| The purpose of this dissertation was to ascertain whether the existence of Swallowing Apnea (SA) was the sole result of glottic closure or the result of its own neural mechanism. Two experiments were undertaken. In Experiment 1, twenty individuals with laryngectomy, composed of ten individuals less than one year status post surgery and ten individuals greater than one year status post surgery participated. Two groups of controls were age and gender matched to each of the participants with laryngectomy. SA duration was assessed via nasal airflow during saliva swallows and 10-, 15-, 20-, and 25-mL bolus volumes across three averaged trials. Significant main effects of group and bolus volume were found. A significant interaction of group X bolus volume was found as well. Both groups with laryngectomy exhibited longer SA duration than their respective control groups; however, only the laryngectomy group greater than one year exhibited significant comparisons of smaller bolus volumes eliciting shorter SA duration than larger bolus volumes. In Experiment 2, forty adults, composed of ten males and ten females in each of two age groups (i.e., 20–30 and 63–79 years) participated. SA onset was assessed during 5- and 20-mL bolus volumes of water and apple juice across three trials. The effects of age, gender, bolus volume, bolus viscosity, and gustation on SA onset relative to lingual bolus propulsion were examined. A significant interaction of age by gender by volume was found. In general older adults initiated SA onset earlier than young adults and large boluses elicited an earlier SA onset than small boluses regardless of group. Young males demonstrated significantly later onset than the older males for large volumes, this difference was not observed for small volumes nor was it found between young and older females. SA onset also was assessed during 5-mL bolus volumes of thin apple juice, thick apple juice, and applesauce across three trials. A significant main effect of viscosity was found revealing that SA onset was initiated later as bolus viscosity increased. Thus, the results of this investigation support the hypothesis that SA is the result of its own neural command. Furthermore, SA duration is affected by age, bolus volume, and bolus viscosity. |
