CORRELATION BETWEEN ANATOMICAL VARIATIONS IN THE ARTERIAL CIRCLE OF WILLIS AND STROKE

• DOI: https://doi.org/10.22533/at.ed.159482417015

• Palavras-chave: "Polígono de Willis", "Variações Anatômicas", "Acidente Vascular Encefálico"

• Keywords: “Circle of Willis”, “Anatomical variations”, “Cerebrovascular accident”

• Abstract:

  Objectives: Review the anatomy of the Arterial Circle of Willis (CoW), highlighting its main anatomical variations and relating them to possible pathophysiological changes capable of increasing the incidence of Cerebral Vascular Accidents (CVA) in the general population. Methods: An anatomical, pathophysiological and epidemiological literature review was carried out in the Pubmed, Scielo and Google Scholar databases, using the descriptors: “Circle of Willis”, “Anatomical variations” and “Cerebrovascular accident”. The classic anatomy of CoW was addressed, also covering the main variations in the vascularization of the skull base and the related epidemiological and pathophysiological aspects, with emphasis on the possibility of increased risks of strokes. Results: Given the potential function of CoW in maintaining adequate blood flow, in the face of processes that compromise cerebral irrigation, the association between some local anatomical variants and the development of an efficient collateral circulation demonstrated to reduce the risks of transient ischemic attack and strokes Brain, when compared to the risks of these events for patients without the development of these collaterals. Furthermore, most cases describe hypoplasia of the posterior communicating artery (PCA) as the main variation found in CoW, with its smaller diameter associated with an increased chance of ischemic events. The reported prevalence range of AcoP hypoplasia was 8% to 28.7%. Also noteworthy is the association between the persistence of fetal arterial segments related to the poor development of compensatory collateral circulation in occlusive conditions, which favors the outcome of strokes. Conclusions: There is evidence that variations in the classic morphology of CoW can generate varied clinical repercussions, with emphasis on cases of arterial hypoplasia and persistence of fetal vessels in adult individuals, with such variations being associated with the poor development of compensatory collateral circulation in occlusive conditions, leading to extensive deficits in ischemic conditions. This way, detailed anatomical knowledge correlated with the understanding of cerebral hemodynamics may help to elucidate questions still present in the scientific community regarding various clinical syndromes, offering the possibility of safer endovascular interventions and open neurosurgical procedures. This makes it possible to offer a more favorable prognosis to patients at increased risk of stroke.