Evaluation of the groove for vertebral artery using CT angiography

Objectives: Groove for vertebral artery (sulcus arteriae vertebralis) is located on the posterior arch of the first cervical vertebra (atlas) where the vertebral artery passes over to reach the foramen magnum. The bony process between the posterior arch and the superior articulating process of the atlas is a common variation usually detected by lateral radiographies. This bony bridge is most commonly named as the ponticulus posticus. The aim of this study was to evaluate the existence of the ponticulus posticus and morphological features of the groove for vertebral artery. Methods: We performed a retrospective analysis of the groove for vertebral artery from 347 head and neck CT angiographies (694 bilaterally) at the Department of Radiology, Hacettepe University School of Medicine. Results: Complete ponticulus posticus incidence was found to be 12.1%, and 27.38% of these were bilateral. Post-sulcus arterial dimensions were found to be narrower than the pre-sulcus dimensions of the vertebral artery if the ponticulus posticus was incomplete. Conclusion: The groove for vertebral artery is a commonly studied variation among different nations and using different methods like lateral dental graphies, cadaveric studies and dry skulls. This study will be a guide for clinical problems like headache, vascular diseases and surgical interventions of the atlas in a very large patient population and using CT angiography, a sensitive method for visualizing this area.