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Wei M, Bannout F, Dastjerdi M, Phan C, Batarseh S, Guo X, Baker N. Immunotherapy in a case of low titre GAD65 antibody-associated spectrum neurological disorders. BMJ Case Rep 2024; 17:e260503. [PMID: 38871638 DOI: 10.1136/bcr-2024-260503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2024] Open
Abstract
We present a rare case of low titre GAD65 antibody-associated autoimmune encephalitis and status epilepticus in a young woman. She initially presented with left arm dystonic movements, contractures and status epilepticus. Due to the concern of autoimmune encephalitis and seizures, the patient received intravenous immunoglobulin empirically. After the detection of low serum GAD65 antibodies, the patient underwent immunomodulation therapy with significant improvement. This case demonstrated that in autoimmune encephalitis, it is important to monitor serum GAD65 antibodies levels and consider immunotherapy, despite mildly elevated serum levels. The patient's history of left arm dystonic movements without impaired awareness may have been due to limb dystonia, a presenting symptom of stiff person syndrome (SPS), despite SPS more commonly affecting axial muscles. This case further demonstrates that GAD65 antibody-related syndromes can manifest with different neurological phenotypes including co-occurrence of epilepsy with possible focal SPS despite low GAD65 antibodies titres.
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Affiliation(s)
- Miao Wei
- Neurology, Loma Linda University School of Medicine, Loma Linda, California, USA
| | - Firas Bannout
- Neurology, Loma Linda University School of Medicine, Loma Linda, California, USA
| | - Mohammad Dastjerdi
- Neurology, Loma Linda University School of Medicine, Loma Linda, California, USA
| | - Cattien Phan
- Neurology, Loma Linda University School of Medicine, Loma Linda, California, USA
| | - Sanad Batarseh
- Neurology, Loma Linda University School of Medicine, Loma Linda, California, USA
| | - Xiaofan Guo
- Neurology, Loma Linda University School of Medicine, Loma Linda, California, USA
| | - Nancy Baker
- Neurology, Loma Linda University School of Medicine, Loma Linda, California, USA
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Qin M, Chen J, Guo X, Xiang X, Nie L, Wang Y, Mao L. Movement disorders in autoimmune encephalitis: an update. J Neurol 2023; 270:5288-5302. [PMID: 37523063 DOI: 10.1007/s00415-023-11881-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/13/2023] [Accepted: 07/13/2023] [Indexed: 08/01/2023]
Abstract
Autoimmune encephalitis (AE) is a form of encephalitis resulting from an immune response targeting central nervous system antigens, which is characterized by cognitive impairment, neuropsychiatric symptoms, seizures, movement disorders (MDs), and other encephalopathy symptoms. MDs frequently manifest throughout the progression of the disease, with recurrent involuntary movements leading to discomfort and, in some cases, necessitating admission to the intensive care unit. Prompt identification and management of MDs can aid in the diagnosis and prognosis of AE. This review synthesizes current knowledge on the characteristics, underlying mechanisms, and treatment options for MDs in the context of AE.
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Affiliation(s)
- Mengting Qin
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Jiaojiao Chen
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xiaoqing Guo
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xuying Xiang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Lei Nie
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yong Wang
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
| | - Ling Mao
- Department of Neurology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
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Dong J, Yi X. The Diagnostic Challenge and Prognosis of Autoimmune Encephalitis in Children: A Single-Center Retrospective Study. Pediatr Neurol 2023; 146:103-109. [PMID: 37467622 DOI: 10.1016/j.pediatrneurol.2023.06.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Revised: 04/11/2023] [Accepted: 06/16/2023] [Indexed: 07/21/2023]
Abstract
BACKGROUND Autoimmune encephalitis (AE) is an immune-mediated encephalitis; nevertheless, its diagnosis in children remains challenging. This study aimed to reveal the clinical characteristics, diagnostic processes, and therapeutic outcomes of AE in children. METHODS A total of 18 children with AE were enrolled. Antibody assay was performed in the cerebrospinal fluid (CSF) and serum samples by indirect immunofluorescence. Electroencephalography (EEG) and magnetic resonance imaging (MRI) were monitored to reflect abnormal neural signals. In addition, demographics data, neurological symptoms, therapeutic strategies, and outcomes were recorded and analyzed. RESULTS Convulsion (50.00%) and emotional disturbance (44.44%) were common clinical symptoms of AE. The biochemical parameters in the CSF had a relatively low diagnostic value. Antibodies in the CSF were dominant in the diagnosis of AE but those in the serum were limited in the diagnosis of anti-MOG or anti-LGI1 AE. In addition, all children showed abnormalities in EEG (72.22%) or MRI (66.67%). Methylprednisolone combined with sequential oral prednisone (83.33%) and gamma globulin (88.89%) were the dominant drugs, achieving an overall recovery rate of 72.22%. However, there were still two patients who had poor outcomes, including Patient 3 with a young age (two years old) and progressive symptom and Patient 12 with a long disease course before treatment (>120 days). CONCLUSIONS The clinical manifestations of AE are varied in children. Antibody in the CSF was dominant, and EEG and MRI were instructive in the diagnosis of AE. Young age, progressive symptom, and prolonged disease course before treatment may contribute to poor outcomes.
