<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Publishing DTD v1.2d1 20170631//EN" "JATS-journalpublishing1.dtd"> <ArticleSet> <Article> <Journal> <PublisherName>jmedicalcasereports</PublisherName> <JournalTitle>Frontiers in Medical Case Reports</JournalTitle> <PISSN>I</PISSN> <EISSN>S</EISSN> <Volume-Issue>Volume 6; Issue 1</Volume-Issue> <PartNumber/> <IssueTopic>Multidisciplinary</IssueTopic> <IssueLanguage>English</IssueLanguage> <Season>(Jan-Feb, 2025)</Season> <SpecialIssue>N</SpecialIssue> <SupplementaryIssue>N</SupplementaryIssue> <IssueOA>Y</IssueOA> <PubDate> <Year>-0001</Year> <Month>11</Month> <Day>30</Day> </PubDate> <ArticleType>Medical Case Reports</ArticleType> <ArticleTitle>AQP4-IgG-Seropositive Patient Who Silently Carried Anti-NMDAR Antibodies Developed Encephalitis During A Relapse</ArticleTitle> <SubTitle/> <ArticleLanguage>English</ArticleLanguage> <ArticleOA>Y</ArticleOA> <FirstPage>1</FirstPage> <LastPage>6</LastPage> <AuthorList> <Author> <FirstName>Andrés María</FirstName> <LastName>Villa</LastName> <AuthorLanguage>English</AuthorLanguage> <Affiliation/> <CorrespondingAuthor>N</CorrespondingAuthor> <ORCID/> <FirstName>Carla</FirstName> <LastName>Seimandi</LastName> <AuthorLanguage>English</AuthorLanguage> <Affiliation/> <CorrespondingAuthor>Y</CorrespondingAuthor> <ORCID/> <FirstName>Ana Mariel</FirstName> <LastName>Finkelsteyn</LastName> <AuthorLanguage>English</AuthorLanguage> <Affiliation/> <CorrespondingAuthor>Y</CorrespondingAuthor> <ORCID/> <FirstName>Analisa</FirstName> <LastName>Manin</LastName> <AuthorLanguage>English</AuthorLanguage> <Affiliation/> <CorrespondingAuthor>Y</CorrespondingAuthor> <ORCID/> <FirstName>Graciela</FirstName> <LastName>Ramos</LastName> <AuthorLanguage>English</AuthorLanguage> <Affiliation/> <CorrespondingAuthor>Y</CorrespondingAuthor> <ORCID/> </Author> </AuthorList> <DOI/> <Abstract>The association of autoimmune diseases is relatively common. Comorbidity anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis and Neuromyelitis Optica Spectrum Disorder (NMOSD) is an unusual and rare overlapping syndrome. We report the case of an AQP4-IgG-seropositive NMOSD patient who developed anti-NMDAR encephalitis during corticosteroid treatment for a relapse of Longitudinal Extensive Transverse Myelitis (LETM), with the presence of anti-NMDAR antibodies in the serum two years earlier. The patient showed significant improvement in both clinical syndromes with a good response to steroid and immunosuppressive therapy. Conclusion Early diagnosis and treatment of overlapping autoimmune syndromes, such as AQP4+IgG seropositive NMOSD with anti-NMDAR encephalitis, are key factors for ensuring early and better recovery outcomes.</Abstract> <AbstractLanguage>English</AbstractLanguage> <Keywords>Encephalitis,Anti-N-Methyl-D-Aspartate Receptor,Neuromyelitis Optica Spectrum Disorders (NMOSD),Overlap Demyelinating Syndrome,AQP4,NMDA</Keywords> <URLs> <Abstract>https://www.jmedicalcasereports.org/ubijournal-v1copy/journals/abstract.php?article_id=15556&title=AQP4-IgG-Seropositive Patient Who Silently Carried Anti-NMDAR Antibodies Developed Encephalitis During A Relapse</Abstract> </URLs> <References> <ReferencesarticleTitle>References</ReferencesarticleTitle> <ReferencesfirstPage>16</ReferencesfirstPage> <ReferenceslastPage>19</ReferenceslastPage> <References>Irani SR. Autoimmune Encephalitis. Continuum (Minneap Minn) 2024; 30: 995-1020. Nan D, Zhang Y, Han J, Jin T. Clinical features and management of coexisting anti-N-methyl-D-aspartate receptor encephalitis and myelin oligodendrocyte glycoprotein antibody-associated encephalomyelitis: a case report and review of the literature. Neurol Sci 2021; 42: 847-855. Sechi E. NMOSD and MOGAD. Continuum (Minneap Minn) 2024; 30: 1052-1087. Shahmohammadi S, Doosti R, Shahmohammadi A, Mohammadianinejad SE, Sahraian MA, Azimi AR, Harirchian MH, Asgari N, Naser Moghadasi A. Autoimmune diseases associated with Neuromyelitis Optica Spectrum Disorders: A literature review. Mult Scler Relat Disord 2019; 27: 350-363. Sinani AA, Maawali SA, Alshekaili J, Kindi MA, Ramadhani KA, Khabouri JA, Nadeem A, Salti AA. Overlapping demyelinating syndrome (Neuromyelitis optica spectrum disorders NMOSD with anti-NMDA receptor encephalitis); A case report. Mult Scler Relat Disord 2020; 42: 102153. Tao S, Zhang Y, Ye H, Guo D. AQP4-IgG-seropositive neuromyelitis optica spectrum disorder (NMOSD) coexisting with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis: A case report and literature review. Mult Scler Relat Disord 2019; 35: 185-192. Villa AM, Manin A, Seimandi C, Guerrero DA, Ramos G. Distinct clinical patterns in AQP4-IgG- positive NMOSD patients vs. Seronegative: Insights from a single-center study in Argentina. Mult Scler Relat Disord 2024; 93: 106223.</References> </References> </Journal> </Article> </ArticleSet>