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Background: Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is an acquired inflammatory demyelinating disease with optic neuritis (ON) as the most frequent clinical symptom. The hallmark of the disease is the presence of autoantibodies against MOG (MOG-IgG) in the serum of patients. Whereas the role of MOG in the experimental autoimmune encephalomyelitis animal model is well-established, the pathogenesis of the human disease and the role of human MOG-IgG is still not fully clear., Evidence Acquisition: PubMed was searched for the terms "MOGAD," "optic neuritis," "MOG antibodies," and "experimental autoimmune encephalomyelitis" alone or in combination, to find articles of interest for this review. Only articles written in English language were included and reference lists were searched for further relevant papers., Results: B and T cells play a role in the pathogenesis of human MOGAD. The distribution of lesions and their development toward the optic pathway is influenced by the genetic background in animal models. Moreover, MOGAD-associated ON is frequently bilateral and often relapsing with generally favorable visual outcome. Activated T-cell subsets create an inflammatory environment and B cells are necessary to produce autoantibodies directed against the MOG protein. Here, pathologic mechanisms of MOG-IgG are discussed, and histopathologic findings are presented., Conclusions: MOGAD patients often present with ON and harbor antibodies against MOG. Furthermore, pathogenesis is most likely a synergy between encephalitogenic T and antibody producing B cells. However, to which extent MOG-IgG are pathogenic and the exact pathologic mechanism is still not well understood., Competing Interests: A. Bauer has participated in meetings sponsored by or received travel funding from Novartis, Sanofi-Genzyme, Merck, Almirall and Biogen. M. Reindl was supported by research support from Euroimmun and Roche (to institution). The University Hospital and Medical University of Innsbruck (Austria, employer of M. Reindl) receives payments for antibody assays (MOG, AQP4, and other autoantibodies) and for MOG and AQP4 antibody validation experiments organized by Euroimmun (Lübeck, Germany). M. Lerch has no conflict of interest to declare., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the North American Neuro-Opthalmology Society.)

