Persistent Proatlantal Intersegmental Artery(PPIA):Are Consideration Based On MSCTA

Persistent Proatlantal Intersegmental Artery(PPIA):Are Consideration Based On MSCTA | 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 Research Article Persistent Proatlantal Intersegmental Artery(PPIA):Are Consideration Based On MSCTA Xiao Qin, Xinju Yang, Yi Mao, Shunan Wang This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-4654199/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 02 Dec, 2024 Read the published version in Surgical and Radiologic Anatomy → Version 1 posted 11 You are reading this latest preprint version Abstract Background Persistent proatlantal intersegmental artery (PPIA) is a rare permanent carotid-basilar anastomosis. Multi-slice spiral CT Angiography (MSCTA) has become the primary non-invasive imaging technique for evaluating cephalic and cervical vascular anatomy. Purpose To investigate the MSCTA imaging characteristics of PPIA and its clinical values, and then to provide a new classification method based on posterior circulation blood supply. Material and Methods The imaging and clinical data of 11 patients with PPIA diagnosed by MSCTA through combined head and neck scanning were analyzed retrospectively. Results The incidence of PPIA was 0.01%. Classification according to the starting position of PPIA revealed 2 cases (18.2%) of type I and 9 cases (81.8%) of type II. When classified according to the blood supply of posterior circulation, type 1 of PPIA had 4 cases (36.4%), type 2 had 4 cases (36.4%), type 3 had 1 case (9.1%), and type 4 had 2 cases (18.2%). Among the 11 PPIA patients, there were 11 cases of ipsilateral vertebral artery absence, 3 cases of contralateral vertebral artery dysplasia, 1 case of contralateral vertebral artery absence, 2 cases of persistent artery dysplasia, and 2 cases of basilar artery dysplasia. Additionally, there were 2 patients with aneurysms, 1 patient with cerebral infarction, and 1 patient with Pulmonary Arteriovenous Fistula (PAVF). Conclusion The new classification of PPIA is more conducive to evaluating posterior circulation blood supply and providing a more comprehensive imaging evaluation for interventional and surgical procedures. MSCTA can accurately diagnose PPIA and reduce the rate of missed diagnoses of other vascular diseases. Persistent proatlantal intersegmental artery Multi-Slice Spiral CT Angiography (MSCTA) Vertebral artery Internal carotid External carotid artery Figures Figure 1 Figure 2 Introduction At the embryonic stage, there were four temporary anastomotic vessels between the primitive carotid artery and the longitudinal neural artery, including those of the primitive trigeminal artery, primitive otic artery, primitive hypoglossal artery, and primitive proatlantal intersegmental artery from top to bottom. If these primitive arteries do not degenerate in adulthood, they are called persistent internal carotid basilar arteries[ 1 ]. PPIA is a rare type of persistent internal carotid basilar artery[ 2 ]. Currently, literature on PPIA has mainly focused on case reports, and its classification still follows the summary of Lasjaunias P in 1978[ 3 ], which was based on anatomical origin. However, there is a lack of study in a large study population, and the incidence rate has not been reported. This study aimed to investigate the prevalence of PPIA in a large study population and use MSCTA to identify its types, including anatomical origin and posterior circulation blood supply. We also discussed their clinical implications and the probable embryological mechanisms by which to explain these observed variants. Material and Methods Patients and the MSCTA technique A total of 105,052 patients underwent head and neck MSCTA examinations from January 2013 to December 2021. Among these patients, 11 cases were diagnosed with PPIA through MSCTA, with ages ranging from 47.0 to 76.0 years and an average age of (59.5 ± 10.4) years. This study retrospectively analyzed the imaging manifestations, including the origin, endpoint, vascular path of PPIA, and its relationship with persistent artery, vertebral artery, basilar artery, posterior communicating artery, and other combined cerebrovascular diseases. Additionally, the study analyzed the clinical symptoms of patients with PPIA. MSCTA was performed using GE Lightspeed VCT (64-slice spiral CT) and Philips Brilliance iCT (256-slice spiral CT). Scanning parameters were set as follows: tube voltage 100 kV, tube current 200 mA, pitch 0.984:1, tube rotation speed 0.8. The contrast medium used was a non-ionic iodine contrast medium (iohexol injection, Omnipaque) with a ratio of 50 ~ 80 mL of contrast medium to 40 ~ 50 mL of normal saline, and the injection rate was 5 ~ 6.5 mL/s. Scanning extended from the aortic arch to the top of the skull. Digital subtraction imaging technology was applied to subtract the images before and after the injection of the contrast agent. Cephalic and cervical artery images were then extracted based on the subtracted images. After scanning, the original data were transmitted to ADW 4.3 for post-processing on a workstation, involving 2D and 3D post-processing techniques such as maximum intensity projection (MIP), multiplanar reconstruction (MPR), and volume rendering (VR). Finally, the processed data were transmitted to the Picture Archiving and Communication Systems (PACS) workstation. Image analysis The diagnosis of all patients in the 'PACS' system is collaboratively conducted by a junior physician holding a practicing physician qualification certificate and an intermediate practicing physician with an intermediate practicing physician qualification certificate. Using the PACS system, we screened all patients who had undergone head and neck MSCTA examinations, imported their data into Excel, eliminated duplicate entries, and then searched for words closely related to PPIA diagnosis, such as 'persistent'、 'primitive'、' anterior atlantic intersegmental artery'、 'connected'、 'variant'、'dysplasia' etc. After retrieving the patient data, two physicians with 7 and 10 years of neuroimaging work experience and a comprehensive understanding of PPIA diagnostic criteria conducted the MSCTA image review. The final diagnosis of PPIA was collaboratively determined by the two physicians. The PPIA images were retrospectively analyzed by two radiologists with a consensus, and PPIA was classified according to our new classifications. They focused on observing Maximum Intensity Projection (MIP) and Volume Rendering (VR) images by combining the cross-section and coronary plane of the original CT sectional images to determine the origin, course, and endpoint of PPIA. Special attention was paid to the relationship between PPIA and the vertebral artery, posterior communicating artery (PcomA), and basilar artery. Additionally, they further analyzed other vascular diseases in the head and neck, including aneurysm, vascular stenosis, vascular dysplasia, etc., reaching an agreement through negotiation in cases of differences of opinion. The study received approval from our institutional review board. Classification of the PPIA PPIA was classified into two types based on anatomical origin [ 3 , 4 ]. Type I of PPIA originated from the internal carotid artery or the bifurcation of the common carotid artery, at the level between the C2 and C4 vertebrae. It then passed through the lateral side of the vertebral transverse process foramen of the C1 vertebra, rose to the anterior atlantal space, and passed through the foramen magnum to anastomose with the ipsilateral or contralateral vertebral arteries. Type II originated from the external carotid artery, equivalent to the level of the C2 or C3 vertebra. It either entered or did not enter the C1 transverse foramen forward, entering the atlantoaxial space, and then passed through the foramen magnum to the intracranial region, eventually anastomosing with the ipsilateral or contralateral vertebral artery. In this study, PPIA was categorized into four types based on the blood supply of the posterior circulation involving persistent artery, vertebral artery, and posterior communicating artery. Type 1 represents the dominant persistent arterial blood supply, where the posterior circulation is primarily supported by persistent arteries. In this type, both the persistent artery and the basilar artery exhibited normal development, and the ipsilateral and contralateral vertebral arteries could be well or poorly developed, with the optional development of the posterior communicating artery (Fig. 1 a). Type 2 was identified as the