EJMS

Abstract

Introduction: It is very important to detect variations of the third part of the vertebral artery and its groove over the atlas vertebra using CT angiography to avoid its injury during operations. Aim of the work: The aim of the present work was to study the curve measurements of the third part of the vertebral artery over the posterior arch of atlas vertebra and detection of its vascular variations using CT angiography. Material & Methods: This study was carried out on twenty adult patients obtained from Department of Radiodiagnosis, Faculty of Medicine, Alexandria University after taken their consent. They were evaluated by cranio-cervical CT angiography for other causes rather than vertebral artery abnormalities. They were subjected to different measurements of the curve of the third part of the vertebral artery over the posterior arch of atlas including its size, height, width and its distance from the mastoid tip. Also we compared the size of the vertebral artery in relation to foramen transversarium. Results: It was found that the mean diameter of curve of the third part of vertebral artery was 4.6 ± 0.59 mm on the right side and 4.4 ± 0.75 mm on the left side. The mean width of its curve was 14.65 ± 2.05 on the right side and 12.8 mm ± 1.79 mm on the left side. The mean height of the curve was 17.4 ± 1.9 mm on the right and 16.35 ± 2.08 mm on the left. The mean distance between the curve and the mastoid tip was 17.4 ± 2.5 mm on the right side and 16.65 ± 1.78 mm on the left side. The mean ratio of the size of the foramen transversarium and vertebral artery was 1.97 ± 0.35 % on the right side and 1.78 ± 0.27% on the left side. In all the studied cases, no abnormal branches or courses were observed. In one out of the twenty cases (5%), the vertebral artery groove was transformed into complete foramen. Left vertebral artery was found to be dominant over the right vertebral artery in 5% of the studied cases Conclusion: It was concluded that before any cranio-vertebral intervention, careful CT imaging of the third part of the vertebral artery is very helpful to avoid its injury during operations.