Contrast-Induced Encephalopathy after Endovascular Treatment: Three Case Reports

Contrast-Induced Encephalopathy after Endovascular Treatment: Three Case Reports | 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 Contrast-Induced Encephalopathy after Endovascular Treatment: Three Case Reports Yiyi Jin, Chunyan Chen, Jing Huang, Nan Nan, Tongtong Yang, Suyan Zhu This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-7966378/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 Contrast-induced encephalopathy (CIE) is a rare yet potentially severe complication that occurs during or after angiography, typically presenting as a transient and self-limiting condition. It often presents with stroke-like symptoms, which can easily lead to clinical misdiagnosis. Herein, we report three cases of CIE in patients who underwent repeated digital subtraction angiography (DSA). Case presentation: Case 1 was a 68-year-old female admitted to the hospital for angiography after aneurysm surgery. However, after the second cerebral angiography, the patient developed left limb weakness. Emergency computed tomography angiography (CTA) showed no abnormalities, and CIE was suspected. Her neurological deficits completely resolved within 24 h of corticosteroid treatment and rehydration. Case 2 was a 50-year-old man with an intracranial aneurysm. After the second aneurysm embolization procedure by DSA, he developed vomit, headaches, skin erythema, slurred speech, and limb weakness. The cerebral computed tomography (CT) scan revealed edema in the interhemispheric fissure, the left sylvian fissure, and parts of the cerebral sulci. On postoperative day 3, his neurologic deficits and allergic reaction completely resolved after treatment with symptomatic supportive therapy. Case 3 was a 70-year-old female admitted for re-embolization of a residual aneurysm sac after multiple DSA procedures. At this time, she developed aphasia, confusion, and right hemiplegia one-hour post-procedure. Magnetic resonance imaging (MRI) revealed left frontal gyral edema. After treatment with corticosteroids, mannitol, and hydration, the patient’s neurological function improved significantly. Conclusions These three cases highlight a potential association between recurrent DSA exposure and the risk of CIE. Clinicians should maintain a high index of suspicion for CIE when evaluating patients with acute neurological impairments after angiography, especially those who have undergone repeated DSA procedures. Case Digital subtraction angiography Contrast media Contrast-induced encephalopathy Iodixanol Figures Figure 1 Figure 2 Figure 3 Background Contrast-induced encephalopathy (CIE) is a rare, acute, and reversible neurological complication that occurs during or after administration of iodinated contrast media (ICM) in various angiographic examinations and endovascular therapeutic procedures [ 1 ]. It can present with a broad spectrum of neurological manifestations, that are highly similar to those of acute ischemic stroke (AIS) or transient ischemic attack (TIA) [ 2 ]. This article reports three cases of patients who developed CIE after undergoing repeated cerebral digital subtraction angiography (DSA) with iodixanol used as the contrast agent during the procedures. Case presentation Case 1 A 68-year-old female patient was admitted to our hospital for follow-up DSA. One year prior, she had undergone stent-assisted coil embolization (SACE) for intracranial aneurysms in our hospital (Fig. S1 ). This was the second follow-up DSA performed after embolization. She had no history of diabetes mellitus, hypertension, coronary artery disease, or stroke. Neither the previous embolization procedure nor the follow-up DSA was complicated by adverse events. On admission, her laboratory test results were within the normal reference range, and a comprehensive neurological examination, including an assessment of cranial nerve function, revealed no abnormalities. Under local anesthesia, cerebral DSA was performed using 116 mL of iodixanol (Iodixanol Injection, Jiangsu Hengrui Medicine Co., Ltd., China) to evaluate the status of the intracranial aneurysm. DSA showed no aneurysm recurrence. The intraoperative period and early postoperative course were uneventful, and the patient was safely returned to the ward after the procedure. Approximately 16 hours after the procedure, the patient reported weakness in the left upper limb. Neurological examination revealed left-hand muscle strength loss (level 4/5). An immediate cranial computed tomography angiography (CTA) scan showed no significant abnormalities (Fig. 1 ). Since DSA and CTA did not reveal cerebrovascular stenosis, the patient was suspected of CIE and was treated with dexamethasone, nimodipine, and adequate hydration therapy. After the aforementioned treatment, the patient’s clinical symptoms completely resolved within 24 h. Case 2 A 50-year-old male patient was admitted to our hospital for follow-up evaluation and endovascular treatment of a left posterior communicating artery (PCOM) aneurysm. The patient had no special medical history or history of allergies to any medications. One month prior, the patient had undergone stent embolization for the same PCOM aneurysm (Fig. S2 A-C). A follow-up CTA examination revealed a residual aneurysm after embolization (Fig. S2 D). After admission, a diagnostic cerebral DSA procedure was performed, which revealed an unhealed partial defect of the aneurysm, the aneurysm measured 2.6 mm × 2.0 mm in size, with a neck length of 2.4 mm (Fig. S2 E). Subsequently, the patient underwent SACE (Fig. S2 F). During the diagnostic cerebral angiography and interventional DSA procedure, 200 mL of iodixanol (Iodixanol Injection, Starry Pharmaceutical Co., Ltd., Shanghai, China) was used as the contrast agent. The patient did not experience any complications during the operation or in the early postoperative period. Approximately seven hours post-procedure, the patient developed vomiting and headache, followed within one hour by the appearance of a cutaneous red rash, slurred speech, and weakness in the right-hand muscle strength (level 4/5). Emergency cranial computed tomography (CT) revealed hyperintensities in the interhemispheric fissure, the left sylvian fissure, and parts of the cerebral sulci (Fig. 2 A). As CTA did not indicate cerebrovascular stenosis (Fig. 2 B-C), CIE was considered. Anti-allergic therapy was administered, consisting of 5 mg dexamethasone and 10 mg loratadine. Concurrently, 0.9% sodium chloride