Role of sensation in swallowing function

Sensation in the oral cavity and laryngopharynx has long been believed to be crucial for normal swallowing. One illustration of this belief has been intense interest in reconstruction after cancer resection using sensate tissue transfer as a means of improving swallowing function. A contrarian view is that mucosal sensation, by itself, is, in fact, relatively unimportant to swallowing function.

A prospective study was designed to test the hypothesis that normal swallow function can occur with anesthesia of the upper aerodigestive tract mucosa.

Baseline (sensate) swallowing function of 13 healthy adults was assessed via video endoscopic swallow studies (VESS). Each subject was then topically anesthetized with lidocaine applied to the oral cavity, oropharynx, hypopharynx, and larynx. Swallowing was then reassessed via VESS and compared to the baseline examination to look for differences in function.

There was little difference in swallowing ability between sensate and anesthetized states, even though all the subjects felt that their swallowing had been profoundly disrupted after lidocaine was applied. The main difference was a small increase in the time from food administration to swallowing. A few experienced trace aspiration, which was instantly eliminated on subsequent swallows with simple coaching.

Normal swallowing can occur spontaneously or with simple coaching even with complete anesthesia of the upper aerodigestive tract mucosa. Current beliefs about the value of sensate free flaps and the importance of sensation in swallowing in general may need refinement.