balanced type, with the posterior circulation mainly supplied by PPIA and the contralateral vertebral artery. This type displayed normal development of PPIA, contralateral vertebral artery, and basilar artery, with dysplastic ipsilateral vertebral artery, and the optional development of the posterior communicating artery (Fig. 1 b). Type 3 represents the vertebral artery-dominant type, where the posterior circulation is primarily supported by the contralateral vertebral artery. It showed normal development of the contralateral vertebral artery and basilar artery, with dysplastic ipsilateral vertebral artery and PPIA, and the optional development of the posterior communicating artery (Fig. 1 c). Type 4 was identified as the posterior communicating artery blood-supply type, where the posterior circulation blood supply was mainly provided by the communicating artery. This type exhibited dysplasia in the bilateral vertebral artery, basilar artery, and PPIA, with normal development of the posterior communicating artery (Fig. 1 d). Results Prevalence and sex distribution of the PPIA A total of 105,052 patients underwent MSCTA, and 11 patients were diagnosed with PPIA, resulting in an incidence of 0.01%. Among them, 5 were males (45.5%) and 6 were females (54.5%). All 11 cases of PPIA occurred unilaterally, with 8 cases on the left side and 3 cases on the right side. The ages ranged from 47.0 to 76.0 years, with an average age of (59.5 ± 10.4) years. Among these patients, 7 had symptoms of cerebral blood insufficiency such as dizziness (n = 6) and headache (n = 1). One patient presented with pontine infarction, resulting in limitation of left limb movement. Another case had a cerebral hemorrhage in the right insular lobe, leading to walking instability. One case was diagnosed with viral encephalitis, exhibiting symptoms such as nausea, vomiting, and mental disorder. One case had no obvious symptoms (Table 1). Classification and anatomical characteristics of the PPIA Based on the anatomical origin of PPIA, it can be classified into PPIA type I and type II. There are 2 cases of type 1, both occurring on the right side. One case originated from the internal carotid artery, and another case originated from the carotid sinus, with both starting points equivalent to the level of the C3 cervical vertebra. Subsequently, it traversed the deep surface of the cervical splenius muscle, entering the preatlantic space directly from the outside of the transverse foramen, and ultimately passed through the foramen magnum into the skull to anastomose with the contralateral vertebral arteries. There were 9 cases of PPIA type II (81.8%), with 8 cases on the left side and 1 case on the right side, all originating from the external carotid artery. The starting point of 2 cases was equivalent to the level of the C3 cervical vertebra, and 7 cases were equivalent to the level of the C2 cervical vertebra. Among them, 4 cases passed through the deep surface of the splenius capitis and C1 transverse foramen, 1 case passed through the deep surface of the splenius cervicis, and 4 cases passed through the deep surface of the longissimus capitis from the outside of the transverse foramen. Subsequently, they traversed the atlantoaxial space and the foramen magnum, anastomosing with the contralateral vertebral arteries eventually. The authors of this study classified PPIA into four types based on its relationship with the vertebral artery and posterior communicating artery in terms of posterior circulation blood supply. Type 1 had four cases where the posterior circulation was primarily supplied by persistent arteries, with normal development of both PPIA and the basilar artery, but with the absence of ipsilateral vertebral artery(Fig. 2 a). Type 2 had four cases where the posterior circulation was mainly supplied by PPIA and contralateral vertebral artery, with normal development of both PPIA, contralateral vertebral artery, and the basilar artery, but with ipsilateral vertebral artery absence(Fig. 2 b). Type 3 had one case where the posterior circulation was mainly supplied by contralateral vertebral artery blood, with normal development of the contralateral vertebral artery and basilar artery, but with ipsilateral vertebral artery absence and PPIA dysplasia, along with contralateral PComA development(Fig. 2 c). Type 4 had two cases where the posterior circulation was mainly supplied by PComA, with bilateral vertebral artery, basilar artery, and PPIA dysplasia, along with bilateral PComA development(Fig. 2 d). PPIA combined with other vascular abnormalities In this study, 11 patients exhibited ipsilateral vertebral artery absence, 3 patients had contralateral vertebral artery agenesis, and 1 patient showed contralateral vertebral artery absence. Additionally, 2 cases presented with basilar artery dysplasia. Among the cases, 5 showed development of PComA, with 3 cases being unilateral and 2 cases bilateral. Two patients with PPIA were complicated with aneurysms, one located at the beginning of PPIA, and the other at the communicating segment of the contralateral internal carotid artery. One patient experienced pontine infarction, and another had a pulmonary arteriovenous fistula. Furthermore, 3 patients exhibited arterial variations: one showed co-trunking of the A2 segment of the anterior cerebral artery, another displayed the left common carotid artery co-trunking with the brachiocephalic trunk, and the third had the left vertebral artery originating from the aortic arch (Table 1). Discussion Embryogenesis of the PPIA In the early embryonic period, four transient vessels originating from the primitive internal carotid artery and dorsal aorta were known as primitive carotid-vertebrobasilar anastomoses, which would supply blood to the future vertebrobasilar artery. If these pathways did not degenerate in adulthood, they were called permanent internal carotid basilar arteries. These persistent arteries were named according to the accompanying cranial nerves, among which PPIA had no accompanying nerves. The persistent arteries were named as PPTA, PPOA, PPHA, and PPIA from top to bottom. In 1948, Dorcas Hager Padget published an authoritative treatise on embryology and the development of the human cerebral vascular system. Based on this, Namba, K., further elaborated on the development and degradation process of the primitive internal carotid basilar artery in 2017 [ 5 ]. At the 3mm stage of the embryo, two branches sprout from the first aortic arch: the primitive internal carotid and the primitive trigeminal arteries. This marks the earliest appearance of the trigeminal artery, communicating with the primordial hindbrain channel. At the 4mm embryonic stage, PPIA, PPOA, PPHA, and PPTA were the anterior branches of the dorsal aorta serving as an anastomosis between the original internal carotid artery and bilateral longitudinal nerve arteries, providing blood supply to the hindbrain. These longitudinal nerve arteries fused at the 5–9 mm embryonic stage, forming the basilar artery for posterior circulation blood supply. The communicating artery developed at the 5–6 mm embryonic stage. At the 11.5mm embryo stage, PPOA, PPHA, and PPTA disappeared in turn. At this time, PPIA and PComA became the main blood vessels for posterior circulation. Normally, these primitive arteries disappear at the 14 mm stage of the embryo, and their functions are completely replaced by the posterior communicating artery and the vertebral basilar artery. The incidence of PTA is the highest, ranging from about 0.1–0.76% [ 6 ], followed by PHA, at approximately 0.02–0.1% [ 7 ], while the incidence of PPIA has not been reported in the literature. The incidence in this study of PPIA is approximately 0.01%. Additionally, PPIA has been reported to occur bilaterally in the literature [ 8 , 9 ], whereas in this study, it was observed unilaterally. Classification of PPIA PPIA was first reported in an autopsy by Gottschuu in 1885 [ 10 ]. In 1954, Padget named it as the intersegmental artery for the first time[ 11 ]. In 1978, Lasjaunias et al. divided it into two types based on the anatomical origin of the persistent anterior atlantic intersegmental artery (PIA)[ 3 ]. Type I originated from the internal carotid artery or carotid sinus, while Type II originated from the external carotid artery. It was reported that the starting position of PPIA Type II was lower than that of Type I, and the distance was longer, requiring passage through the C1 transverse foramen. Therefore, PPIA Type II generally appeared more tortuous and complex than Type I. The origin points