Minimum Amount of Calories needed to Elicit the Vestibulo-Ocular Reflex in Normal Human Subjects

Abstract

Calorie as a unit of heat quantity is considered more appropriate than temperatures and seconds as in conventional caloric testing. In an attempt to determine the minimum amount of calories needed to elicit the vestibulo-ocular reflex, we modified free-flowing irrigation into a closed irrigation of the external meatus. Using this method, we studied 61 ears in 34 normal healthy subjects, revealing the threshold to be 310.26 ± 15.19 calories. Concern about the excessive heat used in conventional stimuli, which is believed to be the the cause of unwanted autonomic responses. has been answered by this finding. Conventional irrigation with water at 44°C is about 5-fold stronger than that minimum. With the closed irrigation technique. the autonomic responses have been reduced relatively.

Key Words:

• caloric test
• strength of stimulus
• nystagmus