Persistent proatlantal intersegmental artery: a consideration based on multi-slice spiral computed tomography angiography.

Background: Multi-slice spiral computed tomography (CT) angiography (MSCTA) has become the primary non-invasive image technique for evaluating cephalic and cervical vascular anatomy, especially vascular variant such as persistent carotid-basilar anastomosis. Persistent proatlantal intersegmental artery (PPIA) is an example of a rare persistent carotid-basilar anastomosis that deserves to be featured through this imaging technic.

Purpose: The aim of this study is to explore the imaging characteristics of the PPIA using MSCTA and to assess its clinical significance. Furthermore, the study seeks to propose a novel classification system predicated on the posterior circulation blood supply.

Materials And Methods: This retrospective analysis evaluated the imaging and clinical data of 11 patients diagnosed with a PPIA using MSCTA.

Results: The incidence of the PPIA was found to be 0.01%. Classification based on the origin of the PPIA identified two cases (18.2%) as type I and nine cases (81.8%) as type II. This study introduced a novel classification system for PPIA, which is based on the posterior circulation blood supply, encompassing the persistent artery, vertebral artery, and posterior communicating artery. Among the 11 patients with PPIA, there were 11 instances of ipsilateral vertebral artery agenesis, three cases of contralateral vertebral artery hypoplasia, one case of contralateral vertebral artery agenesis, two cases of persistent artery hypoplasia, and two cases of basilar artery hypoplasia. Furthermore, the study identified two patients with aneurysms, one with cerebral infarction, and one with a Pulmonary Arteriovenous Fistula.

Conclusion: The proposed classification system for PPIA enhances the understanding of posterior circulation blood supply, which is vital for pre-interventional and pre-surgical imaging assessments. In PPIA cases, the ipsilateral vertebral artery is consistently hypoplastic, and the PPIA predominantly serves the posterior fossa's vascularization in about 75% of cases.