Some Thermal Effects of Ultrasound on the Inner Ear

Abstract

Temperature measurements on isolated human temporal bones in connection with ultrasonic irradiation showed that, when the transducer was applied to the enchondral bone in the angle between the lateral and the superior vertical semicircular canals, the rise in temperature in the vestibule was as great as or greater than that in the facial nerve, while the studies reported in the literature, with the transducer applied to the blue line on the lateral semicircular canal, constantly showed higher temperatures in the facial nerve than in the vestibule. The rise in temperature in the cochlea was small. Measurements of the temperature in the vestibule and in the lateral semicircular canal during ultrasonic irradiation of a patient with Menière's disease yielded roughly the same result at lower ultrasonic powers as the studies of isolated temporal bones, while at higher powers there was a smaller temperature rise in vivo than in the specimens. Ultrasonic treatment of rabbits and human beings in different positions showed that the nystagmus which appears during irradiation is probably a caloric reaction induced by the thermal effect of the ultrasound.