Entrance and Origin of the Extracranial Vertebral Artery: CTA Findings

Entrance and Origin of the Extracranial Vertebral Artery: CTA Findings | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Article Entrance and Origin of the Extracranial Vertebral Artery: CTA Findings Xueting Yi, Ping Xie, Lianwei Zhang, Fengxia Lu, Hao Chen, Kefu Liu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1477797/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 10 You are reading this latest preprint version Abstract Objective To investigated morphological variability of VA origin and its entrance level into cervical transverse foramina by CTA. Methods To retrospectively investigated computed tomography angiograms (CTA) of 223 subjects (446 VA courses). Postprocessing of source images was performed by using a multi-planar reformation (MPR), maximum intensity projection (MIP), multi-planar reconstruction (MPR) and volume rendering (VR) algorithms. Investigated were origin of the VA and its level of entrance into vertebral transverse foramen with notification of the sex and side of variation. Results The VA entered the C6 transverse process in 92.60% of specimens (413 out of 446 VA courses, 64.57% males and 28.03% females). Abnormal entrance of VA was observed in 7.40% of specimens (33 VA courses), with the level of entrance into the C3, C4, C5, or C7 transverse foramen at 0.22%, 2.24%, 4.72% and 0.22% respectively. Comparably, we observed that the overall variability of abnormal origin of VA was 3.14% (7 out of 223 subjects), which LVAs all arose from aortic arch (AA). Comparing subgroups of subjects with normal and abnormal origin, there was significance difference in the frequency of entrance variation in the level of transverse foramen. Conclusion Abnormal entrance and origin of VA were observed in 7.40% and 3.14% of cases, which can be accurately appeared by CTA. Vertebral artery Variability Origin Entrance CTA Figures Figure 1 Figure 2 Figure 3 Figure 4 Entrance And Origin Of The Extracranial Vertebral Artery: Cta Findings The VA is a longitudinal anastomosis of segmental metameric arteries. The present study confirms the presence of anomalous entrance and origin of the extracranial VA. The possibility of an atypical course of the VA should be evaluated by additional advanced imaging such as CTA and ultrasonography to minimize risk of its injury during cervical spine surgery or diagnose vertebrobasilar symptoms where insufficient blood flow is caused by embryologic development. Introduction The anatomical variation of vertebral artery (VA) is essential to clinics and anatomy. Accurate understanding in the variations of vertebral artery are regarded as necessary with the development and popularization of endovascular interventions, anterior decompression of the cervical spine, neck dissection and stellate ganglion block. The anatomical variation of VA, including its origin and its level of entrance into transverse foramen, has been widely investigated, and even some general information has been published in standard atlas, textbooks and the Internet. 8 However, the recent significant findings indicated that the differences of VA variations among different regions raised the issue of potential regional, ethnic and even environmental factors. 9 Up to now, there is a lack of original data available for regions of China. Therefore, our current study investigated morphological variability of VA origin and its entrance level into cervical transverse foramina in population of Suzhou in China. Materials And Methods We retrospectively investigated computed tomography angiograms (CTA) of 223 subjects (446 VA courses) of both sexes (155males and 68 females) and of age between 27 and 88 years (Table 1 ). From the study the patients were excluded with previous or current cerebrovascular accidents, with the history of cervical injuries, atherosclerotic changes (affecting more than 50% of VA diameter), with severe spondylarthrosis. Data were collected and stored in accord to Helsinki Declaration10. The institutional review board of The Affiliated Suzhou Hospital of Nanjing Medical University (Suzhou, China) approved the present retrospective study and waived the requirement for informed consent. Table 1 Demographic data of investigated sample (223 subjects; 446 courses) Gender N X means of agea Standard deviationa Maximum agea Minimum agea Males 155 64.41 12.08 87 27 Females 68 67.79 11.12 88 40 Total 223 65.44 11.87 88 27 a Units are shown in years All imaging-generation and visualization measurements were performed in the Clinical Radiology Department, Affiliated Suzhou hospital of Nanjing Medical University (Suzhou, China). Patients were placed in a supine position with their arms alongside the body, head and neck kept at a neutral position. The imaging examination was performed on a Multi-slice computed tomography (CT) scanner (Philips Brilliance iCT Holland) with the scanning protocol as follows: 120kVp, 153mAs, beam collimation 128 × 0.625mm, gantry rotation time 0.5s, section thickness of 0.9 mm, pitch 0.758 and reconstruction interval of 0.45 mm. During the procedure, infused 50 mL of nonionic iodinated contrast was followed by 30 mL saline and injected via a double power injector into the patient’s antecubital vein (5 mL/s). Images were analyzed at a workstation (Intellispacsportal 9.0; Philips). The VA’s origin and level of entrance into vertebral transverse foramen were recorded, as well as the sex and side of variation. All the data was measured by 2 experienced radiologists with independent double-blind method, and a consensus was reached finally. Statistical analysis was performed using statistical package for the social sciences (SPSS) version 22.0 (IBM Corporation, Somers, NY, USA) statistical software. The data were expressed as means ± standard deviation (SD). The quantitative data were examined by Kolmogorov Smirnov test for normality. Independent “t” test was performed to compare the different variables regarding side. Chi-Square test and Fisher's exact test were used to determine if there was a significant relationship between different variables. p value < 0.05 was considered to be significant. Results Generally, the mean age of patients was 65 years, and the male-to-female ratio was 2.3:1 in the current study. (Table 1 ). In the current study, the VA entered the C6 transverse process in 92.60% of specimens (413 out of 446 VA courses, 64.57% males and 28.03% females). Abnormal entrance of VA was observed in 7.40% of specimens (33 VA courses), with the level of entrance into the C3, C4, C5, or C7 transverse foramen at 0.22%, 2.24%, 4.72% and 0.22% respectively (Table 2 , Fig. 1 –4). In male cases, there was non-significant statistical difference in the frequency of entrance variations of right VA(RVA) and left VA(LVA), nor in female cases. ( p = 0.576 and p = 0.206). Also, there was non-significant statistical difference in the frequency of entrance variations of RVA and LVA ( p = 0.205). Table 2 Origin and entrance into the transverse foramen of the VA in overall population (223 