Serum antibodies directed against myelin oligodendrocyte glycoprotein (MOG) are found in patients with acquired CNS demyelinating syndromes that are distinct from multiple sclerosis and aquaporin-4-seropositive neuromyelitis optica spectrum disorder. Based on an extensive literature review and a structured consensus process, we propose diagnostic criteria for MOG antibody-associated disease (MOGAD) in which the presence of MOG-IgG is a core criterion. According to our proposed criteria, MOGAD is typically associated with acute disseminated encephalomyelitis, optic neuritis, or transverse myelitis, and is less commonly associated with cerebral cortical encephalitis, brainstem presentations, or cerebellar presentations. MOGAD can present as either a monophasic or relapsing disease course, and MOG-IgG cell-based assays are important for diagnostic accuracy. Diagnoses such as multiple sclerosis need to be excluded, but not all patients with multiple sclerosis should undergo screening for MOG-IgG. These proposed diagnostic criteria require validation but have the potential to improve identification of individuals with MOGAD, which is essential to define long-term clinical outcomes, refine inclusion criteria for clinical trials, and identify predictors of a relapsing versus a monophasic disease course., Competing Interests: Declaration of interests BB has or will potentially receive financial compensation for consultancy effort for Novartis, Roche, UCB, Horizon Therapeutics, Biogen, and Immunic Therapeutics for advice on clinical trial design. BB is funded by the National Multiple Sclerosis Society, National Institute of Health, and has been previously funded by the Canadian Multiple Sclerosis Society. JLB has received research grants from Novartis, Mallinckrodt Pharmaceuticals, Alexion, and the National Institutes of Health, license fees from a US patent (2014/0170140); consulting fees from Horizon Therapeutics, Alexion, BeiGene Chugai Pharmaceutical, Genentech, Genzyme, Mitsubishi-Tanabe Pharma, Reistone Biopharma, Roche, and AbbVie; and serves on Data Safety Monitoring Boards for Roche, Genentech, and Clene Nanomedicine. RM reports personal fees from Horizon Therapeutics, Alexion, Roche, and UCB and non-financial support from Horizon Therapeutics, Merck, Biogen, and Roche, outside the submitted work. HJK received a grant from the National Research Foundation of Korea and research support from Aprilbio and Eisai; received consultancy and speaker fees from Alexion, Aprilbio, Altos Biologics, Biogen, Celltrion, Daewoong, Eisai, GC Pharma, HanAll BioPharma, Handok, Horizon Therapeutics (formerly Viela Bio), Kolon Life Science, Mdimune, Merck Serono, Mitsubishi Tanabe Pharma, Novartis, Roche, Sanofi Genzyme, Teva-Handok, and UCB; and is a co-editor for the Multiple Sclerosis Journal and an associated editor for the Journal of Clinical Neurology. FB has received research funding from the National Health and Medical Research Council (Australia), Multiple Sclerosis Research Australia, New South Wales Health, Novartis, and the University of Sydney (Sydney, NSW, Australia). She has received speaker honoraria from Novartis, Biogen, Merck, and Limbic Neurology, and has been on advisory boards for Merck and Novartis. She works at the University of Sydney and at the Children's Hospital at Westmead, Westmead, New South Wales, Australia, which offers MOG-IgG testing. EPF has served on advisory boards for Alexion, Genentech, and Horizon Therapeutics. He has received speaker honoraria from Pharmacy Times and royalties from UpToDate for a topic on MOGAD. He was a site primary investigator in a randomised clinical trial on inebilizumab in neuromyelitis optica spectrum disorder run by Horizon Therapeutics. He is principal investigator on an RO1 on MOG-IgG disease. He works at Mayo Clinic, Rochester, MN, USA, which offers commercial MOG-IgG testing but he receives no royalties from such testing. SR has received research funding from the National Health and Medical Research Council (Australia), the Brain Foundation (Australia), the Royal Australasian College of Physicians, and the University of Sydney. She was supported by an National Health and Medicine Research Council Neil Hamilton Fairley Early Career Fellowship (APP1141169) and is currently supported by an NHMRC Emerging Leadership (EL2) Investigator Grant (APP2008339). She serves as a consultant on an advisory board for UCB and Limbic Neurology, and has been an invited speaker for Biogen, Limbic Neurology, and Excemed. PW has received research grants from Euroimmun AG, Commonwealth Serum Laboratories Behring and patent royalties for antibody testing (W02010046716A1). He is the co-director of the Oxford Autoimmune Neurology Diagnostic Laboratory (Oxford University, Oxford, UK) where MOG-IgG1 autoantibodies are tested and both he and the University of Oxford receive royalties (for antibody tests for LGI1 and CASPR2, W02010046716A1). He has received honoraria or consulting fees from Biogen Idec, F Hoffmann La-Roche, Mereo BioPharma, Retrogenix, UBC, Euroimmun AG, University of British Columbia, and Alexion; and travel grants from the Guthy-Jackson Charitable Foundation. Work in the Oxford Autoimmune Neurology Diagnostic Laboratory is supported by the UK National Health Service Commissioning service for NMOSD. ST has received speaker and consulting fees from Biogen-Idec Argentina, Merck SA, Genzyme-Sanofi, Roche, Novartis Argentina, and Novartis Pharma. She serves as a consultant on an advisory board for Genentech-Roche. and Alexion Pharmaceuticals. JSG has grant or contract research support from the National Multiple Sclerosis Society, Biogen, and Octave Biosciences for work unrelated to the present project. She serves on a steering committee for a trial supported by Novartis. She has received speaker fees from Alexion and Bristol Myers Sqiuibb, and served on an advisory board for Genentech. TC has received compensation for consulting from Biogen, Novartis Pharmaceuticals, Roche, Genentech, and Sanofi Genzyme. She has received research support from the National Institutes of Health, National Multiple Sclerosis Society, US Department of Defense, EMD Serono, Guthy-Jackson Charitable Foundation, I-Mab Biopharma, Mallinckrodt Pharmaceuticals, Novartis, Octave Bioscience, Roche Genentech, The Sumaira Foundation, and Tiziana Life Sciences. AUB has received grant support from Moore Foundation, Clinical and Trnaslational Awards Program, German Federal Ministry of Education and Research (BMBF). He has been named as inventor on several patents and patent applications describing multiple sclerosis serological biomarkers, drug targets for remyelination therapy, marker-less motor function analysis, and retinal image analysis methods. He serves on the Observational Study Monitoring Board for CAVS-MS. He is cofounder, board member, and currently serving as secretary treasurer of IMSVISUAL. He is cofounder and holds stocks of technology startups Motognosis GmbH and Nocturne GmbH. Motognosis GmbH develops and sells systems for assessing motor dysfunction in patients with neurological disorders. Nocturne GmbH offers analysis services for retinal optical coherence tomography. Both companies' products and services are relevant for neurology in general, but not specific to MOGAD. CH reports grant support from the Medical Research Council, Multiple Sclerosis Society, and Vasculitis UK. She serves as a consultant to Novartis, Biogen, Roche, UCB, Viela Bio, and Sanofi. She participated on an independent data safety monitoring board for the Wellcome Trust. RN reports grant support from Multiple Sclerosis Research Foundation (Netherlands). He has participated on a data safety monitoring board or advisory board for EXCEL study (neurofibromatosis). He is board member of the Dutch Pediatric Neurology Society. LP has received speaker honoraria and travel grants from Biogen, and has consulted for Biogen, Novartis, and Sanofi. Her university holds a patent for her invention: Live cell based assay for detection of autoantibodies for NMOSD and related disorders (Indian patent number 202141055841). MR is supported by research grants from the Austrian Science Fund (FWF project P32699), the Austrian Research Promotion Agency, Euroimmun, and Roche, and consulting fees and advisory board from Roche (to institution). MR works at the Clinical Department of the Medical University of Innsbruck (Innsbruck, Austria), which offers diagnostic testing for MOG-IgG and other autoantibodies. AS received personal compensation for consulting, serving on a scientific advisory board, speaking activities with Merck, Sanofi, Biogen, Roche, TEVA Pharmaceuticals, Novartis, Alexion, and Janssen. DKS has received research support from National council for Scientific and Technological Development CNPq Brazil (425331/2016-4 and 308636/2019-8), Fundacao de Amparo Pesquisa do Estado do Rio Grande do Sul (17/2551-0001391-3 and 21/2551-0000077-5), TEVA Pharmaceuticals, Merck, Biogen, and Euroimmun AG; speaker honoraria from Biogen, Novartis, Genzyme, TEVA Pharmaceuticals, Merck, Roche, and Bayer; and participates in advisory boards for Biogen, Roche, and Merck. KR has been an invited speaker for Merck and serves as a consultant for an advisory board for Roche. FP has received honoraria and research support from Alexion, Bayer, Biogen, Chugai, MerckSerono, Novartis, Genyzme, MedImmune, Shire, and Teva Pharmaceuticals, and serves on scientific advisory boards for Alexion, MedImmune, Novartis, and UCB. He has received funding from Deutsche Forschungsgemeinschaft (DFG Exc 257), Bundesministerium für Bildung und Forschung (Competence Network Multiple Sclerosis), Guthy-Jackson Charitable Foundation, EU Framework Program 7, and National Multiple Sclerosis Society of the USA. He serves on the steering committee of the N-Momentum study with inebilizumab (Horizon Therapeutics) and the OCTiMS Study (Novartis). He is an associatee editor with Neurology, Neuroimmunology, and Neuroinflammation and academic editor with PloS One. SJP reports grants, personal fees, and non-financial support from Alexion Pharmaceuticals; grants, personal fees, and non-financial support from MedImmune /Viela Bio; and personal fees for consulting from Genentech, Roche, UCB, and Astellas. He has two patents issued (8889102; application 12-678350; Neuromyelitis Optica Autoantibodies as a Marker for Neoplasia; and 9891219B2; application 12-573942; Methods for Treating Neuromyelitis Optica [NMO] by Administration of Eculizumab to an individual that is Aquaporin-4 [AQP4]-IgG Autoantibody positive). SJP also has patents pending for IgGs to the following proteins as biomarkers of autoimmune neurological disorders: septin-5, kelch-like protein 11, GFAP, PDE10A, and MAP1B. He works at Mayo Clinic, which offers commercial MOG-IgG testing. He receives no royalties from the sale of tests done at the neuroimmunology Laboratory at Mayo Clinic. KF serves as an advisor or on scientific advisory boards for Biogen, Mitsubishi Tanabe, Novartis, Chugai, Roche, Alexion, VielaBio/Horizon Therapeutics, UCB, Merck Biopharma, Japan Tobacco and Abbvie; has received funding for travel and speaker honoraria from Biogen, Eisai, Mitsubishi Tanabe, Novartis, Chugai, Roche, Alexion, VielaBio, Teijin, Asahi Kasei Medical, Merck, and Takeda; and has received the Grants-in-Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan and the Grants-in-Aid for Scientific Research from the Ministry of Health, Welfare and Labor of Japan. JP has received consulting fees from Merck, Novartis, Roche, Mitsubishi Tnabe Pharma, UCB, Alexion, Vitaccess, and Argenx, and MRI support from Medimmune, Merck, and Roche. She has received payment or honoraria for lectures, presentations, speakers bureaus, manuscript writing, or educational events from Merck, VielaBio, Roche and Alexion. She has participated on a data safety monitoring board or advisory board for Novartis, Roche, Argenx, UCB, Alexion, and Sanofi. She is member of the Charcot Foundation Board, Magnetic Resonance in Multiple Sclerosis steering committee, and National Health Service England Intravenous Immune Globulin Committee. She holds stock for AstraZeneca for a product that is not related to MOG-antibody associated disease. She has a patent for Diagnosing Multiple Sclerosis (application no PCT/GB2013/050285, final patent number 13704627.2–1408; client reference 4440; MS reference P37347WO; patent published Sept 13, 2021)., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Background and Objective: The spectrum of myelin oligodendrocyte glycoprotein (MOG) antibody-associated disorder (MOGAD) comprises monophasic diseases such as acute disseminated encephalomyelitis (ADEM), optic neuritis (ON), and transverse myelitis and relapsing courses of these presentations. Persistently high MOG antibodies (MOG immunoglobulin G [IgG]) are found in patients with a relapsing disease course. Prognostic factors to determine the clinical course of children with a first MOGAD are still lacking. The objective of the study is to assess the clinical and laboratory prognostic parameters for a risk of relapse and the temporal dynamics of MOG-IgG titers in children with MOGAD in correlation with clinical presentation and disease course., Methods: In this prospective multicenter hospital-based study, children with a first demyelinating attack and complete data set comprising clinical and radiologic findings, MOG-IgG titer at onset, and clinical and serologic follow-up data were included. Serum samples were analyzed by live cell-based assay, and a titer level of ≥1:160 was classified as MOG-IgG-positive., Results: One hundred sixteen children (f:m = 57:59) with MOGAD were included and initially diagnosed with ADEM (n = 59), unilateral ON (n = 12), bilateral ON (n = 16), myelitis (n = 6), neuromyelitis optica spectrum disorder (n = 8) or encephalitis (n = 6). The median follow-up time was 3 years in monophasic and 5 years in relapsing patients. There was no significant association between disease course and MOG-IgG titers at onset, sex, age at presentation, or clinical phenotype. Seroconversion to MOG-IgG-negative within 2 years of the initial event showed a significant risk reduction for a relapsing disease course. Forty-two/one hundred sixteen patients (monophasic n = 26, relapsing n = 16) had serial MOG-IgG testing in years 1 and 2 after the initial event. In contrast to relapsing patients, monophasic patients showed a significant decrease of MOG-IgG titers during the first and second years, often with seroconversion to negative titers. During the follow-up, MOG-IgG titers were persistently higher in relapsing than in monophasic patients. Decrease in MOG-IgG of ≥3 dilution steps after the first and second years was shown to be associated with a decreased risk of relapses. In our cohort, no patient experienced a relapse after seroconversion to MOG-IgG-negative., Discussion: In this study, patients with declining MOG-IgG titers, particularly those with seroconversion to MOG-IgG-negative, are shown to have a significantly reduced relapse risk., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)

