Introduction. Brain vascular malformations (BVMs) are congenital lesions with evolutive properties that possess a considerable chance of causing intracranial haemorrhage. The most common types are arteriovenous malformations (AVMs), aberrant entanglements of deformed vessels that shunt blood from the arteries directly into the veins, and cavernous malformations (CMs), being mulberry-shaped sinusoid spaces filled with blood. The rate of hemorrhagic stroke varies between these two types of lesions, being the most common form of symptomatic presentation for AVMs, but a much rarer occurrence for CMs. The purpose of our pilot study was to test whether the incidence of intracranial haemorrhage from BVMs varies between seasons, as well as examining a possible causality for this event.
Material and methods. We performed a retrospective analysis on the cases of ruptured BVMs of the brain operated by the senior surgeon in our department between January 2008 and December 2019. We then divided the patients according to the type of lesion and gender, based on the month of the year when their pathologies caused the hemorrhagic stroke. We performed Pearson’s chi-square test to verify the relationship between season and rate of rupture of AVMs and CMs, individual month and rate of rupture, season and gender, and individual month and gender.
Results. There were 87 ruptured vascular malformations, out of which 71 were AVMs and 16 were CMs. There were 51 males (40 AVMs, 11 CMs) and 36 females (31 AVMs, 5 CMs). The majority of hemorrhagic strokes occurred in the months of July (10 AVVMs, 2 CMs) and December (10 AVMs, 1 CM). We obtained a statistically significant correlation between the summer season and presentation with ruptured cavernous malformation, as well as the male sex and presentation with a ruptured AVM in December, whereas the female sex presented a correlation with ruptured AVMs in the month of March. We also obtained a correlation between the male sex and presenting with a ruptured vascular malformation of any kind in December, as well as the female gender and hemorrhagic stroke from any vascular malformation in the months of January and August.
Conclusion. Despite promising statistical results, the relatively low number of cases may not be applicable to a larger patient population. It seems probable that meteorological conditions, especially extreme temperatures, might act as an additional risk factor for hemorrhagic stroke from vascular malformations, however, these findings should be corroborated with supplementary case series from other centres or a large prospective trial.