ABSTRACT
Vertebral artery (VA) variations are important for diagnostic angiographic procedures. This study aimed to describe the anatomical variations of VA using multidetector computed tomography angiography (MDCTA), and to provide a quantitative and qualitative anatomy of the VA groove in dry atlas vertebrae. The study was carried out on 100 MDCTA images from adult Egyptian individuals (69 males; 31 females) and 50 dry atlas fully ossified and of unknown age and sex. MDCTA films were evaluated for VA origin, level of entrance into foramen transversarium, caliber, and distance from the midline. VA grooves in dry bones were examined for the presence of ponticulus posticus (PP). Inner and outer distances from the midline, width and thickness were measured using sliding Vernier caliper. The results revealed that the left VA arose directly from the aortic arch in 7% of cases and was absent in 2% of cases. Atypical entry of VA into foramen transversarium was through C5 (4.5%), followed by C7 (1.5%), then C4 (1%). The left vertebral arteries with direct aortic origin were more medially located than the left arteries with subclavian origin (p=0.005). The mean diameter was significantly greater on the left (3.67±1.07 mm), as compared to the right side (3.36±0.93 mm) (p=0.038). PP was detected in 47% of cases in radiological images and 96% of dry bones. It could be concluded that the most important variations of VA were the aortic origin of the left VA and abnormal entry through transverse foramina. PP was a common variation in atlas vertebrae. These variations should be taken into consideration during radiological and orthopedic procedures
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