Acute Internal Carotid Artery Embolism Combined with Chronic Middle Cerebral Artery Occlusion: A Report of Two Cases

Acute Internal Carotid Artery Embolism Combined with Chronic Middle Cerebral Artery Occlusion: A Report of Two Cases | 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 Case Report Acute Internal Carotid Artery Embolism Combined with Chronic Middle Cerebral Artery Occlusion: A Report of Two Cases Tianyao Ma, Jincheng Wu, Xianjun Wang, Hongyang Sun This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-9127526/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Endovascular thrombectomy (EVT) is the preferred treatment strategy for acute anterior circulation large vessel occlusion (LVO) stroke. Acute LVO most commonly arises from acute embolism or in-situ thrombosis superimposed on atherosclerotic stenosis, while embolic events over pre-existing chronic vascular occlusion are rare. Distinguishing between acute embolism and embolic events superimposed on chronic occlusion is crucial for treatment decision-making. Case presentation We report two cases of acute internal carotid artery (ICA) terminal occlusion diagnosed by preoperative computed tomography angiography (CTA). In Case 1, the microguidewire failed to traverse the middle cerebral artery (MCA) occlusion segment; chronic MCA occlusion was suspected based on preoperative CT perfusion (CTP) and multimodal imaging, so the thrombectomy stent was deployed in the anterior cerebral artery (ACA), achieving successful recanalization. In Case 2, the deployed thrombectomy stent failed to fully expand in the MCA, indicating chronic occlusion; semi-deployment and retrieval of the stent achieved successful recanalization. Conclusion For patients with acute ICA occlusion, the possibility of concomitant chronic MCA occlusion should be considered. Multimodal imaging evaluation and intraoperative tactile feedback can help identify this complex condition and guide treatment strategy. Acute ischemic stroke Internal carotid artery occlusion Chronic middle cerebral artery occlusion Multimodal imaging Endovascular treatment Figures Figure 1 Figure 2 INTRODUCTION EVT has been established as the first-line treatment for acute anterior circulation large vessel occlusion stroke (AIS-LVO), and its efficacy has been confirmed by multiple high-level clinical studies[ 1 , 2 ]. Current clinical practice and research predominantly focus on LVO caused by acute embolism or in-situ thrombosis superimposed on intracranial atherosclerotic stenosis (ICAS), which have well-defined etiologies and standardized management protocols[ 3 , 4 ]. However, a more insidious and challenging clinical entity is increasingly encountered in practice: patients present with acute neurological deficits and imaging evidence of new-onset LVO, but intraoperative findings reveal the acute embolic event is superimposed on a pre-existing chronic occlusive lesion. Among these, acute ICA terminal embolism combined with ipsilateral chronic MCA occlusion is a representative composite lesion. Conventional CTA only visualizes the proximal acute occlusion site, making this entity prone to preoperative misdiagnosis as simple acute ICA embolism. This misdiagnosis may lead to inappropriate intraoperative strategies, increased procedural risks, and compromised treatment outcomes. Currently, clinical reports of such composite lesions are limited, and there is a lack of unified identification processes and treatment decision-making guidelines. Therefore, this study retrospectively analyzes the clinical and surgical data of two patients to provide reference and decision-making ideas for clinical management of such complex conditions. CASE REPORT Case 1 A 56-year-old male patient with a past medical history of ischemic stroke, hypertension, cardiac valve replacement and a baseline modified Rankin Scale (mRS) score of 0 was admitted to the hospital for a 4-hour history of left limb weakness accompanied by speech disturbance.The National Institutes of Health Stroke Scale (NIHSS) score at admission was 16. Emergency cranial CTA + CTP showed: old cerebral infarction in the right frontotemporal insular region (Fig. 1 A), right internal carotid artery occlusion (Fig. 1 B), and extensive hypoperfusion in the right cerebral hemisphere (Fig. 1 C). Emergency digital subtraction angiography (DSA) confirmed right internal carotid artery terminal occlusion (Fig. 1 D). When attempting to pass the microguidewire through the right middle cerebral artery occlusion segment, significant resistance was encountered, and passage was unsuccessful (Fig. 1 E). Based on comprehensive preoperative imaging, although the patient presented with acute neurological deficits, the old infarct lesion in the responsible vascular territory and the distribution characteristics of the ischemic penumbra suggested that the right middle cerebral artery occlusion might be chronic. The microcatheter was therefore advanced to the right anterior cerebral artery (Fig. 1 F), and a 4.0 mm x 20 mm Trevo thrombectomy stent was deployed in the right anterior cerebral artery A2 segment. Successful recanalization