Imaging Sciences Interesting Cases
Case 78
Trushar Sarang, MD
Clinical Presentation: A 56-year-old female presented for preoperative evaluation of a right cerebral middle cerebral artery (MCA) aneurysm.
Imaging Findings: A large artery arising from the cavernous internal carotid artery (ICA), coursing posterior to the sella, supplying the basilar artery.
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| Figure 1. Axial CT angiography (CTA) demonstrates a large vessel arising from the cavernous (ICA) and coursing posteriorly to the basilar artery. |
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| Figure 2. Sagittal CTA demonstrates a large artery coursing posteriorly from the ICA. |
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| Figure 3. Coronal CTA projection demonstrates a large left trigeminal artery supplying the basilar artery with a hypoplastic proximal basilar artery. |
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| Figure 4. CTA surface reconstruction demonstrates a large vessel arising from the ICA and coursing to the basilar artery. |
Diagnosis: Persistent Trigeminal Artery
Discussion: A persistent trigeminal artery is the most common congenital persistent arterial connection between the anterior and posterior circulations of the brain. The trigeminal artery connects the cavernous portion of the internal carotid artery to the basilar artery. The basilar artery below the anastomosis is usually hypoplastic, as seen in this case. In normal embryolic development the trigeminal artery regresses as brain vasculature matures. When it does not, the persistent trigeminal artery results. The incidence is 0.1-0.2% of cerebral angiograms. Other vascular anomalies are present in 25% and include most commonly aneurysms, and less commonly carotid-cavernous fistulas, arteriovenous malformations (AVMs), arterial fenestrations, and neurofibromatosis type 1 (NF-1). In this particular case, the patient had a known right M1 bifurcation aneurysm.
Clinical presentation is most often asymptomatic, usually an incidental finding on imaging. Rarely this anomaly may cause trigeminal neuralgia or pituitary dysfunction. Associated anomalies usually are the cause for presentation, such as subarachnoid hemorrhage from an aneurysm.
The other rarer persistent congenital arteries between the anterior and posterior circulations are the persistent hypoglossal artery, otic artery, and proatlantal intersegmental artery.
References:
- Osborn AG, Blaser SI, Salzman KL, et al. Diagnostic Imaging: Brain, 1st ed., Amirsys; 2004.
- Grossman R, Yousem D. Neuroradiology: the requisites, 2nd ed. St. Louis, MO: Mosby; 2003