Acoustic trauma from the bone cutting burr.

The amplitudes of the stapes footplate movements were determined in human temporal bones when the ossicular chain was drilled with a cutting and a diamond burr. High movements result in comparison to physiological data. The frequency distribution resembles the dB (A) curve. The intensity compared to sound pressure levels on the ear drum is higher than I30 dB. The pressure is constant over the period of contact between the burr and the ossicle. Most likely these unphysiologic movements of the stapes footplate can cause inner ear damage as we had to admit in a case of facial nerve decompression.