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Trigeminal Artery

Summary

  • Persistent trigeminal artery (PTA) is the most common persistent carotid-basilar anastomosis
  • Embryonic connection between the cavernous portion of the internal carotid artery and the basilar artery
  • Usually asymptomatic but can be associated with various neurological symptoms and vascular anomalies1

Embryology

  • The trigeminal artery develops around the 3rd week of gestation
  • It normally regresses by the 7th-8th week of gestation
  • A persistent trigeminal artery results when the artery fails to regress and remains patent

Anatomy

  • Connects the cavernous segment of the internal carotid artery to the basilar artery
  • Two main types:
    • Lateral (petrosal) variant: more common; courses lateral to the dorsum sellae
    • Medial (sphenoidal) variant: less common; courses medial to the dorsum sellae
  • Associated vascular anatomy:
    • Hypoplasia of the basilar artery proximal to the PTA junction
    • Absence or hypoplasia of the posterior communicating arteries

Imaging

  • Angiography (DSA, CTA or MRA):
    • Gold standard for diagnosis
    • Demonstrates direct connection between internal carotid artery and basilar artery
  • CT:
    • May show a rounded or tubular structure in the prepontine cistern
    • Calcifications may be present
  • MRI:
    • T1 and T2-weighted images: Flow void in the prepontine cistern
    • MRA: Clearly demonstrates the persistent trigeminal artery

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  • Incidental finding of a trigeminal artery (red arrow) forming an anastomosis between the cavernous ICA and the basilar artery (blue arrow).

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  • Incidental finding of an anastomosis between the cavernous left ICA and the posterior circulation (red arrow).
  • The vertebrobasilar system was hypoplastic.

Clinical Relevance

  • Found in 0.1-0.6% of cerebral angiograms, usually as an incidental finding in adults
  • No treatment is required for the variant itself
  • Recognition matters because it alters posterior circulation haemodynamics and is associated with aneurysms
  • Usually asymptomatic, but reported associations include:
    • Trigeminal neuralgia
    • Oculomotor palsy
    • Abducens nerve palsy
    • Cerebrovascular insufficiency

Differential diagnosis

Differential Diagnosis Differentiating Feature
Persistent Hypoglossal Artery Arises from cervical internal carotid artery and enters skull through hypoglossal canal
Persistent Proatlantal Artery Connects vertebral artery to external carotid artery
Persistent Otic Artery Passes through internal acoustic meatus
Aberrant Internal Carotid Artery Courses through middle ear cavity
Basilar Artery Fenestration Involves duplication of a segment of the basilar artery
Arteriovenous Malformation Abnormal tangle of blood vessels with direct arterial-venous shunting
Aneurysm Focal dilatation of an artery, typically saccular or fusiform in shape
Cavernous Sinus Fistula Abnormal communication between carotid artery and cavernous sinus
Moyamoya Disease Progressive stenosis of distal internal carotid arteries with collateral vessel formation
Basilar Artery Hypoplasia Underdevelopment of the basilar artery, often associated with persistent fetal circulation

  1. Vasović et al. Trigeminal artery: a review of normal and pathological features. 2012. Child's nervous system : ChNS : official journal of the International Society for Pediatric Neurosurgery - Open in new tab. ↩