Posterior circulation vascular variants and intracranial aneurysm formation: An imaging-based study with implications for risk stratification

Background: Subarachnoid hemorrhage (SAH) from Intracranial Aneurysms (IA) represents a leading cause of death and morbidity from neurological deficits. Emerging research has identified that variations in vascular anatomy may contribute to endothelial dysfunction, hemodynamic stress, and pharmacological responsiveness in cerebrovascular tissues. Objectives: This study aimed to determine whether variations in the posterior circulation vascular system are associated with the development of aneurysms. Additionally, it was explored whether these variations could provide additional risk assessment for cerebrovascular diseases. Methods: A retrospective study of digital subtraction angiography (DSA) and computed tomography angiogram (CTA) of the posterior circulation vascular anatomy in 104 patients, from Jan 2019 to Sept 2022 was conducted. The variables recorded were posterior communicating artery grading, posterior cerebral artery dominance, vertebral artery caliber, persistent fetal type posterior circulation presence and aneurysm laterality. Hypoplastic vertebral arteries were defined as those ? 0.8 mm in diameter. Results: According to the study involving 104 individuals (47 men and 57 women) left-sided posterior communicating artery (PCoA) dominance is frequently present. Right-sided aneurysm formation was higher after exclusion of bilateral and midline aneurysms from the analysis. Persistent fetal-type posterior circulation was noted in 26.9% of all cases with a predominance for formation of right-sided petrosal type. Conclusion: The presence of a vascular phenotype with left-sided PCoA dominance and contralateral vertebral artery hypoplasia increases the risk for formation of an IA in vascular patients with or without persistent fetal-type posterior circulation and therefore could be used to develop pharmacologically-based treatment strategies, including continued stabilizing of endothelial cells using Cilostazol.