Persistent primitive trigeminal artery

Last revised by Craig Hacking on 19 Feb 2024

Persistent primitive trigeminal artery (PPTA) is the most common type of the four persistent carotid-vertebrobasilar anastomoses. It is present in 0.1-0.6% of cerebral angiograms and is usually unilateral.

In utero, the trigeminal artery supplies the basilar artery before the development of the posterior communicating and vertebral arteries. The PPTA arises from the junction between petrous and cavernous segments of the internal carotid artery, 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 are 3 types of PPTA 5:

  • Saltzman type I: PPTA supplies the distal vertebrobasilar arteries. The posterior communicating artery is absent and the caudal basilar is absent or hypoplastic with hypoplastic distal vertebral arteries.

  • Saltzman type II: PPTA supplies the superior cerebellar arteries with the posterior cerebral arteries supplied by the posterior communicating artery

  • Saltzman type III: PPTA does not join the basilar artery, instead directly terminating as the

    • type IIIa: superior cerebellar artery

    • type IIIb: anterior inferior cerebellar artery

    • type IIIc: posterior inferior cerebellar artery

A characteristic tau sign 4 or trident sign is described as its appearance on sagittal CTA or MRA/MRI.

There is an association with intracranial aneurysms and vascular malformations.

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Cases and figures

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  • Case 2
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  • Case 3 : showing "tau" sign
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  • Case 12: type II
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