Elsevier

World Neurosurgery

Volume 108, December 2017, Pages 662-668
World Neurosurgery

Original Article
Anatomic Predictors of Unruptured Anterior Communicating Artery Aneurysm Growth

https://doi.org/10.1016/j.wneu.2017.09.092Get rights and content

Objective

Anatomic variations of the anterior communicating artery (ACOM) complex have been shown to influence ACOM aneurysm morphology. It is not known whether these variations predispose unruptured ACOM aneurysms to grow over time.

Methods

We retrospectively reviewed the course of patients with untreated, unruptured ACOM aneurysms monitored with serial imaging at our institution. The primary outcome of interest was aneurysm growth. Predictors of aneurysm growth were determined using a Cox proportional hazards model.

Results

There were 81 patients with an unruptured ACOM aneurysm who were included in our study. Growth occurred in 9 (11.1%) patients, yielding a yearly growth rate of 2.8%. Aneurysms that grew were larger on initial detection than were those that remained stable in size (8.3 mm vs. 6.2 mm; P = 0.031). The ratio of the diameter of A1 segments was greater in patients with aneurysms that grew (2.1 vs. 1.4; P = 0.003), as was the frequency of patients with an A1 ratio >2.3 (25.0% vs. 6.6%; P = 0.023). Among aneurysms that grew, location at the A1–A2 junction was more common than origination solely from the ACOM (88.9% vs. 11.1%). When follow-up time was adjusted for, increasing aneurysm size (unit relative risk [RR] 1.25, 95% confidence interval [CI] 1.06–1.45; P = 0.011) and location at the A1–A2 junction (RR 6.15, 95% CI 1.12–114.49; P = 0.035) were significant predictors of aneurysm growth.

Conclusions

We identify several anatomic characteristics that may be associated with increased risk of ACOM aneurysm growth. These data could influence management strategies of unruptured ACOM aneurysms.

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.

Section snippets

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.

References (22)

  • T. Hassan et al.

    Proposed parent vessel geometry based classification of the anterior Communicating artery located aneurysms

    World Neurosurg

    (2017)
  • W. Brinjikji et al.

    Risk factors for growth of intracranial aneurysms: a systematic review and meta-analysis

    AJNR Am J Neuroradiol

    (2016)
  • D. Backes et al.

    Patient- and aneurysm-specific risk factors for intracranial aneurysm growth: a systematic review and meta-analysis

    Stroke

    (2016)
  • J.D. Burns et al.

    Intracranial aneurysm enlargement on serial magnetic resonance angiography: frequency and risk factors

    Stroke

    (2009)
  • K. Matsumoto et al.

    Incidence of growth and rupture of unruptured intracranial aneurysms followed by serial MRA

    Acta Neurochir (Wien)

    (2013)
  • F.T. Charbel et al.

    Dominant A1: angiographic and clinical correlations with anterior communicating artery aneurysms

    Neurol Res

    (1991)
  • H. Chen et al.

    A1 segment hypoplasia accompanied by AcomA aneurysms assessed with magnetic resonance angiography

    Surg Radiol Anat

    (2014)
  • R. Jabbarli et al.

    Clinical relevance of anterior cerebral artery asymmetry in aneurysmal subarachnoid hemorrhage

    J Neurosurg

    (2016)
  • A. Krasny et al.

    Association of aneurysms and variation of the A1 segment

    J Neurointerv Surg

    (2014)
  • E. Tarulli et al.

    Potent risk factor for aneurysm formation: termination aneurysms of the anterior communicating artery and detection of A1 vessel asymmetry by flow dilution

    AJNR Am J Neuroradiol

    (2010)
  • T. Hassan et al.

    Influence of parent vessel dominancy on fluid dynamics of anterior communicating artery aneurysms

    Acta Neurochir (Wien)

    (2011)
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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.

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