Background: To investigate age-related severity, patterns of retinal structural damage, and functional visual recovery in pediatric and adult cohorts of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) optic neuritis (ON)., Methods: All MOGAD patients from the 5 participating centers were included. Patients with initial manifestation <18 years were included in the pediatric (MOGAD ped ) cohort and patients with ≥18 years in the adult (MOGAD adult ) cohort. For patients with MOGAD ON, examinations at least ≥6 months after ON onset were included in the analyses. Using spectral domain optical coherence tomography (SD-OCT), we acquired peripapillary retinal nerve fiber layer thickness (pRNFL) and volumes of combined ganglion cell and inner plexiform layer (GCIPL). High- and 2.5% low-contrast visual acuity (HCVA, LCVA) and visual-evoked potentials (VEP) were obtained., Results: Twenty MOGAD ped (10.3±3.7 years, 30 MOGAD ON eyes) and 39 MOGAD adult (34.9±11.6 years, 42 MOGAD ON eyes) patients were included. The average number of ON episodes per ON eye was similar in both groups (1.8±1.3 and 2.0±1.7). In both pediatric and adult MOGAD, ON led to pronounced neuroaxonal retinal atrophy (pRNFL: 63.1±18.7 and 64.3±22.9 μm; GCIPL: 0.42±0.09 and 0.44±0.13 mm 3 , respectively) and moderate delay of the VEP latencies (117.9±10.7 and 118.0±14.5 ms). In contrast, visual acuity was substantially better in children (HCVA: 51.4±9.3 vs. 35.0±20.6 raw letters, p=0.001; LCVA: 22.8±14.6 vs. 13.5±16.4, p=0.028). Complete visual recovery (HCVA-logMAR 0.0) occurred in 73.3% of MOGAD ped and 31% MOGAD adults ON eyes, while 3.3% and 31% demonstrated moderate to severe (logMAR > 0.5) visual impairment. Independent of retinal atrophy, age at ON onset significantly correlated with visual outcome., Conclusion: Pediatric MOGAD ON showed better visual recovery than adult MOGAD ON despite profound and almost identical neuroaxonal retinal atrophy. Age-related cortical neuroplasticity may account for the substantial discrepancy between structural changes and functional outcomes.