of Type I and Type II in this group were located at the level of the C2-C3 cervical vertebra, consistent with the literature report. In type II, four cases of PPIA passed through the deep surface of the splenius capitis and C1 transverse foramen, one case passed through the deep surface of the splenius cervicis, and four cases passed through the deep surface of the longissimus capitis from outside of the transverse foramen, avoiding the transverse foramen of cervical vertebrae. This study suggests that the most typical imaging manifestation of PPIA type II is its origin from the external carotid artery and simultaneous passage through the foramen magnum, with passing through the transverse foramen not being a necessary condition. Two cases of PPIA type I passed through the deep surface of the cervical splenius muscle and directly entered the preatlantic space from the outside of the transverse foramen, consistent with literature reports. Both PPIA type I and PHA originated from the internal carotid artery. PPIA enters the posterior cranial fossa through the foramen magnum, while PHA enters the middle cranial fossa through the hypoglossal canal. The different cranial passages are the most significant feature to distinguish them[ 12 ]. Understanding the origin and course of PPIA could help avoid damaging blood vessels during operations[ 13 , 14 ]. PPIAs pose a potential risk of injury in carotid endarterectomy, carotid stenting, C1-2 cervical fixation, or other neck surgeries[ 15 , 16 ]. In this study, PPIA was classified into four types based on the blood supply from the persistent artery, vertebral artery, and posterior communicating artery to the posterior circulation. There were four cases in type 1 (36.4%) and four cases in type 2 (36.4%), both of which were relatively common. Additionally, there was one case in type 3 (9.1%) and two cases in type 4 (18.2%), and these two types were relatively rare. This classification was primarily based on the blood supply source of the posterior circulation system in PPIA patients, providing a more comprehensive evaluation of the role of PPIA. The relationship between PPIA, the internal carotid artery, and the basilar artery can be considered as an expanded version of the circle of Willis. The main function of PPIA is to serve as a blood circulation channel between the internal carotid artery and the basilar artery[ 17 ]. Since PPIA is often associated with ipsilateral vertebral artery dysplasia, its primary role is frequently to replace the ipsilateral vertebral artery and supplement the blood supply of the posterior circulation. However, in cases where the ipsilateral internal carotid artery with PPIA experiences severe proximal stenosis or is absent, PPIA can serve as a bypass collateral vessel connecting the anterior and posterior circulation to supplement the blood supply of the anterior circulation[ 18 ]. In situations where both vertebral arteries are dysplastic, the presence of PPIA provides a natural channel for intravascular embolization of the posterior circulation[ 19 ]. Ray HM et al. reported the use of percutaneous retrograde external carotid artery embolization to treat bleeding in PPIA II patients[ 20 ]. Therefore, the new classification provides a basis for the selection of interventional surgical approaches. Clinical Presentation and Importance PPIA should undergo atrophy and degeneration after the formation of intracranial anastomotic branches. During the process of degeneration and fusion, relatively fragile endothelial cells may have been retained. The vessels of PPIA may exhibit structural defects in the arterial wall and hemodynamic abnormalities. Consequently, these vessels may be accompanied by aneurysms and vascular variations[ 21 , 22 ]. The literature has reported eight cases of aneurysms associated with PPIA[ 21 , 23 , 24 ]. This study reports 2 cases of aneurysms, with one located in the PPIA artery itself and the other located in the communicating segment of the internal carotid artery. Additionally, this study identified 3 cases of arterial variation, including the A2 segment of the anterior cerebral artery co-trunked, the left carotid artery co-trunked with the brachiocephalic trunk, and the left vertebral artery originating from the aortic arch. Furthermore, one case of PPIA with PAVM was reported for the first time. The degradation process of PPIA coincides with the development process of the vertebral artery and basilar artery. If PPIA does not degenerate, it will replace the function of the vertebral artery for posterior circulation blood supply. Therefore, the presence of PPIA is prone to be associated with vertebral artery and basilar artery dysplasia[ 10 , 16 , 25 ]. In this study, 11 cases with ipsilateral vertebral artery absence, 3 cases with contralateral vertebral artery dysplasia, 1 case with contralateral vertebral artery undeveloped, and 2 cases with basilar artery dysplasia were identified. Among the eleven patients, 7 cases exhibited symptoms of cerebral blood supply insufficiency, including dizziness and headache, which may be closely related to vertebral artery dysplasia and basilar artery dysplasia. Although PPIA can compensate for the blood flow in the posterior circulation, type II PIA, originating from the external carotid artery with a long travel distance and shallow position, may experience continuous pulling or compression by muscles and fascia during cold stimulation or head and neck rotation movements. This can lead to vasospasm and contraction, causing ischemic symptoms in the posterior circulation. Type I PPIA will shunt blood from the internal carotid artery to the posterior circulation, reducing blood flow in the anterior circulation and affecting cerebral perfusion, resulting in transient ischemia of the anterior circulation system. In particular, the symptoms will be aggravated when severe stenosis occurs at the distal end of the internal carotid artery after the internal carotid artery sends out PPIA. In this study, one case of cerebral infarction and one case of cerebral hemorrhage were observed. Although there was no direct evidence linking PPIA to cerebrovascular disease, previous reports indicated that PPIA patients experienced cerebrovascular accidents, including cerebral hemorrhage [ 27 ]. These incidents could be associated with factors such as hypertension, cerebral infarction [ 2 ] resulting from vascular occlusion or thrombosis, and subclavian steal [ 28 ]. Conclusion PPIA was a rare variant of internal carotid basilar artery anastomosis. This study used a new classification method to classify PPIA into 4 types, which was more conducive to the evaluation of posterior circulation blood supply. It provided a basis for selecting the surgical pathway for posterior circulation intervention. Although this variation of PPIA was rare, using MSCTA could reduce the missed diagnosis of PPIA and other cephalic and cervical vascular diseases, and provide a more comprehensive imaging evaluation for interventional and surgical operations. Abbreviations VA vertebral artery BA Basilar artery PComA Posterior communicating artery Eca External carotid artery Ica Internal carotid artery Aca Anterior cerebral artery PAVF Pulmonary arteriovenous fistula C2 Level of the second cervical vertebra C3 Level of the third cervical vertebra Declarations Author Contribution "X.Y. wrote the main manuscript text and M.W. prepared figures 1a-d and figures 2a-d. All authors reviewed the manuscript." References Weon YC, Choi SH, Hwang JC, Shin SH, Kwon WJ, Kang BS (2011) Classification of persistent primitive trigeminal artery (PPTA): a reconsideration based on MRA. 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Supplementary Files Table.zip Cite Share Download PDF Status: Published Journal Publication published 02 Dec, 2024 Read the published version in Surgical and Radiologic Anatomy → Version 1 posted Editorial decision: Revision requested 19 Aug, 2024 Reviews received at journal 19 Aug, 2024 Reviews received at journal 17 Jul, 2024 Reviewers agreed at journal 08 Jul, 2024 Reviews received at journal 04 Jul, 2024 Reviewers agreed at journal 04 Jul, 2024 Reviewers agreed at journal 03 Jul, 2024 Reviewers invited by journal 03 Jul, 2024 Editor assigned by journal 03 Jul, 2024 Submission checks completed at journal 02 Jul, 2024 First submitted to journal 28 Jun, 2024 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. 