In anterior communicating artery aneurysm that accounts for about 30% of intracranial aneurysms, it has been pointed out that the hemodynamic factor plays a very important role in all stages such as initiation, growth and rupture of aneurysm. There are several principles which are generally agreed in surgical field: careful protection of perforators, preparation for temporary clipping of afferent artery of aneurysm and dissection of the neck of aneurysm prior to exposure of the dome However, there is controversy about the direction of approach to the aneurysm. While Yasargil has approached almost all the anterior communicating artery aneurysm through the right side, Flamm said that he operated the anterior communicating artery aneurysm via the same side of the predominant A_(1).
Based upon the angiographic findings, the author reviewed 96 cases of ruptured anterior communicating artery aneurysm to propose a standard related to the direction of surgical approach by analyzing the relationships between unilateral predominance of A_(1), afferent artery and direction of aneurysm. Also by observing the relationship between the findings of brain CT and those of cerebral angiogram, the author tried to suggest a point referred to which carotid artery should be selected first when direct carotid angiography is invitable.
The results were summarized as followings:
1. Of 53 cases which had intracranial hematoma, 28 cases showed unilateral predominance. Among them the predominance of hematoma was opposite to the afferent artery in 82.1% (23/28) and was ipsilateral to the direction of aneurysm in 64.3% (18/28).
2. Of 91 cases which had subarachnoid hemorrhage, 29 cases showed unilateral predominance. Among them the predominance of hemorrhage was opposite to the afferent artery in 72.4% (21/29) and was ipsilateral to the direction of aneurysm in 58.6% (17/29).
3. Asymmetricity of caliber of A_(1) was observed in 71.9% (69/96) and which was 3 times more frequent than of reported incidence of control group(2.2-23%).
4. The incidence of predominance of left A_(1) was 54.2% (52/96) and that of right A_(1) was 17.7% (17/96). Among them, predominant A_(1) was operated as afferent artery in 94.2% (65.69).
5. Of 69 cases in which a unilateral A_(1) showed predominance, the direction of aneurysm was opposite to the side of predominant A_(1) in 66.7% (46/69) and ipsilateral to the predominant A_(1) in only 2.9% (2/69).
6. Above findings suggest that in cases with suspected anterior communicating artery aneurysm rupture that direct carotid angiography is inevitable, contralateral carotid angiography should be undertaken when intracranial hematoma or subarachnoid hemorrhage showed unilateral predominance on brain CT, and left carotid angiography is preferable than right if there is no predominance of intracranial hematoma or subarachnoid hemorrhage on brain CT. And it is desirable to approach the anterior communicating artery aneurysm via the side of the predominant A_(1) when the direction of aneurysm is uncertain on cerebral angiogram.
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