Original ArticleAnatomic Predictors of Unruptured Anterior Communicating Artery Aneurysm Growth
Introduction
Growth of unruptured intracranial aneurysms (UIA) is considered to signify an increased risk of subsequent rupture.1 Although the general risk factors for UIA growth have been identified,1, 2, 3, 4 data on location-specific predictors of growth are comparatively limited. Aneurysms arising from the anterior communicating artery (ACOM) complex often occur in tandem with a unilaterally hypoplastic A1 segment,5, 6, 7, 8, 9 the hemodynamic effects of which have been suggested to drive aneurysm formation at this location.10, 11 Clinically, the presence of A1 segment hypoplasia has been correlated with ACOM aneurysm morphology.12 It is not known whether this anatomic variant also predisposes unruptured ACOM aneurysms to grow over time. Knowledge of the effect of A1 segment hypoplasia on the propensity for growth could influence management strategies of unruptured ACOM aneurysms, particularly because this anatomic variant has also been associated with the incidence of infarction after subarachnoid hemorrhage.7, 13 We examined the incidence of growth in a cohort of patients with unruptured ACOM aneurysms in an attempt to identify clinical and anatomic predictors of growth specific for aneurysms of this location.
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Patient Selection
After approval from our Institutional Review Board, we retrospectively reviewed the clinical course of patients with unruptured saccular aneurysms arising from the ACOM monitored with serial imaging. All patients had aneurysms at least 4 millimeters in size. In general, patients deemed to have a low risk of aneurysm rupture on the basis of aneurysm characteristics were observed, as were patients considered to be at high risk for experiencing complications from treatment. Aneurysm
ACOM Aneurysm Characteristics and Incidence of Growth
There were 81 patients who met our inclusion criteria for analysis. The mean size of ACOM aneurysms at the time of initial discovery in this population was 6.4 mm (standard deviation [SD], 2.8), with 7 aneurysms (8.6%) having a lobulated or irregular appearance. Mean and median follow-up times were 3.9 and 2.6 years, with a total of 317.9 person-years of follow-up. Patients underwent an average of 3.3 imaging studies (SD, 2.1; range, 2–12), with a mean time between imaging studies of 1.6 years
Discussion
In the present study, we identified several anatomic characteristics of ACOM aneurysms associated with growth over time. As has been consistently demonstrated in previous studies investigating risk factors for growth of unruptured aneurysms,1, 2, 3, 4 increasing aneurysm size at the time of initial discovery was associated with growth. In addition, aneurysms at the junction of the A1 and A2 segments were more likely to grow than were aneurysms arising solely from the ACOM. Finally, a
Conclusions
In the present study, we identified multiple anatomic characteristics of ACOM aneurysms associated with growth over time. Although these data need to be confirmed in larger studies, they may be useful in determining management strategies for patients with unruptured aneurysms at this location.
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Conflict of interest statement: The authors declare that the article content was composed in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.