Change of the DPOAE on Contralateral Ear after Exposure of the Drilling Noise

Oh, Jae Kook; Park, Moon Suh; Yoo, Seung Hoon; Kim, Han Sung

Abstract

BACKGROUND AND OBJECTIVES: Drill-generated noise during chronic ear surgery, as well as surgical trauma, has been incriminated as a cause of sensorineural hearing loss in the operated ear. The contralateral ear, on the other hand, is subject to drill noise but is spared the surgical trauma. Using the distortion product otoacoustic emission recording, this study is aimed to evaluate changes in micromechanical cochlear properties which could occur in the contralateral ear following an ear surgery.
MATERIALS AND METHODS
Twenty-seven patients undergoing mastoidectomy procedures were tested both preoperatively and postoperatively using pure tone audiometry, distorsion product otoacoustic emission. Surgical drilling duration was recorded. These patients had no otological history and showed no abnormalities on the physical examination of the contralateral ear. For all frequencies (1-6 kHz), amplitude were measured and analyzed.
RESULTS
1) Pure tone audiometry average was not significantly changed on the preoperative and postoperative day. 2) Average amplitude of DPOAE was significantly lower on the first postoperative day than on the preoperative day. 3) Average amplitude of' DPOAE was recovered on the seventh postoperative day. 4) Duration of drilling affected DPOAE results. CONCLUSION: The drill noise conducted to the nonoperated ear by vibrations of the intact skull exposure results in dysfunction of the outer hair cells, which produce a temporary hearing loss.