Aberrant course of the right petrous internal carotid artery (ICA) associated with right type 1 proatlantal artery and bilateral occipital arteries arising from the ICA diagnosed by computed tomography angiography

Aberrant course of the right petrous internal carotid artery (ICA) associated with right type 1 proatlantal artery and bilateral occipital arteries arising from the ICA diagnosed by computed tomography angiography | 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 Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Aberrant course of the right petrous internal carotid artery (ICA) associated with right type 1 proatlantal artery and bilateral occipital arteries arising from the ICA diagnosed by computed tomography angiography Akira Uchino, Kazuo Tokushige This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-3837191/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 23 Aug, 2024 Read the published version in Surgical and Radiologic Anatomy → Version 1 posted 8 You are reading this latest preprint version Abstract Purpose To describe a case of multiple extremely rare cervical arterial variations. Methods A 55-year-old man with a tentative diagnosis of right internal carotid artery (ICA) stenosis was examined using computed tomography (CT) angiography for the evaluation of vascular lesions in the neck and head region. A 64-slice CT machine was used. Results On CT angiography, there was laterally located and narrowed petrous segment of the right ICA, indicative of aberrant course of the petrous ICA. Right vertebral artery (VA) was small in caliber and a relatively large anomalous artery arose from the proximal right ICA. This anomalous artery entered the posterior fossa via the foramen magnum, indicative of a type 1 proatlantal artery. Right occipital artery (OA) arose from the proximal ICA. The left OA also arose from the proximal ICA. Conclusion An aberrant course of the petrous ICA is an extremely rare arterial variation which is formed by segmental agenesis of the cervical ICA, and the collateral channel passes through the middle ear cavity. It can be dangerous during middle ear surgery. The type 1 proatlantal artery is also an extremely rare arterial variation formed by the persistence of the proatlantal intersegmental artery. It is clinically significant because of its unique blood flow from the carotid system to the vertebrobasilar system. The OA rarely arises from the proximal ICA. Identification of these cervical arterial variations before surgery and vascular intervention are important to avoid complications during the procedure. Cervical arterial variations Computed tomography angiography Internal carotid artery Occipital artery Proatlantal artery Figures Figure 1 Figure 2 Figure 3 Introduction There are many types of cervical arterial variations. Most of these are incidentally detected during daily clinical practice using magnetic resonance (MR) angiography and computed tomography (CT) angiography. Some of these are clinically significant due to their unique courses and distinct hemodynamics. We herein report a case of an aberrant course of the right petrous internal carotid artery (ICA) [ 1 , 4 , 10 , 11 ] associated with the right type 1 proatlantal artery [ 2 , 6 , 7 ] and bilateral occipital arteries (OAs) arising from proximal ICAs [ 3 , 5 , 8 , 9 ]. To our knowledge, this has not been reported in the relevant English-language literature. Case report A 55-year-old man with a tentative diagnosis of right ICA stenosis was sent from a private clinic to our hospital. He had neither significant symptoms or neurological signs. To evaluate arterial lesions, CT angiography was performed from the aortic arch to the intracranial region. A 64-slice CT machine was used (SOMATOM Definition Flash, Siemens Healthineers, Erlangen, Germany). CT angiography revealed a laterally located and narrowed petrous segment of the right ICA. This artery passed through the middle ear cavity, indicative of aberrant course of the petrous ICA. The right vertebral artery (VA) was small in caliber and a relatively large anomalous artery arose from the proximal right ICA. This anomalous artery entered posterior fossa via the foramen magnum, indicative of type 1 proatlantal artery. There was a moderately sized left VA. The right OA also arose from the proximal ICA artery. The left OA arose from the proximal ICA (Figs. 1 – 3 ). No treatments were performed. The patient’s clinical course was uneventful. Discussion There are many types of cervical arterial variations. Arterial variations may develop from the failure of fusion/regression or abnormal fusion/regression during early embryonic stages. Cervical arterial variations have been reported by cadaver dissections, surgeries, and radiological examinations. Recently, both MR angiography and CT angiography are widely and frequently used for the