subjects; 446 courses) Entrance into the transverse foramen Total Sex Origin of right VA a Origin of left VA a Subclavian artery Aortic arch Subclavian artery Aortic arch III 1 (0.22%) M 0 0 0 0 F 0 0 0 1 (0.22%) IV 10 (2.24%) M 7 (1.57%) 0 0 0 F 3 (0.67% 0 0 0 V 21 (4.71%) M 7 (1.57%) 0 3 (0.67%) 4 (0.90%) F 2 (0.45%) 0 5 (1.12%) 0 VI 413 (92.6%) M 140 (31.39%) 0 146 (32.74%) 2 (0.45%) F 63 (14.13%) 0 62 (13.90%) 0 VII 1 (0.22%) M 1 (0.22%) 0 0 0 F 0 0 0 0 Total 446 (100.00%) M 155 (34.75%) 0 149 (33.41%) 6 (1.35%) F 68 (15.25%) 0 67 (15.02%) 1 (0.22%) a Percentage values are shown in parenthese of overall population Comparably, we observed that the overall variability of abnormal origin of VA was 3.14% (7 out of 223 subjects), which LVAs all arose from aortic arch (AA) (Fig. 1 ). Notably, seven subjects (6males and 1female) of the left VA originated from the aortic arch, where the variation rate of vertebral entrance rose up to 50% in corresponding subgroup. Among these anomalous entrance in patient with abnormal origin, one entered the transverse foramen at the level C3, one at level C4, five at level C5, respectively (Table 3 ).When comparing subgroups of subjects with normal and abnormal origin, there was significance difference in the frequency of entrance variation in the level of transverse foramen ( p = 1.5×10 − 5 <0.01). Specifically, the proportion of normal entrance level (C6 level) were statistically decreased and the proportion of higher entrance level (C3,4,5) were statistically increased in abnormal origin subjects when comparing to normal origin subjects, whereas no statistical difference was shown in the proportion of lower entrance level (Table 4 ). Interestingly, one specific case was found that a 43 years old woman whom left subclavian artery (SCA)arose from AA while left VA origin was normal (Fig. 2 ). Table 3 Entrance into the transverse foramen of the VA in subgroup with abnormal origin (7 subjects; 14 courses) Number Sex Age Origin of right VA Entrance of right VA Origin of left VA Entrance of left VA 1 M 69 RSA C6 AA C6 2 F 55 RSA C6 AA C3 3 M 82 RSA C6 AA C5 4 M 51 RSA C6 AA C5 5 M 56 RSA C5 AA C5 6 M 48 RSA C6 AA C6 7 M 54 RSA C4 AA C5 Table 4 Comparison between subgroups with abnormal VA origin and normal VA origin in the variability of entrance into the transverse foramen of the VA (223 subjects; 446 courses) Subgroup Total Entrance at normal level (C6) a Entrance at higher level (C3, C4, C5) a Entrance at lower level (C7) a Subjects with abnormal origin 14 (100%) 7 (50%) 7 (50%) 0 Subjects with normal origin 432 (100%) 406 (93.98%) 25 (5.79%) 1 (0.23%) a Percentage values are shown in parentheses of corresponding subgroup Discussion We could recognize the location of the entrance and origin of the VAs in all our cases due to high-quality CTA, which is a noninvasive and easy imaging technique and is very important for surgery. The entrance and origin of the VA is essential to neck tumor resection as vascular damage may occur when VA goes through the abnormal region, which is sometimes neglected by the surgeon. Additionally, the entrance of the vertebral artery is of significance to the stellate ganglion block. The block is commonly performed on the anterior tubercle of C6 transverse process. When the VA enters the foramen of the C5 transverse process or higher, exposing the VA between the cervical transverse processes, the VA is vulnerable to be located in the needle path. Unawareness of such an aberrant VA may cause life-threatening events. 11 The origin of the vertebral artery is also very important in the placement of the aortic arch stent during peripheral vascular intervention, otherwise could produce injury and local occlusion of the vertebral artery. 12 Literature shows the frequency of origin of the left VA from aortic arch in the range of about 1%-3%. 13 Our results indicated that the overall variability of origin of VA was 3.14%. In addition, we found that the origin variation of vertebral artery all occurred on the left side. Notably, our study found that when the LVA arose from aortic arch, the variability of the entrance level reached to 50%. The proportion of higher entrance level (C3,4,5) were statistically increased in abnormal origin subjects when comparing to normal origin subjects, which was consistent with the Japanese finding that anomalous origin and anomalous entry level into the transverse foramen correlated strongly. 14 Similarly, Lin et al . 15 reported that there was a significantly higher rate of anomalous entrance level (C4 or C5) to normal C6 entrance level of the patient with abnormal VA origin. Meila et al. 16 claimed that LVA originating from the aortic arch would never enter the transverse foramen at the level of C6, which turned out to enter at a higher level at C4 or C5 with an aortic arch origin proximal to the subclavian artery, or at C7 with an aortic arch origin distal to the subclavian artery respectively. However, their view caused contradictory when taking our findings into consideration. Interestingly, our finding revealed that 50% of patients with anomalous LVA origin was observed the correlated anomalous entry level into the transverse foramen, while the rest 50% of them was found with normal entry level; whereas Lin et al. 15 showed that 4.34% of patients with anomalous LVA origin was observed with normal entry level. The large difference in proportion between our study and theirs has aroused our interest in the investigation of embryonic development. A brief review of embryology of the aortic arch and great vessels makes a better understanding of these variations 17 . The embryo develops 6 pairs of matched aortic arches 18 . These aortic arches undergo selective apoptosis, and the remaining branch vessels form the aortic arch and large vessels. During this process, anatomical variation can be formed occasionally. The first and second aortic arches (I and II) degenerates. The paired third arch (III) forms the first part of the bilateral internal carotid artery. The proximal right fourth arch (IV) remains to serve as the origin of the right subclavian artery to the internal mammary artery, while the distal part of the right fourth arch regresses. The left 4 arch (IV) degenerates and forms small segment of the adult arch between the origin of the left common carotid artery and the left subclavian artery. The fifth arch (V) either recedes or is not fully formed. The sixth arch (VI) forms the pulmonary arch and develops into the right pulmonary artery and artery catheter. 19 VA is the longitudinal anastomosis of segmental meristem artery. 20 The bilateral VAs usually develop from the distal end of the seventh intersegmental dorsal arteries. The proximal two-thirds of subclavian artery to the level internal thoracic artery is formed by the left seventh dorsal intersegment, while the distal third of the proximal subclavian artery is formed by the right seventh intersegment. Vascular malformation originated from abnormal anastomosis at any time during the embryonic development of the arch. The timing and location of the anastomosis will determine the ultimate origin of the variation after grown-up. Notably, VA can be anastomosed with ascending and deep carotid arteries. The difference of the level of vertebral artery entrance is associated with the dominance of the ascending or deep cervical artery anastomosis. 