The author describes a gaseous caloric test using Freon to cool the tympanic membrane. The experiment was used to study the temperature of the tympanic membrane and its variation in relation to the temperature of the material containing the Freon. It was found that the tympanic response was stereotyped if the temperature of such material was between 22 and 30 degrees. Comparison with the aqueous caloric test showed twice as long a recovery time for the latter. Study of nystagmographic tracings in 36 patients tested successively with Freon in Bruning's positions I and IV and with water at 30 and 44 degrees showed constant relations and a great similarity in responses. Clinical study of a number of cases also showed identical responses. Statistical calculation revealed satisfactory correlation coefficients between the two methods. The single test using Freon thus represents a rapid and quantitative method for the investigation of vestibular function. It is a useful test in everyday practise.
Adult Aged