Relationship of the angle between the A1 and A2 segments of the anterior cerebral artery with formation and rupture of anterior communicating artery aneurysm.

PURPOSE

To measure the angle between A1 and A2 segments of the anterior cerebral artery and analyze the relationship of this angle with the formation and rupture of anterior communicating artery aneurysm (ACoAA).

METHODS

Patients with ACoAA (n=64) and with non-ACoAA (n=187) randomly chosen were included. The A1-A2 segment angles were measured using multislice spiral computed tomography angiography. The angular dimensions and differences were recorded and compared between the ACoAA and non-ACoAA groups and the ruptured (n=23) and unruptured group (n=41). The A1 segment morphology was divided into predominant and balanced type. The ACoAA aneurysm protrusion direction was divided into five types.

RESULTS

The incidence of ACoAA was significantly higher in patients with A1 predominance compared to A1 balance (p<0.05). The mean A1-A2 segment angle was significantly smaller in the ACoAA group compared with the non-ACoAA group (p<0.001). There was no significant difference in mean A1-A2 segment angle between ruptured and unruptured groups. There was no significant relationship between aneurysm protrusion rupture and direction.

CONCLUSIONS

The formation of ACoAA is more likely when there is A1 segment predominance in the anterior cerebral artery. The A1-A2 angle can help predict the formation of ACoAA but not useful for rupture predicting.