21 In order to better understand the origin and variation of the vertebral artery, we speculated the development pattern based on the findings of CY Lin 15 . RVA was normally generated from the first part of the subclavian artery, and flowed into the transverse foramina in the sixth cervical vertebra C6, then passed through the transverse process of C6 to the first cervical vertebra C1, and eventually extended from C1 to the intracranial segment via foramen magnum. However, anatomical variation of the LVA origin was observed. Anastomose occurred between LVA and ascending carotid artery (ACA), which causes LVA enter at the level of C5 if the ACA took the lead, then climbed up through from C5 to C1, and eventually from C1 to the intracranial segment. Specifically, when the longitudinal intersegmental anastomosis was dominated by ventral group such as ascending cervical artery, the anomalous VA originating from 6th cervical segmental artery ran along with the ascending cervical artery and shifted up to the entry level at C5 or above into the transverse foramen. On the contrary, when the longitudinal intersegmental anastomosis was dominated by dorsal extraspinal group such as deep cervical artery, the anomalous VA ran along with deep cervical artery and shifted down to the entry level at C6 into the transverse foramen. Anatomical variations in the vertebral arteries are important anatomically as well as clinically. If the variations of vertebral arteries were neglected in diagnosis, the VA could be easily damaged in the process of endovascular interventions, anterior decompression of the cervical spine and cervical transforaminal epidural blocking. As noted, a VA of anomalous origin often contributes to the entry into transverse foramen higher than the normal origin, leading to the initial segment of the VA being oppressed and tortuous and a lack of protection of the cervical transverse process. These anatomical variations could cause mechanical pressure on the VA and further stimulated the perivascular sympathetic nerve plexus and induced vasoconstriction, which resulted in a series of clinical symptoms such as recurring vertigo. 22 Kim et al. 23 reported that the areas of the VA were decreased when passing through the higher levels of transverse foramen, which was consistent with our findings of the negative correlation between these two factors. In this scenario, we speculated that the narrowed vessel lumen led to a disturbance of the flow and possibly generated cerebrovascular disease if not treated accordingly. We will enlarge the sample size and cooperate with the ultrasound department to measure the blood flow velocity at the entrance in order to further confirm this hypothesis in the following study. Conclusion Abnormal entrance and origin of VA were observed in 7.40% and 3.14% of cases, which can be accurately appeared by CTA. Declarations Acknowledgement This work was supported by Six Talent Peaks Project in Jiangsu Province (Ref No.LGY2017010), Gusu Medical Professional Project (Ref No.GSWS2019020), Soochow Youth Science and Technology Project (Ref No. kjxw2018034), Science and Technology Development Fund of Nanjing Medical University (Ref No. NMUB201822), and Jiangsu Natural Science Foundation (Ref No.BK20181179). Competing interests The authors declare no competing interests. Data availability statement All data generated or analysed during this study are included in this published article (and its Supplementary Information files). References Sturda C, Steyn C, Olivi A, et al. Extraforaminal Vertebral Artery Until C2 Transverse Foramen in Down Syndrome Patient Affected by Atlantoaxial Subluxation: First Observation and Review of Literature. World neurosurgery 2019;131:230–3. Desouza RM, Crocker MJ, Haliasos N, et al. Blunt traumatic vertebral artery injury: a clinical review. European spine journal: official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society 2011;20:1405–16. Shakir HJ, Davies JM, Shallwani H, et al. Carotid and Vertebral Dissection Imaging. Current pain and headache reports 2016;20:68. Wallace MA, Fukui MB, Williams RL, et al. Complications of Cervical Selective Nerve Root Blocks Performed with Fluoroscopic Guidance. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-1477797","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":94741842,"identity":"f61bc7c7-e0a5-45f6-82cd-428116faea3c","order_by":0,"name":"Xueting Yi","email":"","orcid":"","institution":"Affiliated Suzhou Hospital of Nanjing Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Xueting","middleName":"","lastName":"Yi","suffix":""},{"id":94741843,"identity":"1e90816a-fbb5-4c77-9a78-f2ee5805d62a","order_by":1,"name":"Ping Xie","email":"","orcid":"","institution":"Affiliated Suzhou Hospital of Nanjing Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Ping","middleName":"","lastName":"Xie","suffix":""},{"id":94741844,"identity":"66d31f5c-c913-4313-bc73-78b6bac1c388","order_by":2,"name":"Lianwei Zhang","email":"","orcid":"","institution":"Affiliated Suzhou Hospital of Nanjing Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Lianwei","middleName":"","lastName":"Zhang","suffix":""},{"id":94741845,"identity":"1435ca13-dd23-493f-b99a-5db2cdcb92e0","order_by":3,"name":"Fengxia Lu","email":"","orcid":"","institution":"Affiliated Suzhou Hospital of Nanjing Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Fengxia","middleName":"","lastName":"Lu","suffix":""},{"id":94741846,"identity":"9118cda4-950b-4dc7-aa3b-3c391bf38eb6","order_by":4,"name":"Hao Chen","email":"","orcid":"","institution":"Affiliated Suzhou Hospital of Nanjing Medical University","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Hao","middleName":"","lastName":"Chen","suffix":""},{"id":94741847,"identity":"5bc88a11-b759-479f-a7d6-f94e7f144cf9","order_by":5,"name":"Kefu Liu","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAo0lEQVRIiWNgGAWjYBACPh7G57//VEjI8ROthY2H2UCC54yFsWQDSVp42yoSN5Cg5TCDgeQ8CcYNDMwPH90gSgtvM0OC4TYJZnMGNmPjHKK08PMfOJC4TYLNsoGHTZpILcyMDQfnSPAYHCBaC28zM2Njg4QECVp4DrMxMxyTMJBsJtYv/DzJQC01dfX97M0PHxOlBQGYSVM+CkbBKBgFowAfAABlYiTh2QrLTwAAAABJRU5ErkJggg==","orcid":"","institution":"Affiliated Suzhou Hospital of Nanjing Medical University","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Kefu","middleName":"","lastName":"Liu","suffix":""}],"badges":[],"createdAt":"2022-03-22 12:44:23","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-1477797/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-1477797/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":19866836,"identity":"da658240-9e2f-4731-ab3d-a22b6fed70dd","added_by":"auto","created_at":"2022-04-01 16:09:33","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":656836,"visible":true,"origin":"","legend":"\u003cp\u003eTypical case of subjects with LVA arising from aortic arch (AA). The distal segment enters the transverse foramen at C5 level higher than normal.