Unusual anatomical variations of cervical and cranial arteries with surgical interest: case report.

We report an exceptional case of a large right persistent proatlantal artery (PPPA), defined as a "mixed" type, because it originated as in Type 2 from the external carotid artery and courses as in Type1, i.e. over the vertebral artery groove of the posterior arch of C1, entering the skull via the foramen magnum, without passing through the transverse foramen of any of the cervical vertebra. This "mixed" PPPA was associated first with an azygos anterior cerebral artery and second with a left common carotid artery arising from the brachiocephalic trunk. The right occipital artery arose from the PPPA. In addition, an aneurysm arose from the kinked right cervical internal carotid artery. This case illustrated an association not reported previously, making treatment of the concomitant aneurysm challenging. Moreover, understanding of persistent carotid-vertebral anastomosis is essential to enable evaluation and management before performing endovascular treatment, especially in cases of basilar thrombectomy and for posterior circulation strokes.