Autoimmune encephalitis with Anti-mGluR1 antibodies: a comprehensive review

Anti-mGluR1 encephalitis is a rare autoimmune disorder manifesting with cerebellar syndrome with varying levels of severity. However, limited data exist regarding the clinical features and treatment strategies for patients suffering from encephalitis associated with anti-mGluR1 antibodies. Herein, we comprehensively review and discuss clinical features of anti-mGluR1 encephalitis to enhance our understanding of this rare disorder. Our protocol was developed in accordance with PRISMA guidelines and is registered with the PROSPERO (identification: RD420251101607). To identify potentially relevant literature, we conducted a thorough search of the following bibliographic databases: PubMed, Web of Science, the Cochrane Central Register, and China National Knowledge Infrastructure. The search strategy yielded 402 articles, of which 23 met the inclusion criteria for our systematic review. These 23 articles, comprising 3 case series and 20 case reports, described 44 patients with anti-mGluR1 encephalitis. We independently extracted data on the following variables: publication, year, location, age, gender, associated malignancies, prodromal symptoms, clinical manifestations on the initial presentation, brain magnetic resonance imaging (MRI) findings, cerebrospinal fluid (CSF) testing, treatment, duration of last follow-up, and clinical outcome. From the current systematic review, cerebellar ataxia serves as the most prominent clinical manifestation in patients with anti-mGluR1 encephalitis. Furthermore, the proportion of patients receiving first-line immunotherapy was greater in the favorable prognosis group compared to the poor prognosis group. We underscore the importance of early immunotherapy to prevent irreversible cerebellar damage.