{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,22]],"date-time":"2026-05-22T07:07:17Z","timestamp":1779433637075,"version":"3.53.1"},"reference-count":43,"publisher":"Scientific Scholar","content-domain":{"domain":["surgicalneurologyint.com"],"crossmark-restriction":true},"short-container-title":[],"abstract":"\n Background:<\/jats:title>\n Congenital anomalies of the internal carotid artery (ICA), including hypoplasia, aplasia, and agenesis, are rare vascular conditions with a prevalence below 0.01%. Most patients remain asymptomatic because of collateral cerebral circulation, yet these anomalies may cause cerebrovascular complications, particularly ischemic events and intracranial aneurysm formation.<\/jats:p>\n <\/jats:sec>\n \n Methods:<\/jats:title>\n A narrative literature review was performed to synthesize available data on demographics, embryology, pathophysiology, clinical presentation, imaging evaluation, classification systems, management, and outcomes of congenital ICA anomalies.<\/jats:p>\n <\/jats:sec>\n \n Results:<\/jats:title>\n ICA agenesis is commonly detected incidentally, especially in unilateral cases with adequate collateral pathways. Symptomatic cases, more frequent in bilateral involvement, may present with headache, transient ischemic attack, stroke, or impaired consciousness. Risk factors include bilateral absence, incomplete collateral circulation, and classification patterns such as Lie types C and D and Jamous type 1b, associated with increased hemodynamic stress and aneurysm formation. Computed tomography (CT) angiography, magnetic resonance angiography, and digital subtraction angiography are central to diagnosis, whereas skull base CT distinguishes agenesis from hypoplasia. Management is usually conservative in asymptomatic patients, whereas surgical or endovascular treatment is reserved for aneurysms or hemodynamic compromise.<\/jats:p>\n <\/jats:sec>\n \n Conclusion:<\/jats:title>\n ICA agenesis is a rare but clinically important anomaly. Recognition of variants, imaging features, and complications is essential for diagnosis and procedural planning. Surveillance imaging and individualized management help reduce cerebrovascular morbidity.<\/jats:p>\n <\/jats:sec>","DOI":"10.25259\/sni_272_2026","type":"journal-article","created":{"date-parts":[[2026,5,22]],"date-time":"2026-05-22T06:30:00Z","timestamp":1779431400000},"page":"297","update-policy":"https:\/\/doi.org\/10.25259\/crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Internal carotid artery agenesis: A narrative review"],"prefix":"10.25259","volume":"17","author":[{"given":"Khalid Talal","family":"Alghamdi","sequence":"first","affiliation":[{"name":"Department of Neurosurgery, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Badr E.","family":"Hafiz","sequence":"additional","affiliation":[{"name":"Department of Neurosciences, King Faisal Specialist Hospital and Research Centre, Jeddah, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zubaidah","family":"Alahmari","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, Imam Abdulrahman Bin Faisal University, King Fahad Hospital of the University, Khobar, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Thamer H.","family":"Alsharif","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, King Abdulaziz Specialist Hospital, Taif, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Homoud","family":"Aldahash","sequence":"additional","affiliation":[{"name":"Department of Neurosurgery, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Saleh S.","family":"Baeesa","sequence":"additional","affiliation":[{"name":"Department of Neurosciences, King Faisal Specialist Hospital and Research Centre, Jeddah, Saudi Arabia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"10894","published-online":{"date-parts":[[2026,5,22]]},"reference":[{"key":"10.25259\/SNI_272_2026\/ref-1","doi-asserted-by":"crossref","first-page":"1363","DOI":"10.1007\/s00276-020-02549-w","article-title":"Rare congenital anomalies of the internal carotid artery: Anatomic and radiologic aspects of three cases and review of the literature","volume":"42","author":"Akdemir Akta\u015f","year":"2020","journal-title":"Surg Radiol Anat"},{"key":"10.25259\/SNI_272_2026\/ref-2","doi-asserted-by":"crossref","first-page":"221","DOI":"10.25259\/SNI_238_2020","article-title":"Unilateral absence of