1. Morphology Aneurysm morphology has been long understood to have predictive value for rupture risk. Aneurysms that are multilobulated or that have wall irregularities (including those with daughter sacs) are more susceptible to rupture than are single-sac aneurysms with smooth margins.
2. Family History While it is true that symptomatic individuals with unruptured intracranial aneurysms of 6 mm or smaller generally have a low rate of rupture, familial risk impacts that statistic. Familial aneurysms tend to rupture at a smaller size and younger age than sporadic aneurysms. The annual rupture rate of intracranial aneurysms <= 6 mm in the familial intracranial aneurysm study subjects is 17 times higher than the rupture rate for subjects with an unruptured intracranial aneurysm in the ISUIA study group who had IAs of 6mm and a matched distribution of aneurysm location.
3. Smoking Smoking is a risk factor that is significant to rate of rupture and impacts the treatment decision.
4. Gender Rate of rupture is higher for the female population.