Bilateral congenital absence of the internal carotid artery with a primitive transmaxillary arterial anastomosis.

We report a case of congenital, bilateral absence of the internal carotid artery accompanied by a complex anastomotic plexus arising from the right maxillary artery, a terminal branch of the external carotid artery. We present the clinical features and the radiological diagnostic evidence which consisted of ultrasonography, brain CT and MRI, conventional angiography and skull base CT scan. We review the literature pertaining to this congenital anomaly and correlate embryology of the carotid arteries to this unusual type of collateral circulation.