Cerebral Foreign-Body Granulomatous Reaction: A Rare Non-Ischemic Complication After an Endovascular Procedure

Cerebral Foreign-Body Granulomatous Reaction: A Rare Non-Ischemic Complication After an Endovascular Procedure | 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 Cerebral Foreign-Body Granulomatous Reaction: A Rare Non-Ischemic Complication After an Endovascular Procedure Luis Hernan Vargas-Alvarado, Andrea Liliana Gomez-Aristizabal, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8575131/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 14 You are reading this latest preprint version Abstract We present the case of a 59-year-old woman who, three months after endovascular treatment of two left carotid aneurysms, was admitted to the emergency department with headache and focal neurological symptoms. Further diagnostic workup revealed a cerebral foreign-body granulomatous reaction. This clinical case also serves as the basis for a review of the current literature. endovascular treatment foreign body NICE lesions hydrophilic polymers Figures Figure 1 Figure 2 Figure 3 INTRODUCTION Interventional neuroradiology, driven by continuous technological innovation, allows minimally invasive treatment of complex pathologies with increasingly specialized devices. However, the prolonged and combined use of endovascular materials may lead to rare complications. We present a case of cerebral foreign-body granulomatous reaction, an uncommon non-ischemic vascular complication following endovascular treatment. CASE REPORT A 59-year-old woman was incidentally diagnosed with two adjacent aneurysms located in the clinoid and cavernous segments of the left internal carotid artery (15mm and 4,3mm, respectively). Her family history included cerebral aneurysms in first-degree relatives, some of whom had suffered fatal subarachnoid hemorrhage. She was otherwise healthy, with no relevant medical or oncological history. She was scheduled for endovascular treatment by balloon-assisted coiling (remodeling technique) and flow diverter stent placement. Devices used included ASAHI Fubuki® 7F guide catheter, ECLIPSE 2L® 6x15mm balloon, Echelon™ 10 microcatheter for coiling, Stryker® coils (one XL Helical, one XL 360 Standard and two Helical Nano), Axium Prime coils (four) and a Flow diverter stent by Derivo® deployed with Neuroslider 27 microcatheter (Fig. 1 ). The procedure was uneventful (duration: 2 h 20 min) and she was discharged after 48 hours of hospitalization, according to protocol, on dual antiplatelet therapy (Clopidogrel 75 mg and Aspirin 100 mg daily, initiated five days before the procedure). Three months later, the patient presented to the A&E department with intermittent episodes of aphasia, headache, and seizures. A stroke code was activated. Multimodal CT revealed subcortical vasogenic edema in the left hemisphere, with a patent stent and no evidence of stenosis or oclussion. Laboratory studies were unremarkable. Brain MRI showed with T2/FLAIR hyperintense lesions in subcortical and cortical white matter (mainly MCA territory), leptomeningeal enhancement, and múltiple micronodular foci. SWAN sequences revealed microbleeds ("blooming" artifacts). No diffusion restriction was observed in DWI/ADC. Given the absence of prior medical history, the main diagnostic suspicion was leptomeningeal carcinomatosis from an unknown primary tumor, an open brain biopsy was performed (Fig. 2 ). Histopathology revealed a foreign-body type granulomatous reaction with multinucleated giant cells involving pial vessels, with basophilic, acellular, myxoid material compatible with embolism from hydrophilic coating (Fig. 3 ). No evidence of malignancy was found. The lesion was attributed to the previous endovascular procedure. Notably, the interventional neuroradiology team was not informed of the patient’s admission until the biopsy results became available. The patient was treated with a short course of oral corticosteroids (Dexamethasone 4mg orally three times daily for five days, tapered over an additional 20 days) and Levetiracetam 1000 mg orally twice daily, leading to complete clinical recovery and resolution of seizures. She remains asymptomatic to date. DISCUSSION This entity was first described by Barnwell et al. In 1997 in cases following thrombolysis and tumor embolization (meningioma) ( 1 ) . Since then, multiple isolated cases and small series have been reported, correlating with the increasing use of endovascular devices ( 2 ) . Foreign-body granulomatous reaction is a delayed type IV hypersensitivity response. It is recognized complication not only in neurointerventional procedures but also in other endovascular interventions. Published reports include cases affecting myocardial and renal tissue, large vessels, and even aseptic abscesses at puncture sites ( 3 )( 4 )( 5 ) . Several types of hydrophilic coatings have been developed, including polyvinylpyrrolidone (PVP), polyacrylamide (PAM), polyethylene glycol (PEG), polysaccharides, and proprietary co-polymer blends. These materials absorb water and swell, thereby reducing friction and improving device navigability. However, coating delamination may occur due to factors such as excessive friction or use in tortuous or stenotic vessels. Similarly, excessive or improper device manipulation—including incorrect sizing or pre-shaping—can predispose to coating abrasion ( 6 , 7 ) . In neurointerventional radiology, it has been described after diagnostic angiography, mechanical thrombectomy ( 8 ) , and embolization of aneurysms, malformations and arteriovenous fistulas. A spanish multicenter retrospective study (7446 procedures over seven years) reported an overall incidence of 0.14%; 0.45% in therapeutic procedures, increasing to 1.66% in intracranial aneurysm embolization ( 9 ) . This reaction can be triggered by shedding of hydrophilic coating from catheters, guidewires, coils and stents, as well as embolic agents such as EVOH (ethylene vinyl alcohol) or cyanoacrylate (Glubran2, Magic Glue, Histocryl) ( 10 ) . In the context of mechanical thrombectomy, the incidence may be underestimated, because symptoms can mimic ischemic sequelae or delayed post-hypoxic leukoencephalopathy (DPHL), and active screening is not routinely conducted ( 11 ) . In the case of DPHL, the combination of clinical characteristics (biphasic course with initial hypoxic injury, transient improvement and deterioration after three weeks, consistent with demyelination) and radiological features (lesions showing diffusion restriction without contrast enhancement) can help establish the diagnosis ( 12 ) . Risk factors include coil embolization, repeat procedures with previously implanted devices, and the use of multi-axial systems ( 7 ) . A potential link with nickel allergy (present in nitinol) has been suggested, but no clear association has been established, as the condition is rare despite the high prevalence of nickel sensitivity (up to 16.7%) in the general population ( 13 ) . Clinically, symptoms can appear from days to years after procedure, most often around two months (three months in our case). Headache, seizures, and focal neurological deficits (aphasia, hemiplegia, ataxia) are typical. The literature indicates that symptomatology depends on the location of the inflammatory response, but headache is the most frequent presentation ( 14 )( 15 ) . Cognitive impairment and altered consciousness may also occur. Institutional brain MRI protocols typically include T1 isovolumetric sequences, T2 FSE, T2 FLAIR isovolumetric sequences, SWI/T2*, DWI/ADC, and contrast-enhanced T1 sequences when required. Imaging findings are consistent with non-Ischemic cerebral enhancing (NICE) lesions, characterized by leptomeningeal and cortical/subcortical enhancement, vasogenic edema on T2/FLAIR, and microbleeds on SWAN sequences. Diffusion restriction is usually absent ( 16 ) . The presence of vascular anatomical variants, such as persistent fetal circulation or agenesis of an A1 segment of the anterior cerebral artery (ACA), and their correlation with imaging findings can help the neuroradiologist suspect the condition and facilitate differential diagnosis ( 17 )( 18 ) . The combination of stents, dual antiplatelet therapy, and blood–brain