title: Seasonal variation of Bell's palsy in Athens, Greece - a hospital-based retrospective evaluation over fifteen years.
abstract: Epidemiological data on the incidence of Bell's palsy (BP) are conflicting. The aim of this retrospective study was to evaluate the variation of cases of BP acutely presented in the emergency room of our department over a 15-year period (January 1990 to December 2004). We examined the monthly and seasonal distribution of BPs among 36,312 patients who came to our emergency services and compared it with the assumed equal distribution of cases over the year (null hypothesis) using chi(2) techniques. During the observation period 1,252 of all patients (3.45%) presented due to BP. A decline during the summer was observed, in contrast to a peak documented during the autumn and winter. January and July were the months with the highest and lowest frequency of BP, respectively. Statistical analysis revealed a significantly different seasonal (chi(2) = 10.569; d.f. = 3; p = 0.014) and monthly (chi(2) = 25.445; d.f. = 11; p = 0.008) pattern of BP cases. The distribution of cases of BP shows a significant variation with a decline during the summer and an increase during the colder period of the year. A similar pattern has been described for reactivated herpetic ocular infections. Since a similar pathogenetic mechanism is regarded as the main cause of BP, the chronobiological aspects and the influence of meteorological factors on the reactivation of latent infections deserves further prospective evaluation.
authors.affiliation: University of Athens School of Medicine, Department of Neurology, Eginition Hospital, Greece. spengos@hol.gr
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Spengos
authors.forename: Sofia
authors.initials: S
authors.lastname: Sameli
authors.forename: Georgios
authors.initials: G
authors.lastname: Stouraitis
authors.forename: Angelos
authors.initials: A
authors.lastname: Kolias
authors.forename: Olymbia
authors.initials: O
authors.lastname: Koulouri
authors.forename: Zacharias
authors.initials: Z
authors.lastname: Kokkinos
authors.forename: Irini
authors.initials: I
authors.lastname: Makrylou
authors.forename: Athanassios
authors.initials: A
authors.lastname: Tsivgoulis
authors.forename: Georgios
authors.initials: G
authors.lastname: Tsivgoulis
authors.forename: Demitris
authors.initials: D
authors.lastname: Vassilopoulos
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D020330:Bell Palsy / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D006115:Greece; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012307:Risk Factors; D012621:Seasons; D014505:Urban Population / Q000706:statistics & numerical data*; D014887:Weather