evaluation of neck and head vascular lesions, and their quality has improved. Thus, the incidence of incidentally diagnosed arterial variations is increasing. Aberrant course of petrous ICA An aberrant course of the petrous ICA is an extremely rare but clinically significant arterial variation, which may cause several symptoms such as pulsatile tinnitus [ 1 ]. As this anomalous ICA runs in the middle ear cavity, it is dangerous during middle ear surgery. Lasjaunias et al. [ 4 ] hypothesized the genesis of an aberrant ICA as an alternate flow of blood, in which involution of the cervical ICA due to the persistence of the pharyngeal artery system leads to blood flow via the ascending pharyngeal artery to the enlarged inferior tympanic artery, with retrograde flow through the carotico-tympanic vessels into the horizontal segment of the petrous ICA. An aberrant ICA may be associated with other arterial variations such as the type 1 proatlantal artery [ 11 ] and OA arising from the ICA [ 10 ]. However, we could not find any cases of an aberrant course of the petrous ICA associated with both the type 1 proatlantal artery and OA arising from the ICA in the relevant English-language literature. Type 1 proatlantal artery The type 1 proatlantal artery is an extremely rare congenital anastomosis between the proximal ICA and the VA. It enters the posterior fossa via the foramen magnum. This variation was due to the persistence of the proatlantal intersegmental artery. In contrast, the type 2 proatlantal artery arises from the proximal ECA, enters the foramen magnum, and is formed by the persistence of the first cervical intersegmental artery [ 2 ]. A type 1 proatlantal artery may be associated with other arterial variations. Saito et al. [ 7 ] reported a case of type 1 proatlantal artery associated with an aberrant right subclavian artery and direct aortic arch origin left VA. Our patient also aberrant course of the petrous ICA and bilateral OAs arising from the ICAs. In the case of a large type 1 proatlantal artery, the bilateral VAs are hypoplastic [ 6 ]. In such cases, the brainstem and cerebellum are supplied only by the type 1 proatlantal artery. Our patient had a moderately sized type 1 proatlantal artery, with a tiny ipsilateral VA and a moderately sized contralateral VA. The OA arising from the ICA The OA rarely arises from the proximal ICA. Its MR angiographic prevalence is reported to be 0.09% per artery [ 9 ]. Using CT angiography, its prevalence was reported to be 0.2% per artery [ 3 ]. It usually arises from the posterior or anterior wall of the carotid bulb. Our patient had bilateral OAs arising from the posterior wall. Extremely rarely, the OA can arise at the C2 vertebral body level cervical ICA [ 8 ]. Lasjaunias et al. [ 5 ] reported the formation of OA from the proatlantal artery and arising from the primitive internal carotid, external carotid, and vertebral arteries at points determined by the sites of regression. If the proatlantal artery persists without communication with the VA, an OA arising from the ICA is formed. Conclusions We encountered a case of multiple, extremely rare cervical arterial variations. The identification of these cervical arterial variations before surgery and vascular intervention is very important to avoid complications during the procedure. Declarations Author contributions AU carried out the study design and drafted the manuscript. AU and KT reviewed the manuscript critically, and have read and approved the final manuscript. Funding The authors did not receive support from any organization for the submitted work. Data availability Not applicable. Conflict of interest The authors declare no competing interests. Ethical approval and consent to participate All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. Consent for publication The patient signed informed consent regarding publishing his data and figures. References Endo K, Maruyama Y, Tsukatani T, Furukawa M (2006) Aberrant internal carotid artery as a cause of objective pulsatile tinnitus. Auris Nasus Larynx 33:447–450. 10.1016/j.anl.2006.03.007 Gumus T, Onal B, Ilgit ET (2004) Bilateral persistence of type 1 proatlantal arteries: report of a case and review of the literature. AJNR Am J Neuroradiol 25:1622–1624 Iwai T, Izumi T, Inoue T, Maegawa J, Mitsudo K, Tohnai I (2012) Incidence of the occipital artery arising from the internal carotid artery identified by three-dimensional computed tomographic angiography. Br J Oral Maxillofac Surg 50:373–375. 10.1016/j.bjoms.2011.05.014 Lasjaunias P, Moret J, Manelfe C, Théron J, Hasso T, Seeger J (1977) Arterial anomalies at the base of the skull. Neuroradiology 13:267–272. 10.1007/BF00347072 Lasjaunias P, Théron J, Moret J (1978) The occipital artery. Anatomy–normal arteriographic aspects–embryological significance. Neuroradiology 15:31–37. 