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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-4654199","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":328350789,"identity":"2ac13892-e07f-4990-8c07-efee9751f74c","order_by":0,"name":"Xiao Qin","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA50lEQVRIiWNgGAWjYDACZhBhwCDDcID5AFQogTgtPAwH2BIbiNMCBUAtPIbEaTE4zvzwwZuCOzx8N3K+P7qZc5iBnz3HgOHnDtxaJJvZjA3nGDzjkbyRu7E5d9thBsmeNwaMvWdwa+FnZjCT5jE4zGMA02JwI8eAmbENtxY2ZvZvUC05D8Fa7Alp4WfmgdmSwwixRYKAFslmnmKgXw7zSJ55Zjg7d1s6j8SZZwUHe/FoMTh/fOODN38Oy/EdT37wOXebtRx/e/LGBz/xaAEDHhAhkIBgHyCgAaqMn7C6UTAKRsEoGKEAACjEUVtkyuF6AAAAAElFTkSuQmCC","orcid":"","institution":"Department of Radiology, Daping Hospital, Army Medical University","correspondingAuthor":true,"prefix":"","firstName":"Xiao","middleName":"","lastName":"Qin","suffix":""},{"id":328350790,"identity":"9d7e99a3-7317-4fc5-9872-133e40879190","order_by":1,"name":"Xinju Yang","email":"","orcid":"","institution":"Department of Neurology , The Second People's Hospital of Banan District","correspondingAuthor":false,"prefix":"","firstName":"Xinju","middleName":"","lastName":"Yang","suffix":""},{"id":328350791,"identity":"a05e8e93-13d0-4dde-b546-cbe398b817ef","order_by":2,"name":"Yi Mao","email":"","orcid":"","institution":"Department of Radiology, Daping Hospital, Army Medical University","correspondingAuthor":false,"prefix":"","firstName":"Yi","middleName":"","lastName":"Mao","suffix":""},{"id":328350794,"identity":"86d3b531-4e4b-4619-b66e-1f3cf4038932","order_by":3,"name":"Shunan Wang","email":"","orcid":"","institution":"Department of Radiology, Daping Hospital, Army Medical University","correspondingAuthor":false,"prefix":"","firstName":"Shunan","middleName":"","lastName":"Wang","suffix":""}],"badges":[],"createdAt":"2024-06-28 10:45:49","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-4654199/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-4654199/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00276-024-03524-5","type":"published","date":"2024-12-02T15:57:11+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":61176525,"identity":"4b27c584-eedc-4613-91b0-28e6b15a4f12","added_by":"auto","created_at":"2024-07-26 15:45:40","extension":"jpeg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":473809,"visible":true,"origin":"","legend":"\u003cp\u003eFig1a (Type 1,which was persistent arterial dominance type),Fig1b (Type 2,which was balanced type),Fig1c (Type 3,which was vertebral artery dominance type),Fig1d (Type 4,which was PComA blood-supply type).VA(vertebral artery),BA(Basilar artery),PComA(Posterior communicating artery),Eca(External carotid artery),Ica(Internal carotid artery),PIA I(Type I of PPIA),PIA II(Type II of PPIA).\u003c/p\u003e","description":"","filename":"floatimage116.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4654199/v1/81052ffb449042531bfb5604.jpeg"},{"id":61177409,"identity":"6556460e-7c86-43ca-a0a6-59fd87486b3a","added_by":"auto","created_at":"2024-07-26 15:53:40","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":612647,"visible":true,"origin":"","legend":"\u003cp\u003eFig2a (Type 1,Male, 70s years old, with symptoms of walking instability),Fig2b (Type 2,Female, 50s years old, with headache symptoms),Fig2c (Type 3,Male, 70s years old, with dizziness),Fig2d (Male, 70s years old, with dizziness).The white arrow shows the PPIA.\u003c/p\u003e","description":"","filename":"floatimage313.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-4654199/v1/01649dea09fc2a52c1abca94.jpeg"},{"id":70964646,"identity":"92bc6bfc-1e90-46c3-900d-7f61fe791f70","added_by":"auto","created_at":"2024-12-09 16:13:31","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1452919,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-4654199/v1/965b850d-1fb7-4dc1-ae13-7e830cb0f492.pdf"},{"id":61178713,"identity":"ef35a24d-6b02-49a1-bf67-56e1779e821c","added_by":"auto","created_at":"2024-07-26 16:01:40","extension":"zip","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":15021,"visible":true,"origin":"","legend":"","description":"","filename":"Table.zip","url":"https://assets-eu.researchsquare.com/files/rs-4654199/v1/b444b593ba3d4d904ffbc09a.zip"}],"financialInterests":"No competing interests reported.","formattedTitle":"Persistent Proatlantal Intersegmental Artery(PPIA):Are Consideration Based On MSCTA","fulltext":[{"header":"Introduction","content":"\u003cp\u003eAt the embryonic stage, there were four temporary anastomotic vessels between the primitive carotid artery and the longitudinal neural artery, including those of the primitive trigeminal artery, primitive otic artery, primitive hypoglossal artery, and primitive proatlantal intersegmental artery from top to bottom. If these primitive arteries do not degenerate in adulthood, they are called persistent internal carotid basilar arteries[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. PPIA is a rare type of persistent internal carotid basilar artery[\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Currently, literature on PPIA has mainly focused on case reports, and its classification still follows the summary of Lasjaunias P in 1978[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e], which was based on anatomical origin. However, there is a lack of study in a large study population, and the incidence rate has not been reported. This study aimed to investigate the prevalence of PPIA in a large study population and use MSCTA to identify its types, including anatomical origin and posterior circulation blood supply. We also discussed their clinical implications and the probable embryological mechanisms by which to explain these observed variants.\u003c/p\u003e"},{"header":"Material and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003ePatients and the MSCTA technique\u003c/h2\u003e \u003cp\u003eA total of 105,052 patients underwent head and neck MSCTA examinations from January 2013 to December 2021. Among these patients, 11 cases were diagnosed with PPIA through MSCTA, with ages ranging from 47.0 to 76.0 years and an average age of (59.5\u0026thinsp;\u0026plusmn;\u0026thinsp;10.4) years. This study retrospectively analyzed the imaging manifestations, including the origin, endpoint, vascular path of PPIA, and its relationship with persistent artery, vertebral artery, basilar artery, posterior communicating artery, and other combined cerebrovascular diseases. Additionally, the study analyzed the clinical symptoms of patients with PPIA. MSCTA was performed using GE Lightspeed VCT (64-slice spiral CT) and Philips Brilliance iCT (256-slice spiral CT). Scanning parameters were set as follows: tube voltage 100 kV, tube current 200 mA, pitch 0.984:1, tube rotation speed 0.8. The contrast medium used was a non-ionic iodine contrast medium (iohexol injection, Omnipaque) with a ratio of 50\u0026thinsp;~\u0026thinsp;80 mL of contrast medium to 40\u0026thinsp;~\u0026thinsp;50 mL of normal saline, and the injection rate was 5\u0026thinsp;~\u0026thinsp;6.5 mL/s. Scanning extended from the aortic arch to the top of the skull. Digital subtraction imaging technology was applied to subtract the images before and after the injection of the contrast agent. Cephalic and cervical artery images were then extracted based on the subtracted images. After scanning, the original data were transmitted to ADW 4.3 for post-processing on a workstation, involving 2D and 3D post-processing techniques such as maximum intensity projection (MIP), multiplanar reconstruction (MPR), and volume rendering (VR). Finally, the processed data were transmitted to the Picture Archiving and Communication Systems (PACS) workstation.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eImage analysis\u003c/h2\u003e \u003cp\u003eThe diagnosis of all patients in the 'PACS' system is collaboratively conducted by a junior physician holding a practicing physician qualification certificate and an intermediate practicing physician with an intermediate practicing physician qualification certificate. Using the PACS system, we screened all patients who had undergone head and neck MSCTA examinations, imported their data into Excel, eliminated duplicate entries, and then searched for words closely related to PPIA diagnosis, such as 'persistent'、 'primitive'、' anterior atlantic intersegmental artery'、 'connected'、 'variant'、'dysplasia' etc. After retrieving the patient data, two physicians with 7 and 10 years of neuroimaging work experience and a comprehensive understanding of PPIA diagnostic criteria conducted the MSCTA image review. The final diagnosis of PPIA was collaboratively determined by the two physicians.