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-1477797/v1/e24e83f53ae3a58ad2c4353f.png"},{"id":19867198,"identity":"a1b73f30-75d3-41a9-bce0-3269a79eaa65","added_by":"auto","created_at":"2022-04-01 16:14:33","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":626159,"visible":true,"origin":"","legend":"\u003cp\u003eSpecial case of the subject with left SCA arising from AA while left VA origin was normal.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-1477797/v1/a83140eab47e259a0800dd3e.png"},{"id":19866838,"identity":"0dcc8be9-9bc6-4267-9fa8-920158762db4","added_by":"auto","created_at":"2022-04-01 16:09:33","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":962775,"visible":true,"origin":"","legend":"\u003cp\u003eTypical case of the subjects with anomalous entrance at a higher level into the transverse foramen than normal (LVA: C5; RVA: C4).\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-1477797/v1/2bd6c035d1be31650a642cd9.png"},{"id":19867405,"identity":"8657b109-7c65-41c7-8ced-db762143c38a","added_by":"auto","created_at":"2022-04-01 16:19:33","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":1048200,"visible":true,"origin":"","legend":"\u003cp\u003eTypical case of the subjects with anomalous entrance at a lower level into the transverse foramen than normal (RVA: C7).\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-1477797/v1/0fd077aa9cabb4ed28d1f4c8.png"},{"id":19867407,"identity":"123e2ad8-1ba8-4bb3-8e4b-8f103804c798","added_by":"auto","created_at":"2022-04-01 16:19:36","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":417331,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1477797/v1/38e6b126-e5d9-4f0c-8618-2251effa4e63.pdf"},{"id":19866840,"identity":"c37a44d2-8616-48d7-97a2-c2f54401fb8f","added_by":"auto","created_at":"2022-04-01 16:09:33","extension":"xlsx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":17046,"visible":true,"origin":"","legend":"","description":"","filename":"datasetsupload2022.3.28.xlsx","url":"https://assets-eu.researchsquare.com/files/rs-1477797/v1/ee65e32f3c89f3920de67fbc.xlsx"}],"financialInterests":"No competing interests reported.","formattedTitle":"Entrance and Origin of the Extracranial Vertebral Artery: CTA Findings","fulltext":[{"header":"Entrance And Origin Of The Extracranial Vertebral Artery: Cta Findings","content":"\u003cp\u003eThe VA is a longitudinal anastomosis of segmental metameric arteries. The present study confirms the presence of anomalous entrance and origin of the extracranial VA. The possibility of an atypical course of the VA should be evaluated by additional advanced imaging such as CTA and ultrasonography to minimize risk of its injury during cervical spine surgery or diagnose vertebrobasilar symptoms where insufficient blood flow is caused by embryologic development.\u003c/p\u003e"},{"header":"Introduction","content":"\u003cp\u003eThe anatomical variation of vertebral artery (VA) is essential to clinics and anatomy. Accurate understanding in the variations of vertebral artery are regarded as necessary with the development and popularization of endovascular interventions, anterior decompression of the cervical spine, neck dissection and stellate ganglion block.\u003c/p\u003e \u003cp\u003eThe anatomical variation of VA, including its origin and its level of entrance into transverse foramen, has been widely investigated, and even some general information has been published in standard atlas, textbooks and the Internet.\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e However, the recent significant findings indicated that the differences of VA variations among different regions raised the issue of potential regional, ethnic and even environmental factors.\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e Up to now, there is a lack of original data available for regions of China.\u003c/p\u003e \u003cp\u003eTherefore, our current study investigated morphological variability of VA origin and its entrance level into cervical transverse foramina in population of Suzhou in China.\u003c/p\u003e"},{"header":"Materials And Methods","content":"\u003cp\u003eWe retrospectively investigated computed tomography angiograms (CTA) of 223 subjects (446 VA courses) of both sexes (155males and 68 females) and of age between 27 and 88 years (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). From the study the patients were excluded with previous or current cerebrovascular accidents, with the history of cervical injuries, atherosclerotic changes (affecting more than 50% of VA diameter), with severe spondylarthrosis. Data were collected and stored in accord to Helsinki Declaration10. The institutional review board of The Affiliated Suzhou Hospital of Nanjing Medical University (Suzhou, China) approved the present retrospective study and waived the requirement for informed consent.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDemographic data of investigated sample (223 subjects; 446 courses)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eGender\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eN\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eX means of agea\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eStandard deviationa\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMaximum agea\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eMinimum agea\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMales\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e155\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e64.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e12.08\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eFemales\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e68\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e67.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e11.12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e40\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e223\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e65.44\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e11.87\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c6\"\u003e \u003cp\u003e27\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"6\"\u003e\u003csup\u003ea\u003c/sup\u003e Units are shown in years\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAll imaging-generation and visualization measurements were performed in the Clinical Radiology Department, Affiliated Suzhou hospital of Nanjing Medical University (Suzhou, China). Patients were placed in a supine position with their arms alongside the body, head and neck kept at a neutral position. The imaging examination was performed on a Multi-slice computed tomography (CT) scanner (Philips Brilliance iCT Holland) with the scanning protocol as follows: 120kVp, 153mAs, beam collimation 128 \u0026times; 0.625mm, gantry rotation time 0.5s, section thickness of 0.9 mm, pitch 0.758 and reconstruction interval of 0.45 mm. During the procedure, infused 50 mL of nonionic iodinated contrast was followed by 30 mL saline and injected via a double power injector into the patient\u0026rsquo;s antecubital vein (5 mL/s).