50293/92         ANOMALOUS CIRCLE OF WILLIS

The patient was an 81 year old woman with a history of hypertension and an old right sided cerebrovascular accident. She died following an acute myocardial infarction with left ventricular rupture and pericardial tamponade.

The specimen shows the circle of Willis, which has been dissected off the base of the brain. The basal vessels display the following anomalies:

1.         Duplication of the anterior communicating artery.

2.         The presence of an anomalous third anterior cerebral artery (central median artery of the corpus callosum).

3.         Asymmetry of the posterior communicating and posterior cerebral arteries. The left posterior cerebral artery is supplied almost exclusively by the left internal carotid artery, while the right posterior cerebral artery takes origin from the vertebro-basilar system.