Drilling in ear surgery. A comparison of pre- and postoperative bone-conduction thresholds in both the conventional and extended high-frequency ranges.

The pre- and postoperative bone-conduction thresholds for the frequencies 0.25 through 16 kHz were compared in 46 ears in which a high-speed ear drill was used. In 15 of these, thresholds were also obtained in the contralateral ear. There was no statistically significant postoperative threshold change at any single frequency in either the operated or the contralateral ear. The mean threshold elevation of 1.4 dB for the ipsilateral extended high-frequency octave of 8-16 kHz was marginally significant (p = 0.02), while this was not the case in the contralateral, unoperated ear. These findings are considered to be due to difficulties in placement of the cumbersome Präcitronic KH70 vibrator following bone removal ipsilaterally, with resultant defective transmission to the skull.