The Unusual Journey of Blood in the Brain

Meet John, a 54-year-old man who had a special map of his brain's blood vessels made. This map, called a computed tomography angiogram (CTA), showed something unique. John's left posterior cerebral artery (PCA) wasn't just getting blood from the vertebrobasilar system, like most people. It also had a link to the internal carotid artery (ICA). This connection was made through a vessel called the posterior communicating artery (PComA), which started 7 mm away from where the PCA normally begins. Even more interesting, there was an extra vessel that branched off the ICA, 4. 2 mm away from the PComA's start. This extra vessel was called an accessory posterior cerebral artery (APCA), which is like a super-powered version of the anterior choroidal artery (AChA).Why is this important? Well, the brain's blood supply is like a network of highways. Normally, the PCA's territory gets blood from either the ICA or the vertebrobasilar system, but not both. John's brain had a unique highway system where these two major roads connected. This isn't too common, making John's brain a special case study. Understanding these kinds of variations can help doctors better understand how blood flows through different brains, which can be crucial in treating conditions like strokes.