Ahead of Print: A1-2 Ratio and AComA Aneurysms

Background: Specific morphological factors contribute to the hemodynamics of the Anterior Communicating Artery (AComA). No study has examined the role of the A2 segment on AComA aneurysm presence and rupture.

Objective: To examine the possibility that the ratio between A1 and A2 segments (A1-2 Ratio) represents an independent risk factor for presence and rupture of AComAAs.

Methods: A retrospective review of an institutional aneurysm database was performed; patients with ruptured and unruptured AComAAs were identified. Two control groups were selected: Group A (posterior circulation aneurysms) and Group B (patients without intracranial aneurysms or other vascular malformations). Measurements of A1 and A2 diameters were obtained from DSA (64.1% of 3D rotational DSA), and the A1-A2 ratio calculated.

Results: From January 2009 to April 2011, 156 patients were identified (52 AComAAs, 54 Control Group A and 50 Control Group B). Mean age at time of presentation was 56.09 years. Compared to both control groups, patients with AComAAs had greater A1 diameter (p <.01) and A1-2 Ratio (p < .001) and smaller A2 diameter (p <.01) than the control group. The A1-2 Ratio correlated positively with the presence of AComAAs (p <.001). Ruptured AComAAs were smaller than unruptured ones (5.91mm vs. 9.25mm, p =.02) and associated with higher A1-2 Ratio (p=.02). Presence of a dominant A1 did not predict AComAA rupture (p= .15). The A1-2 Ratio correlated positively with the presence of ruptured AComAAs (p=.04).

Conclusion: A1-2 Ratio correlates positively with presence and rupture of AComAAs and may facilitate treatment decision in cases of small, unruptured AComAAs.

From: The A1-A2 Diameter Ratio May Influence Formation and Rupture Potential of Anterior Communicating Artery Aneurysms by Flores et al.

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