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Affiliation(s)
- Jingjing Dong
- Department of Pediatric Neurology, The Affiliated Children's Hospital, Capital Institute of Pediatrics, Beijing, China.
| | - Xiaoli Yi
- Department of Radiology, The Affiliated Children's Hospital, Capital Institute of Pediatrics, Beijing, China
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Warren N, Freier K, Siskind D, O'Gorman C, Blum S, Gillis D, Scott JG. Anti-glutamic acid decarboxylase antibody screening in first-episode psychosis. Aust N Z J Psychiatry 2023; 57:603-612. [PMID: 35362325 DOI: 10.1177/00048674221089560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
OBJECTIVE The Royal Australian and New Zealand College of Psychiatrists recommends screening for a range of antibodies in first-episode psychosis, including anti-glutamic acid decarboxylase antibodies. Glutamic acid decarboxylase antibody-associated encephalitis occurs with high antibody titres and may cause cognitive dysfunction, seizures and psychiatric symptoms. However, glutamic acid decarboxylase antibodies are more frequently found in lower titre in association with other autoimmune disorders (such as diabetes mellitus type 1) and in healthy individuals. The utility of testing unselected populations of consumers with psychosis is unclear. The psychiatric manifestations of this disorder are also poorly described. METHODS First, systematic review of cohort and case-control studies that tested for IgG glutamic acid decarboxylase antibodies in psychiatric populations was conducted. Random-effects meta-analysis of odds ratio for antibody positivity in cases with psychosis and controls assessed prevalence. Second, literature review of all published cases and case series of glutamic acid decarboxylase antibody-associated limbic encephalitis was assessed for frequency and description of psychotic symptoms. RESULTS There were 17 studies, in which 2754 individuals with psychotic disorders were tested for glutamic acid decarboxylase IgG antibodies. Thirty-one consumers with psychosis (0.7%) had positive glutamic acid decarboxylase antibodies compared to 24 controls (1.0%), all at low titre and not fulfilling diagnostic criteria for autoimmune encephalitis. Meta-analysis found no significant difference in rates of glutamic acid decarboxylase antibody positivity (odds ratio = 1.8, 95% confidence interval: [0.90, 3.63]). Literature review found 321 cases of glutamic acid decarboxylase antibody-associated limbic encephalitis, with psychosis in 15 (4.3%) cases. Clinical screening would have identified all cases that presented to psychiatric services. CONCLUSION Glutamic acid decarboxylase antibodies were uncommon in consumers with psychosis, with no significant difference in prevalence from controls and no cases of encephalitis identified. In cases with established glutamic acid decarboxylase antibody-associated limbic encephalitis, psychotic symptoms were uncommon and identifiable by clinical assessment. Targeted antibody testing guidelines should be further considered.
