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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 anomalies

Pathophysiology

  • Embryologically, the trigeminal artery develops around the 3rd week of gestation
  • Normally regresses by the 7th-8th week of gestation
  • Persistence occurs when the artery fails to regress and remains patent
  • 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

Demographics

  • Incidence: 0.1-0.6% of cerebral angiograms
  • No significant gender predilection
  • Can be found in all age groups, but more commonly diagnosed in adults

Diagnosis

  • Often an incidental finding on imaging studies
  • Clinical presentation:
    • Usually asymptomatic
    • May present with:
    • Trigeminal neuralgia
    • Oculomotor palsy
    • Abducens nerve palsy
    • Cerebrovascular insufficiency

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
  • Associated findings:
    • Hypoplasia of the basilar artery proximal to the PTA junction
    • Absence or hypoplasia of the posterior communicating arteries

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

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

Treatment

  • Generally, no treatment required for asymptomatic cases
  • Management focuses on associated conditions:
    • Aneurysms: Endovascular coiling or surgical clipping
    • Trigeminal neuralgia: Medical management or microvascular decompression
    • Cerebrovascular insufficiency: Antiplatelet therapy or revascularization procedures
  • Endovascular treatment may be considered in symptomatic cases:
    • Occlusion of the PTA using detachable balloons or coils
    • Stent-assisted coiling for associated aneurysms

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