Presence of anatomical variations of the circle of Willis in patients undergoing surgical treatment for ruptured intracranial aneurysms

Abstract

High incidence of asymmetry of Willis circle in the group of patients with ruptured aneurysms imply association of asymmetrical configuration and disorder in haemodynamic relations with forming and rupture of intracranial aneurysms.

The role of circle of Willis anomalies in cerebral aneurysm rupture

“…The association between circle of Willis anomalies and aneurysm rupture in previous reports has been primarily descriptive or consisted of much fewer cases 6 10. De Rooij et al reviewed CT angiograms of 126 patients, looking at incompleteness, asymmetry or dominance of the circle of Willis configuration and found no association with rupture on a per site basis.…”

Vascular variations associated with intracranial aneurysms

“…It was mostly seen in the A1 segment, followed by the P1 segment. Aplastic/hypoplastic A1 was also the most common variation in some reports (17,33). The incidence of hypoplastic and aplastic A1 segment of the anterior cerebral artery was reported as 36% by Kryzewski et al (16).…”

“…In the present study, the overall rate of variations in the circle of Willis configuration with berry aneurysms was 57.8%. The rate of variations in series with accompanying intracranial aneurysms was between 40.7% and 97% (2,12,20,27,32,33). In a recent cadaveric study conducted on the Turkish population, adult configuration of the polygon was detected variation.…”

Analysis of the symmetric configuration of the circle of Willis in a series of autopsied corpses

“…In all asymmetric type B (16%) cases, hyperplasia of the AcoA was present as the adaptive process to ensure adequate perfusion because of the hypoplasia of one A1 ACA [14][15][16] . All this can lead to hemodynamic load and segmental dilatation of AcoA with subsequent formation of aneurysmal changes 2,17,18 . In addition, on the side of the Willis with the hypoplastic A1-ACA, there is a direct perfusion rush from ICA to a. cerebri media (ACM), ipsilaterally, which may lead to increased hemodynamic rush in the middle cerebral artery (MCA) bifurcation area.…”