Digital subtraction angiogram of the internal carotid artery, lateral view, demonstrates a large tortuous vessel (arrow) passing from the internal carotid artery (open arrow) to the basilar artery (arrowhead), and supplying the posterior circulation.
Case Discussion
This anomaly, persistent primitive trigeminal artery, is present in 0.1% to 0.6% of cerebral angiograms and is usually unilateral. In utero, the trigeminal artery supplies the basilar artery before development of the posterior communicating and vertebral arteries.
A PTA arises from the junction between petrous and cavernous ICA, and runs posterolaterally along the trigeminal nerve (41%), or crosses over or through the dorsum sellae (59%). Vertebral, posterior communicating and caudal basilar arteries are often hypoplastic.
There is an association with intracranial aneurysms and vascular malformations.
Credits Dr Jason Wenderoth
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