Detemination of functional range of peripheral vestibular system using air caloric stimulation

Caloric method is the most important test in evaluating the vestibular function and air caloric stimulation is the most popular method for performing this test. As there are no standard normal criteria for this test، the goal of this study was to define normal criteria for different parameters of caloric test which is a part of peripheral vestibular system test battery in Tehran University of Medical Sciences، Iran. These parameters include directional preponderance، unilateral weakness and slow phase velocity. In this cross-sectional (descriptive-analytical) study، thirty two healthy volunteers of 20-45 years of age were included. After obtaining written informed consent and performing basic audiologic examination، Caloric test was performed using INC model of House Infrared/Video ENG System، USA. Its parameters were compared between males and females and within 2 different age groups of 20-30 and 30-45. Data were analyzed with a significant level of 0. 05. In the right eye، slow phase velocity was 15. 23±7. 43°/s، directional preponderance was 10. 49±9. 28% and unilateral weakness was12. 27±6. 45% and these values in the left eye were 15. 94±8. 25°/s، 10. 45±9. 09% and 12. 69±7. 54%، respectively. There was not any significant difference between the two genders and between the two age groups. These results suggest the normal values for different parameters of Caloric test and it can be used to differentiate patients and normal subjects. As there was no statistically significant difference between males and females and two age ranges، the same values can be used for all of them.