10.1007/BF00327443 Montechiari 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 35:863–865. 10.1007/s00276-013-1086-4 Saito N, Uchino A, Ishihara S (2013) Complex anomalies of type 1 proatlantal intersegmental artery and aortic arch variations. Surg Radiol Anat 35:177–180. 10.1007/s00276-012-1017-9 Uchino A, Saito N (2020) Occipital artery arising from the cervical internal carotid artery at the level of the C2 vertebral body: three cases detected utilizing magnetic resonance angiography. Surg Radiol Anat 42:831–834. 10.1007/s00276-020-02460-4 Uchino A, Saito N, Mizukoshi W, Okada Y (2011) Anomalous origin of the occipital artery diagnosed by magnetic resonance angiography. Neuroradiology 53:853–857. 10.1007/s00234-010-0825-z Uchino A, Saito N, Okano N, Kakehi Y (2015) Aberrant internal carotid artery associated with occipital artery arising from the internal carotid artery. Surg Radiol Anat 37:1137–1140. 10.1007/s00276-015-1451-6 Watanabe K, Uchino A, Kimura H, Baba Y (2022) Aberrant course of the petrous internal carotid artery associated with ipsilateral type 1 proatlantal artery. Surg Radiol Anat 44:407–409. 10.1007/s00276-022-02892-0 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 23 Aug, 2024 Read the published version in Surgical and Radiologic Anatomy → Version 1 posted Editorial decision: Revision requested 01 Feb, 2024 Reviews received at journal 13 Jan, 2024 Reviewers agreed at journal 12 Jan, 2024 Reviewers agreed at journal 12 Jan, 2024 Reviewers invited by journal 12 Jan, 2024 Editor assigned by journal 12 Jan, 2024 Submission checks completed at journal 11 Jan, 2024 First submitted to journal 05 Jan, 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. We do this by developing innovative software and high quality services for the global research community. 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Also discoverable on Platform About Our Team In Review Editorial Policies 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-3837191","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":266628405,"identity":"67b0b001-8979-449d-8800-af6514c49486","order_by":0,"name":"Akira Uchino","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA50lEQVRIiWNgGAWjYHACNoYEBgYe+/bmgw+APB4+YrXIGfAcSzYAaWEjSgsQGBtI5JhJwLn4AP+M5GcPHu6wSdzOkJZW+TXHToaNgfnhoxt4tEjcSDM3SDyTlriz4fCx27LbkoEOYzM2zsFnzY0cNonEtsOJDQfb0m5LbmMGauFhk8anRR6u5TCPWbHktnrCWgygWowNjvGYMX7cdpiwFsMzz8yAWtLkJHvYkqUZtx3nYWMm4Be548nPJH+22fDwyz8++PHntmp7fvbmh4/xeh8ZMPOASWKVgwDjD1JUj4JRMApGwYgBAKOfRxxHpWQSAAAAAElFTkSuQmCC","orcid":"","institution":"Saitama Sekishinkai Hospital","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Akira","middleName":"","lastName":"Uchino","suffix":""},{"id":266628406,"identity":"6e08e2ff-25ed-4c06-8dec-a533470b5715","order_by":1,"name":"Kazuo Tokushige","email":"","orcid":"","institution":"Saitama Sekishinkai Hospital","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Kazuo","middleName":"","lastName":"Tokushige","suffix":""}],"badges":[],"createdAt":"2024-01-05 12:14:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-3837191/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-3837191/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1007/s00276-024-03466-y","type":"published","date":"2024-08-23T15:57:47+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":49639635,"identity":"d9ccfaea-31cb-4c0a-8eb0-faf7963b179d","added_by":"auto","created_at":"2024-01-15 18:52:52","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":1351971,"visible":true,"origin":"","legend":"\u003cp\u003ePostero-anterior (a), left posterior oblique (b), left anterior oblique (c), and right anterior oblique (d) projections of volume-rendering images of computed tomography (CT) angiography. There is a laterally located and narrowed petrous segment of the right internal carotid artery (ICA), indicative of an aberrant course of the petrous ICA (\u003cem\u003elong arrows\u003c/em\u003e). The right vertebral artery (VA) is small in caliber and a relatively large anomalous artery is arising from the proximal right ICA. This anomalous artery enters the posterior fossa at the level of the foramen magnum (\u003cem\u003eshort arrows\u003c/em\u003e), indicative of type 1 proatlantal artery. There is a moderately sized left VA. The right occipital artery (OA) also arises from the proximal ICA simultaneously (\u003cem\u003edotted long arrows\u003c/em\u003e). The left OA arises from the proximal ICA (\u003cem\u003edotted short arrows\u003c/em\u003e).\u003c/p\u003e","description":"","filename":"Fig1ab.pptx.png","url":"https://assets-eu.researchsquare.com/files/rs-3837191/v1/0b2635cf080360520c9bf7a2.png"},{"id":49640266,"identity":"9dcee0fc-34a0-4734-9853-5441677f0739","added_by":"auto","created_at":"2024-01-15 19:00:52","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":143888,"visible":true,"origin":"","legend":"\u003cp\u003eCurved maximum-intensity-projection image of CT angiography. The narrowed right ICA runs in the middle ear cavity, indicative of an aberrant course of the petrous ICA (\u003cem\u003elong arrow\u003c/em\u003e).