Background: Bilateral optic neuritis (bilON) is a rare clinical presentation often thought to be associated with relapsing disorders such as neuromyelitis optica spectrum disorders (NMOSD) or multiple sclerosis (MS)., Objective: To characterize the clinical, radiological phenotype and antibody status of children presenting with bilON., Material and Methods: Retrospective multicenter study on children with bilON age <18 years with a first episode aquired demyelinating syndrome (ADS), cMRI, AQP4- and serum MOG-antibody status and follow-up data were collected., Results: 30 patients (f:m = 15:15, median age 8.0y) with bilON met the inclusion criteria. 22/30 (73%) were MOG-positive (median: 1:1280, range: 1:160-1:1520). No patient showed AQP4-abs. 4/30 patients (13%), all with high MOG-abs titers, had recurrent episodes. No patient developed MS. Improvement after IVMP was observed in most patients (26/30; 87%). Outcome was favorable with no sequelae in 22/30 patients. Serial MOG-abs titers tested in 15/22 patients decreased to a median of 1:160 (range: 0-1:640) over a period of 31 months (range: 2-141 months) in 14/15 (93%) patients. MR imaging showed a predominantly anterior affection of the visual system in seropositive patients with bilateral intraorbital lesions in 68% (15/22), compared to 25% in MOG-negative patients (2/8)., Conclusion: Pediatric bilON is associated with high MOG-abs titers in combination with anterior involvement of the visual system. Despite severe loss of vision, the majority of patients shows distinct recovery after IVMP., Competing Interests: Declaration of competing interest E. Wendel, M. Baumann, N. Barisic, A. Blaschek, E. Coelho de Oliveira Koch, A. Della Marina, K. Diepold, A. Hackenberg, A. Hahn, T. von Kalle, M. Karenfort, B. Kornek, C. Lechner, S. Leiz, A. Merkenschlager, M. Nosadini, K. Schanda, M. Schimmel, L. Seemann, V. Tüngler, S. Waltz, A. Wegener-Panzer and G. Wiegand have no disclosures. K. Rostásy received speaker's honoraria from Novartis and served on the advisory board of the PARADIGM study. M. Reindl receives payments for antibody assays (MOG, AQP4, and other autoantibodies) and for MOG and AQP4 antibody validation experiments organized by Euroimmun (Lübeck, Germany)., (Copyright © 2020. Published by Elsevier Ltd.)

