Angiographic Analysis of Middle Cerebral Artery Bifurcation Aneurysm

ABSTRACT

It is generally believed that the important factor in cerebral aneurysmal formation is mural degeneration where sustained hemodynamic stress is maximal. The authors have investigated angiographic findings to evaluate the relationship of aneurysmal formation and anatomical characteristics. Between January 1994 and December 1996, 386 patients with spontaneous subarachnoid haemorrage underwent cerebral angiographic studies. Among these, 83 patients had middle cerebral artery bifurcation aneurysm without intracerebral hematoma in computed tomography and without vasospasm in angiography. These patients were compared with 68 patients with subarachnoid haemorrage who showed normal angiographic finding. Parameters for angiographic measuring were the direction of aneurysm, the length of proximal middle cerebral artery, the ratio of diameter and angles between internal carotid artery, anterior cerebral artery, middle cerebral artery, and superior and inferior trunk of middle cerebral artery. These data were analysed by student t-test, ANOVA, and the results were as follows 1) Fifty-two cases(63%) of middle cerebral artery bifurcation aneurysm directed laterally. 2) The length of proximal middle cerebral artery was not significantly different from that of control group. 3) Middle cerebral artery bifurcation aneurysms were frequently seen in angiography when angle between anterior cerebral artery and middle cerebral artery was more decreased and angle between superior and inferior trunk of middle cerebral artery was more increased. 4) Middle cerebral artery bifurcation aneurysm revealed to be more inferiorly directed when angle between proximal segment of middle cerebral artery and superior trunk of middle cerebral artery was more increased.