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Internal Carotid Artery Bifurcation Aneurysm

Last Updated: September 28, 2018

Clip Ligation of an ICA Bifurcation Aneurysm

Aneurysms at the bifurcation of the internal carotid artery (ICA) are uncommon lesions, accounting for approximately 5-10% of intracranial aneurysms. They frequently occur in conjunction with other aneurysms on the ipsilateral ICA, and appear to be more prevalent among the pediatric population. The hemodynamic stress at the ICA bifurcation, like the one at the basilar bifurcation, leads to aneurysm formation.

The middle cerebral artery (MCA) and ICA are the vessels most likely to harbor mirror aneurysms. These aneurysms occur in 5-10% of patients with single aneurysms and in 36% of patients with multiple aneurysms. Notably, mirror aneurysms are more likely to rupture and tend to rupture earlier in life.

Rupture of an ICA bifurcation aneurysm causes subarachnoid hemorrhage (SAH) and may even cause intracerebral hemorrhage (ICH) in the inferior frontal lobe, basal ganglia, or medial temporal lobe. Most ICA bifurcation aneurysms point superiorly and slightly posteriorly.

Preservation of the medial and posterior perforators arising from the medial borders of the A1, ICA bifurcation, anter...