Limited data exist on isolated optic neuritis in children. We report the clinical features and treatment of pediatric subjects with monophasic and recurrent idiopathic optic neuritis. This retrospective cohort study of patients with isolated optic neuritis identified 10 monophasic and 7 recurrent optic neuritis cases. Monophasic optic neuritis patients were older (mean 13.3 ± 4.22) than those with recurrent idiopathic optic neuritis (9.86 ± 3.63). Females represented 50% of monophasic and 85.7% of recurrent idiopathic optic neuritis cases. Patients with monophasic optic neuritis were less likely to have a bilateral onset than recurrent idiopathic optic neuritis (40% vs 57.1%). Only 1 case had oligoclonal bands in the cerebrospinal fluid CSF. Most recurrent idiopathic optic neuritis cases had evidence of anti-myelin oligodendrocyte glycoprotein (MOG) antibodies (5/7). Treatment of recurrent idiopathic optic neuritis cases included intravenous pulse glucocorticosteroids and immunotherapy. We observed differences between recurrent and monophasic idiopathic optic neuritis. Immunosuppression appeared to prevent further relapses in recurrent idiopathic optic neuritis patients. Weaning immunotherapies after several years of quiescence in recurrent idiopathic optic neuritis may be possible, but larger studies are needed.

Background: Serum antibodies against myelin-oligodendrocyte-glycoprotein (MOG-IgG) are detectable in a proportion of patients with acute or relapsing neuroinflammation. It is unclear, if neuro-axonal damage occurs only in an attack-dependent manner or also progressively. Therefore, this study aimed to investigate longitudinally intra-retinal layer changes in eyes without new optic neuritis (ON) in MOG-IgG-seropositive patients., Methods: We included 38 eyes of 24 patients without ON during follow-up (F/U) [median years (IQR)] 1.9 (1.0-2.2) and 56 eyes of 28 age- and sex-matched healthy controls (HC). The patient group's eyes included 18 eyes without (Eye ON- ) and 20 eyes with history of ON (Eye ON+ ). Using spectral domain optical coherence tomography (OCT), we acquired peripapillary retinal nerve fiber layer thickness (pRNFL) and volumes of combined ganglion cell and inner plexiform layer (GCIP), inner nuclear layer (INL), and macular volume (MV). High-contrast visual acuity (VA) was assessed at baseline., Results: At baseline in Eye ON- , pRNFL (94.3 ± 15.9 μm, p = 0.36), INL (0.26 ± 0.03 mm 3 , p = 0.11), and MV (2.34 ± 0.11 mm 3 , p = 0.29) were not reduced compared to HC; GCIP showed thinning (0.57 ± 0.07 mm 3 ; p = 0.008), and VA was reduced (logMAR 0.05 ± 0.15 vs. - 0.09 ± 0.14, p = 0.008) in comparison to HC. Longitudinally, we observed pRNFL thinning in models including all patient eyes (annual reduction - 2.20 ± 4.29 μm vs. - 0.35 ± 1.17 μm, p = 0.009) in comparison to HC. Twelve Eye ON- with other than ipsilateral ON attacks ≤ 6 months before baseline showed thicker pRNFL at baseline and more severe pRNFL thinning in comparison to 6 Eye ON- without other clinical relapses., Conclusions: We observed pRNFL thinning in patients with MOG-IgG during F/U, which was not accompanied by progressive GCIP reduction. This effect could be caused by a small number of Eye ON- with other than ipsilateral ON attacks within 6 months before baseline. One possible interpretation could be a reduction of the swelling, which could mean that MOG-IgG patients show immune-related swelling in the CNS also outside of an attack's target area.

Background: Recurrent optic neuritis (rON) associated with myelin oligodendrocyte glycoprotein (MOG)-specific antibodies has been initially reported to show a better clinical outcome than aquaporin-4 (AQP4)-seropositive ON in neuromyelitis optica spectrum disorder (NMOSD). Here, we characterize clinical and neuroimaging findings in severe cases of MOG antibody-positive and AQP4 antibody-negative bilateral rON., Methods: Three male adults with rON (ages 18, 44, and 63 years) were evaluated with optical coherence tomography (OCT), MRI, cerebrospinal fluid (CSF), and serological studies., Results: All patients experienced >7 relapses of ON with severe reduction of visual acuity and partial response to steroid treatment. Optic nerves were affected bilaterally, although unilateral relapses were more frequent than simultaneous bilateral recurrences. Patients were MOG-seropositive but repeatedly tested negative for AQP4 antibodies. OCT showed severe thinning of the peripapillary retinal nerve fiber layer. On MRI, contrast-enhancing lesions extended over more than half the length of the optic nerve. CSF analyses during ON episodes were normal. Severe visual deficits accumulated over time in 2 of 3 patients, despite immunosuppressive therapy., Conclusions: MOG-seropositive and AQP4-seronegative rON may be associated with an aggressive disease course and poor functional and structural outcomes. In contrast to previous reports, the severity and pattern of retinal and optic nerve damage closely resembled phenotypes commonly observed in AQP4-seropositive rON without fulfilling current diagnostic criteria for NMOSD.

