Internal Carotid Artery Dissecting Aneurysm Associated with Persistent Trigeminal Artery: A Case Report.

Background: Persistent trigeminal artery (PTA) is the most common vascular anastomosis between the carotid artery and vertebrobasilar systems. We report a very rare case of dissecting aneurysm in the right internal carotid artery (ICA) with ipsilateral PTA and discuss its clinical importance.

Case Report: A 38-year-old male presented to the emergency department with paroxysmal dysphasia for 6h. Brain magnetic resonance (MR) imaging showed acute cerebral infarction of the right corona radiata and right parietal lobe. Three-dimensional time-of-flight MR angiography (3D TOF MRA) revealed severe stenosis of the petrous segment (C1 portion) of the right internal carotid artery and a PTA originating from the right ICA cavernous segment (C4 portion), with a length of approximately 1.8cm and a diameter of approximately 0.2cm. The ICA segments are all named according to the Bouthilier classification. The basilar artery (BA) under union was well developed. The bilateral posterior communicating arteries were also present. One day later, the high-resolution vessel-wall MR demonstrated a dissecting aneurysm in the C1 portion of the right ICA. The length of the dissecting aneurysm is approximately 4.4cm, the diameter of the true lumen at the most severe stenosis is approximately 0.2cm, and the diameter of the false lumen is approximately 0.8cm. Subsequent digital subtraction angiography (DSA) confirmed a dissecting aneurysm in the C1 portion of the right ICA. The patient was treated conservatively and did not undergo interventional surgery. Four months later, head and neck MRA showed that the right ICA blood flow was smooth and that the dissecting aneurysm had disappeared. The Ethics Committee of Liaocheng People's Hospital approved the research protocol in compliance with the Helsinki Declaration. Written informed consent was obtained from the individual for the publication of any potentially identifiable images or data included in this article.

Conclusion: Flow alteration with PTA may have influenced the formation of ICA dissection in this patient. Awareness of this is crucial in clinical practice because it can influence treatment options and intervention procedures.