injection was administered to maintain adequate hydration. Subsequently, head CT was performed (Fig. 2 D). On the day following the procedure, his right-hand muscle strength and speech function showed slight improvements. On the third day, the patient’s symptoms improved and was discharged from the hospital. Two days after discharge, follow-up CT showed improvement in cerebral edema (Fig. 2 E). At the one-week follow-up after discharge, the patient's neurological function had completely recovered. One month postoperatively, repeat CT demonstrated significant resolution of the cerebral edema (Fig. 2 F). Case 3 A 70-year-old female patient was admitted to our hospital for reoperation due to a residual aneurysm sac detected on follow-up DSA. She had multiple intracranial aneurysms, involving the ophthalmic segment of the right internal carotid artery (ICA), the anterior communicating artery (ACA), and the left internal carotid cavernous segment. Several months prior, she had undergone coil embolization for an ACA aneurysm and SACE for the aneurysm in the ophthalmic segment of the right ICA at our hospital (Fig. S3 A-E). Her medical history included sinus bradycardia and a ruptured ACA aneurysm complicated by subarachnoid hemorrhage (SAH) (Hunt-Hess grade 2). Upon physical examination, the patient was conscious and alert with stable vital signs, and no neurological deficits were identified. All laboratory test results on admission were within the normal range. Post-admission diagnostic cerebral DSA revealed an unhealed aneurysm at her left ACA, measuring approximately 2.6 × 2.0 mm. The patient then underwent therapeutic embolization for the residual cerebral aneurysm (Fig. S3 F). A total of 200 mL of Iodixanol (Iodixanol Injection, Starry Pharmaceutical Co., Ltd., Shanghai, China) was used during the therapeutic DSA. No adverse events or complications were observed intraoperatively. One hour postoperatively, the patient developed aphasia, confusion, right-sided weakness (levels 1/5 and 2/5), and a positive right Babinski sign. An immediate cranial CT scan showed swelling of the left frontal lobe and shallowing of the sulci (Fig. 3 A). The patient was initially treated with 5 mg dexamethasone. Four hours later, head CT was performed (Fig. 3 B). After 19 h, a CTA scan did not reveal any cerebral artery occlusion or stenosis (Fig. 3 C). Based on these findings, a diagnosis of CIE was confirmed. We used 80 mg methylprednisolone and 250 ml of glycerol fructose to decrease brain edema. Sodium chloride glucose was used to eliminate the contrast agent. On the third day, although CT revealed an improvement in left frontal lobe edema (Fig. 3 D), the patient’s neurological impairment symptoms did not improve. Her neurological function showed slight improvement, with grade 2 muscle strength in the right upper limb and grade 3 muscle strength in the right lower limb on postoperative day 6. On the 10th day after DSA, the patient’s slurred speech and right limb weakness showed continuous improvement, with grade 5 muscle strength in the right limb. On the 13th postoperative day, MRI showed swelling in multiple gyri of the left frontal lobe. Mild hyperintensity was observed in the left hemispheric gyri on T2-weighted imaging (T2WI), fluid-attenuated inversion recovery (FLAIR), and diffusion-weighted imaging (DWI) sequences, whereas the apparent diffusion coefficient (ADC) map showed no abnormalities (Fig. 3 E). The patient was discharged from the hospital a few days after confirming stable neurological function. Discussion and Conclusions Previous studies have indicated that all types of contrast media agents irrespective of their osmolarity or ionic states, can induce CIE [ 3 , 4 ]. In these three cases, the patients used the third-generation iso-osmolar non-ionic contrast agent iodixanol. Currently, no studies have compared the incidence of CIE between second- and third-generation contrast agents. The current research findings established that non-ionic, iso-osmolar contrast agents are superior to hyperosmolar, ionic contrast agents. Therefore, non-ionic iso-osmolar contrast agents should be prioritized for use in neurointerventional procedures. Multiple studies have demonstrated a significant correlation between the incidence of CIE, but the volume of contrast agent administered has no clear connection between the amount of contrast agent and the incidence of CIE [ 5 , 6 ]. Early diagnosis of CIE can be challenging because its symptoms are very similar to those of cerebrovascular accidents [ 7 ]. CIE lacks unified diagnostic criteria and is a diagnosis of exclusion. Thus, the clinical course and neuroimaging findings are important in ruling out differential diagnoses. Typical findings on brain CT in previous studies included abnormal cortical contrast enhancement and edema, cortical enhancements and hyperintensities in the subarachnoid space, and hyper-density in the cerebral sulci [ 8 ]. Of note, sometimes imaging may be normal, but normal brain imaging does not rule out the diagnosis [ 9 , 10 ]. MRI of the head can better aid in the diagnosis. MRI abnormalities included hyperintensity and gyrus swelling on T2-weighted, fluid-attenuated inversion recovery (FLAIR), and diffusion weighted imaging (DWI), whereas the ADC- sequence has always been unaffected [ 3 , 10 , 11 ]. As shown in these three cases, the patients presented with neurological manifestations mimicking stroke, however, their brain imaging findings were inconsistent. In Case 1, the CTA scan indicate no infarction or hemorrhage. In Cases 2 and 3, multiple CT or MRI scans indicated abnormal imaging manifestations. CIE may have been the leading cause of these clinical manifestations. The patients recovered with short-term corticosteroid therapy and adequate hydration treatment. Risk factors for CIE have been explored in previous studies, including age, sex, renal dysfunction, history of stroke, renal impairment, hypertension, diabetes mellitus, contrast medium type, and contrast medium dose [ 12 – 14 ]. A recently published article indicated that contrast injection from an intradural artery and retreatment of recurrent aneurysms are the main risk factors for CIE [ 15 ]. Our report showed that all three patients underwent recurrent DSA procedures, and Patients 2 and 3 had a history of subarachnoid hemorrhage. The blood-brain barrier (BBB) disruption is a widely accepted theory for the mechanism underlying CIE [ 6 ]. Under normal conditions, the BBB is impermeable to contrast materials. A