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Medicine

Anatomical Variants of the Circle of Willis and Stroke Risk

Quick fact

A well-developed circle of Willis can prevent stroke even when one of the main arteries is completely blocked, but a missing or severely narrowed segment (hypoplasia) can turn a silent blockage into a devastating stroke.

Why this is interesting

What if the 'safety net' at the base of your brain isn't as complete as you think? Up to 70% of people have some variation in the circle of Willis, which could alter their risk of stroke.