the internal carotid artery associated with anterior communicating artery aneurysms: Systematic review and a proposed management algorithm","volume":"11","author":"Al-Khafaji","year":"2020","journal-title":"Surg Neurol Int"},{"key":"10.25259\/SNI_272_2026\/ref-3","first-page":"1154","article-title":"Dysgenesis of the internal carotid artery associated with transsphenoidal encephalocele: A neural crest syndrome?","volume":"20","author":"Blustajn","year":"1999","journal-title":"AJNR Am J Neuroradiol"},{"key":"10.25259\/SNI_272_2026\/ref-4","doi-asserted-by":"crossref","first-page":"375","DOI":"10.1007\/s00276-023-03102-1","article-title":"Proposed new classification for internal carotid artery segmental agenesis based on embryologic and angiographic correlation","volume":"45","author":"Bonasia","year":"2023","journal-title":"Surg Radiol Anat"},{"key":"10.25259\/SNI_272_2026\/ref-5","doi-asserted-by":"crossref","first-page":"252","DOI":"10.1007\/s002340050578","article-title":"Hypoplasia of the internal carotid artery with intercavernous anastomosis","volume":"40","author":"Chen","year":"1998","journal-title":"Neuroradiology"},{"key":"10.25259\/SNI_272_2026\/ref-6","doi-asserted-by":"crossref","first-page":"1027","DOI":"10.1179\/016164110X12767786356273","article-title":"Internal carotid artery agenesis: Diagnosis, clinical spectrum, associated conditions and its importance in the era of stroke interventions","volume":"32","author":"Cohen","year":"2010","journal-title":"Neurol Res"},{"key":"10.25259\/SNI_272_2026\/ref-7","first-page":"1953","article-title":"Congenital absence of the internal carotid artery: Case reports and review of the collateral circulation","volume":"22","author":"Curtis","year":"2001","journal-title":"AJNR Am J Neuroradiol"},{"key":"10.25259\/SNI_272_2026\/ref-8","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1007\/s002340050529","article-title":"Absence of the supraclinoid internal carotid artery in association with intracranial aneurysms","volume":"40","author":"Czarnecki","year":"1998","journal-title":"Neuroradiology"},{"key":"10.25259\/SNI_272_2026\/ref-9","first-page":"168","article-title":"Bilateral internal carotid artery hypoplasia and multiple posterior circulation aneurysms. Importance of 3DCTA for the diagnosis","volume":"19","author":"Erdem","year":"2009","journal-title":"Turk Neurosurg"},{"key":"10.25259\/SNI_272_2026\/ref-10","doi-asserted-by":"crossref","first-page":"1333","DOI":"10.1007\/s00247-012-2455-6","article-title":"Agenesis of the internal carotid artery: Associated malformations including a high rate of aortic and cardiac malformations","volume":"42","author":"Fitzgerald","year":"2012","journal-title":"Pediatr Radiol"},{"key":"10.25259\/SNI_272_2026\/ref-11","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1007\/s002709900334","article-title":"Congenital absence of the internal carotid artery","volume":"22","author":"Florio","year":"1999","journal-title":"Cardiovasc Intervent Radiol"},{"key":"10.25259\/SNI_272_2026\/ref-12","doi-asserted-by":"crossref","first-page":"113","DOI":"10.1016\/j.carpath.2007.04.009","article-title":"Bilateral internal carotid absence: A case report of a rare congenital anomaly","volume":"17","author":"Gonzalez-Cuyar","year":"2008","journal-title":"Cardiovasc Pathol"},{"key":"10.25259\/SNI_272_2026\/ref-13","doi-asserted-by":"crossref","first-page":"165","DOI":"10.2174\/1874364100802010165","article-title":"Rubeosis iridis resulting from agenesis of the internal carotid artery: A case report","volume":"2","author":"Gyotoku","year":"2008","journal-title":"Open Ophthalmol J"},{"key":"10.25259\/SNI_272_2026\/ref-14","first-page":"1307","article-title":"Internal carotid artery agenesis associated with contralateral posterior communicating artery and basilar tip aneurysms: A case report","volume":"6","author":"Hafiz","year":"2022","journal-title":"Int J Med Dev Ctries"},{"key":"10.25259\/SNI_272_2026\/ref-15","doi-asserted-by":"crossref","first-page":"352","DOI":"10.1016\/S0090-3019(97)00491-6","article-title":"Persistent primitive trigeminal artery associated with absence of internal carotid artery","volume":"50","author":"Hattori","year":"1998","journal-title":"Surg Neurol"},{"key":"10.25259\/SNI_272_2026\/ref-16","doi-asserted-by":"crossref","first-page":"308","DOI":"10.1161\/STROKEAHA.107.485185","article-title":"The cerebral