\u003c/p\u003e \u003cp\u003eImages were analyzed at a workstation (Intellispacsportal 9.0; Philips). The VA\u0026rsquo;s origin and level of entrance into vertebral transverse foramen were recorded, as well as the sex and side of variation. All the data was measured by 2 experienced radiologists with independent double-blind method, and a consensus was reached finally.\u003c/p\u003e \u003cp\u003eStatistical analysis was performed using statistical package for the social sciences (SPSS) version 22.0 (IBM Corporation, Somers, NY, USA) statistical software. The data were expressed as means\u0026thinsp;\u0026plusmn;\u0026thinsp;standard deviation (SD). The quantitative data were examined by Kolmogorov Smirnov test for normality. Independent \u0026ldquo;t\u0026rdquo; test was performed to compare the different variables regarding side. Chi-Square test and Fisher's exact test were used to determine if there was a significant relationship between different variables. p value\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered to be significant.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003eGenerally, the mean age of patients was 65 years, and the male-to-female ratio was 2.3:1 in the current study. (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eIn the current study, the VA entered the C6 transverse process in 92.60% of specimens (413 out of 446 VA courses, 64.57% males and 28.03% females). Abnormal entrance of VA was observed in 7.40% of specimens (33 VA courses), with the level of entrance into the C3, C4, C5, or C7 transverse foramen at 0.22%, 2.24%, 4.72% and 0.22% respectively (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u0026ndash;4). In male cases, there was non-significant statistical difference in the frequency of entrance variations of right VA(RVA) and left VA(LVA), nor in female cases. (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.576 and \u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.206). Also, there was non-significant statistical difference in the frequency of entrance variations of RVA and LVA (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.205).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eOrigin and entrance into the transverse foramen of the VA in overall population (223 subjects; 446 courses)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eEntrance into the transverse foramen\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eOrigin of right VA\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c7\" namest=\"c6\"\u003e \u003cp\u003eOrigin of left VA\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eSubclavian artery\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eAortic arch\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eSubclavian artery\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eAortic arch\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1 (0.22%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1 (0.22%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eIV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e10 (2.24%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (1.57%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3 (0.67%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eV\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e21 (4.71%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (1.57%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e3 (0.67%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e4 (0.90%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e2 (0.45%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e5 (1.12%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e413 (92.6%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e140 (31.39%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e146 (32.74%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e2 (0.45%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e63 (14.13%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e62 (13.90%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVII\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1 (0.22%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e1 (0.22%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e446 (100.00%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e155 (34.75%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e149 (33.41%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e6 (1.35%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e68 (15.25%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e67 (15.02%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e1 (0.22%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"7\"\u003e\u003csup\u003ea\u003c/sup\u003e Percentage values are shown in parenthese of overall population\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eComparably, we observed that the overall variability of abnormal origin of VA was 3.14% (7 out of 223 subjects), which LVAs all arose from aortic arch (AA) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Notably, seven subjects (6males and 1female) of the left VA originated from the aortic arch, where the variation rate of vertebral entrance rose up to 50% in corresponding subgroup. Among these anomalous entrance in patient with abnormal origin, one entered the transverse foramen at the level C3, one at level C4, five at level C5, respectively (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).When comparing subgroups of subjects with normal and abnormal origin, there was significance difference in the frequency of entrance variation in the level of transverse foramen (\u003cem\u003ep\u003c/em\u003e\u0026thinsp;=\u0026thinsp;1.5\u0026times;10\u003csup\u003e\u0026minus;\u0026thinsp;5\u003c/sup\u003e\u0026lt;0.01). Specifically, the proportion of normal entrance level (C6 level) were statistically decreased and the proportion of higher entrance level (C3,4,5) were statistically increased in abnormal origin subjects when comparing to normal origin subjects, whereas no statistical difference was shown in the proportion of lower entrance level (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). Interestingly, one specific case was found that a 43 years old woman whom left subclavian artery (SCA)arose from AA while left VA origin was normal (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eEntrance into the transverse foramen of the VA in subgroup with abnormal origin (7 subjects; 14 courses)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNumber\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSex\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eOrigin of right VA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eEntrance of right VA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003eOrigin of left VA\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eEntrance of left