Variant configuration of the arterial circle of Willis

Background: A clear understanding of the anatomical variations in the circle of Willis (CoW) is crucial for the effective surgical management of intracranial emergencies such as hemorrhage, infarction, and aneurysms. This study aims to evaluate the configuration of the CoW and provide data on the regional pattern of vascular variations among Nigerian residents in Delta State. Materials and Methods: Using a cross-sectional design, we analyzed 200 archived computed tomographic brain images (104 males and 96 females) from the imaging department of a hospital in Delta State, Nigeria. This retrospective study was conducted following ethical approval from the hospital’s review board. The prevalence of CoW variants was calculated using the Statistical Package for the Social Sciences (version 27.0), with comparisons made based on gender and laterality. Statistical significance was set at P < 0.05 with a 95% confidence interval. Results: A complete CoW was observed in 86 patients (43%), while 114 patients (57%) had an incomplete configuration. Variants in the anterior and posterior circulations were found in 50 (25%) and 55 (27.5%) patients, respectively, with both circulations affected in nine patients (4.5%). The most common variations were absence of the anterior communicating artery (18, 9%) and hypoplasia of the posterior communicating artery (58, 29%). CoW variations were significantly associated with laterality ( P < 0.05), but no significant differences were found based on gender. Conclusion: The study revealed that hypoplasia of the posterior communicating artery and absence of the anterior communicating artery were the most frequent vascular variations in this population. These findings contribute important regional data on the anatomical variability of the CoW and can serve as a reference for future radiological and clinical evaluations.