- 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.