Effect of temperature on electrophysiological parameters of swallowing.

The effect of three different temperature ranges on the triggering of voluntary-induced swallowing and on the duration of the pharyngeal phase of oropharyngeal swallowing was studied electrophysiologically. The relationship between volume and temperature of liquids swallowed was also explored. This study included 40 nondisabled volunteers (23 male and 17 female). Laryngeal vertical movements and submental electromyographic activity were recorded as each subject swallowed water at three different temperature ranges: normal (23-25 degrees C), cold (8-10 degrees C), and hot (58-60 degrees C). The time for triggering of the pharyngeal phase of swallowing was found to be shorter for cold and hot water than for normal temperature water (p < 0.01). The duration of the pharyngeal phase of oropharyngeal swallowing was also shorter for cold and hot water than for normal temperature water (p < 0.05). The maximum capacity of a single bolus (dysphagia limit) was >20 mL of water in all nondisabled subjects for different temperatures. However, the capacity was significantly less for hot water relative to normal temperature water and cold water (p < 0.05). In conclusion, the temperature ranges used in this study were found to be effective in triggering voluntary-induced swallowing.