Seasonal effects on incidence and outcomes in idiopathic sudden sensorineural hearing loss

To investigate whether seasonal onset of idiopathic sudden sensorineural hearing loss (ISSNHL) influences disease incidence and hearing recovery outcomes, addressing limited and conflicting evidence regarding seasonal prognostic factors.

This retrospective cohort study analyzed 596 patients (mean age 51.5 ± 17.7 years, range 18-88 years) diagnosed with ISSNHL within 14 days of symptom onset at a tertiary referral center between 2012 and 2023. Patients were categorized by seasonal onset: spring (n = 145), summer (n = 140), autumn (n = 147), and winter (n = 164). All patients received standardized treatment according to AAO-HNS guidelines, including high-dose oral corticosteroids, with salvage intratympanic steroid injections for suboptimal responders. Audiometric outcomes included pure-tone average (PTA), speech recognition threshold (SRT), and word recognition score (WRS). A comprehensive literature review identified 14 relevant studies examining seasonal patterns in ISSNHL.

ISSNHL incidence was evenly distributed across seasons (spring: 24.3%; summer: 23.5%; autumn: 24.7%; winter: 27.5%; p = 0.534). No significant differences were observed in baseline demographics, comorbidities, or audiometric parameters across seasons (p > 0.7). Post-treatment improvements ranged from 8.62 to 10.48 dB for PTA, and 9.4 to 14.15% for WRS, with no statistically significant seasonal differences (p > 0.5). Monthly analysis revealed variation without consistent seasonal patterns. Multivariate analyses confirmed that season of onset was not an independent predictor of recovery.

Seasonal onset does not significantly influence ISSNHL incidence or hearing recovery outcomes. This large-scale investigation, representing the most extensive single-center cohort examining seasonal effects on ISSNHL, challenges previous smaller studies suggesting spring-onset superiority and indicates that clinical management should focus on established prognostic factors rather than seasonal timing.