Risk Factors For The Formation, Rupture And Recurrence After Embolization As Well As Hemodynamic Mechanism Of Rupture Of Anterior Communicating Artery Aneurysms

SECTION1Risk Factors for the Formation of Anterior Communicating Artery aneurysmsObjectives:Risk factors for the formation of intracranial aneurysms (IAs) have been widely investigated; however, there is lack of subgroup analysis on risk factors for the formation of anterior communicating artery (ACoA) aneurysms. The purpose of this study was to determine risk factors for the formation of ACoA aneurysms.Methods:This is a retrospective case-control study. Cases consisted of256patients with ACoA aneurysms confirmed by MRA and/or DSA. Controls consisted of512patients without IAs. Possible risk factors for the formation of ACoA aneurysms were collected and analyzed using univariate analysis and multivariate logistic regression. Results:The average age was significantly older in the case group than in the control group (P=0.016). Univariate analysis revealed that hypertension and a dominant or incomplete A1were significantly associated with the presence of ACoA aneurysms. Multivariate logistic regression analysis showed that age (OR1.014,95%CI1.001to1.027), history of hypertension (OR1.627,95%CI1.090to2.135), dominant (OR2.845,95%CI2.019to4.009) or incomplete A1(OR4.301,95%CI2.174to8.507) were independent risk factors for the formation of ACoA aneurysm.Conclusions:Age, hypertension, and a dominant or incomplete A1were independent risk factors for the formation of ACoA aneurysm, for those with these risk factors, a periodical screening with MR angiography might be beneficial to early detection of unruptured ACoA aneurysm. However, the cost-effective of such a screening should be further evaluated. SECTION2Age, aneurysm size and Al anatomic configuration predict rupture of anterior communicating artery aneurysmsObject:The risk factors for the rupture of intracranial aneurysms (IAs) have been widely investigated; however, there is little subgroup analysis on the risk factors for the rupture of anterior communicating artery (ACoA) aneurysms. The purpose of this study was to determine risk factors for the rupture of ACoA aneurysms.Methods:Patients with ACoA aneurysm confirmed by MRA and/or DSA between June2006and October2012were included in this study. Possible risk factors for the rupture of ACoA aneurysms including clinical characteristics, Al anatomic configuration and aneurysm-related characteristics were compared by univariate analysis and multivariate logistic regression between those with ruptured ACoA aneurysms and those with unruptured ACoA aneurysm.Results:A total of256patients with AcomA aneurysm were included,104patients had ruptured ACoA aneurysms. Univariate analysis revealed that age<55years, cigarette smoking, alcohol consumption, a dominant or incomplete Al, and aneurysm size≥3mm were significantly associated with ACoA aneurysms rupture. Multivariate logistic regression analysis showed that only age<55years (OR5.975,95%CI2.739to13.032), a dominant (OR2.463,95%CI1.83to5.13) or incomplete Al (OR6.268,95%CI1.819to21.601) and aneurysm size≥3mm (OR23.429,95%CI10.998to49.908) were independent predictive factors for the rupture of ACoA aneurysms. Conclusion:Age<55years, a dominant or incomplete Al and aneurysm size>3mm were independent predictive factors for the rupture of ACoA aneurysms. For patients with these risk factors, prophylactic treatment should be recommended. SECTION3Hemodynamic Mechanism of Rupture of Anterior Communicating Artery aneurysmsBackground and Purpose:The anterior communicating artery (AcomA) is a predilect location of aneurysms which typically carry higher rupture risks than other locations in the anterior circulation. The purpose of this study was to characterize the different flow types present in AcomA aneurysms and to investigate possible associations with rupture.Materials and Methods:Patient-specific computational models of36AcomA aneurysms were constructed from3D-TOF-MRA images. Visualizations of flow velocity, instantaneous streamlines, and wall shear stress (WSS) were performed. These were analyzed for flow patterns, size of the impaction zone, and peak WSS and then correlations were made with prior history of rupture.Results:4types of flow patterns had been detected, type1(25%) and type2(45%) were the most common. In the18aneurysms with bilateral Al Segments,9showed type A streamlines (50%), the others received blood flow from one side. In the type A streamline,66.7%of them were unruptured aneurysms. And the ratio of ruptured aneurysms were44.4%,53.85and66.7%in typeB, type C, and type D respectively. Maximum intra-aneurysmal WSS (MWSS) in type C streamline were higher than that in type A, type B and typeD. Maximum intra-aneurysmal WSS (MWSS) for the unruptured aneurysms ranged from10to230dyne/cm2(mean,124dyne/cm2) compared with ruptured aneurysms, which ranged from35to1500dyne/cm2(mean, 269dyne/cm2). This difference in MWSS was statistically significant at90%confidence levels.Conclusions:Aneurysms with higher flow rates entering the aneurysm, small impaction zones, and elevated MWSS are associated with a clinical history of previous rupture. SECTION4Endovascular Embolization of Anterior Communicating Artery Aneurysm:Frequency and Risk Factors of RecurrenceBackground and purpose:Possible risk factors for recurrent of a coiled aneurysm over time have been investigated widely, large aneurysm size, wide aneurysm neck, presence of intraluminal thrombus, low packing density, neck remnant, initial incomplete occlusion, duration of follow-up, ruptured aneurysms, location in the posterior circulation and a large neck-dome ratio are associated with a higher risk of recurrence after coiling. However, whether these results can be deduced to a special subgroup of intracranial aneurysm remains unclear. The purpose of this study was to determine risk factors of recurrence after endovascular embolization of ACoA aneurysm.Methods:In this study, we retrospectively analyze clinical, morphological characteristics and initial angiographic results of59patients who underwent coil embolization for ACoA aneurysm and had at least a3-month follow-up angiography between January2006and October2012. Clinical characteristics of patients, characteristics of aneurysm morphology, and immediate angiographic results were were entered into a logistic regression model for the risk factors predictive of aneurysm recurrence.Results:There was no significant difference between the groups in terms of age, gender, history of cigarette smoking, history of alcohol consumption, history of diabetic Mellitus, history of hypertension. There was no significant difference in Hunter-Hess classification and timing of EVT at the time of initial treatment between the groups. Neck size>4(0R=5.570,95%CI,1.377-22.535; P=0.016), neck remnant (OR=4.809,95%CI,1.015-22.792; P=0.048) or incomplete occlusion (OR=14.037,95%CI,2.683-73.447; P=0.002) were identified as independent risk factors for ACoA aneurysm recurrence.Conclusion:Wide neck (neck size>4), neck remnant or incomplete aneurismal embolization at the time of initial endovascular treatment were independent factors predictive for the recurrence of ACoA aneurysm. The present results suggest:1) developing and evaluating new strategies of treatment and technique, especially for wide-neck aneurysms, with a focus on reinforcement and neoendothelialization at the level of the neck as objectives;2) for ACoA aneurysms, packing aneurysm with coil as densely as possible should be performed; and3) for ACoA aneurysms with a wide neck (neck size>4), or neck remnant or incomplete aneurismal embolization at the time of initial endovascular treatment, the strict follow-up angiography should be performed to detect the potential aneurysm recanalization.