was achieved after one thrombectomy attempt. Immediate postoperative angiography showed restoration of antegrade flow in the right anterior cerebral artery (TICI grade 3), with collateral flow to the middle cerebral artery ischemic territory via leptomeningeal branches (Fig. 1 G, 1 H). Cranial CT re-examination at 24 hours post-surgery showed new cerebral infarction lesions in the right frontotemporal insular region, basal ganglia, and periventricular area (Fig. 1 I). CTA showed patent right anterior cerebral artery blood flow, with the right middle cerebral artery still occluded (Fig. 1 J). The patient received standard secondary preventive drug treatment and rehabilitation training, and the NIHSS score decreased to 0 at discharge. At 90-day follow-up, the mRS score was 0. Case 2 A 37-year-old male patient with a past medical history of hypertension, type 2 diabetes mellitus, atrial fibrillation and a baseline modified Rankin Scale (mRS) score of 0 presented with a 5-hour history of left limb weakness accompanied by speech disturbance,with an admission National Institutes of Health Stroke Scale (NIHSS) score of 12. Cranial CTA + CTP showed: no hemorrhage (Fig. 2 A); right internal carotid artery intracranial segment occlusion (Fig. 2 B); right frontoparietal hypoperfusion (Fig. 2 C). Emergency cerebral angiography showed right internal carotid artery terminal occlusion (Fig. 2 D). A synchro2 microguidewire with XT-27 microcatheter successfully passed through the right middle cerebral artery, and a 6.0 mm × 25 mm Trevo thrombectomy stent was deployed. After deployment, the stent did not fully open (Fig. 2 E), suggesting possible chronic middle cerebral artery occlusion. The thrombectomy stent was semi-retrieved, and under balloon guide catheter occlusion, successful recanalization was achieved after one thrombectomy attempt. Immediate postoperative angiography showed a slender right middle cerebral artery M1 segment lumen, with anterior cerebral artery flow recovery and collateral flow to the middle cerebral artery territory via leptomeningeal branches (Fig. 2 F). MRI at 24 hours post-surgery showed new cerebral infarction lesions in the right basal ganglia, frontal lobe, and hippocampal region, with hemorrhagic transformation (Fig. 2 G); magnetic resonance angiography (MRA) showed right middle cerebral artery occlusion, with patent right anterior cerebral artery blood flow (Fig. 2 H). The patient received standard secondary preventive drug treatment and rehabilitation training, and the NIHSS score decreased to 6 at discharge. At 90-day follow-up, the mRS score was 1. Discussion EVT is the established first-line therapy for acute anterior circulation AIS-LVO[ 5 ]. The prevalence of ICAS is markedly high in Asian populations, including the South Asian population served by this journal, which predisposes to the development of chronic intracranial arterial occlusion. In this context, composite lesions of acute embolism superimposed on ipsilateral chronic vascular occlusion are not uncommon, yet remain under-recognized in clinical practice. Accurate identification of chronic occlusion and differentiation from isolated acute embolism is critical for optimizing procedural strategy and predicting clinical outcomes, but remains a significant challenge[ 6 ]. As illustrated by our two cases, this composite lesion has deceptive clinical and radiological manifestations. Patients present with acute, severe neurological deficits caused by acute decompensation of pre-existing collateral circulation due to proximal ICA embolism. Conventional CTA only visualizes the proximal acute occlusion at the ICA terminus, masking the underlying chronic MCA occlusion[ 7 ]. The cases in this group suggest that identification of chronic occlusion mainly relies on clinical history, imaging characteristics, and multimodal imaging: (1) Medical history and baseline imaging: Ipsilateral previous stroke history, poorly controlled risk factors, or old infarcts on imaging (as in Case 1) are important clues suggesting chronic lesions, which can guide intraoperative decision-making and reduce surgical risks.(2) Perfusion imaging: CTP may show that the core infarct area and hypoperfusion area are mainly located in the anterior cerebral artery territory or watershed area, rather than the typical middle cerebral artery watershed. This reflects that the anterior cerebral artery, as the main collateral vessel, is primarily affected when its own load increases and embolic events occur. This mismatch between "responsible vessel" and "perfusion abnormality area" is a key imaging marker warning of composite lesions[ 8 ]. (3) Patients with chronic occlusion often have parenchymal changes in the occluded vessel territory due to long-term hypoperfusion, such as brain atrophy, widened sulci, and leukoaraiosis. They also have good collateral compensation. Preoperative or intraoperative DSA can intuitively display the degree of collateral compensation via anterior cerebral artery leptomeningeal branches, which can directly judge the establishment of collateral circulation after chronic occlusion[ 9 ]. The