history of brain damage increases the risk of contrast agent permeability. In addition, Cases 1 and 3 involved elderly patients, necessitating special attention to safety concerns. In consequence, a comprehensive evaluation should be completed preoperatively to determine whether a patient can use a contrast agent before the DSA procedure, particularly in patients with several clinical features such as old age, renal insufficiency, malignancy, or a prior history of brain damage. CIE should be considered when differentially diagnosing a patient with acute neurological impairments after repeated DSA [ 16 ]. There are no guidelines for the treatment of CIE. A multidisciplinary approach and close postoperative monitoring of the patient’s neurological function are essential. The mainstay in the management of CIE is based on intravenous crystalloids for hydration combined with antiedematous therapy using mannitol and corticosteroids [ 17 , 18 ]. In previously published articles, the treatment outcomes were mostly favorable, most patients achieved complete recovery, and permanent neurological deficits were uncommon. In this study, patients were treated with intravenous hydration and dexamethasone (or methylprednisolone for Case 3), and their neurological deficits progressively improved and achieved complete recovery. In conclusion, doctors performing cerebral vascular angiography and interventions should be aware of the potential harmful effects of repeated DSA on the development of CIE. Neuromonitoring may be useful for the early detection of neurological changes, and timely initiation of treatment is crucial. In the future, large-scale controlled studies are required to identify the risk factors for CIE, especially to ascertain whether the number of cerebral angiographies could be a risk factor for CIE. Abbreviations CIE Contrast-induced encephalopathy DSA Digital subtraction angiography CTA Computer tomography angiography AIS Acute ischemic stroke TIA Transient ischemic attack SACE Stent-assisted coil embolization PCOM Posterior communicating artery CT Computed tomography ICA Internal carotid artery ACA anterior communicating artery SAH subarachnoid hemorrhage T2WI T2-weighted imaging FLAIR Fluid-attenuated inversion recovery DWI Diffusion-weighted imaging ADC Apparent diffusion coefficient MRI Magnetic resonance imaging BBB Blood-brain barrier Declarations Acknowledgements None. Authors' contributions YY J: conception, design, writing, and editing of the manuscript. J H & SY Z: both contributed to the manuscript design and conducted critical reviews of the article. CY C &TT Y: performed data analysis and provided a critical review of the article. N N: analyzed the neuroimaging data. Funding This work was supported by the Natural Science Foundation of Ningbo Municipality [2023J163]. The funder is the first author in our study. Availability of data and materials Not applicable. Ethics approval and consent to participate The ethics committee of The First Affiliated Hospital of Ningbo University has approved this study (NO. 2025-186RS-01). Consent for publication Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor of this journal. Competing interests The authors declare that they have no competing interests. Author details 1 Department of Pharmacy, The First Affiliated Hospital of Ningbo University, Ningbo 315100, China. 2 Department of Nuclear Medicine, The First Affiliated Hospital of Ningbo University, Ningbo 315100, China. References Balasubramanian K, Hussain M, Shakir HJ. Contrast-induced encephalopathy following endovascular treatment of intracranial aneurysms. Sci Prog. 2025;108(3):368504251377944. Zidan M, Ghaei S, Bode F, Radbruch A, Dorn F. Early detection of contrast-induced encephalopathy after mechanical thrombectomy using flat-detector CT: incidence, risk factors, and clinical implications. Neuroradiology. 2025;67(5):1153–62. Spina R, Simon N, Markus R, Muller DW, Kathir K. Contrast-induced encephalopathy following cardiac catheterization. Catheter Cardiovasc Interv. 2017;90(2):257–68. Quintas-Neves M, Araújo JM, Xavier SA, Amorim JM, Cruz ESV, Pinho J. Contrast-induced neurotoxicity related to neurological endovascular procedures: a systematic review. 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(A) DSA revealed an aneurysm of 4.5 mm ∗4.5 mm in size in the paraclinoid of the right ICA. (B) DSA demonstrated a coiling aneurysm embolization. Fig.S2.tif Fig. S2 The imaging examinations before CIE. (A) Brain CTA depicted a subarachnoid hemorrhage. (B) DSA revealed an aneurysm of 2.3 mm ∗ 2.6 mm in size in the left PCOM.(C) DSA demonstrated a coiling aneurysm embolization. (D) Repeat brain CTA after PCOM aneurysm. (E) DSA revealed an unhealed partial aneurysm of 2.6 mm ∗ 2.0 mm in size in the left PCOM. (F) DSA demonstrated a coiling aneurysm embolization. Fig.S3.tif Fig. S3 The imaging examinations before CIE. (A) Brain CTA depicted a subarachnoid hemorrhage. (B) Three-dimensional reconstruction images of CTA showed the aneurysms. (C) DSA demonstrated a coiling aneurysm embolization in the ACA. (D) Repeat brain CTA after ACA aneurysm. (E) DSA demonstrated a coiling aneurysm embolization in the ophthalmic segment of the right ICA. (F) DSA demonstrated a coiling aneurysm embolization in the ACA. 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. 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-7966378","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Case Report","associatedPublications":[],"authors":[{"id":551946769,"identity":"b24e4ceb-f819-42d5-8ab0-afee0448fa43","order_by":0,"name":"Yiyi Jin","email":"","orcid":"","institution":"The First Affiliated Hospital of Ningbo University","correspondingAuthor":false,"prefix":"","firstName":"Yiyi","middleName":"","lastName":"Jin","suffix":""},{"id":551946770,"identity":"6fb21426-592f-416f-979f-dea50ef2d809","order_by":1,"name":"Chunyan Chen","email":"","orcid":"","institution":"The First Affiliated Hospital of Ningbo 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10:06:50","extension":"png","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":335048,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig.2.png","url":"https://assets-eu.researchsquare.com/files/rs-7966378/v1/b1f8a0e6be3ec7bbbfc1c1f5.png"},{"id":97123044,"identity":"f8d58088-8e13-437a-be96-ef61f05eea8b","added_by":"auto","created_at":"2025-12-01 