Weather conditions and Bell's palsy: five-year study and review of the literature

BACKGROUND: Climatic or meteorological condition changes have been implicated in the pathogenesis of Bell's palsy (BP). We evaluate the influence of meteorological parameters, such as temperature, humidity, and atmospheric pressure, and their variation and covariation on the incidence of BP and present a review of the literature on the effect of meteorological conditions on facial nerve function. METHODS: A total of 171 cases of BP admitted to our Department over a five-year period were studied. The meteorological database included daily values of 13 distinct parameters recorded at the meteorological station of the University of Ioannina during this period. A relationship between each meteorological variable and the incidence of BP was investigated by applying (Χ(2)) test on data from 13 contingency tables. In addition, the influence of different weather types on the incidence of BP was also investigated. For this purpose Cluster Analysis was used to create eight clusters (weather types) for the Ioannina prefecture and (Χ(2)) test was applied on the contingency tables consisting of the days of BP cases for each cluster. RESULTS: No significant correlation was found either between BP and each distinct meteorological parameter or between BP and any specific weather. CONCLUSIONS: Meteorological conditions, such as those dominating in the Northwestern Greece, and/or their changes have little effect on the incidence of BP. Multicenter studies taking into account atmospheric pollution, and climatic differences between countries, are necessary to scrutinize the environmental effects on facial nerve function.