VA\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e69\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRSA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eC6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eC6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eF\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRSA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eC6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eC3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e82\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRSA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eC6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eC5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e51\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRSA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eC6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eC5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e56\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRSA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eC5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eC5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e48\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRSA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eC6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eC6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eM\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e54\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eRSA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eC4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003eAA\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003eC5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison between subgroups with abnormal VA origin and normal VA origin in the variability of entrance into the transverse foramen of the VA (223 subjects; 446 courses)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"5\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSubgroup\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTotal\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eEntrance at normal level\u003c/p\u003e \u003cp\u003e(C6)\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eEntrance at higher level\u003c/p\u003e \u003cp\u003e(C3, C4, C5)\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eEntrance at lower level (C7)\u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSubjects with abnormal origin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14 (100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7 (50%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7 (50%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSubjects with normal origin\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e432 (100%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e406 (93.98%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e25 (5.79%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1 (0.23%)\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003ctfoot\u003e \u003ctr\u003e\u003ctd colspan=\"5\"\u003e\u003csup\u003ea\u003c/sup\u003e Percentage values are shown in parentheses of corresponding subgroup\u003c/td\u003e\u003c/tr\u003e \u003c/tfoot\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eWe could recognize the location of the entrance and origin of the VAs in all our cases due to high-quality CTA, which is a noninvasive and easy imaging technique and is very important for surgery. The entrance and origin of the VA is essential to neck tumor resection as vascular damage may occur when VA goes through the abnormal region, which is sometimes neglected by the surgeon. Additionally, the entrance of the vertebral artery is of significance to the stellate ganglion block. The block is commonly performed on the anterior tubercle of C6 transverse process. When the VA enters the foramen of the C5 transverse process or higher, exposing the VA between the cervical transverse processes, the VA is vulnerable to be located in the needle path. Unawareness of such an aberrant VA may cause life-threatening events.\u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e The origin of the vertebral artery is also very important in the placement of the aortic arch stent during peripheral vascular intervention, otherwise could produce injury and local occlusion of the vertebral artery.\u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eLiterature shows the frequency of origin of the left VA from aortic arch in the range of about 1%-3%.\u003csup\u003e13\u003c/sup\u003e Our results indicated that the overall variability of origin of VA was 3.14%. In addition, we found that the origin variation of vertebral artery all occurred on the left side. Notably, our study found that when the LVA arose from aortic arch, the variability of the entrance level reached to 50%. The proportion of higher entrance level (C3,4,5) were statistically increased in abnormal origin subjects when comparing to normal origin subjects, which was consistent with the Japanese finding that anomalous origin and anomalous entry level into the transverse foramen correlated strongly.\u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e Similarly, Lin \u003cem\u003eet al\u003c/em\u003e.\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e reported that there was a significantly higher rate of anomalous entrance level (C4 or C5) to normal C6 entrance level of the patient with abnormal VA origin. Meila \u003cem\u003eet al.\u003c/em\u003e\u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e claimed that LVA originating from the aortic arch would never enter the transverse foramen at the level of C6, which turned out to enter at a higher level at C4 or C5 with an aortic arch origin proximal to the subclavian artery, or at C7 with an aortic arch origin distal to the subclavian artery respectively. However, their view caused contradictory when taking our findings into consideration. Interestingly, our finding revealed that 50% of patients with anomalous LVA origin was observed the correlated anomalous entry level into the transverse foramen, while the rest 50% of them was found with normal entry level; whereas Lin \u003cem\u003eet al.\u003c/em\u003e\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e showed that 4.34% of patients with anomalous LVA origin was observed with normal entry level. The large difference in proportion between our study and theirs has aroused our interest in the investigation of embryonic development.