- The persistent trigeminal artery arises from the proximal cavernous segement of the internal carotid artery and runs dorsally toward the basilar atery. It may course with the trigeminal nerve root. It often joins the basilar artery between the origins of the AICAs and the SCAs.
This patient had a CT angiogram performed for stroke symptoms and was found to have severe stenosis and probable occlusion of the left ICA. However, there was an incidental finding of an abnormal arterial connection between the right ICA and the basilar artery.
Carotid artery to vertebrobasilar artery anastomses are usually incidental findings. They represent anomalous persistent fetal anastomoses between the carotid and vertebrobasilar arterial systems that otherwise normally regress during fetal development.
Although rare, the most common of these anastomses are the trigeminal artery, then less commonly the hypoglossal artery and the proatlantal intersegmental artery, and very rarely the otic artery.