Background and Aims: Laryngeal vestibule penetration is a prerequisite for deglutitive aspiration. This study aimed to analyze the mechanism and model the risk of laryngeal penetration before or during the pharyngeal swallow. Methods: Videofluoroscopic swallowing studies of 29 patients with neurogenic dysphagia with penetration before or during the pharyngeal swallow were compared with 12 controls. A stepwise regression analysis was used to define the coordinative defects leading to bolus penetration into the laryngeal vestibule. The mechanism was biomechanically analyzed. Results: The stepwise regression modeled a laryngeal penetration index from the coordination between laryngeal vestibule closure and bolus release at the glosso-palatal junction and the timing of upper esophageal sphincter opening relative to glossopalatal junction opening. The model accounted for 86% of the observed variance in severity of laryngeal penetration among the dysphagics. The observed incoordination resulted from both delayed initiation and slowed enactment of deglutitive laryngeal elevation. Conclusions: A dysphagic individual's risk of incurring laryngeal penetration before or during 1-, 3-, or 5-mL swallows is proportional to two temporal measures of coordination made from 1-mL swallows. The severity of the relevant defects (delayed and slowed laryngeal elevation) is proportional to the severity of swallow dysfunction.
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