\u003c/p\u003e \u003cp\u003eA brief review of embryology of the aortic arch and great vessels makes a better understanding of these variations\u003csup\u003e\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e. The embryo develops 6 pairs of matched aortic arches\u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e. These aortic arches undergo selective apoptosis, and the remaining branch vessels form the aortic arch and large vessels. During this process, anatomical variation can be formed occasionally. The first and second aortic arches (I and II) degenerates. The paired third arch (III) forms the first part of the bilateral internal carotid artery. The proximal right fourth arch (IV) remains to serve as the origin of the right subclavian artery to the internal mammary artery, while the distal part of the right fourth arch regresses. The left 4 arch (IV) degenerates and forms small segment of the adult arch between the origin of the left common carotid artery and the left subclavian artery. The fifth arch (V) either recedes or is not fully formed. The sixth arch (VI) forms the pulmonary arch and develops into the right pulmonary artery and artery catheter.\u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eVA is the longitudinal anastomosis of segmental meristem artery.\u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e The bilateral VAs usually develop from the distal end of the seventh intersegmental dorsal arteries. The proximal two-thirds of subclavian artery to the level internal thoracic artery is formed by the left seventh dorsal intersegment, while the distal third of the proximal subclavian artery is formed by the right seventh intersegment. Vascular malformation originated from abnormal anastomosis at any time during the embryonic development of the arch. The timing and location of the anastomosis will determine the ultimate origin of the variation after grown-up. Notably, VA can be anastomosed with ascending and deep carotid arteries. The difference of the level of vertebral artery entrance is associated with the dominance of the ascending or deep cervical artery anastomosis. \u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003cp\u003eIn order to better understand the origin and variation of the vertebral artery, we speculated the development pattern based on the findings of CY Lin \u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e. RVA was normally generated from the first part of the subclavian artery, and flowed into the transverse foramina in the sixth cervical vertebra C6, then passed through the transverse process of C6 to the first cervical vertebra C1, and eventually extended from C1 to the intracranial segment via foramen magnum. However, anatomical variation of the LVA origin was observed. Anastomose occurred between LVA and ascending carotid artery (ACA), which causes LVA enter at the level of C5 if the ACA took the lead, then climbed up through from C5 to C1, and eventually from C1 to the intracranial segment.\u003c/p\u003e \u003cp\u003eSpecifically, when the longitudinal intersegmental anastomosis was dominated by ventral group such as ascending cervical artery, the anomalous VA originating from 6th cervical segmental artery ran along with the ascending cervical artery and shifted up to the entry level at C5 or above into the transverse foramen. On the contrary, when the longitudinal intersegmental anastomosis was dominated by dorsal extraspinal group such as deep cervical artery, the anomalous VA ran along with deep cervical artery and shifted down to the entry level at C6 into the transverse foramen.\u003c/p\u003e \u003cp\u003eAnatomical variations in the vertebral arteries are important anatomically as well as clinically. If the variations of vertebral arteries were neglected in diagnosis, the VA could be easily damaged in the process of endovascular interventions, anterior decompression of the cervical spine and cervical transforaminal epidural blocking. As noted, a VA of anomalous origin often contributes to the entry into transverse foramen higher than the normal origin, leading to the initial segment of the VA being oppressed and tortuous and a lack of protection of the cervical transverse process. These anatomical variations could cause mechanical pressure on the VA and further stimulated the perivascular sympathetic nerve plexus and induced vasoconstriction, which resulted in a series of clinical symptoms such as recurring vertigo.\u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e Kim \u003cem\u003eet al.\u003c/em\u003e\u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e reported that the areas of the VA were decreased when passing through the higher levels of transverse foramen, which was consistent with our findings of the negative correlation between these two factors. In this scenario, we speculated that the narrowed vessel lumen led to a disturbance of the flow and possibly generated cerebrovascular disease if not treated accordingly. We will enlarge the sample size and cooperate with the ultrasound department to measure the blood flow velocity at the entrance in order to further confirm this hypothesis in the following study.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eAbnormal entrance and origin of VA were observed in 7.40% and 3.14% of cases, which can be accurately appeared by CTA.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by Six Talent Peaks Project in Jiangsu Province (Ref No.LGY2017010), Gusu Medical Professional Project (Ref No.GSWS2019020), Soochow Youth Science and Technology Project (Ref No. kjxw2018034), Science and Technology Development Fund of Nanjing Medical University (Ref No. NMUB201822), and Jiangsu Natural Science Foundation (Ref No.BK20181179).\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability statement\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated or analysed during this study are included in this published article (and its Supplementary Information files).\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eSturda C, Steyn C, Olivi A, et al. Extraforaminal Vertebral Artery Until C2 Transverse Foramen in Down Syndrome Patient Affected by Atlantoaxial Subluxation: First Observation and Review of Literature. World neurosurgery 2019;131:230\u0026ndash;3.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDesouza RM, Crocker MJ, Haliasos N, et al. Blunt traumatic vertebral artery injury: a clinical review. European spine journal: official publication of the European Spine Society, the European Spinal Deformity Society, and the European Section of the Cervical Spine Research Society 2011;20:1405\u0026ndash;16.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShakir HJ, Davies JM, Shallwani H, et al. Carotid and Vertebral Dissection Imaging. Current pain and headache reports 2016;20:68.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWallace MA, Fukui MB, Williams RL, et al. Complications of Cervical Selective Nerve Root Blocks Performed with Fluoroscopic Guidance. Ajr American Journal of Roentgenology 2007;188:1218\u0026ndash;21.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRabinstein AA, Lanzino G. Aneurysmal Subarachnoid Hemorrhage: Unanswered Questions. Neurosurgery clinics of North America 2018;29:255\u0026ndash;62.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSikka A, Jain A. Bilateral variation in the origin and course of the vertebral artery. Anatomy research international 2012;2012:580765.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKatsuki M, Yamamoto Y, Wada N, et al. Occipital artery to extracranial vertebral artery anastomosis for bilateral vertebral artery stenosis at the origin: A case report. Surgical neurology international 2018;9:82.