Influence of Meteorological Conditions on the Incidence of Chronic Subdural Haematoma, Subarachnoid and Intracerebral Haemorrhages - the "Bleeding Weather Hypothesis".

Aim: To elucidate possible causal relationships on climate change and intracranial haematomas.

Material And Methods: In a retrospective study we examined all patients (N=1169) treated for subarachnoid haemorrhage (SAH; n=484), intracerebral haemorrhage (ICH; n=417) or chronic subdural haematoma (CSDH; n=268) in our department over a 7-yearperiod between 1st June 2005 until 31th May 2012. The date of admission was correlated with the corresponding meteorological parameters which included; mean daily temperature (°C), relative humidity (%), vapor pressure (hPa), barometric pressure (hPa), cloud amount (/8), and wind speed (m/s).

Results: Incidence of SAH tended to increase in April, ICH in January and CSDH in July, respectively, but ?² test did not reveal any statistical significance in seasonality for the three bleeding pathologies. Comparing the arithmetic average of meteorological key parameters of uneventful and eventful days by using student?s t-test within the three groups (SAH, ICH, CSDH) we could not demonstrate any statistical significance (p > 0.05). For SAH, logistic regression analyses revealed an increased risk associated with a decrease of barometric pressure (p=0.021).

Conclusion: Although our data suggest seasonal variabilities of SAH, ICH and CSDH, the single weather parameters do not demonstrate causal relationships with the incidence of cerebrovascular events. However, incidence of SAH tended to increase with changes of barometric pressure which confirms previously published results and might indicate a possible underlying relationship.