A Comprehensive Study of the Anatomical Variations of the Circle of Willis in Adult Human Brains

Abstract

The anatomical variations of the circle of Willis were probably genetically determined, develop in early embryonic stage and persist in post natal life. The amplitude of neck movements, racial, environmental and hemodynamic factors may also modify these variations. These anomalies may alter the occurrence, severity of symptoms, treatment options and recovery from certain cerebrovascular disorders viz., stroke and aneurysms. A detailed knowledge of the vascular variants is useful to surgeons in planning their shunt operations, choice of the patients and also keeps away inadvertent vascular traumas during surgeries.

Study on the Anatomical Variations of the Anterior Part of the Circle of Willi’s in Adult Human Cadavers

“…The incidence of double ACoA is correlating with other studies by Fawcett & Blachford et al, Puchades -Orts et al, and S Iqbal where the incidence was 7.28, 6.4 and 6 respectively [3,12,13]. The union and separation was described as azygous pattern of ACA and the incidence of the present study was little lower than Vaibhav V Sande et al, where they reported in 10% cases [14].…”

“…The union and separation was described as azygous pattern of ACA and the incidence of the present study was little lower than Vaibhav V Sande et al, where they reported in 10% cases [14]. Triplicate ACA was observed in 2.5% specimen in the present study which was higher than the incidence of Sandya Arvind et al, and lowers than S Iqbal reported it as 09% and 4% respectively [13,15]. The third artery was considered as an accessory artery which was of variable length and has almost the same diameter as both the anterior cerebral arteries and was described as the Median artery of Corpus Callosum as it supplies to it.…”

“…The incidence of the Hypoplasia of the proximal segment of ACA was reported in the present DISCUSSION study as 5% whereas S Iqbal, Rigg & Rupp, Kamath et a., and Milenkovic reported as 4%, 11.97%, 2% and 9.16% respectively. The incidence was ranging from 2 to 11.97% where the present study was to it [6,11,13,18]. In the present study duplication of the middle cerebral artery was found in one (2.5%) specimens.…”

External carotid compression: a novel technique to improve cerebral perfusion during selective antegrade cerebral perfusion for aortic arch surgery

“…This right carotid flow provides CBF to the right cerebral hemisphere and subsequently to the left cerebral circulation via collaterals in the Circle of Willis. Nevertheless, even with an intact Circle of Willis (which can be incomplete in 15% of the population), 2 asymmetric CBF is a common occurrence during HCA when SACP is used. 3 Such an occurrence is due to the relatively low resistance pathway away from the left hemisphere via the left carotid artery, which often remains open to the aortic arch in the surgical field and induces a carotid ''steal'' phenomenon.…”

Fetal and Primitive Type of Circle of Willis with Unilateral Trifurcation of Internal Carotid Artery

“…Aneurysms usually tend to occur in the branches or at the bifurcations of cerebral arteries. [6]. The pattern of the circle therefore becomes important in determining the adequacy of the brain circulation in operations for cerebral aneurysms and also in ligation of the internal carotid artery.…”