Congenital absence of the right common carotid artery, internal carotid artery and external carotid artery associated with anterior communicating artery aneurysm: a rare case.

Congenital absence of the common carotid artery (CCA), internal carotid artery (ICA) and external carotid artery (ECA) is very rare. We present such a rare case in a 53-year-old woman, associated with a saccular aneurysm of anterior communicating artery (ACA) presenting with subarachnoid haemorrhage (SAH). An embryological hypothesis for the anomalies of the aortic arch is proposed. The correlation between the abnormal haemodynamic stress of the circle of Willis caused by the absence of the right ICA and the development of intracranial aneurysm is discussed.