Two-Territory Stroke as a Result of Internal Carotid Artery Stenosis and Fetal Posterior Cerebral Artery: A Didactic Paradigm.

A complete configuration of the circle of Willis is not always present, and anatomical variations are observed often. The fetal posterior cerebral artery has been described in cases where the embryonic posterior communicating artery has failed to regress, something that may happen on the right side, the left side, or bilaterally. We describe a case of a male patient with bilateral posterior cerebral arteries with direct communication with the internal carotid artery on both sides who presented with symptoms of stroke allocated to both posterior and middle cerebral artery areas. In our knowledge, although there are several reported cases of occipital infarction from internal carotid artery disease, this is the first case of simultaneous infarction in the territories of the posterior cerebral and middle cerebral arteries due to internal carotid artery disease.