\u003c/p\u003e \u003cp\u003eThe PPIA images were retrospectively analyzed by two radiologists with a consensus, and PPIA was classified according to our new classifications. They focused on observing Maximum Intensity Projection (MIP) and Volume Rendering (VR) images by combining the cross-section and coronary plane of the original CT sectional images to determine the origin, course, and endpoint of PPIA. Special attention was paid to the relationship between PPIA and the vertebral artery, posterior communicating artery (PcomA), and basilar artery. Additionally, they further analyzed other vascular diseases in the head and neck, including aneurysm, vascular stenosis, vascular dysplasia, etc., reaching an agreement through negotiation in cases of differences of opinion. The study received approval from our institutional review board.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eClassification of the PPIA\u003c/h2\u003e \u003cp\u003ePPIA was classified into two types based on anatomical origin [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Type I of PPIA originated from the internal carotid artery or the bifurcation of the common carotid artery, at the level between the C2 and C4 vertebrae. It then passed through the lateral side of the vertebral transverse process foramen of the C1 vertebra, rose to the anterior atlantal space, and passed through the foramen magnum to anastomose with the ipsilateral or contralateral vertebral arteries. Type II originated from the external carotid artery, equivalent to the level of the C2 or C3 vertebra. It either entered or did not enter the C1 transverse foramen forward, entering the atlantoaxial space, and then passed through the foramen magnum to the intracranial region, eventually anastomosing with the ipsilateral or contralateral vertebral artery.\u003c/p\u003e \u003cp\u003eIn this study, PPIA was categorized into four types based on the blood supply of the posterior circulation involving persistent artery, vertebral artery, and posterior communicating artery. Type 1 represents the dominant persistent arterial blood supply, where the posterior circulation is primarily supported by persistent arteries. In this type, both the persistent artery and the basilar artery exhibited normal development, and the ipsilateral and contralateral vertebral arteries could be well or poorly developed, with the optional development of the posterior communicating artery (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e1\u003c/span\u003ea). Type 2 was identified as the balanced type, with the posterior circulation mainly supplied by PPIA and the contralateral vertebral artery. This type displayed normal development of PPIA, contralateral vertebral artery, and basilar artery, with dysplastic ipsilateral vertebral artery, and the optional development of the posterior communicating artery (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e1\u003c/span\u003eb). Type 3 represents the vertebral artery-dominant type, where the posterior circulation is primarily supported by the contralateral vertebral artery. It showed normal development of the contralateral vertebral artery and basilar artery, with dysplastic ipsilateral vertebral artery and PPIA, and the optional development of the posterior communicating artery (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e1\u003c/span\u003ec). Type 4 was identified as the posterior communicating artery blood-supply type, where the posterior circulation blood supply was mainly provided by the communicating artery. This type exhibited dysplasia in the bilateral vertebral artery, basilar artery, and PPIA, with normal development of the posterior communicating artery (Fig.\u0026nbsp;\u003cspan refid=\"Fig9\" class=\"InternalRef\"\u003e1\u003c/span\u003ed).\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003ePrevalence and sex distribution of the PPIA\u003c/h2\u003e \u003cp\u003eA total of 105,052 patients underwent MSCTA, and 11 patients were diagnosed with PPIA, resulting in an incidence of 0.01%. Among them, 5 were males (45.5%) and 6 were females (54.5%). All 11 cases of PPIA occurred unilaterally, with 8 cases on the left side and 3 cases on the right side. The ages ranged from 47.0 to 76.0 years, with an average age of (59.5\u0026thinsp;\u0026plusmn;\u0026thinsp;10.4) years. Among these patients, 7 had symptoms of cerebral blood insufficiency such as dizziness (n\u0026thinsp;=\u0026thinsp;6) and headache (n\u0026thinsp;=\u0026thinsp;1). One patient presented with pontine infarction, resulting in limitation of left limb movement. Another case had a cerebral hemorrhage in the right insular lobe, leading to walking instability. One case was diagnosed with viral encephalitis, exhibiting symptoms such as nausea, vomiting, and mental disorder. One case had no obvious symptoms (Table\u0026nbsp;1).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section2\"\u003e \u003ch2\u003eClassification and anatomical characteristics of the PPIA\u003c/h2\u003e \u003cp\u003eBased on the anatomical origin of PPIA, it can be classified into PPIA type I and type II. There are 2 cases of type 1, both occurring on the right side. One case originated from the internal carotid artery, and another case originated from the carotid sinus, with both starting points equivalent to the level of the C3 cervical vertebra.\u003c/p\u003e \u003cp\u003eSubsequently, it traversed the deep surface of the cervical splenius muscle, entering the preatlantic space directly from the outside of the transverse foramen, and ultimately passed through the foramen magnum into the skull to anastomose with the contralateral vertebral arteries. There were 9 cases of PPIA type II (81.8%), with 8 cases on the left side and 1 case on the right side, all originating from the external carotid artery. The starting point of 2 cases was equivalent to the level of the C3 cervical vertebra, and 7 cases were equivalent to the level of the C2 cervical vertebra. Among them, 4 cases passed through the deep surface of the splenius capitis and C1 transverse foramen, 1 case passed through the deep surface of the splenius cervicis, and 4 cases passed through the deep surface of the longissimus capitis from the outside of the transverse foramen. Subsequently, they traversed the atlantoaxial space and the foramen magnum, anastomosing with the contralateral vertebral arteries eventually.\u003c/p\u003e \u003cp\u003eThe authors of this study classified PPIA into four types based on its relationship with the vertebral artery and posterior communicating artery in terms of posterior circulation blood supply. Type 1 had four cases where the posterior circulation was primarily supplied by persistent arteries, with normal development of both PPIA and the basilar artery, but with the absence of ipsilateral vertebral artery(Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e2\u003c/span\u003ea). Type 2 had four cases where the posterior circulation was mainly supplied by PPIA and contralateral vertebral artery, with normal development of both PPIA, contralateral vertebral artery, and the basilar artery, but with ipsilateral vertebral artery absence(Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e2\u003c/span\u003eb). Type 3 had one case where the posterior circulation was mainly supplied by contralateral vertebral artery blood, with normal development of the contralateral vertebral artery and basilar artery, but with ipsilateral vertebral artery absence and PPIA dysplasia, along with contralateral PComA development(Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e2\u003c/span\u003ec). Type 4 had two cases where the posterior circulation was mainly supplied by PComA, with bilateral vertebral artery, basilar artery, and PPIA dysplasia, along with bilateral PComA development(Fig.\u0026nbsp;\u003cspan refid=\"Fig10\" class=\"InternalRef\"\u003e2\u003c/span\u003ed).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section2\"\u003e \u003ch2\u003ePPIA combined with other vascular abnormalities\u003c/h2\u003e \u003cp\u003eIn this study, 11 patients exhibited ipsilateral vertebral artery absence, 3 patients had contralateral vertebral artery agenesis, and 1 patient showed contralateral vertebral artery absence. Additionally, 2 cases presented with basilar artery dysplasia. Among the cases, 5 showed development of PComA, with 3 cases being unilateral and 2 cases bilateral. Two patients with PPIA were complicated with aneurysms, one located at the beginning of PPIA, and the other at the communicating segment of the contralateral internal carotid artery. One patient experienced pontine infarction, and another had a pulmonary arteriovenous fistula. Furthermore, 3 patients exhibited arterial variations: one showed co-trunking of the A2 segment of the anterior cerebral artery, another displayed the left common carotid artery co-trunking with the brachiocephalic trunk, and the third had the left vertebral artery originating from the aortic arch (Table\u0026nbsp;1).