Nasal backflow and the difficulty of relaxation in the upper esophageal sphincter.

Objectives/hypothesis: Nasal backflow is the regurgitation of material into nasopharynx during swallowing and it can be easily observed by videofluoroscopy. We aimed to evaluate the association between nasal backflow and the prevalence of aspiration, as well as the relationship between nasal backflow and the opening of the upper esophageal sphincter.

Study Design: Retrospective case-control study.