08:03:52","extension":"png","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":724535,"visible":true,"origin":"","legend":"","description":"","filename":"OnlineFig.3.png","url":"https://assets-eu.researchsquare.com/files/rs-7966378/v1/f421291bf1d6bdd26c4c11a3.png"},{"id":97123050,"identity":"ce970a17-9d23-44d2-9d47-f044a5ec6e77","added_by":"auto","created_at":"2025-12-01 08:03:52","extension":"xml","order_by":15,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":56885,"visible":true,"origin":"","legend":"","description":"","filename":"c8d27670fe85479f96d1b325b2aab1ac1structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-7966378/v1/4e1fb103bb7e18204727205d.xml"},{"id":97123039,"identity":"e7b2d3d4-4670-4601-b7e4-a7a957c4527a","added_by":"auto","created_at":"2025-12-01 08:03:52","extension":"html","order_by":16,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":64296,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-7966378/v1/722f3afc96fd490e66516089.html"},{"id":97123031,"identity":"1f0e08c2-d7a0-4b41-ad70-19120d958073","added_by":"auto","created_at":"2025-12-01 08:03:51","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":491645,"visible":true,"origin":"","legend":"\u003cp\u003eEmergent brain CT angiography (CTA).\u003c/p\u003e","description":"","filename":"Fig.1.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7966378/v1/68fff29ce3e536685905c8d3.jpg"},{"id":97141419,"identity":"e5e0264d-51cf-4ef4-87fe-d216c1842d73","added_by":"auto","created_at":"2025-12-01 10:06:41","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":1443729,"visible":true,"origin":"","legend":"\u003cp\u003eBrain CT scans of the CIE patient. (\u003cstrong\u003eA\u003c/strong\u003e) The CT scan was performed after 13 h of the procedure. (\u003cstrong\u003eB-C\u003c/strong\u003e) The brain CTA scan was performed after 22 h of the procedure. (\u003cstrong\u003eD\u003c/strong\u003e) The brain CT scan was performed the following day post-procedure. (\u003cstrong\u003eE\u003c/strong\u003e) The brain CT scan was performed on the 5th day post-procedure. (\u003cstrong\u003eF\u003c/strong\u003e) The brain CT scan was performed a month after the procedure.\u003c/p\u003e","description":"","filename":"Fig.2.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7966378/v1/8b9908691e7072c3994f5869.jpg"},{"id":97141689,"identity":"1c36b4f9-5a3d-4102-b07a-fda12270d00a","added_by":"auto","created_at":"2025-12-01 10:06:53","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":2310327,"visible":true,"origin":"","legend":"\u003cp\u003eBrain CT scans of the CIE patient. (\u003cstrong\u003eA\u003c/strong\u003e) The CT scan was performed after 1 h of the procedure. (\u003cstrong\u003eB\u003c/strong\u003e) The brain CT scan was performed after 4 h of the procedure. (\u003cstrong\u003eC\u003c/strong\u003e) The brain CTA scan was performed after 19 h of the procedure. (\u003cstrong\u003eD\u003c/strong\u003e) The brain CT scan was performed on the 3rd day post-procedure. (\u003cstrong\u003eE\u003c/strong\u003e) The brain MRI on the 13th day post-procedure after the procedure.\u003c/p\u003e","description":"","filename":"Fig.3.tif.jpg","url":"https://assets-eu.researchsquare.com/files/rs-7966378/v1/4b62bbc76b125c5931da9419.jpg"},{"id":97664758,"identity":"56561eea-ab4e-4d4d-9022-302c4d3ae9f5","added_by":"auto","created_at":"2025-12-08 09:13:56","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":4681537,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-7966378/v1/015afa4b-b876-470c-9cef-689134a4a6ce.pdf"},{"id":97123034,"identity":"ff50dc7b-09bf-4c4a-9d7d-90fecb718283","added_by":"auto","created_at":"2025-12-01 08:03:51","extension":"tif","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":1084522,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFig. S1 \u003c/strong\u003eThe imaging examinations before CIE. \u003cstrong\u003e(A) \u003c/strong\u003eDSA revealed an aneurysm of 4.5 mm ∗4.5 mm in size in the paraclinoid of the right ICA.\u003cstrong\u003e (B) \u003c/strong\u003eDSA demonstrated a coiling aneurysm embolization.\u003c/p\u003e","description":"","filename":"Fig.S1.tif","url":"https://assets-eu.researchsquare.com/files/rs-7966378/v1/d545cfd123cf6a6126ff1448.tif"},{"id":97123043,"identity":"59bc2a28-6368-4812-addb-be57cec6ce9a","added_by":"auto","created_at":"2025-12-01 08:03:52","extension":"tif","order_by":2,"title":"","display":"","copyAsset":false,"role":"supplement","size":3276760,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFig. S2 \u003c/strong\u003eThe imaging examinations before CIE. \u003cstrong\u003e(A) \u003c/strong\u003eBrain CTA depicted a subarachnoid hemorrhage.\u003cstrong\u003e (B) \u003c/strong\u003eDSA revealed an aneurysm of 2.3 mm ∗ 2.6 mm in size in the left PCOM.\u003cstrong\u003e(C) \u003c/strong\u003eDSA demonstrated a coiling aneurysm embolization. \u003cstrong\u003e(D)\u003c/strong\u003e Repeat brain CTA after PCOM aneurysm. \u003cstrong\u003e(E) \u003c/strong\u003eDSA revealed an unhealed partial aneurysm of 2.6 mm ∗ 2.0 mm in size in the left PCOM. \u003cstrong\u003e(F)\u003c/strong\u003e DSA demonstrated a coiling aneurysm embolization.\u003c/p\u003e","description":"","filename":"Fig.S2.tif","url":"https://assets-eu.researchsquare.com/files/rs-7966378/v1/9ed5e8e48f5434fc2635a964.tif"},{"id":97141456,"identity":"31bc7208-d2fe-4588-9bb2-3bb0af2d4ac3","added_by":"auto","created_at":"2025-12-01 10:06:43","extension":"tif","order_by":3,"title":"","display":"","copyAsset":false,"role":"supplement","size":3379136,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eFig. S3 \u003c/strong\u003eThe imaging examinations before CIE. \u003cstrong\u003e(A) \u003c/strong\u003eBrain CTA depicted a subarachnoid hemorrhage.\u003cstrong\u003e (B) \u003c/strong\u003eThree-dimensional reconstruction images of CTA showed the aneurysms.\u003cstrong\u003e (C) \u003c/strong\u003eDSA demonstrated a coiling aneurysm embolization in the ACA.\u003cstrong\u003e (D)\u003c/strong\u003e Repeat brain CTA after ACA aneurysm.\u003cstrong\u003e (E) \u003c/strong\u003eDSA demonstrated a coiling aneurysm embolization in the ophthalmic segment of the right ICA.\u003cstrong\u003e (F) \u003c/strong\u003eDSA demonstrated a coiling aneurysm embolization in the ACA.