Air Caloric Test with Continuous Thermal Change

Abstract

A new technique was designed for vestibular testing with an air caloric stimulator. With this technique, the temperature threshold necessary to induce caloric nystagmus was measured at decreasing air temperatures (from 37°C) at a constant velocity. As a pilot study, the air caloric test with continuous thermal change was carried out at 6 different decreasing speeds ; 0.01, 0.03, 0.05, 0.1, 0.15 and 0.2 deg/sec. The speed of 0.05 des/sec gave the minimum standard deviation of temperature threshold in normal subjects. No side effects were observed during or after the air caloric test with continuous thermal change at this speed. The new air caloric test also showed the narrowest normal limits among the ordinary caloric tests hitherto reported.