The circle of Willis was originally described in 1664 [1]. The circle of Willis is a structure receiving arterial blood supply from the internal carotid and basilar arteries. The circle allows for the equalization of blood flow between cerebral hemispheres allowing for anastomotic circulation [2, 3]. The circle of Willis then divides into 3 paired vascular divisions: anterior, middle and poster...

We present a rare case of agenesis of the left internal carotid artery in a 43-year old woman, associated with an aneurysm of the anterior communicating artery and presenting with subarachnoid hemorrhage. The left internal carotid artery was not visualized on the left carotid angiogram. The left middle cerebral artery was perfused from the basilar artery via the dilated posterior communicating ...

Branchio-oto-dysplasia is characterized by abnormalities of embryonic branchial arch system and deafness inherited as autosomal dominant with variable gene expression. We present a rare case of multiple intracranial aneurysms associated with branchio-oto-dysplasia. A 40-yr-old man with severe headache presented as spontaneous subarachnoid hemorrhage on brain computed tomographic scan. The patie...

Circle of Willis (CoW) plays a significant role in maintaining the blood supply for the brain. Specifically, when the stenosis occurs in the internal carotid artery (ICA), abnormal structures of CoW would decrease the compensatory capacity, leading to the local insufficiency of cerebral blood supply. The present paper built a series of lumped parameter models for CoW, and simulated the blood re...