\u003c/p\u003e","description":"","filename":"Fig.S3.tif","url":"https://assets-eu.researchsquare.com/files/rs-7966378/v1/c5c32d75eb3a32d543c9b704.tif"}],"financialInterests":"No competing interests reported.","formattedTitle":"Contrast-Induced Encephalopathy after Endovascular Treatment: Three Case Reports","fulltext":[{"header":"Background","content":"\u003cp\u003eContrast-induced encephalopathy (CIE) is a rare, acute, and reversible neurological complication that occurs during or after administration of iodinated contrast media (ICM) in various angiographic examinations and endovascular therapeutic procedures [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. It can present with a broad spectrum of neurological manifestations, that are highly similar to those of acute ischemic stroke (AIS) or transient ischemic attack (TIA) [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. This article reports three cases of patients who developed CIE after undergoing repeated cerebral digital subtraction angiography (DSA) with iodixanol used as the contrast agent during the procedures.\u003c/p\u003e"},{"header":"Case presentation","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e\u003ch2\u003eCase 1\u003c/h2\u003e\u003cp\u003eA 68-year-old female patient was admitted to our hospital for follow-up DSA. One year prior, she had undergone stent-assisted coil embolization (SACE) for intracranial aneurysms in our hospital (Fig. \u003cspan refid=\"MOESM1\" class=\"InternalRef\"\u003eS1\u003c/span\u003e). This was the second follow-up DSA performed after embolization. She had no history of diabetes mellitus, hypertension, coronary artery disease, or stroke. Neither the previous embolization procedure nor the follow-up DSA was complicated by adverse events. On admission, her laboratory test results were within the normal reference range, and a comprehensive neurological examination, including an assessment of cranial nerve function, revealed no abnormalities.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eUnder local anesthesia, cerebral DSA was performed using 116 mL of iodixanol (Iodixanol Injection, Jiangsu Hengrui Medicine Co., Ltd., China) to evaluate the status of the intracranial aneurysm. DSA showed no aneurysm recurrence. The intraoperative period and early postoperative course were uneventful, and the patient was safely returned to the ward after the procedure.\u003c/p\u003e\u003cp\u003eApproximately 16 hours after the procedure, the patient reported weakness in the left upper limb. Neurological examination revealed left-hand muscle strength loss (level 4/5). An immediate cranial computed tomography angiography (CTA) scan showed no significant abnormalities (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e1\u003c/span\u003e). Since DSA and CTA did not reveal cerebrovascular stenosis, the patient was suspected of CIE and was treated with dexamethasone, nimodipine, and adequate hydration therapy. After the aforementioned treatment, the patient\u0026rsquo;s clinical symptoms completely resolved within 24 h.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eCase 2\u003c/h3\u003e\n\u003cp\u003eA 50-year-old male patient was admitted to our hospital for follow-up evaluation and endovascular treatment of a left posterior communicating artery (PCOM) aneurysm. The patient had no special medical history or history of allergies to any medications. One month prior, the patient had undergone stent embolization for the same PCOM aneurysm (Fig. \u003cspan refid=\"MOESM2\" class=\"InternalRef\"\u003eS2\u003c/span\u003eA-C). A follow-up CTA examination revealed a residual aneurysm after embolization (Fig. \u003cspan refid=\"MOESM2\" class=\"InternalRef\"\u003eS2\u003c/span\u003eD).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003eAfter admission, a diagnostic cerebral DSA procedure was performed, which revealed an unhealed partial defect of the aneurysm, the aneurysm measured 2.6 mm \u0026times; 2.0 mm in size, with a neck length of 2.4 mm (Fig. \u003cspan refid=\"MOESM2\" class=\"InternalRef\"\u003eS2\u003c/span\u003eE). Subsequently, the patient underwent SACE (Fig. \u003cspan refid=\"MOESM2\" class=\"InternalRef\"\u003eS2\u003c/span\u003eF). During the diagnostic cerebral angiography and interventional DSA procedure, 200 mL of iodixanol (Iodixanol Injection, Starry Pharmaceutical Co., Ltd., Shanghai, China) was used as the contrast agent. The patient did not experience any complications during the operation or in the early postoperative period.\u003c/p\u003e\u003cp\u003eApproximately seven hours post-procedure, the patient developed vomiting and headache, followed within one hour by the appearance of a cutaneous red rash, slurred speech, and weakness in the right-hand muscle strength (level 4/5). Emergency cranial computed tomography (CT) revealed hyperintensities in the interhemispheric fissure, the left sylvian fissure, and parts of the cerebral sulci (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e2\u003c/span\u003eA). As CTA did not indicate cerebrovascular stenosis (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e2\u003c/span\u003eB-C), CIE was considered. Anti-allergic therapy was administered, consisting of 5 mg dexamethasone and 10 mg loratadine. Concurrently, 0.9% sodium chloride injection was administered to maintain adequate hydration. Subsequently, head CT was performed (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e2\u003c/span\u003eD). On the day following the procedure, his right-hand muscle strength and speech function showed slight improvements. On the third day, the patient\u0026rsquo;s symptoms improved and was discharged from the hospital. Two days after discharge, follow-up CT showed improvement in cerebral edema (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e2\u003c/span\u003eE). At the one-week follow-up after discharge, the patient's neurological function had completely recovered. One month postoperatively, repeat CT demonstrated significant resolution of the cerebral edema (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e2\u003c/span\u003eF).\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\n\u003ch3\u003eCase 3\u003c/h3\u003e\n\u003cp\u003eA 70-year-old female patient was admitted to our hospital for reoperation due to a residual aneurysm sac detected on follow-up DSA. She had multiple intracranial aneurysms, involving the ophthalmic segment of the right internal carotid artery (ICA), the anterior communicating artery (ACA), and the left internal carotid cavernous segment. Several months prior, she had undergone coil embolization for an ACA aneurysm and SACE for the aneurysm in the ophthalmic segment of the right ICA at our hospital (Fig. \u003cspan refid=\"MOESM3\" class=\"InternalRef\"\u003eS3\u003c/span\u003eA-E). Her medical history included sinus bradycardia and a ruptured ACA aneurysm complicated by subarachnoid hemorrhage (SAH) (Hunt-Hess grade 2). Upon physical examination, the patient was conscious and alert with stable vital signs, and no neurological deficits were identified. All laboratory test results on admission were within the normal range.