Epidemiology of paroxysmal positioning vertigo: correlation with seasons, climate, and pollution.

The aim of this article was to evaluate the time course of paroxysmal positioning vertigo (PPV) and to investigate correlations with environmental and seasonal factors through a retrospective statistical analysis spanning 4 years (2001-2004). Applying rigorous diagnostic criteria, we selected 575 patients (429 women and 146 men; age range, 17-94 years; mean age, 55 years for men and 56 years for women). Statistical analysis included events per month and per year. We conducted a descriptive statistical analysis to investigate the correlation between vertigo events and main environmental factors: air pollution as expressed by daily concentration of nitric monoxide and ultrafine particles; air pressure; mean temperature and sun radiation; and humidity. We referred the environmental data, collected by Regione Lombardia (the regional government of Lombardy), to the greater Milan homogeneous area. We performed an analysis of variance test and observed that PPV is more frequent in middle-aged women (in or around their fifties) and on the right side. PPV is clearly negatively correlated with temperature, and frequency of attacks depends on temperature variations. The role of air pollution, especially particles, is suspected, but it is not yet clearly identified. Factors that link climate and otoconia metabolism require further investigation.