Impact of aneurysm location on hemorrhage risk

Introduction Recent studies have reinforced anterior communicating (AComm) artery location as a significant risk factor for aneurysm rupture in addition to posterior circulation/posterior communicating (PComm) artery location. However, studies stratifying aneurysm location in greater detail are sparse. Methods We reviewed the records of 747 consecutive patients with 1013 aneurysms seen at our institution over a 7 year period, noting aneurysm location and rupture status at the time of presentation. Results High proportions of ruptured aneurysms were seen among frontopolar/pericallosal (59%, OR 3.07, p = 0.011), vertebral/posteroinferior cerebellar (PICA; 53%, OR 2.49, p = 0.0037), AComm (50%, OR 2.46, p < 0.0001), and PComm aneurysms (44%, OR 1.77, p = 0.0016). Low proportions of ruptured aneurysms were seen among superior hypophyseal artery (SHA; 6%, OR 0.12, p = 0.0001), internal carotid artery (ICA) bifurcation (12%, OR 0.27, p = 0.0012), and ophthalmic artery aneurysms (15%, OR 0.33, p = 0.0002). The proportion of ruptured PComm aneurysms demonstrated a trend toward being greater than anterior choroidal artery aneurysms (OR 2.14, p = 0.09); however the proportion was significantly greater among anterior choroidal artery aneurysms as compared to nonPComm intradural ICA aneurysms (OR 2.78, p = 0.03). Notably, the lower rupture rate of SHA aneurysms as compared to ophthalmic artery aneurysms neared statistical significance (OR 0.38, p = 0.10). Conclusion Aneurysm location has a significant impact on risk of rupture and should be stratified in greater detail in future studies of aneurysm natural history.