Radiologic examination of high riding vertebral artery and analysis of secure areas

OBJECTIVE:To radiologically examine the pedicle, lamina, and vertebral artery foraminal anatomies at the C2 vertebra for pedicular and laminar screw instrumentation at the axis in a Turkish population. MATERIALS AND METHODS:From 2018 to 2019, we evaluated 100 patients who underwent cervical computed tomography (CT) for various reasons (excluding cervical pathologies) at Marmara University Hospital. The C2 pedicles were measured on CT images using measurement tools. In addition, axial computed tomography was performed at 0.1-mm intervals. Bilateral measurements were performed for each case. RESULTS:The median right and left pedicle axial diameters were respectively 5.01 and 5.09 mm for the male patients and 4.31 and 4.38 mm for the female patients, showing a statistically significant difference between the sexes (p < 0.01). Of the patients, 15% had narrow pedicles. The pedicle sagittal diameters were smaller than 5 mm in 30% of the computed tomographic series. The internal height was <2 mm in 4% of the cases. CONCLUSION:Our findings suggest significant individual and sex-related differences. Vertebral artery groove anomalies are commonly observed. Before performing a posterior craniocervical instrumentation surgery, a CT examination is beneficial because high-riding vertebral arteries must be kept in mind in determining the appropriate screw diameter and screw trajectory.