Impaired deglutitive airway protection: A videofluoroscopic analysis of severity and mechanism

Background & 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 glossopalatal 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.