Dysphagia after stroke is common. Many authors postulated factors affecting aspiration in discrete swallow, but eating solids and liquids, like soups, is usual in daily meals. Chew-swallow is unique because the chewed solid food is transported to the pharynx (stage II transport) before swallow onset even in healthy subjects. The aim of this study was to compare the factors affecting aspiration both chew-swallow and discrete swallow in stroke patients.

One hundred eighty-one stroke patients (average age 68) who swallowed both a two-phase mixture of 4g of corned beef hash with 5mL of thin liquid, and 10mL of thin liquid during videofluoroscopic examination of swallowing (VF) were retrospectively evaluated. Oral, vallecular, and piriform sinus residue, hyoid elevation, laryngeal elevation, laryngeal closure, movement of epiglottis, mastication, bolus transition time, pharyngeal response time, and leading edge of bolus at swallow onset were evaluated by 2 physiatrists until consensus was reached from careful observation frame by frame. This study was approved by the institutional review board.

The vallecular residue, reduced hyoid elevation, and inadequate mastication caused aspiration in chew-swallow. On the other hand, movement of epiglottis, leading edge of bolus at swallow onset, bolus transition time, pharyngeal response time, and initiation of laryngeal closure are associated in aspiration during discrete swallow. In addition, vallecular residue and reduced hyoid elevation were significant factors affecting aspiration in chew-swallow, while the movement of epiglottis and leading edge of bolus at swallow onset were selected in discrete swallow by multiple logistic regression analysis.

Factors affecting aspiration are different between chew-swallow and discrete swallow in stroke patients. We should check not only discrete swallow but chew-swallow during VF.