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

Abstract

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. Retrospective case-control study. There were 182 cases of videofluoroscopic swallowing studies that were retrospectively reviewed. The presence of nasal backflow and laryngeal aspirations were checked, and the anteroposterior maximum width of the upper esophageal sphincter opening was measured on lateral images of videofluoroscopic swallowing studies. The difference in maximum upper esophageal sphincter width between the group with nasal backflow and the group without nasal backflow was statistically verified. Twenty patients showed nasal backflow, which was closely related to laryngeal aspiration (odds ratio = 10.97; 95% CI = 2.46-48.85; P < 0.05). Their maximal upper esophageal sphincter width (mean ± standard deviation) was 6.82 ± 1.96 mm and significantly different from the group without nasal backflow (9.35 ± 1.56 mm) (P < 0.05). Nasal backflow was closely associated with the presence of aspiration; the opening of upper esophageal sphincters significantly decreased in the cases of nasal backflow.