Abstract 190: Anatomical variants in the circle of Willis as a risk factor for intracranial aneurysms: a study in the Mexican Population using diagnostic angiography.

Introduction/Purpose Hemorrhagic stroke due to ruptured intracranial aneurysms comprises one of the lead causes of overall disability in Mexico and Latin America. The relationship between anatomical variants in the Circle of Willis/Cerebral Arterial Circle (CAC) and Intracranial Aneurysms (IA) remains an ongoing research subject. Materials/Methods We performed a retrospective study of cerebral digital subtraction angiographies at the Interventional Neuroradiology Department of the National Institute of Neurology and Neurosurgery in México, between July 1, 2020, and January 1, 2022. Data regarding Circle of Willis conformation, Avs and IA incidence, and demographic characteristics was collected. Results A total of 150 Diagnostic angiographies were studied, 96 procedures(64 %) belonged to female patients. We registered 144 AVs in the CAC in 96 (64%) angiograms. 75 (50%) were positive for IA. 30 (20%) were reported as non‐pathological. Significant relationships were found between aneurysms in the anterior circulation and A1 segment hypoplasia/ agenesis and IA in the posterior circulation and Posterior Cerebral Artery fetal origin/ hypoplasia. The frequency of angiograms diagnosed without pathology was significantly higher in the category of CAC without variants (80%) than that of pathological angiograms (48.76%) (p=0.003). AVs were found to be more common in patients with aneurismatic pathology than in those without pathology (p=0.048). Conclusions We found a significant relationship between the presence of IA and Avs, especially between specific Avs and IA incidence in the anterior and posterior circulation. This study offers new insights into the understanding of AVs for diagnostic and therapeutic purposes in vascular pathology.