\u003c/p\u003e \u003c/div\u003e"},{"header":"Discussion","content":"\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003eEmbryogenesis of the PPIA\u003c/h2\u003e \u003cp\u003eIn the early embryonic period, four transient vessels originating from the primitive internal carotid artery and dorsal aorta were known as primitive carotid-vertebrobasilar anastomoses, which would supply blood to the future vertebrobasilar artery. If these pathways did not degenerate in adulthood, they were called permanent internal carotid basilar arteries. These persistent arteries were named according to the accompanying cranial nerves, among which PPIA had no accompanying nerves. The persistent arteries were named as PPTA, PPOA, PPHA, and PPIA from top to bottom. In 1948, Dorcas Hager Padget published an authoritative treatise on embryology and the development of the human cerebral vascular system. Based on this, Namba, K., further elaborated on the development and degradation process of the primitive internal carotid basilar artery in 2017 [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. At the 3mm stage of the embryo, two branches sprout from the first aortic arch: the primitive internal carotid and the primitive trigeminal arteries. This marks the earliest appearance of the trigeminal artery, communicating with the primordial hindbrain channel. At the 4mm embryonic stage, PPIA, PPOA, PPHA, and PPTA were the anterior branches of the dorsal aorta serving as an anastomosis between the original internal carotid artery and bilateral longitudinal nerve arteries, providing blood supply to the hindbrain. These longitudinal nerve arteries fused at the 5\u0026ndash;9 mm embryonic stage, forming the basilar artery for posterior circulation blood supply. The communicating artery developed at the 5\u0026ndash;6 mm embryonic stage. At the 11.5mm embryo stage, PPOA, PPHA, and PPTA disappeared in turn. At this time, PPIA and PComA became the main blood vessels for posterior circulation. Normally, these primitive arteries disappear at the 14 mm stage of the embryo, and their functions are completely replaced by the posterior communicating artery and the vertebral basilar artery.\u003c/p\u003e \u003cp\u003eThe incidence of PTA is the highest, ranging from about 0.1\u0026ndash;0.76% [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e], followed by PHA, at approximately 0.02\u0026ndash;0.1% [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e], while the incidence of PPIA has not been reported in the literature. The incidence in this study of PPIA is approximately 0.01%. Additionally, PPIA has been reported to occur bilaterally in the literature [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], whereas in this study, it was observed unilaterally.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section2\"\u003e \u003ch2\u003eClassification of PPIA\u003c/h2\u003e \u003cp\u003ePPIA was first reported in an autopsy by Gottschuu in 1885 [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. In 1954, Padget named it as the intersegmental artery for the first time[\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. In 1978, Lasjaunias et al. divided it into two types based on the anatomical origin of the persistent anterior atlantic intersegmental artery (PIA)[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Type I originated from the internal carotid artery or carotid sinus, while Type II originated from the external carotid artery. It was reported that the starting position of PPIA Type II was lower than that of Type I, and the distance was longer, requiring passage through the C1 transverse foramen. Therefore, PPIA Type II generally appeared more tortuous and complex than Type I. The origin points of Type I and Type II in this group were located at the level of the C2-C3 cervical vertebra, consistent with the literature report.\u003c/p\u003e \u003cp\u003eIn type II, four cases of PPIA passed through the deep surface of the splenius capitis and C1 transverse foramen, one case passed through the deep surface of the splenius cervicis, and four cases passed through the deep surface of the longissimus capitis from outside of the transverse foramen, avoiding the transverse foramen of cervical vertebrae. This study suggests that the most typical imaging manifestation of PPIA type II is its origin from the external carotid artery and simultaneous passage through the foramen magnum, with passing through the transverse foramen not being a necessary condition. Two cases of PPIA type I passed through the deep surface of the cervical splenius muscle and directly entered the preatlantic space from the outside of the transverse foramen, consistent with literature reports. Both PPIA type I and PHA originated from the internal carotid artery. PPIA enters the posterior cranial fossa through the foramen magnum, while PHA enters the middle cranial fossa through the hypoglossal canal. The different cranial passages are the most significant feature to distinguish them[\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. Understanding the origin and course of PPIA could help avoid damaging blood vessels during operations[\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. PPIAs pose a potential risk of injury in carotid endarterectomy, carotid stenting, C1-2 cervical fixation, or other neck surgeries[\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. In this study, PPIA was classified into four types based on the blood supply from the persistent artery, vertebral artery, and posterior communicating artery to the posterior circulation. There were four cases in type 1 (36.4%) and four cases in type 2 (36.4%), both of which were relatively common. Additionally, there was one case in type 3 (9.1%) and two cases in type 4 (18.2%), and these two types were relatively rare.\u003c/p\u003e \u003cp\u003eThis classification was primarily based on the blood supply source of the posterior circulation system in PPIA patients, providing a more comprehensive evaluation of the role of PPIA. The relationship between PPIA, the internal carotid artery, and the basilar artery can be considered as an expanded version of the circle of Willis. The main function of PPIA is to serve as a blood circulation channel between the internal carotid artery and the basilar artery[\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSince PPIA is often associated with ipsilateral vertebral artery dysplasia, its primary role is frequently to replace the ipsilateral vertebral artery and supplement the blood supply of the posterior circulation. However, in cases where the ipsilateral internal carotid artery with PPIA experiences severe proximal stenosis or is absent, PPIA can serve as a bypass collateral vessel connecting the anterior and posterior circulation to supplement the blood supply of the anterior circulation[\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. In situations where both vertebral arteries are dysplastic, the presence of PPIA provides a natural channel for intravascular embolization of the posterior circulation[\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. Ray HM et al. reported the use of percutaneous retrograde external carotid artery embolization to treat bleeding in PPIA II patients[\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Therefore, the new classification provides a basis for the selection of interventional surgical approaches.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section2\"\u003e \u003ch2\u003eClinical Presentation and Importance\u003c/h2\u003e \u003cp\u003ePPIA should undergo atrophy and degeneration after the formation of intracranial anastomotic branches. During the process of degeneration and fusion, relatively fragile endothelial cells may have been retained. The vessels of PPIA may exhibit structural defects in the arterial wall and hemodynamic abnormalities. Consequently, these vessels may be accompanied by aneurysms and vascular variations[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. The literature has reported eight cases of aneurysms associated with PPIA[\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e, \u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e]. This study reports 2 cases of aneurysms, with one located in the PPIA artery itself and the other located in the communicating segment of the internal carotid artery. Additionally, this study identified 3 cases of arterial variation, including the A2 segment of the anterior cerebral artery co-trunked, the left carotid artery co-trunked with the brachiocephalic trunk, and the left vertebral artery originating from the aortic arch. Furthermore, one case of PPIA with PAVM was reported for the first time.