\u003c/p\u003e","description":"","filename":"Fig2.pptx.png","url":"https://assets-eu.researchsquare.com/files/rs-3837191/v1/743f29ec603bd0080904244e.png"},{"id":49639634,"identity":"81a2323a-dc55-4fa3-8703-6136e61c56c3","added_by":"auto","created_at":"2024-01-15 18:52:52","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":121418,"visible":true,"origin":"","legend":"\u003cp\u003eCT angiographic source image of the foramen magnum level. The anomalous artery originating from the proximal right ICA enters via the foramen magnum, indicative of a type 1 proatlantal artery (\u003cem\u003eshort arrow\u003c/em\u003e).\u003c/p\u003e","description":"","filename":"Fig3.pptx.png","url":"https://assets-eu.researchsquare.com/files/rs-3837191/v1/fa8612f7f8a0cca7b2d2a8cd.png"},{"id":63300712,"identity":"167c0c8f-bbec-4877-97ca-2cd9f7774686","added_by":"auto","created_at":"2024-08-26 16:16:54","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2195550,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-3837191/v1/16935069-594c-41cd-8d53-ec8fbd3ebf58.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Aberrant course of the right petrous internal carotid artery (ICA) associated with right type 1 proatlantal artery and bilateral occipital arteries arising from the ICA diagnosed by computed tomography angiography","fulltext":[{"header":"Introduction","content":"\u003cp\u003eThere are many types of cervical arterial variations. Most of these are incidentally detected during daily clinical practice using magnetic resonance (MR) angiography and computed tomography (CT) angiography. Some of these are clinically significant due to their unique courses and distinct hemodynamics.\u003c/p\u003e \u003cp\u003eWe herein report a case of an aberrant course of the right petrous internal carotid artery (ICA) [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] associated with the right type 1 proatlantal artery [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] and bilateral occipital arteries (OAs) arising from proximal ICAs [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. To our knowledge, this has not been reported in the relevant English-language literature.\u003c/p\u003e"},{"header":"Case report","content":"\u003cp\u003eA 55-year-old man with a tentative diagnosis of right ICA stenosis was sent from a private clinic to our hospital. He had neither significant symptoms or neurological signs. To evaluate arterial lesions, CT angiography was performed from the aortic arch to the intracranial region. A 64-slice CT machine was used (SOMATOM Definition Flash, Siemens Healthineers, Erlangen, Germany).\u003c/p\u003e \u003cp\u003eCT angiography revealed a laterally located and narrowed petrous segment of the right ICA. This artery passed through the middle ear cavity, indicative of aberrant course of the petrous ICA. The right vertebral artery (VA) was small in caliber and a relatively large anomalous artery arose from the proximal right ICA. This anomalous artery entered posterior fossa via the foramen magnum, indicative of type 1 proatlantal artery. There was a moderately sized left VA. The right OA also arose from the proximal ICA artery. The left OA arose from the proximal ICA (Figs.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eNo treatments were performed. The patient\u0026rsquo;s clinical course was uneventful.\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eThere are many types of cervical arterial variations. Arterial variations may develop from the failure of fusion/regression or abnormal fusion/regression during early embryonic stages. Cervical arterial variations have been reported by cadaver dissections, surgeries, and radiological examinations. Recently, both MR angiography and CT angiography are widely and frequently used for the evaluation of neck and head vascular lesions, and their quality has improved. Thus, the incidence of incidentally diagnosed arterial variations is increasing.\u003c/p\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003eAberrant course of petrous ICA\u003c/h2\u003e \u003cp\u003eAn aberrant course of the petrous ICA is an extremely rare but clinically significant arterial variation, which may cause several symptoms such as pulsatile tinnitus [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. As this anomalous ICA runs in the middle ear cavity, it is dangerous during middle ear surgery. Lasjaunias et al. [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] hypothesized the genesis of an aberrant ICA as an alternate flow of blood, in which involution of the cervical ICA due to the persistence of the pharyngeal artery system leads to blood flow via the ascending pharyngeal artery to the enlarged inferior tympanic artery, with retrograde flow through the carotico-tympanic vessels into the horizontal segment of the petrous ICA.