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBergman RA, Afifi AF, R M. Illustrated Encyclopedia of Human Anatomic Variation: Opus II: Cardiovascular System.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBhatia K, Ghabriel MN, Henneberg M. Anatomical variations in the branches of the human aortic arch: a recent study of a South Australian population. Folia morphologica 2005;64:217\u0026ndash;23.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eItalian AI. [World Medical Association (AMM). Helsinki Declaration. Ethical principles for medical research involving human subjects]. 2001;20:104.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNarouze S. Ultrasound-guided stellate ganglion block: safety and efficacy. Current pain and headache reports 2014;18:424.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eM\u0026uuml;ller-H\u0026uuml;lsbeck, S. Subclavian and Vertebral Arterial Interventions. Seminars in Interventional Radiology 2007;24:258\u0026ndash;67.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDaseler EH, Anson BJ. Surgical anatomy of the subclavian artery and its branches. Surg Gynecol Obstet 1959;108:149\u0026ndash;74.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUchino A, Saito N, Takahashi M, et al. Variations in the origin of the vertebral artery and its level of entry into the transverse foramen diagnosed by CT angiography. Neuroradiology 2013.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLin C, Liu Y, Chen Y, et al. Variations in the Origin and Course of the Extracranial Vertebral Artery on Multidetector Computed Tomography Angiography. Iran J Radiol 2018;15:e61623.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMeila D, Tysiac M, Petersen M, et al. Origin and Course of the Extracranial Vertebral Artery: CTA Findings and Embryologic Considerations. 2012;22:327 \u0026ndash; 33.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVitums A. Development and transformation of the aortic arches in the equine embryos with special attention to the formation of the definitive arch of the aorta and the common brachiocephalic trunk. Zeitschrift f\u0026uuml;r Anatomie und Entwicklungsgeschichte 1969;128:243\u0026ndash;70.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKhalid N, Bordoni B. Embryology, Great Vessel. StatPearls. Treasure Island (FL), 2019.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGupta SK, Gulati GS, Anderson RH. Clarifying the anatomy of the fifth arch artery. Annals of pediatric cardiology 2016;9:62\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNamba K. Carotid-vertebrobasilar Anastomoses with Reference to Their Segmental Property. Neurologia medico-chirurgica 2017;57:267\u0026ndash;77.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLasjanias. Surgical Neuroangiography / 1 Clinical Vascular Anatomy and Variations. 2001.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYates BJ, Bolton PS, Macefield VG. Vestibulo-sympathetic responses. Comprehensive Physiology 2014;4:851\u0026ndash;87.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKim C, Lee SH, Park SS, et al. A Quantitative Comparison of the Vertebral Artery and Transverse Foramen Using CT Angiography. Journal of clinical neurology 2012;8:259\u0026ndash;64.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Vertebral artery, Variability, Origin; Entrance, CTA","lastPublishedDoi":"10.21203/rs.3.rs-1477797/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-1477797/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eObjective\u003c/h2\u003e \u003cp\u003eTo investigated morphological variability of VA origin and its entrance level into cervical transverse foramina by CTA.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eTo retrospectively investigated computed tomography angiograms (CTA) of 223 subjects (446 VA courses). Postprocessing of source images was performed by using a multi-planar reformation (MPR), maximum intensity projection (MIP), multi-planar reconstruction (MPR) and volume rendering (VR) algorithms. Investigated were origin of the VA and its level of entrance into vertebral transverse foramen with notification of the sex and side of variation.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe VA entered the C6 transverse process in 92.60% of specimens (413 out of 446 VA courses, 64.57% males and 28.03% females). Abnormal entrance of VA was observed in 7.40% of specimens (33 VA courses), with the level of entrance into the C3, C4, C5, or C7 transverse foramen at 0.22%, 2.24%, 4.72% and 0.22% respectively. Comparably, we observed that the overall variability of abnormal origin of VA was 3.14% (7 out of 223 subjects), which LVAs all arose from aortic arch (AA). Comparing subgroups of subjects with normal and abnormal origin, there was significance difference in the frequency of entrance variation in the level of transverse foramen.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eAbnormal entrance and origin of VA were observed in 7.40% and 3.14% of cases, which can be accurately appeared by CTA.\u003c/p\u003e","manuscriptTitle":"Entrance and Origin of the Extracranial Vertebral Artery: CTA Findings","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-04-01 16:09:31","doi":"10.21203/rs.3.rs-1477797/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Major revision","date":"2022-05-31T12:03:05+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2022-05-26T22:44:45+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2022-05-22T03:11:08+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"4c09def6-ac44-408a-9ec2-f706ab0cf35e","date":"2022-05-20T12:32:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"492c9ebb-a826-4a43-a4a4-97be4d5d7d7e","date":"2022-05-13T15:39:46+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2022-05-13T13:24:50+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2022-04-26T04:23:10+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2022-03-30T10:55:05+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2022-03-30T10:46:57+00:00","index":"","fulltext":""},{"type":"submitted","content":"Scientific Reports","date":"2022-03-22T12:38:05+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"scientific-reports","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"scirep","sideBox":"Learn more about [Scientific Reports](http://www.nature.com/srep/)","snPcode":"","submissionUrl":"","title":"Scientific Reports","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Scientific Reports","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"43e79ef2-f44c-42fc-9e66-79e7a73e0879","owner":[],"postedDate":"April 1st, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2022-08-30T07:59:12+00:00","versionOfRecord":[],"versionCreatedAt":"2022-04-01 16:09:31","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-1477797","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-1477797","identity":"rs-1477797","version":["v1"]},"buildId":"WrCJVZZCHTDjtuVLN7oU0","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}