barrier disruption caused by inflammation may explain some cases of delayed parenchymal hemorrhage ( 19 ) , although further studies are needed. The differential diagnosis includes subacute infarction, cerebral microabscesses, and leptomeningeal carcinomatosis. However, careful history taking, awareness of prior procedures, and correlation of lesion location with the treated vascular territory are key to raising suspicion for this entity. Histological diagnosis is based on the presence of acellular myxoid material in pial vessels, accompanied by chronic inflammation with multinucleated giant cells, lymphocytes, neutrophils, and epithelioid cells. Absence of the acellular material does not rule out the diagnosis, as it may be lost during tissue processing ( 20 ) . There are no standardized treatment recommendations. The condition is often self-limiting, although short corticosteroid regimens are frequently required. In our case, the patient received dexamethasone (4 mg orally three times daily for five days, tapered over 20 days) and levetiracetam (1000 mg twice daily for seizure control), with full recovery. In recurrent or persistent cases, long-term corticosteroids or immunomodulatory agents such as azathioprine, mycophenolate mofetil, or methotrexate may be considered to reduce steroid-related complications ( 21 ) . Therapeutic strategies should be individualized according to clinical response and radiological regression of lesions. The recognition, reporting, and publication of this pathology have historically faced multiple challenges. Early on, obstacles included stringent editorial review by specialized journals, underestimation of its clinical and manufacturing impact, conflicts of interest involving device manufacturers, and limited reporting by clinical personnel due to work overload, low hospital autopsy rates, or the voluntary nature of reporting ( 22 ) . Closer patient follow-up, with an emphasis on identifying subtle signs or symptoms that may raise suspicion, combined with contrast-enhanced MRI, may allow timely diagnosis and appropriate treatment while avoiding invasive diagnostic procedures. In addition, systematic reporting of cases in the literature could help clarify the true incidence of this condition. More stringent and specific quality standards for hydrophilic coatings should be established by regulatory authorities, while manufacturers should be required to provide both in vivo and ex vivo evidence supporting their safety. In 2015, the FDA released a communication entitled “Critical-to-Quality (CtQ) Indicators: Hydrophilic and Hydrophobic Coated Vascular and Neurological Devices” ( 23 ) , which outlined essential safety considerations for manufacturers. Surveillance efforts were subsequently intensified, and a comprehensive literature review led to the publication of the safety communication “Lubricious coating separation from intravascular medical devices” alerting physicians to potential risks and providing recommendations for clinical practice. In 2019, the FDA published “Intravascular Catheters, Wires, and Delivery Systems with Lubricious Coatings — Labeling Considerations, Guidance for Industry and Food and Drug Administration Staff” . This document not only highlighted serious adverse events such as cerebral infarction, embolism, tissue necrosis, and death, but also issued recommendations for information to be included in device labeling ( 24 ) . Preventive measures include strictly using devices according to their indications, limiting the use of multi-axial systems where possible, replacing devices when overuse is suspected, and minimizing handling time. Genetic studies may help clarify patient-specific idiosyncratic mechanisms, potentially enabling targeted therapies or the development of less cytotoxic devices. CONCLUSION Foreign-body granulomatous reaction is an uncommon but clinically significant complication of neurointerventional procedures. It should be considered in patients presenting with headache or neurological symptoms and a recent history of endovascular treatment, particularly when imaging reveals NICE lesions. The factors most strongly associated with this complication are coil embolization, the use of multi-axial systems, and endovascular re-treatment after prior stent placement. Early recognition may prevent unnecessary invasive procedures, such as biopsy, and facilitate timely, effective treatment. Abbreviations A&E Accident & emergency department A1 Proximal segment of the anterior cerebral artery ACA Anterior cerebral artery CT Computed tomography CtQ Critical-to-Quality FDA Food and drug administration DPHL Delayed post-hypoxic leukoencephalopathy DSA Digital Subtraction Angiography ECL ECLIPSE 2L remodeling balloon EVOH Ethylene vinyl alcohol FSE Fast spin echo MCA Middle cerebral artery FLAIR Fluid-Attenuated Inversion Recovery SWAN Susceptibility-weighted angiography SWI Diffusion-Weighted Imaging) ADC Apparent Diffusion Coefficient MRI Magnetic Resonance Imaging NICE Non-Ischemic cerebral enhancing PVP Polyvinylpyrrolidone PAM Polyacrylamide PEG Polyethylene glicol Declarations Ethics approval: Ethical approval was not requiered for this case. Consent to participate and publication Written informed consent was obtained from the patient for publication of this case and accompanying images. Competing Interests Juan Carlos Llibre-Guerra is a consultant for Iberhospitex and Medtronic. Other authors do not present conflicts of interest. Funding: This research recieved no external funding. Author Contribution Luis Hernan Vargas-Alvarado wrote the main manuscript text.Luis Hernan Vargas-Alvarado and Andrea Liliana Gomez-Aristizabal prepared figures 1 and 2.Johanna Gabriela Leon Gil prepared figure 3.Luis Hernan Vargas-Alvarado, Andrea Liliana Gomez-Aristizabal, Miguel Angel Castaño Blazquez, Johanna Gabriela León Gil, Guillermo Santabrigida Oreja, Jose Antonio De las Heras Garcia and Juan Carlos Llibre-Guerra reviewed the manuscript. Acknowledgement Not applicable. Data Availability The data supporting the findings are included withing the article. References Barnwell SL, D’Agostino AN, Shapiro SL, Nesbit GM, Kellogg JX. Foreign bodies in small arteries after use of an infusion microcatheter. AJNR Am J Neuroradiol. 1997 Nov-Dec;18(10):1886–9. PMID:9403448; PMCID:PMC8337381. Shapiro M, Ollenschleger MD, Baccin C, Becske T, Spiegel GR, Wang Y, Song X, Raz E, Zumofen D, Potts MB, Nelson PK. Foreign body emboli following cerebrovascular interventions: clinical, radiographic, and histopathologic features. AJNR Am J Neuroradiol. 2015;36(11):2121–6. 10.3174/ajnr.A4415 . Epub 2015 Aug 20. PMID:26294650; PMCID:PMC7964857. Levi N, Jacobzon E, Tobar A, Weitsman T, Maleszewski JJ, Hasin T. Embolized hydrophilic coating polymers found in left ventricular assist device apical core specimen. JACC Case Rep. 2022;4(13):819–21. 10.1016/j.jaccas.2022.03.035 . Chen CL, Chen NC, Wang JS. Acute hydrophilic-polymer nephropathy and acute renal failure. N Engl J Med. 2015;372(18). 10.1056/NEJMc1414822 . Blasco A, Oteo JF, Fontanilla T, Salamanca J, Ocaranza R, Goicolea J. Complicaciones inusuales del cateterismo por vía radial. Rev Esp Cardiol. 2005;58(10):1233–5. Ishikawa S, et al. Cerebral foreign body granulomas after mechanical thrombectomy: two case reports and a review of the literature. J Stroke Cerebrovasc Dis. 2023;32(3):106990. 10.1016/j.jstrokecerebrovasdis.2022.106990 . Mehta RI, Perrin RJ, Baldzizhar R, Mehta RI. Polymer Coating Embolism: Cause of Cerebral Vasculopathy and Death following Congenital Heart Repair in Two Infants. J Neuropathol Exp Neurol. 2017;76:978–80. [PubMed: 29044414]. Mehta RI, Mehta RI. Polymer-induced central nervous system complications following vascular procedures: Spectrum of iatrogenic injuries and review of outcomes. Hum Pathol. 2016;53:178–90. [PubMed: 27072640]. Moreno Estébanez A, Luna Rodríguez A, Pérez Concha T, Fernández Maiztegi C, Freijo Guerrero MdM, Díaz Cuervo I, et al. Symptomatic intracranial embolic foreign-body reactions after endovascular neurointerventional procedures: a retrospective study in a tertiary hospital. Clin Neurol Neurosurg. 2021;200:106323. 