A CT scan demonstrated a subarachnoid hemorrhage. A followup four-vessel cerebral angiogram demonstrated bilateral anomalous ACAs, with the origin at the level of the ophthalmic artery proximal to the posterior communicating and anterior choroidal arteries. The proximal portion of each ectopic proximal segment was horizontal , suggesting that both ACAs coursed below the optic nerves (Figs . 1 A...

A 52-year-old man presented with an anterior communicating artery aneurysm associated with splitting, penetration, and visual symptoms of the optic nerve and manifesting as sudden onset of severe headache. Angiography disclosed a 10-mm anterior communicating artery aneurysm projecting supero-posteriorly, and operative findings revealed unexpected splitting of the optic nerve. Moreover, the opti...

Advances in imaging techniques allow for in vivo identification of abnormalities and normal variants of cerebral arteries. These arterial variations can be asymptomatic and uncomplicated although, some of them increase the risk of aneurysm formation, acute intracranial hemorrhage, play a vital role in neurosurgical planning or can be misidentified as serious pathology and medical errors. The go...

A case of a congenital solitary internal carotid artery with complicated anastomosis is presented. This rare anomaly was an incidental finding at cerebral angiography in a patient with a poor-grade subarachnoid hemorrhage and a ruptured anterior communicating artery aneurysm.

We present two cases of subarachnoid hemorrhage caused by aneurysm development and enlargement in the anterior communicating artery complex. The cases occurred in a series of 58 balloon occlusions for unclippable giant aneurysms of the internal carotid artery.

Anterior cerebral artery is the smaller terminal branch of the internal carotid artery. It is one of the arteries involved in the formation of the arterial circle of Willis at the base of the brain. Its hypoplasia or absence can cause serious problems during neurosurgery or in the vascular dynamics of the brain. We found a rare variation of the right anterior cerebral artery during the dissecti...

The Hemodynamic Importance of the Geometry of Bifurcations in the Circle of Willis (Glass Model Studies) • The critical Reynolds number, Rec, at which turbulence developed in glass model bifurcations was measured with an Evans blue indicator for bifurcations with a branch/trunk area ratio of unity, and bifurcation angles of 45°, 90°, 135°, and 180°. The Rec dropped from 2,500 in a straight tube...

Agenesis of the internal carotid artery associated with an anomalous middle cerebral artery originating from the contralateral internal carotid artery is rare. We report a patient with agenesis of the internal carotid artery presented with a subarachnoid hemorrhage due to a rupture of an aneurysm in the anterior communicating artery.

BACKGROUND AND PURPOSE Several recent prospective studies have found that unruptured intracranial aneurysms at various anatomic locations have different propensities for future rupture. This study aims to uncover the lack of understanding regarding rupture-prone characteristics, such as morphology and hemodynamic factors, associated with different intracranial aneurysm location. MATERIALS AND...