STAPEDOTOMY BY ULTRASOUND - AN EXPERIMENT AL ANIMAL STUDY ON POSSIBLEADVERSE-EFFECTS ON VESTIBULAR FUNCTION

Stapedotomy by ultrasound has been proposed as an alternative method f or perforating the stapes footplate in surgery for otosclerosis. Possi ble functional adverse effects of ultrasound perforation of the otic c apsule in guinea pigs were investigated in the present study by means of vestibular evoked potentials (VsEP). VsEP were elicited by pulsed l inear accelerations applied to the animal's head following surgical re moval of the middle ear, following intense ultrasound drilling around the otic capsule and after drilling a small hole in the anterior bony wall of the vestibule. All manipulations did not affect amplitudes and latencies of the early potential N-1 (less than 1 msec after onset of acceleration). Significant alterations of N-1 occurred following dire ct mechanical damage of the otolithic organs, indicating that VsEP can be used to detect lesions of these receptors and therefore may be use d as a parameter of vestibular function in experimental animals. Findi ngs indicate that perforation of the otic capsule by ultrasound is pos sible without inducing functional lesions of the otolithic organs.