PHARYNGEAL SWALLOWING ELICITED BY FLUID INFUSION - ROLE OF VOLITION AND VALLECULAR CONTAINMENT

Nonalimentary swallows minimize aspiration by clearing accumulated flu id from the pharynx. This study aimed to define 1) the pharyngeal sens ory field to elicit swallowing and 2) the effect of infusion rate, vol ition, taste, and temperature on pharyngeal swallows. Test solutions w ere directed into the valleculae at 6.5, 11.5, and 32 ml/min through a catheter in eight healthy volunteers. Deglutition was signaled with e lectromyography and electroglottography. Spatial distribution of infus ate before swallowing was studied using videofluoroscopy coupled with a video timer. Volitional control was assessed with rapid or restraine d swallows. Pharyngeal swallow latency decreased as the instillation r ate increased, was potently modified with volition, and was unchanged by infusate taste or temperature. Water infusion into the valleculae d id not trigger pharyngeal swallowing until liquids overflowed and reac hed the aryepiglottic folds or pyriform sinuses. The variation in swal low latency among flow rates was mainly due to the duration of liquid containment within the valleculae. This suggests that the valleculae a ct to contain pharyngeal secretions and residue and prevent aspiration by diverting their contents around the larynx before swallowing.