CT Measurement Of Transverse Foramen In The Prevention Of Vertebral Artery Injury In Anterior Vertebral Surgery

ObejectiveTo know the incidence of transverse foramen variability,and to provide reference for the anterior cervical spine surgery by measuring the track lines of the transverse foramen on CT images,so as to further emphasize the importance of preoperative conventional CT examination in the intraoperative vertebral artery injury prevention.MethodCT image data was collected in China Medical University First Affiliated Hospital,and China Medical University Shaoxing Hospital in 2007～2008.In accordance with the relationship between the outer edge of vertebral body and the inner edge of transverse foramen,the transverse foramen was divided into three types:the extra-vertebra type(Type A),the intermediate type(Type B) and the intra-vertebra type(Type C).The transverse diameter(line a),sagittal diameter(line b), the transverse foramen inner margin distance(line e),distance between the inner edge of the transverse foramen and the vertebral body midline(line d),distance between the inner edge of the transverse foramen and the outer edge of the vertebral body(line c),and the shortest distance between the inner edge of the transverse foramen and the spinal canal(line f) were measured on the CT images.All data was treated by statistical software spss12.0 to analyze the measurement.Result1.TypeA,typeB and typeC accounted for 83.34%,16.37%and 0.29%, respectively.There were two cases of transverse foramen intruding into the vertebral body apparently.2.Transverse foramen aperture diameters of the measurement results showed as following:at the left side line a was 0.68±0.19cm,with line b 0.56±0.18cm,line c 0.14±0.20cm,line d 1.30±0.28cm,and line f 0.48±0.18cm,respectively;at the right side line a was 0.65±0.17cm,with line b 0.53±0.17cm,line c 0.16±0.21cm,line d 1.28±0.30cm,line f 0.46±0.18cm;line e 2.57±0.18 cm,respectively.There was some lack of clarity in the measurement of line c so that it could not be completely measured.3.Statistical analysis of the results:mesurement of bilateral transverse foramen of the same vertebral body show that line b of C4 was left＞right,with C5 left＞right; mesurement of ipsilateral vertebral transverse foramen transverse diameter show that at the left side line a was C5＜C3,with the right side C5＜C4,C6＜C4,and at both sides the data of line b was C3＜C5,C3＜C6,C4＜C5,C4＜C6,and all the data of line d,e and f was C3＜C5＜C6,C4＜C5＜C6.All the differences were significant.Conclusion1.Of about 0.29%the inner edge of transverse foramen probably crossed the outer edge of the vertebral body;2.Except for C3,C4 vertebrae,the transverse foramen inner margin distance and the shortest distance between the inner edge of the transverse foramen and the spinal canal at C3～C6 vertebral body gradually increased;3.The pre-operative examinations should be carefully checked before doing anterior cervical spine surgery as to avoid intraoperative vertebral artery injury,and help guide the surgery.