\u003c/p\u003e \u003cp\u003eThe degradation process of PPIA coincides with the development process of the vertebral artery and basilar artery. If PPIA does not degenerate, it will replace the function of the vertebral artery for posterior circulation blood supply. Therefore, the presence of PPIA is prone to be associated with vertebral artery and basilar artery dysplasia[\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e25\u003c/span\u003e]. In this study, 11 cases with ipsilateral vertebral artery absence, 3 cases with contralateral vertebral artery dysplasia, 1 case with contralateral vertebral artery undeveloped, and 2 cases with basilar artery dysplasia were identified. Among the eleven patients, 7 cases exhibited symptoms of cerebral blood supply insufficiency, including dizziness and headache, which may be closely related to vertebral artery dysplasia and basilar artery dysplasia. Although PPIA can compensate for the blood flow in the posterior circulation, type II PIA, originating from the external carotid artery with a long travel distance and shallow position, may experience continuous pulling or compression by muscles and fascia during cold stimulation or head and neck rotation movements. This can lead to vasospasm and contraction, causing ischemic symptoms in the posterior circulation. Type I PPIA will shunt blood from the internal carotid artery to the posterior circulation, reducing blood flow in the anterior circulation and affecting cerebral perfusion, resulting in transient ischemia of the anterior circulation system. In particular, the symptoms will be aggravated when severe stenosis occurs at the distal end of the internal carotid artery after the internal carotid artery sends out PPIA.\u003c/p\u003e \u003cp\u003eIn this study, one case of cerebral infarction and one case of cerebral hemorrhage were observed. Although there was no direct evidence linking PPIA to cerebrovascular disease, previous reports indicated that PPIA patients experienced cerebrovascular accidents, including cerebral hemorrhage [\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e27\u003c/span\u003e]. These incidents could be associated with factors such as hypertension, cerebral infarction [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] resulting from vascular occlusion or thrombosis, and subclavian steal [\u003cspan citationid=\"CR28\" class=\"CitationRef\"\u003e28\u003c/span\u003e].\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusion","content":"\u003cp\u003ePPIA was a rare variant of internal carotid basilar artery anastomosis. This study used a new classification method to classify PPIA into 4 types, which was more conducive to the evaluation of posterior circulation blood supply. It provided a basis for selecting the surgical pathway for posterior circulation intervention. Although this variation of PPIA was rare, using MSCTA could reduce the missed diagnosis of PPIA and other cephalic and cervical vascular diseases, and provide a more comprehensive imaging evaluation for interventional and surgical operations.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eVA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003evertebral artery\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eBA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eBasilar artery\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePComA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePosterior communicating artery\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eEca\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eExternal carotid artery\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eIca\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eInternal carotid artery\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eAca\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAnterior cerebral artery\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePAVF\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePulmonary arteriovenous fistula\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eC2\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eLevel of the second cervical vertebra\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eC3\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eLevel of the third cervical vertebra\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003e\"X.Y. wrote the main manuscript text and M.W. prepared figures 1a-d and figures 2a-d. All authors reviewed the manuscript.\"\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eWeon YC, Choi SH, Hwang JC, Shin SH, Kwon WJ, Kang BS (2011) Classification of persistent primitive trigeminal artery (PPTA): a reconsideration based on MRA. Acta Radiol 52(9):1043\u0026ndash;1051\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUchino A, Saito N, Inoue K (2012) Type 2 proatlantal intersegmental artery associated with persistent trigeminal artery diagnosed by MR angiography. Surg Radiol Anat 34(8):773\u0026ndash;776\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLasjaunias P, Th\u0026eacute;ron J, Moret J (1978) The occipital artery. Anatomy\u0026ndash;normal arteriographic aspects\u0026ndash;embryological significance. Neuroradiology 15(1):31\u0026ndash;37\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUchino A, Saito N, Kohyama S (2019) Persistent second cervical intersegmental artery diagnosed by MR angiography. Radiol Case Rep 14(8):967\u0026ndash;970\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNamba K (2017) Carotid-vertebrobasilar Anastomoses with Reference to Their Segmental Property. Neurol Med Chir (Tokyo) 57(6):267\u0026ndash;277\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMeckel S, Spittau B, McAuliffe W (2013) The persistent trigeminal artery: development, imaging anatomy, variants, and associated vascular pathologies. Neuroradiology 55(1):5\u0026ndash;16\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVasović L, Milenković Z, Jovanović I, Cukuranović R, Jovanović P, Stefanović I (2008) Hypoglossal artery: a review of normal and pathological features. Neurosurg Rev 31(4):385\u0026ndash;395 discussion 395\u0026thinsp;\u0026ndash;\u0026thinsp;386\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePelz D, Ranjith K, Menon RH, Swartz RI, Aviv (2013) Sean P Symons. Bilateral Type II Persistent Proatlantal Intersegmental Arteries. Can J Neurol Sci 40(6):873\u0026ndash;874\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFang Y, Li S, Zhang C (2022) Bilateral type IIpersistent proatlantal intersegmental artery: a rare variant of persistent carotid-vertebrobasilar anastomoses. BJR Case Rep 8(2):20210154\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eVasović L, Mojsilović M, Andelković Z, Jovanović I, Arsić S, Vlajković S et al (2009) Proatlantal intersegmental artery: a review of normal and pathological features. Childs Nerv Syst 25(4):411\u0026ndash;421\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDH P (1954) Designation of the embryonic intersegmental arteries in reference to the vertebral artery and subclavian stem. Anat Rec 119(3):349\u0026ndash;356\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAnderson RA, Sondheimer FK (1976) Rare carotid-vertebrobasilar anastomoses with notes on the differentiation between proatlantal and hypoglossal arteries. Neuroradiology 11(3):113\u0026ndash;118\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDuntze J, Pech-gourg G, Adetchessi T, Armaganian G, Rakotozanany P (2012) Fuentes SModified posterior atlantoaxial screw-rod fixation in a case of persistent first intersegmental artery. Case report and literature review. Neurochirurgie 58(6):369\u0026ndash;371\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eUmebayashi D, Hara M, Nakajima Y, Nishimura (2013) Y,Wakabayashi T.Posterior fixation for atlantoaxial subluxation in a case with complex anomaly of persistent first intersegmental artery and assimilation in the C1 vertebra. Neurol Med Chir (Tokyo) 53(12):882\u0026ndash;886\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGrego F, Straman\u0026agrave; R, Lepidi S, Antonello M, Bonvini S, Zaramella M et al (2004) Primitive proatlantal intersegmental artery and carotid