Bilateral persistent hypoglossal arteries: MRI findings

Abstract

Persistence of foetal anastomoses between carotid and vertebrobasilar arteries is well recognised, but their bilateral presence is rare. We report a case of bilateral persistent hypoglossal arteries. Absence of bilateral vertebral arteries was incidentally noted on neck ultrasound examination. Subsequent MRI confirmed this and revealed persistent hypoglossal arteries that arose bilaterally from the cervical internal carotid artery, entered the cranium through the hypoglossal canal and joined the lower portion of the basilar artery.

Figure 1

(a) Right posterior oblique view of three-dimensional time-of-flight (3D-TOF) MR angiography in the supra-aortic region (repetition time (TR)/time to echo (TE) = 25/3.2, 20° flip angle) demonstrates anomalous arteries arising from cervical segment of the internal carotid artery at the C3 vertebral level on the right-side and the C1–2 level on the left (arrows). The bilateral vertebral arteries were absent from their origin. (b) Coronal and (c) axial reformatted views of 2 slab 3D-TOF MR angiography in the brain (TR/TE=25/5.4, 15° flip angle). In the coronal view, the anomalous arteries (arrows) apparently followed the normal course of the vertebral artery and joined the lower portion of the basilar artery. In the axial view, the arteries arose from the cervical segment of the internal carotid artery (arrows) took an abnormal dorsal course and entered the cranium before joining the basilar artery. (d) Constructive interference in steady state image (TR/TE=5.6/2.8, 37° flip angle) clearly shows that the anomalous arteries entered the cranium through the hypoglossal canal on both sides. (e) Persistent foetal carotid-vertebrobasilar anastomoses are shown. The trigeminal, otic and hypoglossal arteries run with the corresponding cranial nerves. The proatlantal artery runs most proximal. The hypoglossal and proatlantal arteries take similar courses. ICA, internal carotid artery; P-com, posterior communicating artery.