clinical experience of the operating physician is equally important. The tactile feedback when passing the microguidewire and microcatheter through the occlusion segment can assist in judgment. In Case 1, passage was difficult during the operation, suggesting that the middle cerebral artery had a chronic, tough occlusive mechanism, and the anterior cerebral artery was the main collateral source. The strategy was therefore changed from "opening the chronic occluded vessel" to "restoring and ensuring collateral flow." Successful recanalization via anterior cerebral artery thrombectomy rapidly improved global collateral perfusion, resulting in a good prognosis. In Case 2, after deploying the thrombectomy stent, the stent did not fully expand, suggesting possible chronic occlusion. Therefore, when retrieving the stent, the thrombectomy stent was semi-retrieved. Fortunately, the thrombus was successfully retrieved, but hemorrhagic transformation still occurred. Conclusion Acute ICA embolism combined with ipsilateral chronic MCA occlusion is a challenging, under-recognized composite lesion in AIS-LVO, with a high risk of preoperative misdiagnosis and inappropriate procedural planning. Enhanced clinical suspicion, combined with integrated assessment of clinical history, multimodal imaging, intraoperative tactile feedback, and collateral circulation evaluation, is the key to accurate diagnosis and optimal management. The two cases presented here provide practical, individualized endovascular strategies for this complex entity, which is particularly relevant in Asian populations with a high burden of ICAS. Abbreviations ACA Anterior Cerebral Artery AIS-LVO Acute Anterior Circulation Large Vessel Occlusion Stroke CTA Computed Tomography Angiography CTP Computed Tomography Perfusion DSA Digital Subtraction Angiography EVT Endovascular Thrombectomy ICA Internal Carotid Artery ICAS Intracranial Atherosclerotic Stenosis LVO Large Vessel Occlusion MCA Middle Cerebral Artery MRI Magnetic Resonance Imaging MRA Magnetic Resonance Angiography mRS modified Rankin Scale NIHSS National Institutes of Health Stroke Scale TICI Thrombolysis in Cerebral Infarction Declarations Ethics approval and consent to participate This study was conducted in strict accordance with the Declaration of Helsinki. The study protocol was reviewed and formally approved by the Ethics Committee of Linyi City. Written informed consent for all clinical treatment procedures was obtained from the patients themselves, and written informed consent for the publication of this case series, including all clinical details and imaging findings of the two enrolled patients, was also provided by each patient prior to manuscript submission. Consent for publication Written informed consent for the publication of clinical details, imaging findings and case data was obtained from both patients prior to manuscript submission. Competing interests The authors declare that they have no competing interests. Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Author Contribution TYM and HYS conceived the study design. TYM, JCW and XJW collected the clinical and imaging data. TYM and HYS drafted the manuscript. All authors participated in the data interpretation, critical revision of the manuscript, and approved the final version for submission. All authors agree to be accountable for all aspects of the work. Acknowledgements The authors thank the patients for their consent to publish this case series. Data Availability All data generated or analyzed during this study are included in this published article. The raw imaging data and clinical records are available from the corresponding author upon reasonable request. References Tao C, Nogueira RG, Zhu Y, Sun J, Han H, Yuan G, Wen C, Zhou P, Chen W, Zeng G, et al. Trial of Endovascular Treatment of Acute Basilar-Artery Occlusion. N Engl J Med. 2022;387(15):1361–72. Saver JL, Chapot R, Agid R, Hassan A, Jadhav AP, Liebeskind DS, Lobotesis K, Meila D, Meyer L, Raphaeli G et al. Thrombectomy for Distal, Medium Vessel Occlusions: A Consensus Statement on Present Knowledge and Promising Directions. STROKE 2020, 51(9):2872–2884. Suzuki K, Nakajima N, Kunimoto K, Hatake S, Sakamoto Y, Hokama H, Nomura K, Hayashi T, Aoki J, Suda S et al. Emergent Large Vessel Occlusion Screen Is an Ideal Prehospital Scale to Avoid Missing Endovascular Therapy in Acute Stroke. STROKE 2018, 49(9):2096–2101. Gao F, Tong X, Jia B, Yang M, Pan Y, Ren Z, Burgin WS, Liu L, Zhao X, Wang Y, et al. Randomised study of bailout intracranial angioplasty following thrombectomy for acute large vessel occlusion (ANGEL-REBOOT): protocol of a multicentre randomised controlled trial. STROKE VASC NEUROL. 2024;9(2):181–8. Nguyen TN, Abdalkader M, Fischer U, Qiu Z, Nagel S, Chen HS, Miao Z, Khatri P. Endovascular management of acute stroke. Lancet (London England). 2024;404(10459):1265–78. Chung Y, Bae Y, Hong CE, Won YS, Baek JH, Chung PW, Kim MS, Rho MH. Hyperattenuations on flat-panel computed tomography after successful recanalization of mechanical thrombectomy for anterior circulation occlusion. QUANT IMAG MED SURG. 2022;12(2):1051–62. Shuaib A, Butcher K, Mohammad AA, Saqqur M, Liebeskind DS. Collateral blood vessels in acute ischaemic stroke: a potential therapeutic target. Lancet Neurol. 