10.1016/j.clineuro.2020.106323 . Lopez-Calle J, et al. Foreign body granuloma reaction after endovascular therapy of an unruptured right frontal arteriovenous malformation. J Cerebrovasc Endovasc Neurosurg. 2020;22(4):267–72. 10.7461/jcen.2020.e2019.09.006 . Mellemkjær T, Chandra RV, Speiser L, Ulhøi BP, Simonsen CZ. Delayed leukoencephalopathy from suspected polymer embolism after neuroendovascular procedures: case report. Neuroradiol J. 2021;0(0):1–6. 10.1177/19714009211029172 . Beeskow AB, Oberstadt M, Saur D, Hoffmann KT, Lobsien D. Delayed post-hypoxic leukoencephalopathy (DPHL)—an uncommon variant of hypoxic brain damage in adults. Front Neurol. 2018;9:708. 10.3389/fneur.2018.00708 . PMID:30210433; PMCID:PMC6119709. Shotar E, et al. Non-ischemic cerebral enhancing lesions secondary to endovascular aneurysm therapy: nickel allergy or foreign body reaction? Case series and review of the literature. Neuroradiology. 2016;58:877–85. 10.1007/s00234-016-1699-5 . Bayas A, Christ M, Berlis A, Naumann M, Ertl M, Joachimski F, et al. Incidence, clinical spectrum, and immunotherapy of non-ischemic cerebral enhancing lesions after endovascular therapy. Ther Adv Neurol Disord. 2022;15:1–13. 10.1177/17562864211072372 . Giordan E, et al. Teaching neuroimages: intracranial foreign body reaction after endovascular procedures. Neurology. 2018;90:296–7. 10.1212/WNL.0000000000004938 . Ibañez Gabarrón I, et al. Lesiones cerebrales no isquémicas relacionadas con el tratamiento endovascular de aneurismas intracraneales, a propósito de un caso. Neurol Perspect. 2022;2(espec Cong1):316. Ontañón Garcés JM, Saralegui Prieto I, Zaldumbide-Duñas L, Fernándezruanova B, Cabrera Zubizarreta A, Vicente Olabarria I. Foreign body granuloma as a complication of endovascular treatment of brain aneurysm. Interdiscip Neurosurg. 2020;22:101068. 10.1016/j.inat.2020.101068 . Daneshmand A, et al. Plastic in the brain: delayed recognition of progressive unilateral hemispheric lesions. Neurocrit Care. 2019;31:222–4. 10.1007/s12028-018-0576-y . Ansari SA, et al. Hydrophilic polymer embolic complication during diagnostic cerebral angiography presenting with delayed intracranial hemorrhage: case report and literature review. J Neurointerv Surg. 2019;11:80–3. 10.1136/neurintsurg-2018-014189 . Mehta RI, Mehta RI, Solis OE, Jahan R, Salamon N, Tobis JM, et al. Hydrophilic polymer emboli: an under-recognized iatrogenic cause of ischemia and infarct. Mod Pathol. 2010;23(7):921–30. 10.1038/modpathol.2010.74 . Boyle T, et al. Medical treatment of polymeric cerebral granulomatous reactions following endovascular procedures. J Neurointerv Surg. 2021;13:1032–6. 10.1136/neurintsurg-2020-016806 . Mehta RI, Mehta RI. Hydrophilic polymer embolism: Implications for manufacturing, regulation, and postmarket surveillance of coated intravascular medical devices. J Patient Saf. 2021;17(8):e1069–79. 10.1097/PTS.0000000000000473 . U.S. Food and Drug Administration. Critical to Quality Information for Hydrophilic Coated and Hydrophobic Coated Vascular and Neurological Devices. FDA; Silver Spring MD: Aug, 2015. U.S. Food and Drug Administration. Intravascular Catheters, Wires, and Delivery Systems with Lubricious Coatings – Labeling Considerations. Guidance for Industry and FDA Staff. Silver Spring, MD: FDA; 2019 Oct. Additional Declarations Competing interest reported. Juan Carlos Llibre-Guerra is a consultant for Iberhospitex and Medtronic. Other authors do not present conflicts of interest. Cite Share Download PDF Status: Under Review Version 1 posted Editorial decision: Revision requested 04 Feb, 2026 Reviews received at journal 02 Feb, 2026 Reviews received at journal 31 Jan, 2026 Reviewers agreed at journal 26 Jan, 2026 Reviews received at journal 23 Jan, 2026 Reviews received at journal 23 Jan, 2026 Reviewers agreed at journal 23 Jan, 2026 Reviewers agreed at journal 22 Jan, 2026 Reviewers agreed at journal 21 Jan, 2026 Reviewers invited by journal 21 Jan, 2026 Editor invited by journal 21 Jan, 2026 Editor assigned by journal 16 Jan, 2026 Submission checks completed at journal 16 Jan, 2026 First submitted to journal 11 Jan, 2026 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. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-8575131","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":578975369,"identity":"c50574be-4a9a-4d7e-83eb-39010d58528d","order_by":0,"name":"Luis Hernan Vargas-Alvarado","email":"data:image/png;base64,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","orcid":"","institution":"Complejo Hospitalario de Salamanca","correspondingAuthor":true,"prefix":"","firstName":"Luis","middleName":"Hernan","lastName":"Vargas-Alvarado","suffix":""},{"id":578975371,"identity":"ca37cf02-68eb-47d6-89a3-9df2e526a7f4","order_by":1,"name":"Andrea Liliana Gomez-Aristizabal","email":"","orcid":"","institution":"Complejo Hospitalario de Salamanca","correspondingAuthor":false,"prefix":"","firstName":"Andrea","middleName":"Liliana","lastName":"Gomez-Aristizabal","suffix":""},{"id":578975372,"identity":"275d0408-30ff-4b35-85a6-d7d4eb164053","order_by":2,"name":"Miguel Angel Castaño Blazquez","email":"","orcid":"","institution":"Complejo Hospitalario de Salamanca","correspondingAuthor":false,"prefix":"","firstName":"Miguel","middleName":"Angel Castaño","lastName":"Blazquez","suffix":""},{"id":578975373,"identity":"9b17b117-b2cc-4205-9b98-02d7fcd76260","order_by":3,"name":"Johanna Gabriela Leon Gil","email":"","orcid":"","institution":"Complejo Hospitalario de Salamanca","correspondingAuthor":false,"prefix":"","firstName":"Johanna","middleName":"Gabriela Leon","lastName":"Gil","suffix":""},{"id":578975375,"identity":"17bf419c-4a2b-42d9-b21a-7e413ce512ca","order_by":4,"name":"Guillermo Santabrigida Oreja","email":"","orcid":"","institution":"Complejo Hospitalario de Salamanca","correspondingAuthor":false,"prefix":"","firstName":"Guillermo","middleName":"Santabrigida","lastName":"Oreja","suffix":""},{"id":578975376,"identity":"0d79f785-ac66-4411-a8f2-8445a968dacc","order_by":5,"name":"Jose Antonio de las Heras","email":"","orcid":"","institution":"Complejo Hospitalario de Salamanca","correspondingAuthor":false,"prefix":"","firstName":"Jose","middleName":"Antonio de las","lastName":"Heras","suffix":""},{"id":578975377,"identity":"2e375b12-5d6a-4946-9145-7e6ec1c683e1","order_by":6,"name":"Juan Carlos Guerra Llibre","email":"","orcid":"","institution":"Complejo Hospitalario de Salamanca","correspondingAuthor":false,"prefix":"","firstName":"Juan","middleName":"Carlos Guerra","lastName":"Llibre","suffix":""}],"badges":[],"createdAt":"2026-01-11 17:53:16","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8575131/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8575131/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":101206115,"identity":"ecfb1a3f-950b-44cc-a21b-85dd8eb69dcb","added_by":"auto","created_at":"2026-01-27 09:54:57","extension":"jpg","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":36755423,"visible":true,"origin":"","legend":"","description":"","filename":"FIG3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/0bba32597acc89d485f52022.jpg"},{"id":101170875,"identity":"143e2a3e-f1d8-4bd0-a89c-c3449bfd8383","added_by":"auto","created_at":"2026-01-27 00:05:31","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1643516,"visible":true,"origin":"","legend":"","description":"","filename":"CasereportCerebralForeignBodyGranulomasBMC.docx","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/f5547b17c4e9b07e78ec72c8.docx"},{"id":101170893,"identity":"1d5ca5ac-a046-4ac1-ab5f-7e0455be61c8","added_by":"auto","created_at":"2026-01-27 00:05:31","extension":"jpg","order_by":2,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":30133995,"visible":true,"origin":"","legend":"","description":"","filename":"Fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/4257374dff01512e8a39f636.jpg"},{"id":101170883,"identity":"14cfe7ad-1064-4b5a-b6e6-cb528806e2a1","added_by":"auto","created_at":"2026-01-27 00:05:31","extension":"jpg","order_by":3,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":10460501,"visible":true,"origin":"","legend":"","description":"","filename":"Fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/c19bd7f77047dc516ac94fc0.jpg"},{"id":101170910,"identity":"91ad4b91-eadb-4bbe-ae70-043821d66bf5","added_by":"auto","created_at":"2026-01-27 