Hearing and hearing rehabilitation after obliteration of troublesome mastoid cavities

Purpose: The purpose of this study is the evaluation of post-operative hearing threshold after revision surgery and obliteration of troublesome canal wall down mastoidectomy cavities (CWDMCs). The ability to use and tolerate conventional hearing aids (CHAs) was also evaluated. Methods: A retrospective chart analysis of 249 patients with chronically draining CWDMCs who underwent revision surgery including obliteration of the mastoid cavity between 2007 and 2017 at the AMC location of the Amsterdam University Medical Centers (Amsterdam UMC) was performed. Patient characteristics, pre- and post-operative Merchant grade, surgical outcomes, pre- and post-operative hearing thresholds, and the ability/necessity to use a CHA or the ability/necessity to use a Bone Conduction Device (BCD) were recorded. Results: Dry ears were found in 95% of the total cohort. Residual disease was detected in 1.6% during MRI follow-up with no residual cholesteatoma in the obliterated area. In 3.2% of the patients, recurrent disease was found. A significant improvement in mean air conduction level, mean bone conduction level, and mean air-bone gap (ABG) was found post-operatively (p < 0.05). For all types of ossicular chain reconstruction, a significant improvement in mean Pure Tone Average was observed (p < 0.05). The percentage of patients with an indication for CHA was similar pre- and post-operatively (67% both pre- and post-operatively). The ability to use a CHA improved from 3% pre-operatively to 57% post-operatively (p < 0.001). Conclusion: This study shows that revision surgery and obliteration of CWDMCs enable successful CHA rehabilitation post-operatively. Upon this type of surgery, hearing thresholds improve significantly, but the need for rehabilitation with a CHA remains necessary in most cases.