Background: Antibodies against myelin oligodendrocyte glycoprotein (MOG-IgG) have been reported in patients with aquaporin-4 antibody (AQP4-IgG)-negative neuromyelitis optica spectrum disorders (NMOSD). The objective of this study was to describe optic neuritis (ON)-induced neuro-axonal damage in the retina of MOG-IgG-positive patients in comparison with AQP4-IgG-positive NMOSD patients., Methods: Afferent visual system damage following ON was bilaterally assessed in 16 MOG-IgG-positive patients with a history of ON and compared with that in 16 AQP4-IgG-positive NMOSD patients. In addition, 16 healthy controls matched for age, sex, and disease duration were analyzed. Study data included ON history, retinal optical coherence tomography, visual acuity, and visual evoked potentials., Results: Eight MOG-IgG-positive patients had a previous diagnosis of AQP4-IgG-negative NMOSD with ON and myelitis, and eight of (mainly recurrent) ON. Twenty-nine of the 32 eyes of the MOG-IgG-positive patients had been affected by at least one episode of ON. Peripapillary retinal nerve fiber layer thickness (pRNFL) and ganglion cell and inner plexiform layer volume (GCIP) were significantly reduced in ON eyes of MOG-IgG-positive patients (pRNFL = 59 ± 23 μm; GCIP = 1.50 ± 0.34 mm 3 ) compared with healthy controls (pRNFL = 99 ± 6 μm, p < 0.001; GCIP = 1.97 ± 0.11 mm 3 , p < 0.001). Visual acuity was impaired in eyes after ON in MOG-IgG-positive patients (0.35 ± 0.88 logMAR). There were no significant differences in any structural or functional visual parameters between MOG-IgG-positive and AQP4-IgG-positive patients (pRNFL: 59 ± 21 μm; GCIP: 1.41 ± 0.27 mm 3 ; Visual acuity = 0.72 ± 1.09 logMAR). Importantly, MOG-IgG-positive patients had a significantly higher annual ON relapse rate than AQP4-IgG-positive patients (median 0.69 vs. 0.29 attacks/year, p = 0.004), meaning that on average a single ON episode caused less damage in MOG-IgG-positive than in AQP4-IgG-positive patients. pRNFL and GCIP loss correlated with the number of ON episodes in MOG-IgG-positive patients (p < 0.001), but not in AQP4-IgG-positive patients., Conclusions: Retinal neuro-axonal damage and visual impairment after ON in MOG-IgG-positive patients are as severe as in AQP4-IgG-positive NMOSD patients. In MOG-IgG-positive patients, damage accrual may be driven by higher relapse rates, whereas AQP4-IgG-positive patients showed fewer but more severe episodes of ON. Given the marked damage in some of our MOG-IgG-positive patients, early diagnosis and timely initiation and close monitoring of immunosuppressive therapy are important.

Background: Some pediatric patients with inflammatory demyelinating central nervous system disorders cannot be classified under any of the established disease entities, making their treatment and prognosis difficult., Objective: The objective of this study is to characterize a subgroup of pediatric patients with recurrent demyelinating central nervous system disorders., Methods: This study includes a case series of pediatric patients with monophasic or recurrent acute disseminated encephalomyelitis (ADEM) who later presented with either monophasic or recurrent optic neuritis (ON)., Results: We describe seven patients with a median follow-up of six years (five females, two males) who presented at a median age of 6 years (range 4-8 years) with monophasic (n = 4) or recurrent ADEM (two to four attacks) followed by monophasic (n = 3) or recurrent ON (two to nine attacks). Cranial magnetic resonance imaging (MRI) was typical for ADEM (n = 6) with complete or almost complete resolution of lesions on follow-up. Cerebrospinal (CSF) studies at the time of ADEM showed a pleocytosis in six patients and were negative for oligoclonal bands (OCBs) in all. In all patients high titers for serum anti-MOG antibodies were detected., Conclusion: ADEM followed by ON is a rare but distinct clinical phenotype among pediatric patients. Further studies are needed to allow recommendations on treatment or prognosis.