2011;10(10):909–21. Hoebers LP, Claessen BE, Dangas GD, Råmunddal T, Mehran R, Henriques JPS. Contemporary overview and clinical perspectives of chronic total occlusions. Nat Rev Cardiol. 2014;11(8):458–69. Yuan HW, Ji RJ, Wang AL, Lin YJ, Chen HF, Xu ZQ, Peng GP, Luo BY. A Grading Scale for Pial Collaterals in Middle Cerebral Artery Total Occlusion Based on Time-of-flight MR Angiography Source Images. Magn Reson Med sciences: MRMS : official J Japan Soc Magn Reson Med. 2019;18(1):62–9. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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. 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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-9127526","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":620627889,"identity":"fe4eaee7-4c6c-4a0a-a392-c9a87fba6cc6","order_by":0,"name":"Tianyao Ma","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Tianyao","middleName":"","lastName":"Ma","suffix":""},{"id":620627890,"identity":"003e4888-1fb0-4bf2-90a0-028200b95293","order_by":1,"name":"Jincheng Wu","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Jincheng","middleName":"","lastName":"Wu","suffix":""},{"id":620627891,"identity":"5f14efa3-7a79-468b-a386-1240190a9889","order_by":2,"name":"Xianjun Wang","email":"","orcid":"","institution":"","correspondingAuthor":false,"prefix":"","firstName":"Xianjun","middleName":"","lastName":"Wang","suffix":""},{"id":620627892,"identity":"0ba3c066-5aa4-426e-86ff-c7231e67eca1","order_by":3,"name":"Hongyang Sun","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAy0lEQVRIiWNgGAWjYBACNmbm45//GPyrt79/+ABxWvjY2dIYeAoOJDDcYEsgToscP48ZA88HkBYeA2Idxpb2QMLgTh7j7J6PN94w2MnpNhDUwnzcwMDgWTGzzNnNlnMYko3NDhC2JUEiwYCZsY0hd5s0D8OBxG2EtfAYSBwAaulhyHlGtBYzyQaDw4kzJHLYiNXClmzMYJBmbMBzzNhyjgERfpHvP3zwMcMfGzkD9uaHN95U2MkR1IICJIiNGmQtpOoYBaNgFIyCEQEAxoc9W0DwY9oAAAAASUVORK5CYII=","orcid":"","institution":"","correspondingAuthor":true,"prefix":"","firstName":"Hongyang","middleName":"","lastName":"Sun","suffix":""}],"badges":[],"createdAt":"2026-03-15 09:23:17","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-9127526/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-9127526/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":107042868,"identity":"df9a589d-b07b-436a-b969-a6aa872127de","added_by":"auto","created_at":"2026-04-16 06:43:44","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":41217,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(A)\u003c/strong\u003e Preoperative cranial CT: Old cerebral infarction in the right frontotemporal insular lobe;\u003cstrong\u003e(B) \u003c/strong\u003ePreoperative cranial CTA: Occlusion of the right intracranial ICA and MCA;\u003cstrong\u003e(C)\u003c/strong\u003e Preoperative cranial CTP: Hypoperfusion in the right frontotemporoparietal lobe;\u003cstrong\u003e(D)\u003c/strong\u003e DSA: Distal occlusion of the right internal carotid artery;\u003cstrong\u003e(E) \u003c/strong\u003eMicro-guidewire met resistance and became rigid when crossing the MCA occlusion, indicating a hard lesion;\u003cstrong\u003e(F\u003c/strong\u003e) Trevo stent deployed at ACA A2 segment; BGC inflated in proximal ICA to arrest blood flow;\u003cstrong\u003e(G)\u003c/strong\u003e DSA (lateral view): ACA antegrade flow restored, ACA compensates MCA via leptomeningeal branches, TICI 3;\u003cstrong\u003e(H) \u003c/strong\u003eDSA (anterior view): ACA antegrade flow restored, ACA compensates MCA via leptomeningeal branches, TICI 3;\u003cstrong\u003e(I)\u003c/strong\u003e 24h postoperative CT: Infarction in right frontotemporal insular lobe, basal ganglia and periventricular area;\u003cstrong\u003e(J)\u003c/strong\u003e24h postoperative CTA: Right ACA flow restored; right MCA not visualized.\u003c/p\u003e","description":"","filename":"Picture1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9127526/v1/e6ce8f9062794f161772ae12.jpg"},{"id":107042869,"identity":"469defc3-3a69-4eac-b313-c82ebb397884","added_by":"auto","created_at":"2026-04-16 06:43:44","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":43920,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(A)\u003c/strong\u003ePreoperative cranial CT scan: No high-density hemorrhagic lesions observed; \u003cstrong\u003e(B)\u003c/strong\u003ePreoperative cranial CTA: Occlusion of the right internal carotid artery;\u003cstrong\u003e(C) \u003c/strong\u003ePreoperative cranial CTP: Hypoperfusion in the right frontal and parietal lobes;\u003cstrong\u003e (D)\u003c/strong\u003eDSA: Occlusion of the distal segment of the right internal carotid artery;\u003cstrong\u003e(E) \u003c/strong\u003eTrevo stent retrieval combined with balloon catheter guidewire extraction and thrombectomy; \u003cstrong\u003e(F)\u003c/strong\u003eDSA: Patency of the right middle cerebral artery M1 segment with thin lumen, compensatory soft meningeal branch of the anterior cerebral artery supplying the middle cerebral artery region, TICI grade 3; \u003cstrong\u003e(G) \u003c/strong\u003ePostoperative 24-hour MRI: Focal low signal areas within the right basal ganglia, frontal lobe, and hippocampus, suggestive of hemorrhagic transformation;\u003cstrong\u003e(H)\u003c/strong\u003ePostoperative 24-hour MRA: Signal loss in the right middle cerebral artery and patency of the right anterior cerebral artery.