Correlation between the incidence and severity of Bell's palsy and seasonal variations in Taiwan

Objective: To investigate possible correlations between the incidence and severity of Bell's palsy and seasonal variations in Taiwan. Methods: We studied data on the incidence of Bell's palsy over a 3-year period in Taiwan. The electroneurographic quotient was used as an index for the severity of nerve involvement. A higher electroneurographic quotient indicates less severe disease. Results: Data were collected from 775 patients. We analyzed the data using the chi-square goodness-of-fit test, and the results showed that seasonality was significantly associated with the incidence of Bell's palsy among men, with the incidence increasing during the cold months (p = 0.012). A significant association was evident between age and incidence, with a higher incidence among patients aged 50 years or younger (p = 0.027). By contrast, no significant relationship was found between seasonality and either female sex or older age. No statistical association was found between the degree of nerve involvement and season of onset in patients with Bell's palsy. Conclusion: Bell's palsy increased among men and among younger patients during the cold seasons in Taiwan. No association emerged between the severity of Bell's palsy and the season of onset.