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et al. evaluated 214 patients with BPPV , over and only included data from a single Lisbon
6 years, in Porto Alegre (Brazil) and reported tertiary institution. Second, this study
an association between the incidence of included patients with BPPV who had visited
BPPV and solar radiation, with more patients our Otorhinolaryngology emergency room
with BPPV during the autumn and winter, and did not include patients with BPPV who
when there was low solar radiation. Shu et al. had visited other departments, such as the
12
evaluated 1269 patients with BPPV in Shanghai Neurology Department. However, at our
(China), over 6 years and reported an increase institution, the great majority of patients who
in BPPV incidence in winter months and also visited other departments were referred to
a moderate negative correlation with patients the Otorhinolaryngology emergency room
serum 25-hydroxyvitamin D levels. On the when BPPV was suspected. Despite these
14
contrary, Seidel et al. examined 11153 patients limitations, we were able to include a large
with BPPV using a large German nationwide number of patients with BPPV and showed
database and reported no seasonal variation. 9 climate factors that could explain the seasonal
In our population, we found that the incidence variation in BPPV incidence. Additional studies
of BPPV decreases in the summer months based on prospective multi-center data are
and that has its peak in winter period. required.
The effects of climate factors are related to the
amount of time spent indoors and outdoors, Conclusions
which differs between weekdays and the In our population, the incidence of BPPV
weekends. We calculated BPPV incidence decreases in the summer months, when
7
and climate factors weekly to reduce this atmospheric temperature, solar radiation and
effect. Saeed et al. demonstrated a correlation daylight time are higher and cloud amount
between temperature and the incidence is lower. No association was found between
of BPPV. It has also been reported that an atmospheric pressure or humidity with the
increased incidence of BPPV is associated with incidence of BPPV.
a seasonal decrease in serum vitamin D levels.
15
Calcium is the main component of otoconia in Conflicts of Interest
the utricular macula, and the metabolism of The authors declare that there is no conflict
calcium is affected by vitamin D. The synthesis of interests regarding the publication of this
2
of vitamin D is influenced by skin exposure paper.
to ultraviolet B radiation, season, time of day,
cloud amount, latitude, altitude, air pollution, Data Confidentiality
clothing, and sunscreen use. 12,15 Consequently, The authors declare having followed the
the increase in cloud amount may decrease protocols in use at their working center
serum vitamin D levels, which may result regarding patients’ data publication.
in increased BPPV occurrence. As there is
16
a great interconnection between climatic Protection of humans and animals
factors, our study analyzed six of them. As The authors declare that the procedures
result, we demonstrated a significant negative were followed according to the regulations
and statistically significant association established by the Clinical Research and Ethics
between atmospheric temperature, daylight Committee and to the 2013 Helsinki Declaration
time and solar radiation with the number of of the World Medical Association.
BPPV patients diagnosed per week; and a
positive and significant association between Funding Sources
cloud amount and the incidence of BPPV. This work did not receive any contribution,
There are several limitations to this study. funding or scholarship.
First, our study is retrospective in design
34 Revista Portuguesa de Otorrinolaringologia - Cirurgia de Cabeça e Pescoço