00:05:33","extension":"json","order_by":4,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":7339,"visible":true,"origin":"","legend":"","description":"","filename":"b94a1fcd4f7d47e0b1dcd747ae3a48b8.json","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/c71094a418787063f9ef9131.json"},{"id":101170911,"identity":"99b4fd63-21c5-4e24-b92e-1c5f96f4f948","added_by":"auto","created_at":"2026-01-27 00:05:33","extension":"xml","order_by":5,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":67932,"visible":true,"origin":"","legend":"","description":"","filename":"b94a1fcd4f7d47e0b1dcd747ae3a48b81enriched.xml","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/1c58c0e3593ec64c95dc246d.xml"},{"id":101170904,"identity":"e3c9f283-7933-4a80-ae0c-ef58a0b8d019","added_by":"auto","created_at":"2026-01-27 00:05:32","extension":"jpg","order_by":6,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":36755423,"visible":true,"origin":"","legend":"","description":"","filename":"FIG3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/c83cdeb51894cd9d1bfc5ce8.jpg"},{"id":101170900,"identity":"dc931bcd-9fc6-4030-bfcc-5233b73c6086","added_by":"auto","created_at":"2026-01-27 00:05:31","extension":"jpg","order_by":7,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":30133995,"visible":true,"origin":"","legend":"","description":"","filename":"Fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/c1fd2be9dcd2e82b757921b2.jpg"},{"id":101170912,"identity":"8112c608-1bc3-4696-893d-040bccfced75","added_by":"auto","created_at":"2026-01-27 00:05:33","extension":"jpg","order_by":8,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":10460501,"visible":true,"origin":"","legend":"","description":"","filename":"Fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/e5a6a42c42203185d1a76c41.jpg"},{"id":101206425,"identity":"1f7d47b7-1f65-4c34-9a1c-8f6381db5910","added_by":"auto","created_at":"2026-01-27 09:56:12","extension":"jpeg","order_by":9,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":348559,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage1.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/c794f809ded7a2e3e84b3d46.jpeg"},{"id":101170894,"identity":"b64756f7-7463-4ad1-8349-a1cf606e22c1","added_by":"auto","created_at":"2026-01-27 00:05:31","extension":"jpeg","order_by":10,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":253460,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/30e5bddad650a7ee73c67a38.jpeg"},{"id":101170907,"identity":"129347c7-f76b-4bb1-af04-6c4773afa3fd","added_by":"auto","created_at":"2026-01-27 00:05:32","extension":"jpeg","order_by":11,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":1018571,"visible":true,"origin":"","legend":"","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/98804ac2d181f1e153bc06ad.jpeg"},{"id":101170908,"identity":"02d8cfe2-7c1a-4283-8e96-e06f1cd6eb38","added_by":"auto","created_at":"2026-01-27 00:05:33","extension":"png","order_by":12,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":9345784,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFIG3.png","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/9b7d41937c7ed7cd03bba6c1.png"},{"id":101170898,"identity":"b406c39a-90d7-4e24-b1c7-c8a5b4d0346b","added_by":"auto","created_at":"2026-01-27 00:05:31","extension":"png","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":4155725,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig1.png","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/25ad375fe8ecc563087bd06d.png"},{"id":101170902,"identity":"338ab2e1-6b8f-46d0-b480-8bacb4244285","added_by":"auto","created_at":"2026-01-27 00:05:31","extension":"png","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":3473997,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig2.png","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/89bc3dfda5469fe5ff27f35d.png"},{"id":101170901,"identity":"8e6b05dd-8c77-43a4-b610-6f3f5f3a4ef6","added_by":"auto","created_at":"2026-01-27 00:05:31","extension":"png","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":127090,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/bbffe7937199766497543f86.png"},{"id":101206180,"identity":"8306583b-c0dc-42b3-8df0-fc803437e440","added_by":"auto","created_at":"2026-01-27 09:55:34","extension":"png","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":165075,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/56f30fdedb093feb43062545.png"},{"id":101170906,"identity":"2e0c0943-c8a8-4cc5-8aba-b43a882bffea","added_by":"auto","created_at":"2026-01-27 00:05:32","extension":"png","order_by":17,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":736628,"visible":true,"origin":"","legend":"","description":"","filename":"Onlinefloatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/66ad3e3b0a6ea671e07b945d.png"},{"id":101206476,"identity":"1cd1d2d2-dc8b-4f3d-8c14-435a5a16a16e","added_by":"auto","created_at":"2026-01-27 09:56:22","extension":"xml","order_by":18,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":66455,"visible":true,"origin":"","legend":"","description":"","filename":"b94a1fcd4f7d47e0b1dcd747ae3a48b81structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/a8bfda2e1b6ed2df8d2901fe.xml"},{"id":101170905,"identity":"d447b3f7-7048-49f0-8432-3326b5b1a8dc","added_by":"auto","created_at":"2026-01-27 00:05:32","extension":"html","order_by":19,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":77284,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/fe4ba992d773fe04f452ed97.html"},{"id":101170903,"identity":"ede96e41-97f6-4458-acfb-3c31377bd1c2","added_by":"auto","created_at":"2026-01-27 00:05:32","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":30133995,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eEmbolization procedure.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eA) Diagnostic DSA of the left internal carotid artery showing the aneurysmal lesions. B) 3D reconstruction of the left internal carotid artery showing the aneurysmal lesions (white arrows: cavernous aneurysm, 4.3mm maximum diameter; clinoid aneurysm, 15mm maximum diameter). C. Endovascular treatment with coiling and single remodeling technique. D) Deployment of the DERIVO stent via Neuroslider 27 microcatheter (white arrows). Coils are marked with asterisks in each aneurysm. The FUBUKI catheter is indicated with a yellow arrowhead. E) Angioplasty of the DERIVO stent (yellow bracket) using ECL balloon 6 x 20mm (white bracket). F) Final angiography showing no intracraneal complications.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"Fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/e29c124dd095feddf5b0f68f.jpg"},{"id":101170889,"identity":"e3e1e7c6-d8a0-4625-ba8e-698c7eb93a64","added_by":"auto","created_at":"2026-01-27 00:05:31","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":10460501,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eBrain MRI three months after the procedure.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eBrain MRI: \u003c/em\u003e\u003cem\u003e\u003cstrong\u003eA)\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e and \u003c/em\u003e\u003cem\u003e\u003cstrong\u003eB)\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e: T2-weighted sequences showing hyperintense subcortical vasogenic edema in the vascular territory of the left MCA (white arrows), with some foci of altered gyral cortical signal (white asterisks). \u003c/em\u003e\u003cem\u003e\u003cstrong\u003eC)\u003c/strong\u003e\u003c/em\u003e\u003cem\u003eand \u003c/em\u003e\u003cem\u003e\u003cstrong\u003eD)\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e Susceptibility-weighted imaging (SWI) showing isolated foci of blooming, representing associated cerebral microbleeds. \u003c/em\u003e\u003cem\u003e\u003cstrong\u003eE)\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e T1-weighted sequences after contrast administration demonstrating foci of leptomeningeal enhancement as well as confluent micronodular lesions (white asterisks). \u003c/em\u003e\u003cem\u003e\u003cstrong\u003eF)\u003c/strong\u003e\u003c/em\u003e\u003cem\u003eT1-weighted sequence after contrast, showing similar findings as in \u003c/em\u003e\u003cem\u003e\u003cstrong\u003eC)\u003c/strong\u003e\u003c/em\u003e\u003cem\u003eand post-craniotomy changes (white arrows).