Effects of Wind Chill Factor, Temperature and Other Meteorological Parameters on the Incidence of Bell's Palsy: Results Based on a Retrospective, 7-Year Long, Greek Population Study

Abstract

Background: The etiology of Bell's palsy (BP), the most common type of dysfunction of the facial nerve, remains unclear despite vigorous research. Data concerning the effects of meteorological factors (MFs) on its appearance are inconclusive. The aim of our study was to examine the demographics of a convenience sample of patients with BP and to determine the effects of several MFs in the recorded number of cases per month (cpm). Methods: We retrospectively reviewed 568 files of BP patients and concomitant data of MFs during an 84-month observation period. Information collected included age, gender, diabetic status, number of cpm (months further categorized as winter or summer), mean daily and monthly temperatures and wind speeds and monthly values of wind chill factor (WCF), a measure dependent on both temperature and wind speed. Potential correlations were estimated by univariate analyses (p = 0.05). Results: Demographics were in line with previous research regarding age and diabetic status, but indicative of slight male preponderance. Summer months and mean monthly temperatures showed significant negative correlations with cpm (p = 0.002 and <0.000, respectively) and strong positive correlation with WCF (p < 0.000). Conclusions: MFs can substantially influence the possibility for BP appearance. We propose WCF as a novel, reliable estimator of the overall MF-derived risk.

The etiology of Bell’s palsy: a review

“…Information collected included the number of cases per month, monthly temperatures, wind speeds, and monthly wind chill factor levels. The results showed that the number of cases per month was significantly and negatively correlated with the summer months and mean monthly temperatures (p = 0.002 and < 0.000, respectively) and had a significant positive correlation with the monthly wind chill factor (p < 0.000) [82]. These results suggest that the wind chill factor, which depends on both temperature and wind speed, is a novel, reliable estimator of the overall meteorological factor derived risks that influence the probability of BP occurrence.…”

“…However, some researchers have found that BP is more frequent in warm seasons (spring and summer), with its incidence peaking in September [81] More deeply, one study evaluated the influences of meteorological factors on the incidence and onset of BP. Evidence suggests that stronger wind speed of preceding day may be related to the occurrence of Bell's palsy [82] One study retrospectively reviewed 568 files of Bell's palsy patients and concomitant data of meteorological factors. The result showed the number of cases per month was significantly and negatively was significantly and negatively correlated with the summer months and mean monthly temperatures (p = 0.002 and < 0.000, respectively) and strong positive correlation with monthly wind chill factor (p < 0.000).…”

Weather, Weather Changes and the Risk of Bell’s Palsy: A Multicenter Case-Crossover Study

“…Another small study from Greece did not find an association between weather or rapid weather changes and risk of BP [10]. Kokotis and Katsavos [24] found no association between the risk of BP and ambient temperature, but a positive correlation with the "Wind chill factor," a measure reflecting ambient temperature and wind speed. However, these were single center studies involving smaller study populations.…”

Immune‐related gene expression profiles of hypothermia adipocytes: Implications for Bell's palsy

“…Bell's palsy is most likely to represent an autoimmune reaction in response to a component of the peripheral nerve myelin, leading to demyelination of the facial nerve (Greco et al, ). This autoimmune disease can be triggered by a viral infection as well as acute cold (Jeon et al, ; Khedr et al, ; Kokotis & Katsavos, ; Wakisaka et al, ) and accounts for 60%–75% of all cases of unilateral facial paralysis (Adel, Kawthar, Amine, Youssef Souha, & Abdellatif, ). Subcutaneous fat is the primary line of defense against cold stimuli, which can release various secretory factors or adipokines that signal the immune system (Huh, Park, Ham, & Kim, ; Vielma, Klein, Levingston, & Young, ).…”

“…Although the pathogenesis is still unclear, a cell‐mediated autoimmune demyelination mechanism is widely accepted (Abramsky, Webb, Teitelbaum, & Arnon, ; Demirci, Demirci, Kutluhan, Koyuncuoglu, & Yurekli, ; Eryilmaz, Basal, Tosun, Kurt Omurlu, & Basak, ; Greco et al, ; Ozdemir, ). Recently, accumulating evidence from epidemiological studies has shown that the incidence of Bell's palsy is related to temperature and cold wind factors (Franzke et al, ; Kokotis & Katsavos, ; Spengos et al, ; Zhao et al, ). Specifically, the incidence of Bell's palsy was found to increase during cold days or in regions with a large diurnal temperature difference, indicating that a sharp temperature change may be one of the risk factors for facial palsy (Hsieh, Wang, & Lee, ; Khedr et al, ).…”