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Affiliation(s)
- Nicola Warren
- School of Medicine, The University of Queensland, Brisbane, QLD, Australia
- Metro South Addiction and Mental Health Service, Brisbane, QLD, Australia
| | - Karen Freier
- Metro South Addiction and Mental Health Service, Brisbane, QLD, Australia
| | - Dan Siskind
- School of Medicine, The University of Queensland, Brisbane, QLD, Australia
- Metro South Addiction and Mental Health Service, Brisbane, QLD, Australia
| | - Cullen O'Gorman
- School of Medicine, The University of Queensland, Brisbane, QLD, Australia
- Department of Neurology, The Princess Alexandra Hospital, Brisbane, QLD, Australia
- Mater Centre for Clinical Neurosciences, Mater Hospital, Brisbane, QLD, Australia
| | - Stefan Blum
- School of Medicine, The University of Queensland, Brisbane, QLD, Australia
- Department of Neurology, The Princess Alexandra Hospital, Brisbane, QLD, Australia
- Mater Centre for Clinical Neurosciences, Mater Hospital, Brisbane, QLD, Australia
| | - David Gillis
- Pathology Queensland Central Laboratory, Division of Immunology, Royal Brisbane and Women's Hospital, Brisbane, QLD, Australia
| | - James G Scott
- QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia
- Metro North Mental Health Service, Brisbane, QLD, Australia
- Queensland Centre for Mental Health Research, Brisbane, QLD, Australia
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Song W, Li K, Li J, Liu X, Wu X, Xu X, Xiong K, Chen X, Zhang Y. Thymoma-associated autoimmune encephalitis: Analysis of factors determining prognosis. CNS Neurosci Ther 2023; 29:1213-1221. [PMID: 36914970 PMCID: PMC10068466 DOI: 10.1111/cns.14166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 02/24/2023] [Accepted: 02/28/2023] [Indexed: 03/16/2023] Open
Abstract
INTRODUCTION Autoimmune encephalitis (AE) is a heterogeneous group of inflammatory central nervous system disorders caused by a misdirected immune response against self-antigens expressed in the central nervous system. The thymus is a central organ in the immune system and thymic tumors are thought to be possible initiators of many neurological disorders. Recently, there is growing evidence that thymomas are associated with autoimmune encephalitis. AIMS Our study initially explored the characteristics of patients with autoimmune encephalitis combined with thymoma. METHODS We used patient data from January 1, 2011 to October 1, 2021 from the PubMed, Web of Science, Ovid, and CNKI platforms to analyze overall demographics, frequency of symptoms and associations, and treatment prognosis outcomes. RESULTS A total of 68 patients were included. There were 39 female cases (57.4%). The mean age was 50 years (IQR 40-66 years). All had acute and subacute onset. The clinical manifestations were mostly cognitive changes (70.6%), mental disorders (57.4%), and epilepsy (50.0%). The most common neuronal antibody was alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA). Magnetic resonance imaging (MRI) abnormalities were present in 81.0% of patients, mostly in the hippocampus, temporal lobe, and some in cortical and subcortical areas. Abnormalities in the electroencephalogram (EEG) in 69.8% of patients. Treatment involved immunotherapy and thymoma treatment, with 79.7% of patients improving after treatment. While 20.3% of patients had a poor prognosis. Further, 14.8% of patients relapsed. Mental disorders, autonomic dysfunction, sleep disturbances, anti-Ma2, and thymoma untreated were more frequent in patients with poor prognosis. CONCLUSION Thymoma-associated autoimmune encephalitis is a unique disease entity. Long-term follow-up of chest CT findings is recommended for patients with autoimmune encephalitis.
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Affiliation(s)
- Wenli Song
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Keru Li
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Jiao Li
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Xiaoni Liu
- Department of Neurology, Huashan Hospital and Institute of Neurology, Fudan University, Shanghai, China.,National Center for Neurological Disorders, Fudan University, Shanghai, China
| | - Xiaoke Wu
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Xiaodong Xu
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Kangping Xiong
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, China
| | - Xiangjun Chen
- Department of Neurology, Huashan Hospital and Institute of Neurology, Fudan University, Shanghai, China.,National Center for Neurological Disorders, Fudan University, Shanghai, China.,Human Phenome Institute, Fudan University, Shanghai, China
| | - Yanlin Zhang
- Department of Neurology and Clinical Research Center of Neurological Disease, The Second Affiliated Hospital of Soochow University, Suzhou, China
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A Case of Anti-GAD 65 Autoimmune Encephalitis Associated with Focal Segmental Stiff-Person Syndrome. Brain Sci 2023; 13:brainsci13020369. [PMID: 36831912 PMCID: PMC9954581 DOI: 10.3390/brainsci13020369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 02/10/2023] [Accepted: 02/16/2023] [Indexed: 02/23/2023] Open
Abstract
Glutamic acid decarboxylase (GAD) antibody-related encephalitis is an autoimmune disease associated with intracellular neuronal antigens. We report on a rare case of GAD antibody-associated encephalitis complicated with focal segmental stiffness-person syndrome (SPS) in a middle-aged woman. The disease course lasted for >10 years, initially presenting with drug-resistant epilepsy, followed by stiffness of the right lower limb, and right upper limb involvement. The patient experienced anxiety and depression symptoms due to long-term illness. During hospitalization, serum and cerebrospinal fluid GAD antibodies were positive and no tumor was found. The symptoms were significantly relieved after corticosteroid therapy and intravenous immunoglobulin immunomodulation therapy. To the best of our knowledge, this case is the first to discuss the early recognition and treatment of chronic epilepsy and focal segmental SPS caused by anti-GAD antibody-related encephalitis.
