One hundred & ten consecutive cases of aneurysm at the anterior communicating artery have been treated under the microscope since 1976 in Kyushu University Hospital.
The site of the neck of anterior communicating artery aneurysms was classified into three types as follows; Type I: the neck is located at the junction of the larger Al segment and anterior communicating artery (ACoA), with a contralateral hypoplastic Al segment. Type II: the neck is located at the junction of the Al segment and ACoA; both Al segments are equal in size. Type III: the neck is located widely on the ACoA; the Al segments are equal in size. Fifty-seven out of 110 cases (52%) were Type I. Forty-four of 57 cases (79%) had the Al hypoplasia on the right side. Thirteen of 110 cases (12%) had vascular variations of the ACoA associated with the aneurysm. Duplicate or fenestrated ACoA was observed in 8 cases, a combination of fenestrated ACoA and triplicate A2 in 3 cases, a combination of fenestrated ACoA and fenestrated MCA in one case, and a combination of triplicate ACoA and triplicate A2 in one case. Preoperative bilateral carotid angiograms were reviewed in 10 of 13 cases and vascular variations of the ACoA associated with the aneurysms could be pointed out on angiograms in 4 cases, retrospectively. Anatomical and radiological aspects associated with anterior communicating artery aneurysms are discussed in this paper.