\u003c/p\u003e \u003cp\u003eAn aberrant ICA may be associated with other arterial variations such as the type 1 proatlantal artery [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e] and OA arising from the ICA [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. However, we could not find any cases of an aberrant course of the petrous ICA associated with both the type 1 proatlantal artery and OA arising from the ICA in the relevant English-language literature.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eType 1 proatlantal artery\u003c/h3\u003e\n\u003cp\u003eThe type 1 proatlantal artery is an extremely rare congenital anastomosis between the proximal ICA and the VA. It enters the posterior fossa via the foramen magnum. This variation was due to the persistence of the proatlantal intersegmental artery. In contrast, the type 2 proatlantal artery arises from the proximal ECA, enters the foramen magnum, and is formed by the persistence of the first cervical intersegmental artery [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eA type 1 proatlantal artery may be associated with other arterial variations. Saito et al. [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e] reported a case of type 1 proatlantal artery associated with an aberrant right subclavian artery and direct aortic arch origin left VA. Our patient also aberrant course of the petrous ICA and bilateral OAs arising from the ICAs. In the case of a large type 1 proatlantal artery, the bilateral VAs are hypoplastic [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. In such cases, the brainstem and cerebellum are supplied only by the type 1 proatlantal artery. Our patient had a moderately sized type 1 proatlantal artery, with a tiny ipsilateral VA and a moderately sized contralateral VA.\u003c/p\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003eThe OA arising from the ICA\u003c/h2\u003e \u003cp\u003eThe OA rarely arises from the proximal ICA. Its MR angiographic prevalence is reported to be 0.09% per artery [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. Using CT angiography, its prevalence was reported to be 0.2% per artery [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. It usually arises from the posterior or anterior wall of the carotid bulb. Our patient had bilateral OAs arising from the posterior wall. Extremely rarely, the OA can arise at the C2 vertebral body level cervical ICA [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Lasjaunias et al. [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] reported the formation of OA from the proatlantal artery and arising from the primitive internal carotid, external carotid, and vertebral arteries at points determined by the sites of regression. If the proatlantal artery persists without communication with the VA, an OA arising from the ICA is formed.\u003c/p\u003e \u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eWe encountered a case of multiple, extremely rare cervical arterial variations. The identification of these cervical arterial variations before surgery and vascular intervention is very important to avoid complications during the procedure.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAuthor contributions\u0026nbsp;\u003c/strong\u003eAU carried out the study design and drafted the manuscript. AU and KT reviewed the manuscript critically, and have read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e The authors did not receive support from any organization for the submitted work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability\u003c/strong\u003e Not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConflict of interest\u003c/strong\u003e The authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthical approval and consent to participate\u003c/strong\u003e All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e The patient signed informed consent regarding publishing his data and figures.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eEndo K, Maruyama Y, Tsukatani T, Furukawa M (2006) Aberrant internal carotid artery as a cause of objective pulsatile tinnitus. Auris Nasus Larynx 33:447\u0026ndash;450. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.anl.2006.03.007\u003c/span\u003e\u003cspan address=\"10.1016/j.anl.2006.03.007\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGumus T, Onal B, Ilgit ET (2004) Bilateral persistence of type 1 proatlantal arteries: report of a case and review of the literature. AJNR Am J Neuroradiol 25:1622\u0026ndash;1624\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIwai T, Izumi T, Inoue T, Maegawa J, Mitsudo K, Tohnai I (2012) Incidence of the occipital artery arising from the internal carotid artery identified by three-dimensional computed tomographic angiography. 