Objective: To study the humoral immune response directed at myelin oligodendrocyte glycoprotein (MOG)in pediatric patients with isolated and recurrent optic neuritis(ON)., Design: Observational prospective case series., Setting: Six pediatric hospitals in Germany and Austria., Patients: Thirty-seven patients 18 years or younger with single or recurrent episodes of ON were recruited from 6 different hospitals., Main Outcome Measures: Clinical features, magnetic resonance imaging findings, intrathecal IgG synthesis,and outcome were recorded. A live cell–based immunofluorescence assay was used to measure serum IgG antibodies to MOG and aquaporin 4., Results: A single episode of ON was observed in 10 patients,and 15 experienced 2 to 12 episodes. The acute episode of ON was part of a clinically isolated syndrome in 12 patients, of whom 8 were subsequently classified as having multiple sclerosis. High-titer serum MOG-IgG antibodies (1:160) were detected in 17 patients (46%).In addition, high titers of MOG-IgG antibodies were more frequently observed in 12 of the 15 patients with recurrent episodes of ON (80%; median titer, 1:640)compared with 2 of the 10 patients with monophasic ON(20%; median titer, 0) and 3 of the 12 patients with ON as part of a clinically isolated syndrome (25%; median titer, 0)., Conclusion: High-titer MOG-IgG antibodies are predominantly detected in pediatric patients with recurrent ON, indicating that anti-MOG-specific antibodies may exert a direct role in the pathogenesis of ON in this subgroup.

Interestingly, no patient in our cohort suffered from a relapse after time of first seroconversion, although fluctuating MOG-IgG titres with increase after a period of low or even negative MOG-IgG titres were reported in selected patients. Likewise, onset serum MOG-IgG titres, despite being important for the diagnosis of MOGAD, do not predict recovery or relapse.[1],[7] In most patients MOG-IgG titres decline with time, but may also remain positive in other patients for years. [Extracted from the article]

In the past few years, acquired demyelinating syndromes of the central nervous system associated with antibodies against myelin oligodendrocyte glycoprotein (MOG) have evolved into a new inflammatory disease entity distinct from neuromyelitis optica spectrum disorders or multiple sclerosis. The meticulous clinical description of patients with MOG IgG antibodies (MOG-IgG) has been achieved by development and use of highly specific cell-based assays. MOG-IgG associated disorders comprise a wide spectrum of syndromes ranging from acute disseminated encephalomyelitis predominantly in children to optic neuritis or myelitis mostly in adults. In recent studies, phenotype of MOG-IgG associated disorders has further broadened with the description of cases of brainstem encephalitis, encephalitis with seizures and overlap syndromes with other types of autoimmune encephalitis. In this review, we provide an overview of current knowledge of MOG-IgG associated disorders, describe the clinical presentations identified, highlight differences from neuromyelitis optica spectrum disorders and multiple sclerosis, summarize clinical outcome and concepts of immune treatment, depict the underlying mechanisms of antibody pathogenicity and provide the methodological essentials of MOG-IgG assays. [ABSTRACT FROM AUTHOR]

Background: Neuromyelitis optica spectrum disorders (NMOSD) are severe inflammatory demyelinating disorders of the central nervous system mainly characterized by recurrent episodes of uni- or bilateral optic neuritis (ON), transverse myelitis (TM) and brainstem syndromes (BS). The majority of adult patients has serum antibodies directed against the water channel protein aquaporin 4 (AQP4-abs). In pediatric patients, AQP4-abs are less, while antibodies against myelin oligodendrocyte glycoprotein (MOG-abs) are more frequently detectable than in adults. Some children with NMOSD have neither AQP4- nor MOG-ab (double-seronegative). Objective: Evaluation of epidemiological data regarding incidence and prevalence of pediatric NMOSD in Germany and Austria. Methods: We recruited pediatric NMOSD patients between 1 March 2017 and 28 February 2019 with five different tools: (1) ESPED (Surveillance Unit for Rare Pediatric Disorders in Germany), (2) ESNEK (Surveillance for Rare Neurological Disorders during Childhood), (3) pediatric neurology working group within the Austrian Society of Pediatrics and Adolescent Medicine, (4) BIOMARKER Study and (5) NEMOS (Neuromyelitis optica Study Group). We requested data regarding clinical symptoms, antibody status, therapy regimen and response via a standardized questionnaire. Results: During the 2-year recruitment period, 46 (both incidental and prevalent) patients with a suspected diagnosis of NMOSD were brought to our attention. Twenty-two of these patients did not fulfill the inclusion criteria. Of the remaining 24 children, 22 had a median age at onset of 11 (range 3–17) years and 16/22 were female (72.7%) (no data in two patients). Sixteen of 24 patients were AQP4-ab positive (67%), 4/24 MOG-ab positive (16.7%), three children were double-seronegative and in one patient no antibody testing was done. We calculated an incidence rate of 0.022 per 100,000 person-years for Germany, while there was no incidental case in Austria during the recruitment period. The prevalence rate was 0.147 and 0.267 per 100,000 persons in Germany and Austria, respectively. Conclusion: Pediatric NMOSD, with and without associated antibodies, are very rare even considering the different limitations of our study. An unexpected finding was that a considerable proportion of patients was tested neither for AQP4- nor MOG-abs during diagnostic work-up, which should prompt to establish and disseminate appropriate guidelines. [ABSTRACT FROM AUTHOR]

