Intracranial aneurysm
（重定向自Cerebral Aneurysms）
![](/Images/godic/202501/03/Cerebellar_aneurysm1640.png")
![Diagram of cerebral aneurysm.](/Images/godic/202501/03/Cerebral_aneurysm_NIH1640.jpg")
![The most common sites of intracranial saccular aneurysms.](/Images/godic/202501/03/Wikipedia_intracranial_aneurysms_-_inferior_view_-_heat_map1640.jpg")
![A selection of Mayfield and Drake aneurysm clips ready for implantation.](/Images/godic/202501/03/AneurysmClips1640.jpg")
An intracranial aneurysm (also called cerebral or brain aneurysm) is a cerebrovascular disorder in which weakness in the wall of a cerebral artery or vein causes a localized dilation or ballooning of the blood vessel.
Aneurysms in the posterior circulation (basilar artery, vertebral arteries and posterior communicating artery) have a higher risk of rupture. Basilar artery aneurysms represent only 3%-5% of all intracranial aneurysms but are the most common aneurysms in the posterior circulation.