\u003c/p\u003e","description":"","filename":"Picture2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-9127526/v1/feb5e3ac72efd0ed15c17a79.jpg"},{"id":108381119,"identity":"d82cb2f7-37d3-43fa-803d-743448121bd5","added_by":"auto","created_at":"2026-05-04 04:55:04","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":237879,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-9127526/v1/f99fc53d-ba7c-4790-ba9f-bf44e66f2774.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Acute Internal Carotid Artery Embolism Combined with Chronic Middle Cerebral Artery Occlusion: A Report of Two Cases","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eEVT has been established as the first-line treatment for acute anterior circulation large vessel occlusion stroke (AIS-LVO), and its efficacy has been confirmed by multiple high-level clinical studies[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. Current clinical practice and research predominantly focus on LVO caused by acute embolism or in-situ thrombosis superimposed on intracranial atherosclerotic stenosis (ICAS), which have well-defined etiologies and standardized management protocols[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eHowever, a more insidious and challenging clinical entity is increasingly encountered in practice: patients present with acute neurological deficits and imaging evidence of new-onset LVO, but intraoperative findings reveal the acute embolic event is superimposed on a pre-existing chronic occlusive lesion. Among these, acute ICA terminal embolism combined with ipsilateral chronic MCA occlusion is a representative composite lesion. Conventional CTA only visualizes the proximal acute occlusion site, making this entity prone to preoperative misdiagnosis as simple acute ICA embolism. This misdiagnosis may lead to inappropriate intraoperative strategies, increased procedural risks, and compromised treatment outcomes.\u003c/p\u003e \u003cp\u003eCurrently, clinical reports of such composite lesions are limited, and there is a lack of unified identification processes and treatment decision-making guidelines. Therefore, this study retrospectively analyzes the clinical and surgical data of two patients to provide reference and decision-making ideas for clinical management of such complex conditions.\u003c/p\u003e"},{"header":"CASE REPORT","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eCase 1\u003c/h2\u003e \u003cp\u003eA 56-year-old male patient with a past medical history of ischemic stroke, hypertension, cardiac valve replacement and a baseline modified Rankin Scale (mRS) score of 0 was admitted to the hospital for a 4-hour history of left limb weakness accompanied by speech disturbance.The National Institutes of Health Stroke Scale (NIHSS) score at admission was 16. Emergency cranial CTA\u0026thinsp;+\u0026thinsp;CTP showed: old cerebral infarction in the right frontotemporal insular region (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eA), right internal carotid artery occlusion (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eB), and extensive hypoperfusion in the right cerebral hemisphere (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eC). Emergency digital subtraction angiography (DSA) confirmed right internal carotid artery terminal occlusion (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eD). When attempting to pass the microguidewire through the right middle cerebral artery occlusion segment, significant resistance was encountered, and passage was unsuccessful (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eE).\u003c/p\u003e \u003cp\u003eBased on comprehensive preoperative imaging, although the patient presented with acute neurological deficits, the old infarct lesion in the responsible vascular territory and the distribution characteristics of the ischemic penumbra suggested that the right middle cerebral artery occlusion might be chronic. The microcatheter was therefore advanced to the right anterior cerebral artery (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eF), and a 4.0 mm x 20 mm Trevo thrombectomy stent was deployed in the right anterior cerebral artery A2 segment. Successful recanalization was achieved after one thrombectomy attempt. Immediate postoperative angiography showed restoration of antegrade flow in the right anterior cerebral artery (TICI grade 3), with collateral flow to the middle cerebral artery ischemic territory via leptomeningeal branches (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eG, \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eH).