vasculopathy of PHACES syndrome","volume":"39","author":"Heyer","year":"2008","journal-title":"Stroke"},{"key":"10.25259\/SNI_272_2026\/ref-17","doi-asserted-by":"crossref","first-page":"311","DOI":"10.1007\/s00234-003-1090-1","article-title":"Unilateral agenesis and hypoplasia of the internal carotid artery: A report of three cases","volume":"47","author":"Ito","year":"2005","journal-title":"Neuroradiology"},{"key":"10.25259\/SNI_272_2026\/ref-18","first-page":"647","article-title":"Collateral blood flow patterns in patients with unilateral ICA agenesis and cerebral aneurysm","volume":"28","author":"Jamous","year":"2007","journal-title":"Neuro Endocrinol Lett"},{"key":"10.25259\/SNI_272_2026\/ref-19","doi-asserted-by":"crossref","first-page":"658","DOI":"10.1136\/jmg.37.9.658","article-title":"JAGGED1 expression in human embryos: Correlation with the Alagille syndrome phenotype","volume":"37","author":"Jones","year":"2000","journal-title":"J Med Genet"},{"key":"10.25259\/SNI_272_2026\/ref-20","doi-asserted-by":"crossref","first-page":"1354","DOI":"10.1161\/01.CIR.0000121361.01862.A4","article-title":"Vascular anomalies in Alagille syndrome: A significant cause of morbidity and mortality","volume":"109","author":"Kamath","year":"2004","journal-title":"Circulation"},{"key":"10.25259\/SNI_272_2026\/ref-21","article-title":"Surgical Neuroangiography: Endovascular Treatment of Craniofacial Lesions","author":"Lasjaunias","year":"2012"},{"key":"10.25259\/SNI_272_2026\/ref-22","article-title":"Surgical Neuroangiography: Clinical Vascular Anatomy and Variations","author":"Lasjaunias","year":"2001"},{"key":"10.25259\/SNI_272_2026\/ref-23","doi-asserted-by":"crossref","first-page":"133","DOI":"10.1007\/BF01773165","article-title":"Segmental agenesis of the internal carotid artery: Angiographic aspects with embryological discussion","volume":"6","author":"Lasjaunias","year":"1984","journal-title":"Anat Clin"},{"key":"10.25259\/SNI_272_2026\/ref-24","doi-asserted-by":"crossref","first-page":"117","DOI":"10.1007\/s00701-002-1046-y","article-title":"Aplasia of the internal carotid artery","volume":"145","author":"Lee","year":"2003","journal-title":"Acta Neurochir (Wien)"},{"key":"10.25259\/SNI_272_2026\/ref-25","doi-asserted-by":"crossref","first-page":"186","DOI":"10.1177\/1971400917692162","article-title":"Internal carotid artery agenesis: A case report and review of literature","volume":"30","author":"Li","year":"2017","journal-title":"Neuroradiol J"},{"key":"10.25259\/SNI_272_2026\/ref-26","article-title":"Congenital Anomalies of the Carotid Arteries","author":"Lie","year":"1968"},{"key":"10.25259\/SNI_272_2026\/ref-27","doi-asserted-by":"crossref","first-page":"444","DOI":"10.1007\/s00234-003-1086-x","article-title":"Bilateral segmental regression of the carotid and vertebral arteries with rete compensation in a Western patient","volume":"46","author":"Mahadevan","year":"2004","journal-title":"Neuroradiology"},{"key":"10.25259\/SNI_272_2026\/ref-28","doi-asserted-by":"crossref","first-page":"385","DOI":"10.1007\/BF01628506","article-title":"Radiologic anatomy of segmental agenesis of the internal carotid artery","volume":"19","author":"Meder","year":"1997","journal-title":"Surg Radiol Anat"},{"key":"10.25259\/SNI_272_2026\/ref-29","doi-asserted-by":"crossref","first-page":"774","DOI":"10.3390\/diagnostics15060774","article-title":"A silent threat: Internal carotid artery hypoplasia and its role in basilar artery aneurysm formation-a case study","volume":"15","author":"Me\u017evinska","year":"2025","journal-title":"Diagnostics (Basel)"},{"key":"10.25259\/SNI_272_2026\/ref-30","doi-asserted-by":"crossref","first-page":"e35016","DOI":"10.1097\/MD.0000000000035016","article-title":"The ambiguous \u201cinternal carotid artery\u201d-Ultrasound diagnosis of congenital absence of the internal carotid artery: A case report and review of the literature","volume":"102","author":"Ning","year":"2023","journal-title":"Medicine (Baltimore)"},{"key":"10.25259\/SNI_272_2026\/ref-31","article-title":"Diagnostic Cerebral Angiography","author":"Osborn","year":"1999","edition":"2nd ed"},{"key":"10.25259\/SNI_272_2026\/ref-32","doi-asserted-by":"crossref","first-page":"858","DOI":"10.1007\/s003300000683","article-title":"Bilateral internal carotid agenesis: Value of CT angiography and correlation to