\u003c/em\u003e\u003c/p\u003e","description":"","filename":"Fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/651884285bfb1002caa39eaa.jpg"},{"id":101170909,"identity":"b5450b27-0690-4397-8a0d-f126dc71ae15","added_by":"auto","created_at":"2026-01-27 00:05:33","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":36755423,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eAnatomopathological findings.\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e\u003cstrong\u003eA)\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e Hematoxylin and eosin staining showing myxoid material within the lumen of some meningeal vessels (black arrows) corresponding to the embolized polymetric material. \u003c/em\u003e\u003cem\u003e\u003cstrong\u003eB)\u003c/strong\u003e\u003c/em\u003e\u003cem\u003e Granulomatous inflammatory reaction with numerous inflammatory and epithelioid cells, the most prominent being multinucleated giant cells.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"FIG3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/427807d24527c86f88ee2d2a.jpg"},{"id":101297508,"identity":"a26eeb3d-5ad4-456f-82e3-28f24e934ba5","added_by":"auto","created_at":"2026-01-28 09:27:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":77857491,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8575131/v1/df7ac52c-9f12-47b2-9363-25358aa7b06f.pdf"}],"financialInterests":"Competing interest reported. Juan Carlos Llibre-Guerra is a consultant for Iberhospitex and Medtronic. Other authors do not present conflicts of interest.","formattedTitle":"Cerebral Foreign-Body Granulomatous Reaction: A Rare Non-Ischemic Complication After an Endovascular Procedure","fulltext":[{"header":"INTRODUCTION","content":"\u003cp\u003eInterventional neuroradiology, driven by continuous technological innovation, allows minimally invasive treatment of complex pathologies with increasingly specialized devices. However, the prolonged and combined use of endovascular materials may lead to rare complications. We present a case of cerebral foreign-body granulomatous reaction, an uncommon non-ischemic vascular complication following endovascular treatment.\u003c/p\u003e"},{"header":"CASE REPORT","content":"\u003cp\u003eA 59-year-old woman was incidentally diagnosed with two adjacent aneurysms located in the clinoid and cavernous segments of the left internal carotid artery (15mm and 4,3mm, respectively). Her family history included cerebral aneurysms in first-degree relatives, some of whom had suffered fatal subarachnoid hemorrhage. She was otherwise healthy, with no relevant medical or oncological history.\u003c/p\u003e \u003cp\u003eShe was scheduled for endovascular treatment by balloon-assisted coiling (remodeling technique) and flow diverter stent placement. Devices used included ASAHI Fubuki\u0026reg; 7F guide catheter, ECLIPSE 2L\u0026reg; 6x15mm balloon, Echelon\u0026trade; 10 microcatheter for coiling, Stryker\u0026reg; coils (one XL Helical, one XL 360 Standard and two Helical Nano), Axium Prime coils (four) and a Flow diverter stent by Derivo\u0026reg; deployed with Neuroslider 27 microcatheter (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). The procedure was uneventful (duration: 2 h 20 min) and she was discharged after 48 hours of hospitalization, according to protocol, on dual antiplatelet therapy (Clopidogrel 75 mg and Aspirin 100 mg daily, initiated five days before the procedure).\u003c/p\u003e \u003cp\u003eThree months later, the patient presented to the A\u0026amp;E department with intermittent episodes of aphasia, headache, and seizures. A stroke code was activated. Multimodal CT revealed subcortical vasogenic edema in the left hemisphere, with a patent stent and no evidence of stenosis or oclussion. Laboratory studies were unremarkable. Brain MRI showed with T2/FLAIR hyperintense lesions in subcortical and cortical white matter (mainly MCA territory), leptomeningeal enhancement, and m\u0026uacute;ltiple micronodular foci. SWAN sequences revealed microbleeds (\"blooming\" artifacts). No diffusion restriction was observed in DWI/ADC.\u003c/p\u003e \u003cp\u003eGiven the absence of prior medical history, the main diagnostic suspicion was leptomeningeal carcinomatosis from an unknown primary tumor, an open brain biopsy was performed (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Histopathology revealed a foreign-body type granulomatous reaction with multinucleated giant cells involving pial vessels, with basophilic, acellular, myxoid material compatible with embolism from hydrophilic coating (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). No evidence of malignancy was found. The lesion was attributed to the previous endovascular procedure. Notably, the interventional neuroradiology team was not informed of the patient\u0026rsquo;s admission until the biopsy results became available.\u003c/p\u003e \u003cp\u003eThe patient was treated with a short course of oral corticosteroids (Dexamethasone 4mg orally three times daily for five days, tapered over an additional 20 days) and Levetiracetam 1000 mg orally twice daily, leading to complete clinical recovery and resolution of seizures. She remains asymptomatic to date.\u003c/p\u003e "},{"header":"DISCUSSION","content":"\u003cp\u003eThis entity was first described by Barnwell et al. In 1997 in cases following thrombolysis and tumor embolization (meningioma) \u003csup\u003e(\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e)\u003c/sup\u003e. Since then, multiple isolated cases and small series have been reported, correlating with the increasing use of endovascular devices\u003csup\u003e(\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e)\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eForeign-body granulomatous reaction is a delayed type IV hypersensitivity response. It is recognized complication not only in neurointerventional procedures but also in other endovascular interventions. Published reports include cases affecting myocardial and renal tissue, large vessels, and even aseptic abscesses at puncture sites\u003csup\u003e(\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e)(\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e)(\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e)\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eSeveral types of hydrophilic coatings have been developed, including polyvinylpyrrolidone (PVP), polyacrylamide (PAM), polyethylene glycol (PEG), polysaccharides, and proprietary co-polymer blends. These materials absorb water and swell, thereby reducing friction and improving device navigability. However, coating delamination may occur due to factors such as excessive friction or use in tortuous or stenotic vessels. Similarly, excessive or improper device manipulation\u0026mdash;including incorrect sizing or pre-shaping\u0026mdash;can predispose to coating abrasion \u003csup\u003e(\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e)\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eIn neurointerventional radiology, it has been described after diagnostic angiography, mechanical thrombectomy\u003csup\u003e(\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e)\u003c/sup\u003e, and embolization of aneurysms, malformations and arteriovenous fistulas. A spanish multicenter retrospective study (7446 procedures over seven years) reported an overall incidence of 0.14%; 0.45% in therapeutic procedures, increasing to 1.66% in intracranial aneurysm embolization \u003csup\u003e(\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e)\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThis reaction can be triggered by shedding of hydrophilic coating from catheters, guidewires, coils and stents, as well as embolic agents such as EVOH (ethylene vinyl alcohol) or cyanoacrylate (Glubran2, Magic Glue, Histocryl) \u003csup\u003e(\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e)\u003c/sup\u003e. In the context of mechanical thrombectomy, the incidence may be underestimated, because symptoms can mimic ischemic sequelae or delayed post-hypoxic leukoencephalopathy (DPHL), and active screening is not routinely conducted \u003csup\u003e(\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e)\u003c/sup\u003e. In