\u003c/p\u003e \u003cp\u003eCranial CT re-examination at 24 hours post-surgery showed new cerebral infarction lesions in the right frontotemporal insular region, basal ganglia, and periventricular area (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eI). CTA showed patent right anterior cerebral artery blood flow, with the right middle cerebral artery still occluded (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003eJ). The patient received standard secondary preventive drug treatment and rehabilitation training, and the NIHSS score decreased to 0 at discharge. At 90-day follow-up, the mRS score was 0.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eCase 2\u003c/h3\u003e\n\u003cp\u003eA 37-year-old male patient with a past medical history of hypertension, type 2 diabetes mellitus, atrial fibrillation and a baseline modified Rankin Scale (mRS) score of 0 presented with a 5-hour history of left limb weakness accompanied by speech disturbance,with an admission National Institutes of Health Stroke Scale (NIHSS) score of 12. Cranial CTA\u0026thinsp;+\u0026thinsp;CTP showed: no hemorrhage (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eA); right internal carotid artery intracranial segment occlusion (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eB); right frontoparietal hypoperfusion (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eC). Emergency cerebral angiography showed right internal carotid artery terminal occlusion (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eD). A synchro2 microguidewire with XT-27 microcatheter successfully passed through the right middle cerebral artery, and a 6.0 mm \u0026times; 25 mm Trevo thrombectomy stent was deployed. After deployment, the stent did not fully open (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eE), suggesting possible chronic middle cerebral artery occlusion. The thrombectomy stent was semi-retrieved, and under balloon guide catheter occlusion, successful recanalization was achieved after one thrombectomy attempt.\u003c/p\u003e \u003cp\u003eImmediate postoperative angiography showed a slender right middle cerebral artery M1 segment lumen, with anterior cerebral artery flow recovery and collateral flow to the middle cerebral artery territory via leptomeningeal branches (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eF). MRI at 24 hours post-surgery showed new cerebral infarction lesions in the right basal ganglia, frontal lobe, and hippocampal region, with hemorrhagic transformation (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eG); magnetic resonance angiography (MRA) showed right middle cerebral artery occlusion, with patent right anterior cerebral artery blood flow (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003eH). The patient received standard secondary preventive drug treatment and rehabilitation training, and the NIHSS score decreased to 6 at discharge. At 90-day follow-up, the mRS score was 1.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eEVT is the established first-line therapy for acute anterior circulation AIS-LVO[\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The prevalence of ICAS is markedly high in Asian populations, including the South Asian population served by this journal, which predisposes to the development of chronic intracranial arterial occlusion. In this context, composite lesions of acute embolism superimposed on ipsilateral chronic vascular occlusion are not uncommon, yet remain under-recognized in clinical practice. Accurate identification of chronic occlusion and differentiation from isolated acute embolism is critical for optimizing procedural strategy and predicting clinical outcomes, but remains a significant challenge[\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAs illustrated by our two cases, this composite lesion has deceptive clinical and radiological manifestations. Patients present with acute, severe neurological deficits caused by acute decompensation of pre-existing collateral circulation due to proximal ICA embolism. Conventional CTA only visualizes the proximal acute occlusion at the ICA terminus, masking the underlying chronic MCA occlusion[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The cases in this group suggest that identification of chronic occlusion mainly relies on clinical history, imaging characteristics, and multimodal imaging: (1) Medical history and baseline imaging: Ipsilateral previous stroke history, poorly controlled risk factors, or old infarcts on imaging (as in Case 1) are important clues suggesting chronic lesions, which can guide intraoperative decision-making and reduce surgical risks.