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e\u003cp\u003ePost-admission diagnostic cerebral DSA revealed an unhealed aneurysm at her left ACA, measuring approximately 2.6 \u0026times; 2.0 mm. The patient then underwent therapeutic embolization for the residual cerebral aneurysm (Fig. \u003cspan refid=\"MOESM3\" class=\"InternalRef\"\u003eS3\u003c/span\u003eF). A total of 200 mL of Iodixanol (Iodixanol Injection, Starry Pharmaceutical Co., Ltd., Shanghai, China) was used during the therapeutic DSA. No adverse events or complications were observed intraoperatively.\u003c/p\u003e\u003cp\u003eOne hour postoperatively, the patient developed aphasia, confusion, right-sided weakness (levels 1/5 and 2/5), and a positive right Babinski sign. An immediate cranial CT scan showed swelling of the left frontal lobe and shallowing of the sulci (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e3\u003c/span\u003eA). The patient was initially treated with 5 mg dexamethasone. Four hours later, head CT was performed (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e3\u003c/span\u003eB). After 19 h, a CTA scan did not reveal any cerebral artery occlusion or stenosis (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e3\u003c/span\u003eC). Based on these findings, a diagnosis of CIE was confirmed. We used 80 mg methylprednisolone and 250 ml of glycerol fructose to decrease brain edema. Sodium chloride glucose was used to eliminate the contrast agent. On the third day, although CT revealed an improvement in left frontal lobe edema (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e3\u003c/span\u003eD), the patient\u0026rsquo;s neurological impairment symptoms did not improve. Her neurological function showed slight improvement, with grade 2 muscle strength in the right upper limb and grade 3 muscle strength in the right lower limb on postoperative day 6. On the 10th day after DSA, the patient\u0026rsquo;s slurred speech and right limb weakness showed continuous improvement, with grade 5 muscle strength in the right limb. On the 13th postoperative day, MRI showed swelling in multiple gyri of the left frontal lobe. Mild hyperintensity was observed in the left hemispheric gyri on T2-weighted imaging (T2WI), fluid-attenuated inversion recovery (FLAIR), and diffusion-weighted imaging (DWI) sequences, whereas the apparent diffusion coefficient (ADC) map showed no abnormalities (Fig.\u0026nbsp;\u003cspan refid=\"Fig6\" class=\"InternalRef\"\u003e3\u003c/span\u003eE). The patient was discharged from the hospital a few days after confirming stable neurological function.\u003c/p\u003e\u003cp\u003e\u003c/p\u003e"},{"header":"Discussion and Conclusions","content":"\u003cp\u003ePrevious studies have indicated that all types of contrast media agents irrespective of their osmolarity or ionic states, can induce CIE [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. In these three cases, the patients used the third-generation iso-osmolar non-ionic contrast agent iodixanol. Currently, no studies have compared the incidence of CIE between second- and third-generation contrast agents. The current research findings established that non-ionic, iso-osmolar contrast agents are superior to hyperosmolar, ionic contrast agents. Therefore, non-ionic iso-osmolar contrast agents should be prioritized for use in neurointerventional procedures. Multiple studies have demonstrated a significant correlation between the incidence of CIE, but the volume of contrast agent administered has no clear connection between the amount of contrast agent and the incidence of CIE [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eEarly diagnosis of CIE can be challenging because its symptoms are very similar to those of cerebrovascular accidents [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. CIE lacks unified diagnostic criteria and is a diagnosis of exclusion. Thus, the clinical course and neuroimaging findings are important in ruling out differential diagnoses. Typical findings on brain CT in previous studies included abnormal cortical contrast enhancement and edema, cortical enhancements and hyperintensities in the subarachnoid space, and hyper-density in the cerebral sulci [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Of note, sometimes imaging may be normal, but normal brain imaging does not rule out the diagnosis [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. MRI of the head can better aid in the diagnosis. MRI abnormalities included hyperintensity and gyrus swelling on T2-weighted, fluid-attenuated inversion recovery (FLAIR), and diffusion weighted imaging (DWI), whereas the ADC- sequence has always been unaffected [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. As shown in these three cases, the patients presented with neurological manifestations mimicking stroke, however, their brain imaging findings were inconsistent. In Case 1, the CTA scan indicate no infarction or hemorrhage. In Cases 2 and 3, multiple CT or MRI scans indicated abnormal imaging manifestations. CIE may have been the leading cause of these clinical manifestations. The patients recovered with short-term corticosteroid therapy and adequate hydration treatment.\u003c/p\u003e\u003cp\u003eRisk factors for CIE have been explored in previous studies, including age, sex, renal dysfunction, history of stroke, renal impairment, hypertension, diabetes mellitus, contrast medium type, and contrast medium dose [\u003cspan additionalcitationids=\"CR13\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. A recently published article indicated that contrast injection from an intradural artery and retreatment of recurrent aneurysms are the main risk factors for CIE [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Our report showed that all three patients underwent recurrent DSA procedures, and Patients 2 and 3 had a history of subarachnoid hemorrhage. The blood-brain barrier (BBB) disruption is a widely accepted theory for the mechanism underlying CIE [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Under normal conditions, the BBB is impermeable to contrast materials. A history of brain damage increases the risk of contrast agent permeability. In addition, Cases 1 and 3 involved elderly patients, necessitating special attention to safety concerns. In consequence, a