A new hypothesis for fluidification of vocal-fold mucus: scintigraphic study

Abstract

Objective: Our aim was to establish a new hypothesis for the fluidification of the mucus of the vocal folds, by using a scintigraphic method to analyze the relationship of the saliva from the oral and pharyngeal cavities to the mucosa of the laryngeal vestibule.

Study design: We theorized that the saliva that is adsorbed on the oral and pharyngeal mucosa enters the larynx and is also adsorbed on its mucosa, as a natural layer, fluidizing the mucus of the vestibule wall.

Method: A saline solution of sodium pertechnetate (Na(99m)TcO(4)) with radioactivity of 1.0 mCi was sprayed in the oral cavity of seven healthy volunteers, who were instructed to chew a piece of apple for as long as possible without swallowing. The migration of the radioactive saliva was recorded by a gamma-chamber apparatus.

Results: We observed radioactivity in the laryngeal mucosa in six of the seven volunteers, who developed no complaints and no respiratory-defense reactions. The results for frequency were statistically significant (Mann-Whitney test, P=0.05).

Conclusion: The results indicate that an increased volume of saliva enters the larynx and is adsorbed in its mucosa, producing mucus fluidification. This supports our alternative hypothesis to the unlikely concept that hydration by water ingestion is the factor responsible for reduction of the mucus viscosity of the vocal folds.