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Mueller C, Elben S, Day GS, Alves P, Hebert J, Tang-Wai DF, Holtmann O, Iorio R, Perani D, Titulaer MJ, Hansen N, Bartsch T, Johnen A, Illes Z, Borm L, Willison AG, Wiendl H, Meuth SG, Kovac S, Bölte J, Melzer N. Review and meta-analysis of neuropsychological findings in autoimmune limbic encephalitis with autoantibodies against LGI1, CASPR2, and GAD65 and their response to immunotherapy. Clin Neurol Neurosurg 2022; 224:107559. [PMID: 36549220 DOI: 10.1016/j.clineuro.2022.107559] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 12/06/2022] [Accepted: 12/08/2022] [Indexed: 12/14/2022]
Abstract
OBJECTIVES It is assumed that autoimmune limbic encephalitis (ALE) demonstrates distinct neuropsychological manifestations with differential responses to immunotherapy according to which associated autoantibody (AAB), if any, is identified. Towards investigating whether this is the case, this study aims to summarize respective findings from the primary literature on ALE with AABs binding to cell surface neural antigens and ALE with AABs against intracellular neural antigens. METHODS We chose ALE with AABs against leucine-rich, glioma inactivated protein 1 (LGI1) and contactin-associated protein-like 2 (CASPR2) as the most frequent cell surface membrane antigens, and ALE with AABs to Embryonic Lethal, Abnormal Vision, Like 1 (ELAVL) proteins (anti-Hu) and glutamic acid decarboxylase 65 (GAD65) as the most frequent intracellular neural antigens. The PubMed and Scopus databases were searched on March 1st, 2021 for neuropsychological test and -screening data from patients with ALE of these AAB-types. Findings were reviewed according to AAB-type and immunotherapy status and are presented in a review section and are further statistically evaluated and presented in a meta-analysis section in this publication. RESULTS Of the 1304 initial hits, 32 studies on ALE with AABs against LGI1, CASPR2, and GAD65 reporting cognitive screening data could be included in a review. In ALE with AABs against LGI1, CASPR2 and GAD65, memory deficits are the most frequently reported deficits. However, deficits in attention and executive functions including working memory, fluency, and psychological function have also been reported. This review shows that ALE patients with AABs against both LGI1 and CASPR2 show higher percentages of neuropsychological deficits compared to ALE patients with AABs against GAD65 before and after initiation of immunotherapy. However, the methodologies used in these studies were heterogenous, and longitudinal studies were not comparable. Moreover, 21 studies including ALE patients with AABs against LGI1 and GAD65 were also suitable for meta-analysis. No suitable study on ALE with AABs against ELAVL proteins could be identified. Meta-Analyses could be executed for cognitive screening data and only partially, due to the small number of studies. However, in statistical analysis no consistent effect of AAB or immunotherapy on performance in cognitive screening tests could be found. CONCLUSION Currently, there is no definite evidence supporting the notion that different AAB-types of ALE exhibit distinct neuropsychological manifestations and respond differently to immunotherapy. Overall, we could not identify evidence for any effect of immunotherapy on cognition in ALE. More systematic, in-depth and longitudinal neuropsychological assessments of patients with different AAB-types of ALE are required in the future to investigate these aspects.
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Affiliation(s)
- Christoph Mueller
- Department of Neurology with Institute of Translational Neurology, Westfälische Wilhelms-University of Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany.
| | - Saskia Elben
- Department of Neurology, Medical Faculty, Heinrich-Heine University of Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany.
| | - Gregory S Day
- Department of Neurology, Mayo Clinic Florida, 4500 San Pablo Road, Jacksonville, United States.
| | - Pedro Alves
- Serviço de Neurologia, Departamento de Neurociências e Saúde Mental, Hospital de Santa Maria, CHULN, Lisboa, Portugal; Laboratório de Estudos de Linguagem, Centro de Estudos Egas Moniz, Faculdade de Medicina, Universidade de Lisboa, Portugal.
| | - Julien Hebert
- Department of Medicine, Division of Neurology, University of Toronto, Toronto, Canada.
| | - David F Tang-Wai
- Department of Medicine, Division of Neurology, University of Toronto, Toronto, Canada; Memory Clinic, Toronto Western Hospital (University Health Network), Toronto, Canada.
