破裂前交通動脈瘤に対する手術法の検討II: 血管写上の特徴と手術法の選択について

Abstract

In this paper, operative indications, especially as regards the selection of surgical approach for anterior communicating artery aneurysms (ACAA) are discussed with precise and detailed analyses of angiographical anatomy of the aneurysm and the surrounding arteries in 120 surgical cases.Aneurysms originating in the anterior communicating artery itself were much less frequently observed (18.3%), and the majority have their origins on the A1-A2 junction (81.7%). Fifty percent of the A1 segments of the anterior cerebral arteries were dominant on the left side. The right-dominant and the equi-A, type comprised 25% each. In 60% of the cases, the left A2 was anterior to the right one, in 25% vice versa and only in 15% both A, were running in parallel. These inequalities of the arteries surrounding the ACAA seemingly affect the incidence of aneurysmal type. That is, about one third (31.7%) of the ACAA projected laterally from the origin on the A1-A2 junction, and for this lateral-type aneurysm the most suitable surgical approach is the interhemispheric (IH), among numbers of access methods.The location of the neck of the aneurysm, the direction of its dome and the side of the dominant A1 segment of the anterior cerebral artery are important factors in deciding what type of surgical approach is to be done. Though the anteriority of the A, segment is a factor that cannot be disregarded in the pterional (PT) approach, the authors believe that it is not essential in considering the IH approach because this approach can be used for any type of ACAA. At the same time, surgeons should not stick to a single method, especially in the acute stage of subarachnoid hemorrhage because, in this situation, they must try to accomplish the operation as safely, quickly and, of course, completely as possible. In the authors' series, the pterional approach was used in 66 cases (55.0%), the interhemispheric approach in 47 (39.2%), and the bilateral subfrontal and trans-hematoma access were chosen for 4 and 3 cases respectively. And there were 11 cases in which the IH approach with an additional PT approach was used for securing the Al segment which was hidden behind the dome of the aneurysm from the IH surgical view and/or for removal of diffuse and thick subarachnoid clots.