the case of DPHL, the combination of clinical characteristics (biphasic course with initial hypoxic injury, transient improvement and deterioration after three weeks, consistent with demyelination) and radiological features (lesions showing diffusion restriction without contrast enhancement) can help establish the diagnosis\u003csup\u003e(\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e)\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eRisk factors include coil embolization, repeat procedures with previously implanted devices, and the use of multi-axial systems\u003csup\u003e(\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e)\u003c/sup\u003e. A potential link with nickel allergy (present in nitinol) has been suggested, but no clear association has been established, as the condition is rare despite the high prevalence of nickel sensitivity (up to 16.7%) in the general population \u003csup\u003e(\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e)\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eClinically, symptoms can appear from days to years after procedure, most often around two months (three months in our case). Headache, seizures, and focal neurological deficits (aphasia, hemiplegia, ataxia) are typical. The literature indicates that symptomatology depends on the location of the inflammatory response, but headache is the most frequent presentation \u003csup\u003e(\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e)(\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e)\u003c/sup\u003e. Cognitive impairment and altered consciousness may also occur.\u003c/p\u003e \u003cp\u003eInstitutional brain MRI protocols typically include T1 isovolumetric sequences, T2 FSE, T2 FLAIR isovolumetric sequences, SWI/T2*, DWI/ADC, and contrast-enhanced T1 sequences when required. Imaging findings are consistent with non-Ischemic cerebral enhancing \u003cem\u003e(NICE)\u003c/em\u003e lesions, characterized by leptomeningeal and cortical/subcortical enhancement, vasogenic edema on T2/FLAIR, and microbleeds on SWAN sequences. Diffusion restriction is usually absent\u003csup\u003e(\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e)\u003c/sup\u003e. The presence of vascular anatomical variants, such as persistent fetal circulation or agenesis of an A1 segment of the anterior cerebral artery (ACA), and their correlation with imaging findings can help the neuroradiologist suspect the condition and facilitate differential diagnosis \u003csup\u003e(\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e)(\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e)\u003c/sup\u003e. The combination of stents, dual antiplatelet therapy, and blood\u0026ndash;brain barrier disruption caused by inflammation may explain some cases of delayed parenchymal hemorrhage \u003csup\u003e(\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e)\u003c/sup\u003e, although further studies are needed.\u003c/p\u003e \u003cp\u003eThe differential diagnosis includes subacute infarction, cerebral microabscesses, and leptomeningeal carcinomatosis. However, careful history taking, awareness of prior procedures, and correlation of lesion location with the treated vascular territory are key to raising suspicion for this entity.\u003c/p\u003e \u003cp\u003eHistological diagnosis is based on the presence of acellular myxoid material in pial vessels, accompanied by chronic inflammation with multinucleated giant cells, lymphocytes, neutrophils, and epithelioid cells. Absence of the acellular material does not rule out the diagnosis, as it may be lost during tissue processing \u003csup\u003e(\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e)\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThere are no standardized treatment recommendations. The condition is often self-limiting, although short corticosteroid regimens are frequently required. In our case, the patient received dexamethasone (4 mg orally three times daily for five days, tapered over 20 days) and levetiracetam (1000 mg twice daily for seizure control), with full recovery. In recurrent or persistent cases, long-term corticosteroids or immunomodulatory agents such as azathioprine, mycophenolate mofetil, or methotrexate may be considered to reduce steroid-related complications\u003csup\u003e(\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e)\u003c/sup\u003e. Therapeutic strategies should be individualized according to clinical response and radiological regression of lesions.\u003c/p\u003e \u003cp\u003eThe recognition, reporting, and publication of this pathology have historically faced multiple challenges. Early on, obstacles included stringent editorial review by specialized journals, underestimation of its clinical and manufacturing impact, conflicts of interest involving device manufacturers, and limited reporting by clinical personnel due to work overload, low hospital autopsy rates, or the voluntary nature of reporting \u003csup\u003e(\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e)\u003c/sup\u003e. Closer patient follow-up, with an emphasis on identifying subtle signs or symptoms that may raise suspicion, combined with contrast-enhanced MRI, may allow timely diagnosis and appropriate treatment while avoiding invasive diagnostic procedures. In addition, systematic reporting of cases in the literature could help clarify the true incidence of this condition.\u003c/p\u003e \u003cp\u003eMore stringent and specific quality standards for hydrophilic coatings should be established by regulatory authorities, while manufacturers should be required to provide both in vivo and ex vivo evidence supporting their safety. In 2015, the FDA released a communication entitled \u003cem\u003e\u0026ldquo;Critical-to-Quality (CtQ) Indicators: Hydrophilic and Hydrophobic Coated Vascular and Neurological Devices\u0026rdquo;\u003c/em\u003e\u003csup\u003e(\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e)\u003c/sup\u003e, which outlined essential safety considerations for manufacturers. Surveillance efforts were subsequently intensified, and a comprehensive literature review led to the publication of the safety communication \u003cem\u003e\u0026ldquo;Lubricious coating separation from intravascular medical devices\u0026rdquo;\u003c/em\u003e alerting physicians to potential risks and providing recommendations for clinical practice. In 2019, the FDA published \u003cem\u003e\u0026ldquo;Intravascular Catheters, Wires, and Delivery Systems with Lubricious Coatings \u0026mdash; Labeling Considerations, Guidance for Industry and Food and Drug Administration Staff\u0026rdquo;\u003c/em\u003e. This document not only highlighted serious adverse events such as cerebral infarction, embolism, tissue necrosis, and death, but also issued recommendations for information to be included in device labeling \u003csup\u003e(\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e)\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003ePreventive measures include strictly using devices according to their indications, limiting the use of multi-axial systems where possible, replacing devices when overuse is suspected, and minimizing handling time. Genetic studies may help clarify patient-specific idiosyncratic mechanisms, potentially enabling targeted therapies or the development of less cytotoxic devices.\u003c/p\u003e"},{"header":"CONCLUSION","content":"\u003cp\u003eForeign-body granulomatous reaction is an uncommon but clinically significant complication of neurointerventional procedures. It should be considered in patients presenting with headache or neurological symptoms and a recent history of endovascular treatment, particularly when imaging reveals \u003cem\u003eNICE\u003c/em\u003e lesions. The factors most strongly associated with this complication are coil embolization, the use of multi-axial systems, and endovascular re-treatment after prior stent placement. Early recognition may prevent unnecessary invasive procedures, such as biopsy, and facilitate timely, effective treatment.