The V2 segment of the vertebral artery in anterior and anterolateral cervical spinal surgery: A cadaver angiographic study

Abstract

Objective The second segment of the vertebral artery is under the risk of injury during anterior and anterolateral cervical spine procedures. To avoid such a risk, one needs to be familiar with the regional anatomy. The aim of this study was to measure the distance between the vertebral artery and the uncinate process, midline, and the medial side of the longus colli muscle using vertebral artery angiograms at the level of C6, C5, C4, and C3 vertebrae. Materials and methods In 12 human cadavers, the vertebral arteries were first irrigated with water. Then the arteries were filled with silicon and barium, and finally their angiographic images were obtained. Results The transverse diameter of the vertebral artery was measured at C6, C5, C4, C3, and C2 level. The values on the left were bigger than the values on the right ( p > 0.05). The distance between the vertebral artery and the midline decreased from C6 (17.2 ± 5.6 mm on the right, 17.2 ± 2.3 mm on the left) to C3 (15.8 ± 5.3 mm on the right, 13.8 ± 2.1 mm on the left) ( p > 0.05). The distance between the apex of the uncinate process and the medial side of the vertebral artery was found to be longer at C4 (2.7 ± 1.0 mm on the right, 2.2 ± 1.0 mm on the left) and C5 (2.5 ± 1.1 mm on the right, 2.5 ± 1.0 mm on the left) vertebra levels on the right side ( p = 0.339 at C4, p = 0.862 at C5). The distance between the medial side of the longus colli muscle and the medial side of the vertebral artery was measured as 9.7 ± 2.7 mm (9.5 ± 2.9 mm on the right, 9.8 ± 2.6 mm on the left) at C6 level, 9.2 ± 2.6 mm (8.6 ± 2.4 mm on the right, 9.8 ± 3.1 mm on the left) at C5, 9.4 ± 1.9 mm (9.2 ± 2.1 mm on the right, 9.5 ± 2.0 mm on the left) at C4, and 10.4 ± 2.7 mm (10.5 ± 3.0 mm on the right, 10.1 ± 2.6 mm on the left) at C3 vertebra level. No significant difference was found between the right and the left ( p > 0.05). The angle between the vertebral artery and the midline was measured as 4.0 ± 1.9° on the right and 2.2 ± 1.4° on the left side ( p = 0.030). Conclusion It was considered that the values obtained could be useful in anterolateral and anterior cervical approaches in terms of evaluating the position of the vertebral artery and its relation to vertebral structures. It is also concluded that the risk of injury in upper subaxial cervical spine is higher than in the lower part of the subaxial cervical spine.