 Intracranial aneurysms are rare in childhood, with over 95% of all aneurysms occurring in adults.Incidence rates are two to three times higher in males, while there are more large and giant aneurysms and fewer multiple aneurysms.Intracranial hemorrhages are 1.6 times more likely to be due to aneurysms than cerebral arteriovenous malformations in whites, but four times less in certain Asian populations.