(2) Perfusion imaging: CTP may show that the core infarct area and hypoperfusion area are mainly located in the anterior cerebral artery territory or watershed area, rather than the typical middle cerebral artery watershed. This reflects that the anterior cerebral artery, as the main collateral vessel, is primarily affected when its own load increases and embolic events occur. This mismatch between \"responsible vessel\" and \"perfusion abnormality area\" is a key imaging marker warning of composite lesions[\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. (3) Patients with chronic occlusion often have parenchymal changes in the occluded vessel territory due to long-term hypoperfusion, such as brain atrophy, widened sulci, and leukoaraiosis. They also have good collateral compensation. Preoperative or intraoperative DSA can intuitively display the degree of collateral compensation via anterior cerebral artery leptomeningeal branches, which can directly judge the establishment of collateral circulation after chronic occlusion[\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eThe clinical experience of the operating physician is equally important. The tactile feedback when passing the microguidewire and microcatheter through the occlusion segment can assist in judgment. In Case 1, passage was difficult during the operation, suggesting that the middle cerebral artery had a chronic, tough occlusive mechanism, and the anterior cerebral artery was the main collateral source. The strategy was therefore changed from \"opening the chronic occluded vessel\" to \"restoring and ensuring collateral flow.\" Successful recanalization via anterior cerebral artery thrombectomy rapidly improved global collateral perfusion, resulting in a good prognosis. In Case 2, after deploying the thrombectomy stent, the stent did not fully expand, suggesting possible chronic occlusion. Therefore, when retrieving the stent, the thrombectomy stent was semi-retrieved. Fortunately, the thrombus was successfully retrieved, but hemorrhagic transformation still occurred.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eAcute ICA embolism combined with ipsilateral chronic MCA occlusion is a challenging, under-recognized composite lesion in AIS-LVO, with a high risk of preoperative misdiagnosis and inappropriate procedural planning. Enhanced clinical suspicion, combined with integrated assessment of clinical history, multimodal imaging, intraoperative tactile feedback, and collateral circulation evaluation, is the key to accurate diagnosis and optimal management. The two cases presented here provide practical, individualized endovascular strategies for this complex entity, which is particularly relevant in Asian populations with a high burden of ICAS.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003e \u003cp\u003eACA Anterior Cerebral Artery\u003c/p\u003e \u003cp\u003eAIS-LVO Acute Anterior Circulation Large Vessel Occlusion Stroke\u003c/p\u003e \u003cp\u003eCTA Computed Tomography Angiography\u003c/p\u003e \u003cp\u003eCTP Computed Tomography Perfusion\u003c/p\u003e \u003cp\u003eDSA Digital Subtraction Angiography\u003c/p\u003e \u003cp\u003eEVT Endovascular Thrombectomy\u003c/p\u003e \u003cp\u003eICA Internal Carotid Artery\u003c/p\u003e \u003cp\u003eICAS Intracranial Atherosclerotic Stenosis\u003c/p\u003e \u003cp\u003eLVO Large Vessel Occlusion\u003c/p\u003e \u003cp\u003eMCA Middle Cerebral Artery\u003c/p\u003e \u003cp\u003eMRI Magnetic Resonance Imaging\u003c/p\u003e \u003cp\u003eMRA Magnetic Resonance Angiography\u003c/p\u003e \u003cp\u003emRS modified Rankin Scale\u003c/p\u003e \u003cp\u003eNIHSS National Institutes of Health Stroke Scale\u003c/p\u003e \u003cp\u003eTICI Thrombolysis in Cerebral Infarction\u003c/p\u003e \u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e \u003cp\u003eThis study was conducted in strict accordance with the Declaration of Helsinki. The study protocol was reviewed and formally approved by the Ethics Committee of Linyi City. Written informed consent for all clinical treatment procedures was obtained from the patients themselves, and written informed consent for the publication of this case series, including all clinical details and imaging findings of the two enrolled patients, was also provided by each patient prior to manuscript submission.\u003c/p\u003e \u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent for publication\u003c/strong\u003e \u003cp\u003e Written informed consent for the publication of clinical details, imaging findings and case data was obtained from both patients prior to manuscript submission.\u003c/p\u003e \u003c/p\u003e\u003cp\u003e \u003ch2\u003eCompeting interests\u003c/h2\u003e \u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eThis research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eTYM and HYS conceived the study design. TYM, JCW and XJW collected the clinical and imaging data. TYM and HYS drafted the manuscript. All authors participated in the data interpretation, critical revision of the manuscript, and approved the final version for submission. All authors agree to be accountable for all aspects of the work.\u003c/p\u003e\u003ch2\u003eAcknowledgements\u003c/h2\u003e \u003cp\u003e The authors thank the patients for their consent to publish this case series.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eAll data generated or analyzed during this study are included in this published article. The raw imaging data and clinical records are available from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eTao C, Nogueira RG, Zhu Y, Sun J, Han H, Yuan G, Wen C, Zhou P, Chen W, Zeng G, et al. Trial of Endovascular Treatment of Acute Basilar-Artery Occlusion. N Engl J Med. 2022;387(15):1361\u0026ndash;72.