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Abstract

Background & Introduction: Idiopathic sudden sensorineural hearing loss (ISSNHL) is characterized by rapid onset, typically unilateral presentation and variable recovery. The objective of this case-control observational study is to improve patient counseling by objectively characterizing long-term hearing loss progression following ISSNHL, using sequential audiometry in the largest-to-date cohort of ISSNHL patients. Methods: Patients diagnosed with ISSNHL at a tertiary referral hospital from 1994 through 2018 with sequential audiometry were studied. Case controls with sensorineural hearing loss (SNHL) were matched by age, sex, baseline hearing status and frequency of sequential audiometry. Hearing loss progression was quantified using Kaplan-Meier analysis to account for variable follow-up duration. Subgroup analysis was performed by age, sex, preexisting comorbidities, ISSNHL-associated symptoms, ISSNHL treatment, and degree of post-ISSNHL hearing recovery. Results: A total of 660 patients were identified with ISSNHL. In patients with post-ISSNHL recovery to good hearing (pure tone average [PTA]70%), median time to progression to non-serviceable (PTA>50 dB or WRS<50%) SNHL was 16.4 years. In patients with incomplete post-ISSNHL hearing recovery, contralateral ears were also at significantly higher risk of SNHL progression over the following 12-year period. Male sex was associated with increased risk of SNHL progression [OR 3.45 male vs. female] at 5-year follow up. No other subgroup factors influenced likelihood of SNHL progression. Discussion & Conclusion: Patients should be counseled on continued risk to long-term hearing even after stabilization of hearing post-ISSNHL, with particular emphasis on greater risk to the contralateral ear in those with incomplete ipsilateral recovery.