The impact of climate and environmental factors on the incidence of Bell’s palsy: a nationwide population study

Background Bell’s palsy, a sudden paralysis of the facial nerve, lacks a clear etiology, with climatic and environmental factors suggested as possible triggers. Identifying these associations could offer insights into effective preventive and therapeutic strategies.Objectives This study aimed to explore the potential relationships between the incidence of Bell’s palsy in the Korean population and specific meteorological and environmental factors.Materials and Methods A retrospective analysis was conducted using data from the Korean National Health Insurance Service for 2010 to 2020. The study assessed the incidence rates of Bell’s palsy and how they correlated with meteorological indicators (temperature, humidity, precipitation, wind velocity, insolation) and environmental factors (air pollutants, including NO2, CO, SO2, PM10, PM2.5, and O3).Results The analysis identified 530,701 cases of Bell’s palsy, with an average incidence rate of 93.90 per 100,000 individuals. The condition was more prevalent among individuals in their 50s, and no significant annual trend was evident. Seasonal variations were not linked to substantial differences, while meteorological factors exhibited notable correlations. Increased temperature and relative humidity corresponded to reduced incidence rates, while drier and sunnier conditions were linked with a higher occurrence of Bell’s palsy. Air pollutants, particularly NO2, CO, PM10, and PM2.5, were positively correlated with the incidence of Bell’s palsy. Surprisingly, a lower concentration of O3 was associated with a higher incidence.Conclusions and significance This study provides valuable insights into the complex interplay of Bell’s palsy and meteorological and environmental factors. The detected correlations among climatic indicators, air pollutants, and the incidence of Bell’s palsy underscores the potential impact of external factors on the condition’s development. These findings contribute to a comprehensive understanding of Bell’s palsy, highlighting the need to consider both climatic and environmental influences in its etiology.