Anatomical diversity in the anomalous circle of Willis and its correlation with artery involved in ischemic stroke

Abstract Background: The circle of Willis (CoW) is a crucial blood vessel arrangement known for its role in ensuring continuous brain perfusion. Variations in CoW anatomy can compromise its compensatory function, potentially leading to ischemic stroke. The significance of CoW variations in the development of stroke and therapeutic implications is increasingly recognized. Objective: This study aimed to investigate the correlation between anatomical variations in the CoW and intracranial blood vessel involvement in ischemic stroke cases. Materials and Methods: From February 2021 to December 2022, cases of acute ischemic stroke showing anomalous CoW were studied. Acute ischemic stroke cases underwent imaging (computerized tomography angiography/magnetic resonance angiography/digital subtraction angiography) to assess the type of CoW, those with anomalous CoW were included in the study, whereas those with complete CoW or with poor quality of images were excluded. A total of 80 acute ischemic stroke cases with anomalous CoW were studied and further, data on demographics, risk factors, stroke site, and comorbidities were collected. Results: The median age was 55 years, predominantly male (75%). Anatomical variations were more frequent on the left (43.75%) compared with the right (33.75%). Variations in anterior and posterior CoW segments were present in 65% and 57.5% of cases, respectively. Hypoplasia of the A1 segment of the anterior cerebral artery and hypoplasia of the posterior communicating artery were the most common variations. Middle cerebral artery involvement was most common (71.25%) and left-sided strokes slightly prevailed (51.25%). Conclusion: Our study revealed that anomalous CoW in the anterior part has a propensity for anterior circulation stroke, whereas, in the posterior part of CoW has a propensity for stroke in posterior circulation and anterior circulation as well. In addition, we found that anatomical variations in CoW are closely linked to hypertension, which in itself is an independent risk factor for stroke.