Changes in Wide-band Tympanometry Absorbance Following Cochlear Implantation.

Abstract

Determine if changes in middle ear absorbance measured with wide-band tympanometry (WBT) occur following hearing-preservation cochlear implantation (CI). Such measures may provide insight into the mechanisms of acoustic hearing loss postimplantation. Clinical capsule report. Tertiary academic referral center. WBT absorbance was measured bilaterally during pre- and postoperative clinical office visits in five unilaterally-implanted cochlear implant recipients. Pre- and postoperative WBT measures were compared within each subject in the implanted and contralateral, unimplanted ears. In general, WBT absorbance measurements show a broad spectral pattern including two or three distinct peaks measured over a frequency range of 226 to 8000 Hz. Grand average and linear mixed model comparisons between the pre- and postoperative WBT patterns show significantly reduced (p < 0.05) low-frequency absorbance in the implanted ears in the frequency region over 0.6 to 1.1 kHz, but not in the unimplanted ears. The maximum effect occurred at 1 kHz with absorbance decreasing from ∼0.8 to ∼0.5 after implantation. The limited data are consistent with expected relationships between WBT absorbance and air- and bone-conduction thresholds, assuming an increased air-bone gap reflects conductive hearing loss. Cochlear implantation can result in reduction of low-frequency acoustic absorbance as measured by WBT. WBT may be a useful and sensitive tool for monitoring the mechanical status of the middle and inner ears following cochlear implantation.