embryogenesis","volume":"11","author":"Pilleul","year":"2001","journal-title":"Eur Radiol"},{"key":"10.25259\/SNI_272_2026\/ref-33","first-page":"61","article-title":"Azygous right internal carotid artery with congenital absence of the cervical left internal carotid artery associated with bilateral aberrant subclavian arteries","volume":"18","author":"Ross","year":"2024","journal-title":"J Radiol Case Rep"},{"key":"10.25259\/SNI_272_2026\/ref-34","doi-asserted-by":"crossref","first-page":"L130","DOI":"10.1007\/s00330-002-1742-2","article-title":"Bilateral congenital absence of the internal carotid artery","volume":"13","author":"Rumboldt","year":"2003","journal-title":"Eur Radiol"},{"key":"10.25259\/SNI_272_2026\/ref-35","first-page":"701","article-title":"Flow diversion with the pipeline embolization device in complex intracranial aneurysms: A US multicenter experience","volume":"71","author":"Siddiqui","year":"2012","journal-title":"Neurosurgery"},{"key":"10.25259\/SNI_272_2026\/ref-36","doi-asserted-by":"crossref","first-page":"213","DOI":"10.1002\/(SICI)1097-0096(199805)26:4<213::AID-JCU7>3.0.CO;2-G","article-title":"Agenesis of the internal carotid artery: Color Doppler, CT, and MR angiography findings","volume":"26","author":"Sliwka","year":"1998","journal-title":"J Clin Ultrasound"},{"key":"10.25259\/SNI_272_2026\/ref-37","doi-asserted-by":"crossref","first-page":"511","DOI":"10.1111\/j.1440-1754.2008.01357.x","article-title":"Bilateral agenesis of the internal carotid artery: Case report and approach to management","volume":"44","author":"Steer","year":"2008","journal-title":"J Paediatr Child Health"},{"key":"10.25259\/SNI_272_2026\/ref-38","doi-asserted-by":"crossref","first-page":"206","DOI":"10.1136\/jnnp.61.2.206","article-title":"Bilateral internal carotid artery agenesis","volume":"61","author":"Sunada","year":"1996","journal-title":"J Neurol Neurosurg Psychiatry"},{"key":"10.25259\/SNI_272_2026\/ref-39","first-page":"715","article-title":"EC-IC bypass surgery in hemodynamic cerebrovascular insufficiency","volume":"62","author":"Sundt","year":"1985","journal-title":"J Neurosurg"},{"key":"10.25259\/SNI_272_2026\/ref-40","first-page":"264","article-title":"Congenital hypoplasia of the internal carotid artery: A short review","volume":"9","author":"Suri","year":"2020","journal-title":"Brain Disord Ther"},{"key":"10.25259\/SNI_272_2026\/ref-41","doi-asserted-by":"crossref","first-page":"339","DOI":"10.1016\/j.amjoto.2004.04.008","article-title":"Congenital absence or hypoplasia of the carotid artery: Radioclinical issues","volume":"25","author":"Ta\u015far","year":"2004","journal-title":"Am J Otolaryngol"},{"key":"10.25259\/SNI_272_2026\/ref-42","first-page":"895","article-title":"A case of complete absence of the left internal carotid artery associated with an aneurysm of the anterior communicating artery (author\u2019s transl)","volume":"5","author":"Tsuruta","year":"1977","journal-title":"No Shinkei Geka"},{"key":"10.25259\/SNI_272_2026\/ref-43","doi-asserted-by":"crossref","first-page":"141","DOI":"10.1111\/j.1552-6569.2007.00092.x","article-title":"Internal carotid aplasia\/ hypoplasia and intracranial saccular aneurysms: Series of three new cases and systematic review of the literature","volume":"17","author":"Zink","year":"2007","journal-title":"J Neuroimaging"}],"container-title":["Surgical Neurology International"],"original-title":[],"language":"en","link":[{"URL":"http:\/\/surgicalneurologyint.com\/internal-carotid-artery-agenesis-a-narrative-review\/","content-type":"text\/html","content-version":"vor","intended-application":"text-mining"},{"URL":"http:\/\/surgicalneurologyint.com\/surgicalint-articles\/internal-carotid-artery-agenesis-a-narrative-review\/","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,22]],"date-time":"2026-05-22T06:30:07Z","timestamp":1779431407000},"score":1,"resource":{"primary":{"URL":"http:\/\/surgicalneurologyint.com\/surgicalint-articles\/internal-carotid-artery-agenesis-a-narrative-review\/"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,5,22]]},"references-count":43,"alternative-id":["10.25259\/SNI_272_2026"],"URL":"https:\/\/doi.org\/10.25259\/sni_272_2026","relation":{},"ISSN":["2152-7806","2229-5097"],"issn-type":[{"value":"2152-7806","type":"electronic"},{"value":"2229-5097","type":"print"}],"subject":[],"published":{"date-parts":[[2026,5,22]]},"article-number":"297"}}