Abstract
Background and Introduction: Idiopathic sudden sensorineural hearing loss (ISSNHL) is characterized by rapid onset, typically unilateral presentation, and variable recovery. This case-control observational study aimed to improve patient counseling by objectively characterizing long-term hearing loss progression following ISSNHL, using sequential audiometry in the largest-to-date cohort of patients with ISSNHL.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 (K–M) analysis to account for variable follow-up duration. A 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) <30 dB and word recognition score (WRS) > 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 [odds ratio (OR) 3.45 male vs. female] at 5-year follow up. No other subgroup factors influenced the likelihood of SNHL progression.Discussion and Conclusion: Patients should be counseled on continued risk to long-term hearing after stabilization of hearing post-ISSNHL, with particular emphasis on greater risk to the contralateral ear in those with incomplete ipsilateral recovery.
Highlights
Idiopathic sudden sensorineural hearing loss (ISSNHL) occurs most often without any obvious triggering cause, reaches maximum deficit within an acute time period, and demonstrates variable recovery [1]
Results of K–M survival analysis in Figure 2A shows that patients with recovery to good hearing after ISSNHL demonstrated significantly faster decline in hearing compared with both contralateral ears and compared with age- and sex-matched case controls (p < 0.0001)
The greater risk of hearing loss progression ipsilaterally may be due to continued presence of systemic risk factors or repeated exposure to the cause of the initial insult, or due to the recovered ear maintaining a certain level of residual “hidden” hearing loss that is not detected by conventional audiometry; in this case, the loss and recovery of hearing with ISSNHL would be considered as similar to the temporary threshold shift seen in acoustic trauma [29]
Summary
Idiopathic sudden sensorineural hearing loss (ISSNHL) occurs most often without any obvious triggering cause, reaches maximum deficit within an acute time period, and demonstrates variable recovery [1]. Previous research has supported a wide range of underlying comorbidities as being positively associated with ISSNHL, such as vascular, metabolic, allergic, autoimmune, and depressive disorders [4,5,6,7,8,9,10,11] Environmental factors such as weather patterns have been explored as a potential contributor to disease incidence with little in the way of significant findings, with the possible role of seasonally-associated factors being alternately supported or refuted [12,13,14,15,16]. Idiopathic sudden sensorineural hearing loss (ISSNHL) is characterized by rapid onset, typically unilateral presentation, and variable recovery. This case-control observational study aimed to improve patient counseling by objectively characterizing long-term hearing loss progression following ISSNHL, using sequential audiometry in the largest-to-date cohort of patients with ISSNHL
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