circle of Willis


Also found in: Dictionary, Thesaurus, Medical, Legal, Financial, Wikipedia.

circle of Willis

[′sər·kəl əv ′wil·əs]
(anatomy)
A ring of arteries at the base of the cerebrum.
Mentioned in ?
References in periodicals archive ?
Conclusion: There was a wide variability in the anatomy of the Circle of Willis in Pakistani adults asymptomatic for cerebrovascular disease.
This case is an example of unilateral internal carotid agenesis with intracavernous anastomosis, with collateral flow from both the circle of Willis and from a persistent fetal vessel.
Battacharya SK, Hutchinson EC, McCall AJ: "The Circle of Willis, the incidence of abnormalities in normal infarcted brains.
The Japanese term "moyamoya" was later coined to describe the hazy, cloudy "puff of smoke" appearance of the network of dilated, abnormal microvasculature occurring in the region of the circle of Willis (2).
KEY WORDS: Posterior communicating artery, Circle of Willis, Aplasia, Hypoplasia.
Morphometric measurements were used to obtain information on the diameters of the blood vessels that form part of the circle of Willis circle of people with normal cerebrovascular status.
There is a growing body of literature suggesting that patients with atherosclerotic middle cerebral artery (MCA) stenosis are at a higher risk of future ischemic stroke, and that the risk of future cerebral ischemic events would be low if the blood flow with unilateral MCA stenosis or occlusion is compensated by circle of Willis, or by the collateral circulation from cortical artery, otherwise, the patients would suffer from cerebral ischemia and anoxaemia.
For example, data on unoperated patients who were enrolled in the 5,500patient ISUIA (International Study of Unruptured Intracranial Aneurysms) suggest that smaller aneurysms located in the anterior circulation of the circle of Willis and the cavernous segment of the internal carotid artery are quite unlikely to hemorrhage when they are followed conservatively for 5 years.
In other words, if the vessels are occluded in the neck compensation occurs through the circle of Willis, but if the occlusion occurs distal to the circle of Willis the collateralisation is extremely poor.
On imaging with four-vessel angiography and computed brain tomography, a bullet was noted in the right internal carotid artery with no distal flow, the circle of Willis was patent, and a right fronto-parietal infarct was seen on the brain scan (Figs 1 and 2).