Assessment of variation throughout the year in the incidence of idiopathic sudden sensorineural hearing loss.

OBJECTIVE This study was conducted to determine whether the incidence of idiopathic sudden sensorineural hearing loss (ISSHL) varies throughout the year. STUDY DESIGN This study is a retrospective case review. SETTING This study was conducted at a tertiary referral center within a teaching hospital. PATIENTS Inclusion criteria were a diagnosis of ISSHL confirmed by audiometric data. Exclusion criteria were intracranial neoplasms, a history of Ménière's disease, previous ear procedures, chemotherapy, or radiation therapy to the head or neck. There was no exclusion criterion based on age. Ninety-seven patients met these criteria. The median age was 52 years (range, 26-85 yr), and there were 53 (54.6%) women and 44 (45.4%) men. MAIN OUTCOME MEASURES Monthly incidence counts were compiled across a 3-year period. Counts were analyzed for uneven incidence distributions and seasonal variation via standard statistical tests. RESULTS Overall, no evidence was found for an uneven distribution or for a peak either by chi2 (p > 0.1), which assesses for any uneven distribution, or by the circular mean (p > 0.1), which assesses for a pattern of seasonal variation. In the subset of patients (24 of 97; 24.7%) who reported experiencing an upper respiratory infection before or concurrent with the onset of ISSHL, no evidence was found for an uneven distribution of hearing loss onset throughout the year either by chi2 (p > 0.1) or by the circular mean (p > 0.1). CONCLUSION The results of this study suggest that ISSHL incidence does not display uneven distribution throughout the year.