Impact of Mastoid Drilling on the Healthy Contralateral Ear

Abstract Introduction: Chronic otitis media (COM) is prevalent in India, affecting approximately 5.2% of the population. Mastoidectomies, often necessary for managing COM, involve drilling that may risk hearing in the contralateral ear. This study aimed to evaluate the impact of mastoid drilling on the healthy contralateral ear using pure tone audiometry (PTA) and Distortion Product Otoacoustic Emissions (DPOAEs). Materials and Methods: A prospective observational study enrolled 45 patients with unilateral COM and healthy contralateral ears. Audiological assessments were conducted preoperatively and at 24 h, 72 h, and 7 days postsurgery. Statistical analyses included Student’s t -test and ANOVA, with a significance level set at P < 0.05. Results: The average mastoid drilling time was 53.8 ± 17.2 min. PTA showed a significant increase in mean hearing thresholds at 24 h (21.1 ± 3.8 dB) compared to preoperative levels (18.6 ± 2.6 dB), with recovery by day 7 ( P < 0.001). DPOAE indicated initial cochlear dysfunction in six patients at 24 h, reducing to 2 by day 7 ( P = 0.005). No significant correlation was found between drilling time and audiological outcomes. Conclusion: Mastoid drilling causes significant temporary hearing changes in the contralateral ear, independent of drilling duration. These findings highlight the need for protective strategies during surgery to mitigate auditory risks.