Cerebral aneurysms are usually not congenital, but rather often form over days, weeks, or months.
It is hypothesized that the critical size for rupture is smaller for newly formed aneuryms; thus, treat newly discovered aneurysms that were previously radiographically absent more proactively and cautiously.
While hypertension and cigarette smoking are not thought to cause aneurysmal rupture, they do contribute to the problem; Hypertensive smokers are at a 15-fold increased risk of SAH compared to non-hypertensive non-smokers.
