Intracranial aneurysms: characteristics of aneurysms by site, with special reference to anterior communicating artery aneurysms.

Data are presented from an unselected series of 212 aneurysm patients for aneurysms at three major sites: the internal carotid-posterior communicating artery junction, the anterior communicating artery, and the middle cerebral artery. More than 70% of the anterior communicating artery aneurysms occurred as single aneurysms; less than 30% of the middle cerebral artery aneurysms were single. Anterior communicating artery aneurysms showed a right-side predominance in males but not in females. Both males and females had significantly higher mean systolic and diastolic blood pressures for left-sided anterior communicating artery aneurysms than for right-side aneurysms. A brief review of factors relevant to anterior communicating artery aneurysms is presented.