Intracranial aneurysms are caused by local congenital defects in the wall of cerebral arteries and increased intraluminal pressure, and are abnormal protrusions in the wall of intracranial arteries. The aneurysms are congenital (developmental) aneurysms, infected aneurysms, traumatic aneurysms, atherosclerotic aneurysms, and dissecting aneurysms. The age of prevalence is 40-60 years old, and it is more common in women.