sequential water swallowing (SWS) was mostly investigated by the videofluoroscopic and endoscopic methods. However some physiological features of SWS was rarely evaluated by neurophysiological techniques. Our aim was to investigate some neural and muscular changes on sequences of SWS using electromyography (EMG) methods.

Fifty-eight normal adults were investigated. SWS was initiated voluntarily with 50ml and 100ml water volumes from a cup. Submental EMG, respiratory signals, heart rate, and sympathetic skin responses (SSR) were measured during SWS.

All parameters were increased significantly during the 100ml SWS. During swallowing apnea period, compensatory respiration cycles occurred in 24% and 48% of participants in the 50ml and 100ml SWS, respectively. Heart rate increased during swallowing apnea. SSR were evoked just before and just after the SWS in more than halves of participants. A foreburst EMG in SM muscles at the initiation of SWS was recorded in 86% of normal participants. Older age was associated with a prolonged duration of the apnea period.

All parameters of the SWS could be recorded numerically and objectively using electrphysiological methods. These are similar to those obtained by videofluoroscopic and similar methods. The foreburst activity of the initiation of SWS may represents preparatory activity from the activation of the fast cortical descending motor pathway. Increasing heart rate and the prolonged apnea urged that older people and patients could be carefully tested for respiratory and cardiac rhythm disorders.