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSaver JL, Chapot R, Agid R, Hassan A, Jadhav AP, Liebeskind DS, Lobotesis K, Meila D, Meyer L, Raphaeli G et al. Thrombectomy for Distal, Medium Vessel Occlusions: A Consensus Statement on Present Knowledge and Promising Directions. \u003cem\u003eSTROKE\u003c/em\u003e 2020, 51(9):2872\u0026ndash;2884.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSuzuki K, Nakajima N, Kunimoto K, Hatake S, Sakamoto Y, Hokama H, Nomura K, Hayashi T, Aoki J, Suda S et al. Emergent Large Vessel Occlusion Screen Is an Ideal Prehospital Scale to Avoid Missing Endovascular Therapy in Acute Stroke. \u003cem\u003eSTROKE\u003c/em\u003e 2018, 49(9):2096\u0026ndash;2101.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGao F, Tong X, Jia B, Yang M, Pan Y, Ren Z, Burgin WS, Liu L, Zhao X, Wang Y, et al. Randomised study of bailout intracranial angioplasty following thrombectomy for acute large vessel occlusion (ANGEL-REBOOT): protocol of a multicentre randomised controlled trial. STROKE VASC NEUROL. 2024;9(2):181\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eNguyen TN, Abdalkader M, Fischer U, Qiu Z, Nagel S, Chen HS, Miao Z, Khatri P. Endovascular management of acute stroke. Lancet (London England). 2024;404(10459):1265\u0026ndash;78.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChung Y, Bae Y, Hong CE, Won YS, Baek JH, Chung PW, Kim MS, Rho MH. Hyperattenuations on flat-panel computed tomography after successful recanalization of mechanical thrombectomy for anterior circulation occlusion. QUANT IMAG MED SURG. 2022;12(2):1051\u0026ndash;62.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShuaib A, Butcher K, Mohammad AA, Saqqur M, Liebeskind DS. Collateral blood vessels in acute ischaemic stroke: a potential therapeutic target. Lancet Neurol. 2011;10(10):909\u0026ndash;21.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHoebers LP, Claessen BE, Dangas GD, R\u0026aring;munddal T, Mehran R, Henriques JPS. Contemporary overview and clinical perspectives of chronic total occlusions. Nat Rev Cardiol. 2014;11(8):458\u0026ndash;69.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYuan HW, Ji RJ, Wang AL, Lin YJ, Chen HF, Xu ZQ, Peng GP, Luo BY. A Grading Scale for Pial Collaterals in Middle Cerebral Artery Total Occlusion Based on Time-of-flight MR Angiography Source Images. Magn Reson Med sciences: MRMS : official J Japan Soc Magn Reson Med. 2019;18(1):62\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Acute ischemic stroke, Internal carotid artery occlusion, Chronic middle cerebral artery occlusion, Multimodal imaging, Endovascular treatment","lastPublishedDoi":"10.21203/rs.3.rs-9127526/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-9127526/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eEndovascular thrombectomy (EVT) is the preferred treatment strategy for acute anterior circulation large vessel occlusion (LVO) stroke. Acute LVO most commonly arises from acute embolism or in-situ thrombosis superimposed on atherosclerotic stenosis, while embolic events over pre-existing chronic vascular occlusion are rare. Distinguishing between acute embolism and embolic events superimposed on chronic occlusion is crucial for treatment decision-making.\u003c/p\u003e\u003ch2\u003eCase presentation\u003c/h2\u003e \u003cp\u003eWe report two cases of acute internal carotid artery (ICA) terminal occlusion diagnosed by preoperative computed tomography angiography (CTA). In Case 1, the microguidewire failed to traverse the middle cerebral artery (MCA) occlusion segment; chronic MCA occlusion was suspected based on preoperative CT perfusion (CTP) and multimodal imaging, so the thrombectomy stent was deployed in the anterior cerebral artery (ACA), achieving successful recanalization. In Case 2, the deployed thrombectomy stent failed to fully expand in the MCA, indicating chronic occlusion; semi-deployment and retrieval of the stent achieved successful recanalization.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eFor patients with acute ICA occlusion, the possibility of concomitant chronic MCA occlusion should be considered. Multimodal imaging evaluation and intraoperative tactile feedback can help identify this complex condition and guide treatment strategy.\u003c/p\u003e","manuscriptTitle":"Acute Internal Carotid Artery Embolism Combined with Chronic Middle Cerebral Artery Occlusion: A Report of Two Cases","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-04-16 06:43:40","doi":"10.21203/rs.3.rs-9127526/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"8edd7072-0836-4e3e-9017-f2361d47a142","owner":[],"postedDate":"April 16th, 2026","published":true,"recentEditorialEvents":[{"type":"decision","content":"Rejected","date":"2026-05-04T04:40:30+00:00","index":"","fulltext":""}],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-05-04T04:54:16+00:00","versionOfRecord":[],"versionCreatedAt":"2026-04-16 06:43:40","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-9127526","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-9127526","identity":"rs-9127526","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}