endarterectomy. J Vasc Surg 39(3):691\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLin CM, Chang CH, Wong HF (2021) Management of intracranial vertebral artery stenosis with ipsilateral vertebral artery hypoplasia and contralateral vertebral artery occlusion via type 2 proatlantal intersegmental artery. Biomed J 44(3):369\u0026ndash;372\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZuflacht JP, Liang C, Burkhardt JK, Favilla CG (2022) Whole-Brain Perfusion via Right Common Carotid Artery With Type 2 Proatlantal Intersegmental Artery. Stroke 53(11):e481\u0026ndash;e482\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHaiqi Z, Feng L, Cong L (2020) Reflux compensation of persistent proatlantal intersegmental artery: report of one case. Br J Neurosurg. :1\u0026ndash;3\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhao L, Yang L, Liu X, Wang X, Zhang G, Wu J (2022) Case Report: Stent Retriever Thrombectomy of Acute Basilar Artery Occlusion via the Type 1 Proatlantal Intersegmental Artery. Front Neurol 13:812458\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eRay HM, Kuban JD, Tam AL, Huynh TT, Pisimisis GT (2020) Percutaneous retrograde left external carotid artery coil embolization for management of hemorrhage from a persistent proatlantal intersegmental artery type 2. J Vasc Surg Cases Innov Tech 6(2):250\u0026ndash;253\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSaito N, Uchino A, Ishihara S (2013) Complex anomalies of type 1 proatlantal intersegmental artery and aortic arch variations. Surg Radiol Anat 35(2):177\u0026ndash;180\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003ePurkayastha S, Gupta AK, Varma R, Kapilamoorthy TR (2005) Proatlantal intersegmental arteries of external carotid artery origin associated with Galen's vein malformation. AJNR Am J Neuroradiol 26(9):2378\u0026ndash;2383\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNonaka Y, Nakatani K, Tanigawara T, Hattori T, Ohkuma A, Kaku Y et al (2001) A case of a persistent primitive proatlantal intersegmental artery with a ruptured basilar bifurcation aneurysm. No Shinkei Geka 29(8):775\u0026ndash;779\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSato H, Fujiwara S, Otabe K, Sato S (1985) [A case of persistent primitive proatlantal intersegmental artery (proatlantal artery I) with aneurysm\u0026ndash;a case report]. No Shinkei Geka 13(1):117\u0026ndash;121\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYu W, Feng Z, Zhao C, Fu C (2017) Proatlantal intersegmental artery with internal carotid artery stenosis. Neurology 89(1):104\u0026ndash;105\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMontechiari M, Iadanza A, Falini A, Politi LS (2013) Monolateral type I proatlantal artery with bilateral absence of vertebral arteries: description of a case and review of the literature. Surg Radiol Anat 35(9):863\u0026ndash;865\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eTakahashi S, Itoh Y (1989) [Proatlantal intersegmental artery associated with hypertensive intracerebral hemorrhage. Case report]. Neurol Med Chir (Tokyo) 29(2):146\u0026ndash;150\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbla AA, Kan P, Jahshan S, Dumont TM, Levy EI, Siddiqui AH (2014) External carotid dissection and external carotid proatlantal intersegmental artery with subclavian steal prompting external carotid and subclavian artery stenting. J Neuroimaging 24(4):399\u0026ndash;403\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTable 1 is available in the Supplementary Files section.\u003c/p\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":"surgical-and-radiologic-anatomy","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"sara","sideBox":"Learn more about [Surgical and Radiologic Anatomy](http://link.springer.com/journal/276)","snPcode":"276","submissionUrl":"https://submission.nature.com/new-submission/276/3","title":"Surgical and Radiologic Anatomy","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"Persistent proatlantal intersegmental artery, Multi-Slice Spiral CT Angiography (MSCTA), Vertebral artery, Internal carotid, External carotid artery","lastPublishedDoi":"10.21203/rs.3.rs-4654199/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4654199/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003ePersistent proatlantal intersegmental artery (PPIA) is a rare permanent carotid-basilar anastomosis. Multi-slice spiral CT Angiography (MSCTA) has become the primary non-invasive imaging technique for evaluating cephalic and cervical vascular anatomy.\u003c/p\u003e\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eTo investigate the MSCTA imaging characteristics of PPIA and its clinical values, and then to provide a new classification method based on posterior circulation blood supply.\u003c/p\u003e\u003ch2\u003eMaterial and Methods\u003c/h2\u003e \u003cp\u003eThe imaging and clinical data of 11 patients with PPIA diagnosed by MSCTA through combined head and neck scanning were analyzed retrospectively.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eThe incidence of PPIA was 0.01%. Classification according to the starting position of PPIA revealed 2 cases (18.2%) of type I and 9 cases (81.8%) of type II. When classified according to the blood supply of posterior circulation, type 1 of PPIA had 4 cases (36.4%), type 2 had 4 cases (36.4%), type 3 had 1 case (9.1%), and type 4 had 2 cases (18.2%). Among the 11 PPIA patients, there were 11 cases of ipsilateral vertebral artery absence, 3 cases of contralateral vertebral artery dysplasia, 1 case of contralateral vertebral artery absence, 2 cases of persistent artery dysplasia, and 2 cases of basilar artery dysplasia. Additionally, there were 2 patients with aneurysms, 1 patient with cerebral infarction, and 1 patient with Pulmonary Arteriovenous Fistula (PAVF).\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eThe new classification of PPIA is more conducive to evaluating posterior circulation blood supply and providing a more comprehensive imaging evaluation for interventional and surgical procedures. MSCTA can accurately diagnose PPIA and reduce the rate of missed diagnoses of other vascular diseases.\u003c/p\u003e","manuscriptTitle":"Persistent Proatlantal Intersegmental Artery(PPIA):Are Consideration Based On MSCTA","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-07-26 15:45:35","doi":"10.21203/rs.3.rs-4654199/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-08-19T21:27:01+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-08-19T13:38:41+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-17T17:27:44+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"22715340706493679366152123406602661691","date":"2024-07-08T09:01:35+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-07-04T12:13:29+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"215299245106210216253515004517038872300","date":"2024-07-04T09:27:23+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"190719830874664149909447650546342256567","date":"2024-07-03T21:57:09+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-07-03T21:15:02+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-07-03T15:49:17+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-07-02T05:16:06+00:00","index":"","fulltext":""},{"type":"submitted","content":"Surgical and Radiologic Anatomy","date":"2024-06-28T10:44:32+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"surgical-and-radiologic-anatomy","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"sara","sideBox":"Learn more about [Surgical and Radiologic Anatomy](http://link.springer.com/journal/276)","snPcode":"276","submissionUrl":"https://submission.nature.com/new-submission/276/3","title":"Surgical and Radiologic Anatomy","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"0140ed97-dd44-472a-aa5a-23e4cf625490","owner":[],"postedDate":"July 26th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-12-09T16:00:16+00:00","versionOfRecord":{"articleIdentity":"rs-4654199","link":"https://doi.org/10.1007/s00276-024-03524-5","journal":{"identity":"surgical-and-radiologic-anatomy","isVorOnly":false,"title":"Surgical and Radiologic Anatomy"},"publishedOn":"2024-12-02 15:57:11","publishedOnDateReadable":"December 2nd, 2024"},"versionCreatedAt":"2024-07-26 15:45:35","video":"","vorDoi":"10.1007/s00276-024-03524-5","vorDoiUrl":"https://doi.org/10.1007/s00276-024-03524-5","workflowStages":[]},"version":"v1","identity":"rs-4654199","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4654199","identity":"rs-4654199","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}