Introduction Carotid-Basilar Anastomoses were original described in London in 1844 by Quain’s. They are named using the cranial nerves and there are different persistent fetal anastomoses between the carotid and basilar artery including the primitive trigeminal, otic (acoustic), hypoglossal, and pro-atlantal intersegment arteries.
Persistent trigeminal artery (PTA) is an anatomic anomaly that result of failure the trigeminal artery to regress. PTA is the most common of these that persist into adulthood. Uchino et al, reported an incidence of 0.76% in a study done with MR angiographic.Luh et al, described in 1999, these fetal anastomoses emerge at the 4 to 5 mm embryonic stage, persist for approximately one week, and regress by the time of posterior communicating and vertebral arteries develop. The first to disappear is the optic artery, followed by the hypoglossal artery, the trigeminal artery, and then the pro-atlantal intersegmental artery.
We present a patient in whom a variant of PTA aneurysm was incidentally found terminating in the superior cerebellar artery (SCA), Saltzman classification type IIIa.
Methods A review of the medical literature using standard search engines was performed to locate articles regarding Carotid-Basilar anastomoses focusing in anatomic variants of the persistent trigeminal artery.
Results 61-year-old female who presented with quadriparesis after traumatic cervical spinal cord C4-C5 compression; requiring anterior cervical discectomy and fusion. During pre-operatory work up, she was found to have a posterior circulation aneurysm in CT angiogram. Patient had a digital subtraction angiography (DSA) that showed a persistent trigeminal artery mid segment aneurysm 5.7 mm x 5.5 mm in the dominant hemispheric branch and terminate in the SCA territory (Saltzman classification IIIa). After a DSA patient is schedule for endovascular treatment.
Conclusion Persistent trigeminal artery is one of the remnant fetal anastomoses that connect the cavernous segment of carotid artery to the basilar artery. PTA are classified according to angiography by Saltzman in 1959, he reviewed previous reports of PTA along with presenting eight cases and made an angiographic classification dividing in 3 groups. In addition, aneurysms of the PTA are extremely rare in the literature with previous cases reported. This case is unique because there is not report with a 3D rotational DSA of variant PTA aneurysm terminating in the SCA, Saltzman classification type IIIa.
Disclosures A. Ravelo: None. R. Williamson: None.
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