| | - Olga Holtmann
- Institute of Medical Psychology and Systems Neuroscience, Westfälische Wilhelms-University of Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany.
| | - Raffaele Iorio
- Neurology Unit, Fondazione Policlinico Universitario "A. Gemelli" IRCCS, Rome, Italy; Università Cattolica del Sacro Cuore, Rome, Italy.
| | - Daniela Perani
- Division of Neuroscience, University Vita-Salute San Raffaele, Via Olgettina, 58, 20132 Milano, MI, Italy.
| | - Maarten J Titulaer
- Department of Neurology, Neuropsychology and Immunology, Erasmus Medical Center, Doctor Molewaterplein 40, 3015 GD Rotterdam, the Netherlands.
| | - Niels Hansen
- Department of Psychiatry and Psychotherapy, University of Göttingen, Von-Siebold-Str. 5, 37075 Göttingen, Germany.
| | - Thorsten Bartsch
- Department of Neurology, University Medical Center Schleswig-Holstein, Rosalind-Franklin-Straße 10, 24105 Kiel, Germany.
| | - Andreas Johnen
- Department of Neurology with Institute of Translational Neurology, Westfälische Wilhelms-University of Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany.
| | - Zslot Illes
- Department of Neurology with Institute of Clinical Research, University of Southern Denmark, J. B. Winsløws Vej 4, 5000 Odense, Denmark.
| | - Leah Borm
- Institute of Psychology, Westfälische Wilhelms-University of Münster, Fliednerstraße 21, 48149 Münster, Germany.
| | - Alice G Willison
- Department of Neurology, Medical Faculty, Heinrich-Heine University of Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany.
| | - Heinz Wiendl
- Department of Neurology with Institute of Translational Neurology, Westfälische Wilhelms-University of Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany.
| | - Sven G Meuth
- Department of Neurology with Institute of Translational Neurology, Westfälische Wilhelms-University of Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany; Department of Neurology, Medical Faculty, Heinrich-Heine University of Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany.
| | - Stjepana Kovac
- Department of Neurology with Institute of Translational Neurology, Westfälische Wilhelms-University of Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany.
| | - Jens Bölte
- Institute of Psychology, Westfälische Wilhelms-University of Münster, Fliednerstraße 21, 48149 Münster, Germany.
| | - Nico Melzer
- Department of Neurology with Institute of Translational Neurology, Westfälische Wilhelms-University of Münster, Albert-Schweitzer-Campus 1, 48149 Münster, Germany; Department of Neurology, Medical Faculty, Heinrich-Heine University of Düsseldorf, Moorenstraße 5, 40225 Düsseldorf, Germany.
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[18F]FDG brain PET and clinical symptoms in different autoantibodies of autoimmune encephalitis: a systematic review. Neurol Sci 2022; 43:4701-4718. [PMID: 35486333 DOI: 10.1007/s10072-022-06094-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2022] [Accepted: 04/21/2022] [Indexed: 12/17/2022]
Abstract
INTRODUCTION Autoimmune encephalitis (AE) is caused by the antibodies that target receptors and intracellular or surface proteins. To achieve the appropriate therapeutic results, early and proper diagnosis is still the most important issue. In this review, we provide an overview of FDG-PET imaging findings in AE patients and possible relation to different subtypes and clinical features. METHODS PubMed, Web of Science, and Scopus were searched in August 2021 using a predefined search strategy. RESULTS After two-step reviewing, 22 studies with a total of 332 participants were entered into our qualitative synthesis. In anti-NMDAR encephalitis, decreased activity in the occipital lobe was present, in addition, to an increase in frontal, parietal, and specifically medial temporal activity. Anti-VGKC patients showed altered metabolism in cortical and subcortical regions such as striata and cerebellum. Abnormal metabolism in patients with anti-LGI1 has been reported in diverse areas of the brain including medial temporal, hippocampus, cerebellum, and basal ganglia all of which had hypermetabolism. Hypometabolism in parietal, frontal, occipital lobes, temporal, frontal, and hippocampus was observed in AE patients with anti-GAD antibodies. CONCLUSION Our results indicate huge diversity in metabolic patterns among different AE subtypes and it is hard to draw a firm conclusion. Moreover, the timing of imaging, seizures, and acute treatments can alter the PET patterns strongly. Further prospective investigations with specific inclusion and exclusion criteria should be carried out to identify the metabolic defect in different AE subtypes.
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