The impact of biotropic weather on the incidence and severity of aneurysmal subarachnoid hemorrhage: a single-center observational explorative study

Controversy surrounds seasonal variations in aneurysmal subarachnoid hemorrhage (aSAH) incidence and course. Investigating weather effects associated with weather fronts may provide more insights. Meteorological parameters are grouped into classes describing biotropic weather conditions influencing human health. Known as bio-synop classes, they impact human health by influencing biological processes. Our study explores the relationship between these classes and aSAH occurrence and severity using data from our neurovascular center and the German national weather registry. Data from 605 aSAH patients treated between 2006 and 2021 was analyzed. The Kruskal-Wallis Test was used to assess the incidence and severity of aSAH, classified by Hunt&Hess (HH) grades across bio-synop classes. Additionally, we explored seasonal clustering of aSAH events. While no significant difference in ASAH incidence across specific bio-synop classes was observed (p = 0.165), class 4 "Low-pressure with cold air advection" was significantly associated with a higher incidence of poorer HH grades (p = 0.022). Further, we observed a decrease in aSAH cases in June in month-to-month comparisons (May vs. June p < 0.001). Although bio-synop classes may not directly affect aSAH incidence, they appear linked to aSAH severity. The reduction in June aSAH cases suggests a potential seasonal influence, indicating a complex interplay of environmental factors warranting further investigation.