Relationship of A1 segment hypoplasia to anterior communicating artery aneurysm morphology and risk factors for aneurysm formation

Lorenzo Rinaldo, Brandon A. McCutcheon, Meghan E. Murphy, Mohamad Bydon, Alejandro Rabinstein, Giuseppe Lanzino

Research output: Contribution to journalArticle

12 Scopus citations

Abstract

OBJECTIVE Hypoplasia of the A1 segment of the anterior cerebral artery is frequently observed in patients with anterior communicating artery (ACoA) aneurysms. The effect of this anatomical variant on ACoA aneurysm morphology is not well understood. METHODS Digital subtraction angiography images were reviewed for 204 patients presenting to the authors' institution with either a ruptured or an unruptured ACoA aneurysm. The ratio of the width of the larger A1 segment to the smaller A1 segment was calculated. Patients with an A1 ratio greater than 2 were categorized as having A1 segment hypoplasia. The relationship of A1 segment hypoplasia to both patient and aneurysm characteristics was then assessed. RESULTS Of 204 patients that presented with an ACoA aneurysm, 34 (16.7%) were found to have a hypoplastic A1. Patients with A1 segment hypoplasia were less likely to have a history of smoking (44.1% vs 62.9%, p = 0.0410). ACoA aneurysms occurring in the setting of a hypoplastic A1 were also found to have a larger maximum diameter (mean 7.7 vs 6.0 mm, p = 0.0084). When considered as a continuous variable, increasing A1 ratio was associated with decreasing aneurysm dome-to-neck ratio (p = 0.0289). There was no significant difference in the prevalence of A1 segment hypoplasia between ruptured and unruptured aneurysms (18.9% vs 10.7%; p = 0.1605). CONCLUSIONS Our results suggest that a hypoplastic A1 may affect the morphology of ACoA aneurysms. In addition, the relative lack of traditional risk factors for aneurysm formation in patients with A1 segment hypoplasia argues for the importance of hemodynamic factors in the formation of ACoA aneurysms in this anatomical setting.

Original languageEnglish (US)
Pages (from-to)89-95
Number of pages7
JournalJournal of Neurosurgery
Volume127
Issue number1
DOIs
StatePublished - Jul 1 2017

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Keywords

  • A1 hypoplasia
  • Aneurysm morphology
  • Anterior communicating artery aneurysms
  • Dome-to-neck ratio
  • Vascular disorders

ASJC Scopus subject areas

  • Surgery
  • Medicine(all)
  • Clinical Neurology

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