Incidence and Risk Factors of Sensorineural Hearing Loss After Mastoidectomy for Chronic Otitis Media: A Prospective Study

Objective: To evaluate the incidence, severity, and recovery of sensorineural hearing loss (SNHL) in patients undergoing mastoidectomy for chronic otitis media (COM), and to identify associated surgical risk factors. Methods: A prospective comparative study was conducted at Upgraded Institute of Otorhinolaryngology, Madras Medical College, Chennai, India) from May 2017 to October 2018. One hundred adults aged 18–60 years with unilateral COM (tubotympanic or atticoantral type) requiring cortical or modified radical mastoidectomy. Patients with pre-existing SNHL, bilateral COM, prior otologic surgery, or systemic conditions affecting hearing were excluded. Preoperative and postoperative hearing was assessed using pure tone audiometry (PTA) and distortion product otoacoustic emissions (DPOAE) at 6 hours, 24 hours, 48 hours, 72 hours, 96 hours, 1 month, and 3 months post-surgery. Paired t-tests, independent t-tests, and chi-square tests were used for statistical analysis (p<0.05). Results: SNHL occurred in 22% of patients (12% ipsilateral, 10% contralateral), with 16% experiencing temporary threshold shifts (TTS) recovering within 2 months and 6% showing permanent threshold shifts (PTS). Ipsilateral high-frequency (>2000 Hz) thresholds increased significantly post-surgery (p=0.01–0.03), with partial recovery by 3 months. Contralateral thresholds showed milder, non-significant shifts (p>0.05). Drilling duration >1 hour (p=0.02), cutting burr use (p=0.04), and ossicular manipulation (p=0.01) were associated with SNHL. DPOAE amplitudes decreased significantly in the ipsilateral ear (p=0.04). Conclusions: Mastoidectomy for COM carries a 22% risk of SNHL, primarily temporary and high-frequency, with permanent loss in 6%. Prolonged drilling, cutting burrs, and ossicular manipulation increase risk.