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eA\u0026amp;E\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAccident \u0026amp; emergency department\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eA1\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eProximal segment of the anterior cerebral artery\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eACA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eAnterior cerebral artery\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eCT\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eComputed tomography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cem\u003eCtQ\u003c/em\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003e \u003cem\u003eCritical-to-Quality\u003c/em\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eFDA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eFood and drug administration\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eDPHL\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eDelayed post-hypoxic leukoencephalopathy\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eDSA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eDigital Subtraction Angiography\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eECL\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eECLIPSE 2L remodeling balloon\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eEVOH\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eEthylene vinyl alcohol\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eFSE\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eFast spin echo\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMCA\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMiddle cerebral artery\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cem\u003eFLAIR\u003c/em\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003e \u003cem\u003eFluid-Attenuated Inversion Recovery\u003c/em\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cem\u003eSWAN\u003c/em\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003e \u003cem\u003eSusceptibility-weighted angiography\u003c/em\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cem\u003eSWI\u003c/em\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003e \u003cem\u003eDiffusion-Weighted Imaging)\u003c/em\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cem\u003eADC\u003c/em\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003e \u003cem\u003eApparent Diffusion Coefficient\u003c/em\u003e \u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eMRI\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eMagnetic Resonance Imaging\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003eNICE\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eNon-Ischemic cerebral enhancing\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePVP\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePolyvinylpyrrolidone\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePAM\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePolyacrylamide\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003ePEG\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003ePolyethylene glicol\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eEthics approval:\u003c/h2\u003e \u003cp\u003eEthical approval was not requiered for this case.\u003c/p\u003e \u003cp\u003e \u003cstrong\u003eConsent to participate and publication\u003c/strong\u003e \u003cp\u003e \u003cb\u003e\u003c/b\u003eWritten informed consent was obtained from the patient for publication of this case and accompanying images.\u003c/p\u003e \u003ch2\u003eCompeting Interests\u003c/h2\u003e\u003cp\u003eJuan Carlos Llibre-Guerra is a consultant for Iberhospitex and Medtronic. Other authors do not present conflicts of interest.\u003c/p\u003e\u003ch2\u003eFunding:\u003c/h2\u003e \u003cp\u003eThis research recieved no external funding.\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eLuis Hernan Vargas-Alvarado wrote the main manuscript text.Luis Hernan Vargas-Alvarado and Andrea Liliana Gomez-Aristizabal prepared figures 1 and 2.Johanna Gabriela Leon Gil prepared figure 3.Luis Hernan Vargas-Alvarado, Andrea Liliana Gomez-Aristizabal, Miguel Angel Casta\u0026ntilde;o Blazquez, Johanna Gabriela Le\u0026oacute;n Gil, Guillermo Santabrigida Oreja, Jose Antonio De las Heras Garcia and Juan Carlos Llibre-Guerra reviewed the manuscript.\u003c/p\u003e\u003ch2\u003eAcknowledgement\u003c/h2\u003e\u003cp\u003eNot applicable.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003eThe data supporting the findings are included withing the article.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBarnwell SL, D\u0026rsquo;Agostino AN, Shapiro SL, Nesbit GM, Kellogg JX. Foreign bodies in small arteries after use of an infusion microcatheter. AJNR Am J Neuroradiol. 1997 Nov-Dec;18(10):1886\u0026ndash;9. PMID:9403448; PMCID:PMC8337381.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShapiro M, Ollenschleger MD, Baccin C, Becske T, Spiegel GR, Wang Y, Song X, Raz E, Zumofen D, Potts MB, Nelson PK. Foreign body emboli following cerebrovascular interventions: clinical, radiographic, and histopathologic features. AJNR Am J Neuroradiol. 2015;36(11):2121\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3174/ajnr.A4415\u003c/span\u003e\u003cspan address=\"10.3174/ajnr.A4415\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. Epub 2015 Aug 20. PMID:26294650; PMCID:PMC7964857.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLevi N, Jacobzon E, Tobar A, Weitsman T, Maleszewski JJ, Hasin T. Embolized hydrophilic coating polymers found in left ventricular assist device apical core specimen. JACC Case Rep. 2022;4(13):819\u0026ndash;21. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jaccas.2022.03.035\u003c/span\u003e\u003cspan address=\"10.1016/j.jaccas.2022.03.035\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen CL, Chen NC, Wang JS. Acute hydrophilic-polymer nephropathy and acute renal failure. N Engl J Med. 2015;372(18). \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1056/NEJMc1414822\u003c/span\u003e\u003cspan address=\"10.1056/NEJMc1414822\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBlasco A, Oteo JF, Fontanilla T, Salamanca J, Ocaranza R, Goicolea J. Complicaciones inusuales del cateterismo por v\u0026iacute;a radial. Rev Esp Cardiol. 2005;58(10):1233\u0026ndash;5.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIshikawa S, et al. Cerebral foreign body granulomas after mechanical thrombectomy: two case reports and a review of the literature. J Stroke Cerebrovasc Dis. 2023;32(3):106990. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.jstrokecerebrovasdis.2022.106990\u003c/span\u003e\u003cspan address=\"10.1016/j.jstrokecerebrovasdis.2022.106990\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMehta RI, Perrin RJ, Baldzizhar R, Mehta RI. Polymer Coating Embolism: Cause of Cerebral Vasculopathy and Death following Congenital Heart Repair in Two Infants. J Neuropathol Exp Neurol. 2017;76:978\u0026ndash;80. [PubMed: 29044414].\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMehta RI, Mehta RI. Polymer-induced central nervous system complications following vascular procedures: Spectrum of iatrogenic injuries and review of outcomes. Hum Pathol. 2016;53:178\u0026ndash;90. [PubMed: 27072640].\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMoreno Est\u0026eacute;banez A, Luna Rodr\u0026iacute;guez A, P\u0026eacute;rez Concha T, Fern\u0026aacute;ndez Maiztegi C, Freijo Guerrero MdM, D\u0026iacute;az Cuervo I, et al. Symptomatic intracranial embolic foreign-body reactions after endovascular neurointerventional procedures: a retrospective study in a tertiary hospital. Clin Neurol Neurosurg. 2021;200:106323. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.clineuro.2020.106323\u003c/span\u003e\u003cspan address=\"10.1016/j.clineuro.2020.106323\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLopez-Calle J, et al. Foreign body granuloma reaction after endovascular therapy of an unruptured right frontal arteriovenous malformation. J Cerebrovasc Endovasc Neurosurg. 2020;22(4):267\u0026ndash;72. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.7461/jcen.2020.e2019.09.006\u003c/span\u003e\u003cspan address=\"10.7461/jcen.2020.e2019.09.006\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMellemkj\u0026aelig;r T, Chandra RV, Speiser L, Ulh\u0026oslash;i BP, Simonsen CZ. Delayed leukoencephalopathy from suspected polymer embolism after neuroendovascular procedures: case report. Neuroradiol J. 2021;0(0):1\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1177/19714009211029172\u003c/span\u003e\u003cspan address=\"10.1177/19714009211029172\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBeeskow AB, Oberstadt M, Saur D, Hoffmann KT, Lobsien D. Delayed post-hypoxic leukoencephalopathy (DPHL)\u0026mdash;an uncommon variant of hypoxic brain damage in adults. Front Neurol. 2018;9:708. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.3389/fneur.2018.00708\u003c/span\u003e\u003cspan address=\"10.3389/fneur.2018.00708\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e. PMID:30210433; PMCID:PMC6119709.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eShotar E, et al. Non-ischemic cerebral enhancing lesions secondary to endovascular aneurysm therapy: nickel allergy or foreign body reaction? Case series and review of the literature. Neuroradiology. 2016;58:877\u0026ndash;85. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s00234-016-1699-5\u003c/span\u003e\u003cspan address=\"10.1007/s00234-016-1699-5\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBayas A, Christ M, Berlis A, Naumann M, Ertl M, Joachimski F, et al. Incidence, clinical spectrum, and immunotherapy of non-ischemic cerebral enhancing lesions after endovascular therapy. Ther Adv Neurol Disord. 2022;15:1\u0026ndash;13. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1177/17562864211072372\u003c/span\u003e\u003cspan address=\"10.1177/17562864211072372\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGiordan E, et al. Teaching neuroimages: intracranial foreign body reaction after endovascular procedures. Neurology. 2018;90:296\u0026ndash;7. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1212/WNL.0000000000004938\u003c/span\u003e\u003cspan address=\"10.1212/WNL.0000000000004938\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eIba\u0026ntilde;ez Gabarr\u0026oacute;n I, et al. Lesiones cerebrales no isqu\u0026eacute;micas relacionadas con el tratamiento endovascular de aneurismas intracraneales, a prop\u0026oacute;sito de un caso. Neurol Perspect. 2022;2(espec Cong1):316.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eOnta\u0026ntilde;\u0026oacute;n Garc\u0026eacute;s JM, Saralegui Prieto I, Zaldumbide-Du\u0026ntilde;as L, Fern\u0026aacute;ndezruanova B, Cabrera Zubizarreta A, Vicente Olabarria I. Foreign body granuloma as a complication of endovascular treatment of brain aneurysm. Interdiscip Neurosurg. 2020;22:101068. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1016/j.inat.2020.101068\u003c/span\u003e\u003cspan address=\"10.1016/j.inat.2020.101068\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDaneshmand A, et al. Plastic in the brain: delayed recognition of progressive unilateral hemispheric lesions. Neurocrit Care. 2019;31:222\u0026ndash;4. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1007/s12028-018-0576-y\u003c/span\u003e\u003cspan address=\"10.1007/s12028-018-0576-y\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAnsari SA, et al. Hydrophilic polymer embolic complication during diagnostic cerebral angiography presenting with delayed intracranial hemorrhage: case report and literature review. J Neurointerv Surg. 2019;11:80\u0026ndash;3. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1136/neurintsurg-2018-014189\u003c/span\u003e\u003cspan address=\"10.1136/neurintsurg-2018-014189\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMehta RI, Mehta RI, Solis OE, Jahan R, Salamon N, Tobis JM, et al. Hydrophilic polymer emboli: an under-recognized iatrogenic cause of ischemia and infarct. Mod Pathol. 2010;23(7):921\u0026ndash;30. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1038/modpathol.2010.74\u003c/span\u003e\u003cspan address=\"10.1038/modpathol.2010.74\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBoyle T, et al. Medical treatment of polymeric cerebral granulomatous reactions following endovascular procedures. J Neurointerv Surg. 2021;13:1032\u0026ndash;6. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1136/neurintsurg-2020-016806\u003c/span\u003e\u003cspan address=\"10.1136/neurintsurg-2020-016806\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMehta RI, Mehta RI. Hydrophilic polymer embolism: Implications for manufacturing, regulation, and postmarket surveillance of coated intravascular medical devices. J Patient Saf. 2021;17(8):e1069\u0026ndash;79. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003e10.1097/PTS.0000000000000473\u003c/span\u003e\u003cspan address=\"10.1097/PTS.0000000000000473\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eU.S. Food and Drug Administration. Critical to Quality Information for Hydrophilic Coated and Hydrophobic Coated Vascular and Neurological Devices. FDA; Silver Spring MD: Aug, 2015.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eU.S. Food and Drug Administration. Intravascular Catheters, Wires, and Delivery Systems with Lubricious Coatings \u0026ndash; Labeling Considerations. Guidance for Industry and FDA Staff. Silver Spring, MD: FDA; 2019 Oct.\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":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-neurology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"nurl","sideBox":"Learn more about [BMC Neurology](http://bmcneurol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/nurl","title":"BMC Neurology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"endovascular treatment, foreign body, NICE lesions, hydrophilic polymers","lastPublishedDoi":"10.21203/rs.3.rs-8575131/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8575131/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eWe present the case of a 59-year-old woman who, three months after endovascular treatment of two left carotid aneurysms, was admitted to the emergency department with headache and focal neurological symptoms. Further diagnostic workup revealed a cerebral foreign-body granulomatous reaction. This clinical case also serves as the basis for a review of the current literature.\u003c/p\u003e","manuscriptTitle":"Cerebral Foreign-Body Granulomatous Reaction: A Rare Non-Ischemic Complication After an Endovascular Procedure","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-27 00:05:26","doi":"10.21203/rs.3.rs-8575131/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-02-04T16:44:14+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-02T20:29:44+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-31T12:25:55+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"98481655179936255997242749281324172354","date":"2026-01-26T23:48:56+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-23T20:13:21+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-01-23T05:50:50+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"6347146807560910434656105124251350808","date":"2026-01-23T05:36:14+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"277978414236032525619341759405958023581","date":"2026-01-22T09:18:07+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"167351139324927847910908626982094764670","date":"2026-01-22T04:54:11+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-21T22:34:46+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-01-21T22:28:58+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-16T09:11:03+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-16T09:08:45+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Neurology","date":"2026-01-11T17:36:46+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-neurology","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"nurl","sideBox":"Learn more about [BMC Neurology](http://bmcneurol.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/nurl","title":"BMC Neurology","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"c6609704-4444-4f16-8320-0b6e54900cc7","owner":[],"postedDate":"January 27th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-03-24T16:23:03+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-27 00:05:26","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8575131","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8575131","identity":"rs-8575131","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}