OTOACOUSTIC EMISSIONS (TEOAES AND DPOAES) FOLLOWING MIDDLE-EAR SURGERY

Background: The behavior of transitory evoked otoacoustic emissions (T EOAE) and distortion products (DPOAE) in patients after middle ear sur gery is unknown. Methods: We examined TEOAEs and DPOAEs in 37 ears fol lowing stapes surgery, 16 ears following tympanoplasty type I, and nin e ears after reconstruction of the ossicular chain. In all patients, t he postoperative conductive hearing loss was less than 15 dB HL. In so me cases, there was additional sensorineural hearing loss in the high frequencies. Results: Surprisingly, TEOAEs were present only in 10 of 62 ears postoperatively compared to all 22 control subjects. TEOAEs we re detected in four of 37 ears after stapes surgery, in six of 16 ears after tympanoplasty type I, and in none of the nine ears who had unde rgone reconstruction of the ossicular chain. DPOAEs were detected in o nly four of 31 ears postoperatively compared to all 22 control ears. C onclusions: These results and their relation to the retrograde OAE tra nsmission in the middle ear are discussed. Changes enhancing the stiff ness of the middle ear seem to have a greater effect than those enhanc ing the mass.