Is Idiopathic Sudden Sensorineural Hearing Loss Seasonal?

Objective To investigate the circannual rhythm (seasonal incidence) of idiopathic sudden sensorineural hearing loss (ISSNHL). Methods Data were retrieved from the medical files of an original cohort of all consecutive patients with ISSNHL in a tertiary medical center between 2012 and 2020. A systematic literature search of “MEDLINE” via “PubMed,” “Embase,” and “Web of Science” on comparable published cases was performed. A Google Trends analysis of the term [sudden hearing loss] and related terms between 2014 and 2020 was also performed. Results Most of the published series (9/12) reported the highest ISSNHL incidence in the spring and the lowest in the winter (8/12). In our local series, the incidence during the winter was significantly lower than that for the other seasons by a factor of 0.69 (95% confidence interval, 0.65–0.77; p = 0.041; r = 0.36). Google Trends data showed no significant correlation between the calendric month and the incidence of ISSNHL in any of the analyzed countries ( p = 0.873, r 2 = 0.029). Conclusion The ISSNHL incidence was lowest during the winter season in our cohort and reported for other cohorts worldwide. Google Trends–based model analysis did not determine any circannual rhythm.