The persistent trigeminal artery: development, imaging anatomy, variants, and associated vascular pathologies

The persistent trigeminal artery (PTA) is the most common and most cephalad-located embryological anastomosis between the developing carotid artery and vertebrobasilar system to persist into adulthood. As such, it is frequently reported as an incidental finding in computed tomography angiography and magnetic resonance angiography studies. Here, we review the embryology, anatomy, and angiographic imaging findings, including important variants of this commonly encountered cerebrovascular anomaly (reported incidence of PTA/PTA variants ranges from 0.1% to 0.76%). Further, the aim is to present the range of associated arterial anomalies or syndromes, as well as pathologies that are associated with a PTA: aneurysms, trigeminal cavernous fistulas, and trigeminal nerve compression. Besides summarizing the risks and clinical presentation of such pathologies, their management is discussed with endovascular strategies mostly being the primary choice for aneurysms and trigeminal cavernous fistulas. Symptomatic trigeminal nerve compression can be treated with microvascular decompression surgery. As an illustrative example, a case of a trigeminal cavernous fistula on a PTA variant is included, mainly to emphasize the importance of understanding the variant anatomy for treatment planning in such pathologies. Finally, recommendations on how to manage patients with PTA-associated vascular pathologies are advanced.