comprehensive evaluation should be completed preoperatively to determine whether a patient can use a contrast agent before the DSA procedure, particularly in patients with several clinical features such as old age, renal insufficiency, malignancy, or a prior history of brain damage. CIE should be considered when differentially diagnosing a patient with acute neurological impairments after repeated DSA [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eThere are no guidelines for the treatment of CIE. A multidisciplinary approach and close postoperative monitoring of the patient\u0026rsquo;s neurological function are essential. The mainstay in the management of CIE is based on intravenous crystalloids for hydration combined with antiedematous therapy using mannitol and corticosteroids [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e, \u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. In previously published articles, the treatment outcomes were mostly favorable, most patients achieved complete recovery, and permanent neurological deficits were uncommon. In this study, patients were treated with intravenous hydration and dexamethasone (or methylprednisolone for Case 3), and their neurological deficits progressively improved and achieved complete recovery.\u003c/p\u003e\u003cp\u003eIn conclusion, doctors performing cerebral vascular angiography and interventions should be aware of the potential harmful effects of repeated DSA on the development of CIE. Neuromonitoring may be useful for the early detection of neurological changes, and timely initiation of treatment is crucial. In the future, large-scale controlled studies are required to identify the risk factors for CIE, especially to ascertain whether the number of cerebral angiographies could be a risk factor for CIE.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eCIE\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eContrast-induced encephalopathy\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\"\u003eCTA\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eComputer tomography angiography\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eAIS\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eAcute ischemic stroke\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eTIA\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eTransient ischemic attack\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eSACE\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eStent-assisted coil embolization\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003ePCOM\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003ePosterior communicating artery\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\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\"\u003eICA\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eInternal carotid artery\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eACA\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eanterior communicating artery\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eSAH\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003esubarachnoid hemorrhage\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eT2WI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eT2-weighted imaging\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eFLAIR\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eFluid-attenuated inversion recovery\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eDWI\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eDiffusion-weighted imaging\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003cdiv class=\"DefinitionListEntry\"\u003e\u003cdiv class=\"Term\"\u003eADC\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eApparent diffusion coefficient\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\"\u003eBBB\u003c/div\u003e\u003cdiv class=\"Description\"\u003e\u003cp\u003eBlood-brain barrier\u003c/p\u003e\u003c/div\u003e\u003c/div\u003e\u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eYY J: conception, design, writing, and editing of the manuscript.\u003c/p\u003e\n\u003cp\u003eJ H \u0026amp; SY Z: both contributed to the manuscript design and conducted critical reviews of the article.\u003c/p\u003e\n\u003cp\u003eCY C \u0026amp;TT Y: performed data analysis and provided a critical review of the article.\u003c/p\u003e\n\u003cp\u003eN N: analyzed the neuroimaging data.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the Natural Science Foundation of Ningbo Municipality [2023J163]. The funder is the first author in our study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe ethics committee of The First Affiliated Hospital of Ningbo University has approved this study (NO. 2025-186RS-01).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWritten informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor of this journal.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that they have no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor details\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e1\u003c/sup\u003eDepartment of Pharmacy, The First Affiliated Hospital of Ningbo University, Ningbo 315100, China.\u003c/p\u003e\n\u003cp\u003e\u003csup\u003e2\u003c/sup\u003eDepartment of Nuclear Medicine, The First Affiliated Hospital of Ningbo University, Ningbo 315100, China.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBalasubramanian K, Hussain M, Shakir HJ. Contrast-induced encephalopathy following endovascular treatment of intracranial aneurysms. Sci Prog. 2025;108(3):368504251377944.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZidan M, Ghaei S, Bode F, Radbruch A, Dorn F. Early detection of contrast-induced encephalopathy after mechanical thrombectomy using flat-detector CT: incidence, risk factors, and clinical implications. Neuroradiology. 2025;67(5):1153\u0026ndash;62.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSpina R, Simon N, Markus R, Muller DW, Kathir K. Contrast-induced encephalopathy following cardiac catheterization. Catheter Cardiovasc Interv. 2017;90(2):257\u0026ndash;68.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eQuintas-Neves M, Ara\u0026uacute;jo JM, Xavier SA, Amorim JM, Cruz ESV, Pinho J. Contrast-induced neurotoxicity related to neurological endovascular procedures: a systematic review. Acta Neurol Belg. 2020;120(6):1419\u0026ndash;24.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLi M, Liu J, Chen F, Fan C, Yang X, Sun X. Contrast-induced encephalopathy following endovascular treatment for intracranial aneurysms-risk factors analysis and clinical strategy. Neuroradiology. 