Geometry and Symmetry of Willis’ Circle and Middle Cerebral Artery Aneurysms Development

Carmelo Lucio Sturiale, Alba Scerrati, Luca Ricciardi, Oriela Rustemi, Anna Maria Auricchio*, Nicolò Norri, Amedeo Piazza, Fabio Raneri, Alberto Benato, Alessio Albanese, Annunziato Mangiola, Donato Carlo Zotta, Giancarlo D’Andrea, Veronica Picotti, Antonino Raco, Lorenzo Volpin, Gianluca Trevisi

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Background: A relationship between the geometry and symmetry of Willis’ circle and intracranial aneurysms was reported for anterior communicating and posterior communicating (PCom) aneurysms. A similar association with the middle cerebral artery (MCA) aneurysms instead appeared weaker. Methods: We reviewed 432 patients from six Italian centers with unilateral MCA aneurysms, analyzing the relationship between the caliber and symmetry of Willis’ circle and the presence of ruptured and unruptured presentation. CT-angiograms were evaluated to assess Willis’ circle geometrical characteristics and the MCA aneurysm side, dimension and rupture status. Results: The hypoplasia of the first segment of the anterior cerebral artery (A1) was in approximately one-quarter of patients and PCom hypoplasia was in almost 40%. About 9% had a fetal PCom ipsilaterally to the aneurysm. By comparing the aneurysmal and healthy sides, only the PCom hypoplasia appeared significantly higher in the affected side. Finally, the caliber of the internal carotid artery (ICA) and the first segment of MCA (M1) caliber were significantly greater in patients with unruptured aneurysms, and PCom hypoplasia appeared related to the incidence of an ipsilateral MCA aneurysm and its risk of rupture. Conclusions: Although according to these findings asymmetries of Willis’ circle are shown to be a risk factor for MCA aneurysm formation and rupture, the indifferent association with ipsilateral or contralateral hypoplasia remains a datum of difficult hemodynamic interpretation, thereby raising the concern that this association may be more casual than causal.

Original languageEnglish
Article number2808
JournalJournal of Clinical medicine
Volume13
Issue number10
DOIs
Publication statusPublished - May 2024

Keywords

  • hypoplasia
  • MCA geometry
  • ruptured status
  • unruptured aneurysms

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