What is the most common anomaly of the Circle of Willis?

The most common anomaly of the Circle of Willis is the absence or hypoplasia of one or both communicating arteries. The Circle of Willis is a critical network of arteries located at the base of the brain that provides collateral circulation. Variations in its anatomy are common, but the absence or reduced size (hypoplasia) of the communicating arteries is particularly prevalent.

This absence can significantly influence blood flow dynamics in the brain, potentially leading to diverse clinical implications, especially in cases of ischemia or stroke, where collateral circulation becomes crucial. Understanding this anomaly is vital for vascular technologists and other healthcare professionals who deal with cerebrovascular conditions, as it can create challenges in treatment and diagnostic approaches.

In contrast, the other options, such as the presence of multiple communicating arteries, double anterior cerebral arteries, and enlargement of the basilar artery, are less common and may not have the same clinical significance in terms of overall frequency in the population.