Morphometric and Morphological Analysis of the Circle of Willis and its Variants in Adult Human Cadaver: A Retrospective Observational Study

Introduction: Knowledge of variations in the vascular anatomy of the circle of Willis is necessary for radiologists and neurosurgeons performing radiological procedures and intracranial surgeries. Aim: To identify vessels forming the Circle of Willis and to determine the incidence of its variations in the Circle of Willis in cadaveric brain specimens. Materials and Methods: A retrospective observational study was conducted in the Department of Anatomy, PSG Institute of Medical Sciences and Research, Coimbatore Tamil Nadu, India, from February 2021 to January 2024. A total of 30 brain specimens, including those of both genders, were removed and fixed in formalin. The variations that were observed are hypoplasia, aplasia, duplication, and differences in the dimensions between opposite segments. Observations regarding shape, symmetry and architecture were noted. The variations in the vessels that form the Circle of Willis were identified. Comparison of length and diameter between right and left-sided arteries of the Circle of Willis was done with Student’s paired t-test. Results: Out of the total of 30 available human brain specimens, 22 specimens presented with the classic shape (heptagonal) of the Circle of Willis. Eight specimens showed variation in the Anterior Cerebral Artery (ACA). One specimen showed variation in the Posterior Cerebral Artery (PCA). Ten specimens showed variation in the Anterior Communicating Artery (ACoA) and 12 specimens showed variations in the Posterior Communicating Artery (PCoA). Conclusion: Knowledge of variations in the Circle of Willis is essential for radiologists and neurosurgeons to interpret angiography and plan neurovascular procedures accurately