Abnormal circle of Willis morphology

What it means

An anomaly of the circle of Willis, also known as the cerebral arterial circle.

The circle of Willis is a circulatory anastomosis in the brain comprised of the anterior cerebral arteries, the anterior communicating artery, the internal carotid arteries, the posterior cerebral arteries, and the posterior communicating arteries.

Rare diseases that can present with this1

The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.

Part of the broader category

Also called: Abnormality of the cerebral arterial circle