Morphologic Variations in the Circle of Willis as a Risk Factor for Aneurysm Rupture in the Anterior and Posterior Communicating Arteries

World Neurosurg. 2021 Oct:154:e155-e162. doi: 10.1016/j.wneu.2021.06.151. Epub 2021 Jul 14.

Abstract

Background: Intracranial aneurysms are acquired abnormal vascular dilations. The most dangerous complication of a cerebral aneurysm is its rupture, with a high rate of mortality. This study aimed to determine whether there is an association between anatomic variations in the circle of Willis and ruptured aneurysms in the anterior and posterior communicating arteries.

Methods: A cross-sectional study of adult patients with a diagnosis of intracranial aneurysm was carried out between March 2015 and March 2019. The patients were divided into groups of ruptured or unruptured aneurysm in the anterior and posterior communicating arteries.

Results: A total of 132 patients with anterior and posterior communicating artery aneurysms were included. The presence of anatomic variation in the circle of Willis presented a statistically significant association with ruptured aneurysms (odds ratio [OR], 2.28; 95% confidence interval [CI], 1.11-4.65; P = 0.024). There was a statistically significant difference between the presence of nonspherical aneurysm and rupture (OR, 6.9; 95% CI, 3.12-15.48; P < 0.0001). Multivariate logistic regression observed smoking (OR, 2.4; 95% CI, 1.01-5.9; P = 0.4), anterior complex variations (OR, 2.68; 95% CI, 1.01-7.18; P < 0.04), and nonspherical morphology (OR, 4.7; 95% CI, 1.93-11.45; P = 0.001) presented a statistically significant association with the rupture.

Conclusions: Our results suggest that the studied variations of the circle of Willis and nonspherical morphology, in addition to playing a role in the development of cerebral aneurysms, may contribute to their rupture.

Keywords: Anatomic variation; Circle of Willis; Intracranial aneurysm; Ruptured aneurysm; Unruptured aneurysm.

MeSH terms

  • Aged
  • Anatomic Variation
  • Aneurysm, Ruptured / diagnostic imaging*
  • Aneurysm, Ruptured / epidemiology
  • Anterior Cerebral Artery / diagnostic imaging*
  • Cerebral Angiography
  • Circle of Willis / diagnostic imaging*
  • Computed Tomography Angiography
  • Cross-Sectional Studies
  • Female
  • Humans
  • Image Processing, Computer-Assisted
  • Intracranial Aneurysm / diagnostic imaging*
  • Intracranial Aneurysm / epidemiology
  • Male
  • Middle Aged
  • Posterior Cerebral Artery / diagnostic imaging*
  • Risk Factors