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Surg Radiol Anat 37:1137\u0026ndash;1140. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00276-015-1451-6\u003c/span\u003e\u003cspan address=\"10.1007/s00276-015-1451-6\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWatanabe K, Uchino A, Kimura H, Baba Y (2022) Aberrant course of the petrous internal carotid artery associated with ipsilateral type 1 proatlantal artery. Surg Radiol Anat 44:407\u0026ndash;409. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00276-022-02892-0\u003c/span\u003e\u003cspan address=\"10.1007/s00276-022-02892-0\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\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":"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":"Cervical arterial variations, Computed tomography angiography, Internal carotid artery, Occipital artery, Proatlantal artery","lastPublishedDoi":"10.21203/rs.3.rs-3837191/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-3837191/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003ePurpose\u003c/h2\u003e \u003cp\u003eTo describe a case of multiple extremely rare cervical arterial variations.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA 55-year-old man with a tentative diagnosis of right internal carotid artery (ICA) stenosis was examined using computed tomography (CT) angiography for the evaluation of vascular lesions in the neck and head region. A 64-slice CT machine was used.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eOn CT angiography, there was laterally located and narrowed petrous segment of the right ICA, indicative of aberrant course of the petrous ICA. Right vertebral artery (VA) was small in caliber and a relatively large anomalous artery arose from the proximal right ICA. This anomalous artery entered the posterior fossa via the foramen magnum, indicative of a type 1 proatlantal artery. Right occipital artery (OA) arose from the proximal ICA. The left OA also arose from the proximal ICA.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eAn aberrant course of the petrous ICA is an extremely rare arterial variation which is formed by segmental agenesis of the cervical ICA, and the collateral channel passes through the middle ear cavity. It can be dangerous during middle ear surgery. The type 1 proatlantal artery is also an extremely rare arterial variation formed by the persistence of the proatlantal intersegmental artery. It is clinically significant because of its unique blood flow from the carotid system to the vertebrobasilar system. The OA rarely arises from the proximal ICA. Identification of these cervical arterial variations before surgery and vascular intervention are important to avoid complications during the procedure.\u003c/p\u003e","manuscriptTitle":"Aberrant course of the right petrous internal carotid artery (ICA) associated with right type 1 proatlantal artery and bilateral occipital arteries arising from the ICA diagnosed by computed tomography angiography","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-01-15 18:52:47","doi":"10.21203/rs.3.rs-3837191/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2024-02-01T21:34:03+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-01-13T07:22:33+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"e2c4694d-8516-4f7b-ab09-22c8e65859d8","date":"2024-01-12T07:12:08+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"14cc6afd-de2d-4e43-bb90-b3b6abc9d96a","date":"2024-01-12T07:10:24+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-01-12T06:49:19+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-01-12T06:31:11+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-01-11T05:12:41+00:00","index":"","fulltext":""},{"type":"submitted","content":"Surgical and Radiologic Anatomy","date":"2024-01-05T12:12:12+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":"59514b13-280a-41af-a43f-5ac7a3f1ca97","owner":[],"postedDate":"January 15th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2024-08-26T16:09:33+00:00","versionOfRecord":{"articleIdentity":"rs-3837191","link":"https://doi.org/10.1007/s00276-024-03466-y","journal":{"identity":"surgical-and-radiologic-anatomy","isVorOnly":false,"title":"Surgical and Radiologic Anatomy"},"publishedOn":"2024-08-23 15:57:47","publishedOnDateReadable":"August 23rd, 2024"},"versionCreatedAt":"2024-01-15 18:52:47","video":"","vorDoi":"10.1007/s00276-024-03466-y","vorDoiUrl":"https://doi.org/10.1007/s00276-024-03466-y","workflowStages":[]},"version":"v1","identity":"rs-3837191","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-3837191","identity":"rs-3837191","version":["v1"]},"buildId":"omnImTCwR2MFx8CMYfrG7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}