2023;65(3):629\u0026ndash;35.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNagamine Y, Hayashi T, Kakehi Y, Yamane F, Ishihara S, Uchino A, et al. Contrast-induced encephalopathy after coil embolization of an unruptured internal carotid artery aneurysm. Intern Med. 2014;53(18):2133\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhao W, Zhang J, Song Y, Sun L, Zheng M, Yin H, et al. Irreversible fatal contrast-induced encephalopathy: a case report. BMC Neurol. 2019;19(1):46.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eNiimi Y, Kupersmith MJ, Ahmad S, Song J, Berenstein A. Cortical blindness, transient and otherwise, associated with detachable coil embolization of intracranial aneurysms. AJNR Am J Neuroradiol. 2008;29(3):603\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eSpina R, Simon N, Markus R, Muller DW, Kathir K. Recurrent contrast-induced encephalopathy following coronary angiography. Intern Med J. 2017;47(2):221\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eDeb-Chatterji M, Sch\u0026auml;fer L, Grzyska U, Gelderblom M. Stroke-mimics: An acute brainstem syndrome after intravenous contrast medium application as a rare cause of contrast-induced neurotoxicity. Clin Neurol Neurosurg. 2018;174:244\u0026ndash;6.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eLiao MT, Lin TT, Lin LY, Hwang JJ, Tseng CD. Contrast-Induced Encephalopathy after Percutaneous Coronary Intervention. Acta Cardiol Sin. 2013;29(3):277\u0026ndash;80.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eZhong Z, Ni H, Zhu J, Jiang H, Hu J, Lin D, et al. Association between general anesthesia and contrast-induced encephalopathy after endovascular treatment on neurovascular diseases. Front Neurol. 2023;14:1146194.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eAllison C, Sharma V, Park J, Schirmer CM, Zand R. Contrast-Induced Encephalopathy after Cerebral Angiogram: A Case Series and Review of Literature. Case Rep Neurol. 2021;13(2):405\u0026ndash;13.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eMeijer FJA, Steens SCA, Tuladhar AM, van Dijk ED, Boogaarts HD. Contrast-induced encephalopathy-neuroimaging findings and clinical relevance. Neuroradiology. 2022;64(6):1265\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eFuga M, Tanaka T, Tachi R, Yamana S, Irie K, Kajiwara I, et al. Contrast Injection from an Intermediate Catheter Placed in an Intradural Artery is Associated with Contrast-Induced Encephalopathy following Neurointervention. AJNR Am J Neuroradiol. 2023;44(9):1057\u0026ndash;63.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eRen J, Ge Y, Wen R, Zhang Y, Shen J, Chen W. Contrast-induced encephalopathy after an embolization procedure for a cerebral aneurysm in a female with subarachnoid hemorrhage: a case report. BMC Neurol. 2024;24(1):38.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eJankovic D, Tanaka R, Sasaki K, Miyatani K, Chemate S, Nakipuria M, et al. Contrast-Induced Encephalopathy after Endovascular Treatment: Two Case Reports. Asian J Neurosurg. 2023;18(4):813\u0026ndash;7.\u003c/span\u003e\u003c/li\u003e\u003cli\u003e\u003cspan\u003eChisci E, Setacci F, de Donato G, Setacci C. A case of contrast-induced encephalopathy using iodixanol. J Endovasc Ther. 2011;18(4):540\u0026ndash;4.\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":"Case, Digital subtraction angiography, Contrast media, Contrast-induced encephalopathy, Iodixanol","lastPublishedDoi":"10.21203/rs.3.rs-7966378/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-7966378/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e\u003cp\u003eContrast-induced encephalopathy (CIE) is a rare yet potentially severe complication that occurs during or after angiography, typically presenting as a transient and self-limiting condition. It often presents with stroke-like symptoms, which can easily lead to clinical misdiagnosis. Herein, we report three cases of CIE in patients who underwent repeated digital subtraction angiography (DSA).\u003c/p\u003e\u003ch2\u003eCase presentation:\u003c/h2\u003e\u003cp\u003eCase 1 was a 68-year-old female admitted to the hospital for angiography after aneurysm surgery. However, after the second cerebral angiography, the patient developed left limb weakness. Emergency computed tomography angiography (CTA) showed no abnormalities, and CIE was suspected. Her neurological deficits completely resolved within 24 h of corticosteroid treatment and rehydration. Case 2 was a 50-year-old man with an intracranial aneurysm. After the second aneurysm embolization procedure by DSA, he developed vomit, headaches, skin erythema, slurred speech, and limb weakness. The cerebral computed tomography (CT) scan revealed edema in the interhemispheric fissure, the left sylvian fissure, and parts of the cerebral sulci. On postoperative day 3, his neurologic deficits and allergic reaction completely resolved after treatment with symptomatic supportive therapy. Case 3 was a 70-year-old female admitted for re-embolization of a residual aneurysm sac after multiple DSA procedures. At this time, she developed aphasia, confusion, and right hemiplegia one-hour post-procedure. Magnetic resonance imaging (MRI) revealed left frontal gyral edema. After treatment with corticosteroids, mannitol, and hydration, the patient\u0026rsquo;s neurological function improved significantly.\u003c/p\u003e\u003ch2\u003eConclusions\u003c/h2\u003e\u003cp\u003eThese three cases highlight a potential association between recurrent DSA exposure and the risk of CIE. Clinicians should maintain a high index of suspicion for CIE when evaluating patients with acute neurological impairments after angiography, especially those who have undergone repeated DSA procedures.\u003c/p\u003e","manuscriptTitle":"Contrast-Induced Encephalopathy after Endovascular Treatment: Three Case Reports","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-01 08:03:47","doi":"10.21203/rs.3.rs-7966378/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":"922b5150-96b0-474f-9ab9-b25dfd66a592","owner":[],"postedDate":"December 1st, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-12-02T20:53:28+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-01 08:03:47","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-7966378","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-7966378","identity":"rs-7966378","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}