Anti-myelin oligodendrocyte glycoprotein (MOG) antibodies (MOG-Abs) were first detected by immunoblot and enzyme-linked immunosorbent assay nearly 30 years ago, but their association with multiple sclerosis (MS) was not specific. Use of cell-based assays with native MOG as the substrate enabled identification of a group of MOG-Ab-positive patients with demyelinating phenotypes. Initially, MOG-Abs were reported in children with acute disseminated encephalomyelitis (ADEM). Further studies identified MOG-Abs in adults and children with ADEM, seizures, encephalitis, anti-aquaporin-4-antibody (AQP4-Ab)-seronegative neuromyelitis optica spectrum disorder (NMOSD) and related syndromes (optic neuritis, myelitis and brainstem encephalitis), but rarely in MS. This shift in our understanding of the diagnostic assays has re-invigorated the examination of MOG-Abs and their role in autoimmune and demyelinating disorders of the CNS. The clinical phenotypes, disease courses and responses to treatment that are associated with MOG-Abs are currently being defined. MOG-Ab-associated disease is different to AQP4-Ab-positive NMOSD and MS. This Review provides an overview of the current knowledge of MOG, the metrics of MOG-Ab assays and the clinical associations identified. We collate the data on antibody pathogenicity and the mechanisms that are thought to underlie this. We also highlight differences between MOG-Ab-associated disease, NMOSD and MS, and describe our current understanding on how best to treat MOG-Ab-associated disease. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the frequency and implications of antibodies to myelin oligodendrocyte glycoprotein (MOG-ab) and aquaporin 4 antibodies (AQP4-ab) in adult patients with suspected limited forms of neuromyelitis optica (NMO). The study is investigated by cell-based assays, Mann-Whitney U test, and Chi-square test. Results show that MOG-ab is commonly detected in the serum of patients with NMO, longitudinally extensive myelitis (LETM), and optic neuritis (ON).

The article presents a study which describes the cognitive dysfunction in pediatric transverse myelitis (TM) patients. The study also explores the impact of depression, medication, and fatigue on cognitive functioning. The study uses the neuropsychological screening as the method of the study. Results show that a slight higher frequencies of impairment were observed as compared to processing speed and verbal fluency.

• NfL levels are increased in patients with MOGAD at onset • NfL levels decrease over time in most patients with MOGAD • NfL levels do not increase significantly during relapses in patients with MOGAD • Axonal damage predominantly occurs at onset in patients with MOGAD The unpredictable course and uncertain impact of relapses make treatment strategies of anti-myelin oligodendrocyte glycoprotein antibodies associated disorders (MOGAD) challenging. We analysed neurofilament light chain levels (NfL) in onset and follow-up sera of 18 patients with MOGAD to clarify the timing of axonal damage. In comparison with disease onset values (median 8.9 pg/mL, range 1.8-97), NfL levels remained stable or decreased in most follow-up measurements (n=52, median 6.7 pg/mL, range 0.2-207), including those measured on relapses. The predominant axonal damage occurs during onset, which could be the main driving factor of final disability, with subsequent relevant clinical and therapeutic implications. [ABSTRACT FROM AUTHOR]

Background Neuromyelitis optica (NMO) is a severe autoimmune inflammatory disorder of the central nervous system. NMO and its abortive forms are referred to as NMO spectrum disorders (NMOSD). NMOSD are mostly associated with antibodies to aquaporin-4 (AQP4-IgG). However, recent studies have demonstrated antibodies to myelin oligodendrocyte glycoprotein (MOG-IgG) in a subset of patients. Data on NMOSD in North Africa are sparse. Objective To describe the frequency of MOG-IgG and AQP4-IgG among patients with optic neuritis (ON) and/or myelitis in Algeria as well as the clinical and paraclinical features associated with these antibodies. Methods Retrospective testing of 42 patients with optic neuritis and/or myelitis treated at the teaching hospital of TiziOuzou for MOG-IgG and AQP4-IgG, and retrospective evaluation of the patients' medical records. Results Six of 42 (14.3%) patients were positive for AQP4-IgG and 3/42 (7.1%) were positive for MOG-IgG. No patient was positive for both AQP4-IgG and MOG-IgG. All antibody-positive patients were women. MOG-IgG was associated with severe episodes of ON in all MOG-IgG-positive patients. Steroid treatment was followed by complete remission in two patients. AQP4-IgG was associated with ON and/or longitudinally extensive transverse myelitis (LETM), often with severe onset. While all six of the AQP4-IgG-positive patients met the 2015 IPND criteria for NMOSD, only one of the three MOG-IgG-positive patients did so. Interestingly, clinically silent extensive spinal cord or brain lesions were present in two of the three MOG-IgG-positive patients, and altered visual evoked potentials without clinical evidence of ON were found in three of the six AQP4-IgG-positive patients. Conclusion MOG-IgG and AQP4-IgG are found in a substantial subset of Algerian patients with ON and/or myelitis, are present predominantly in women, and may be associated with differences in clinical presentation and, possibly, outcome. Only a subset of MOG-IgG positive patients meets the current diagnostic criteria for NMOSD. [ABSTRACT FROM AUTHOR]

Myelin oligodendrocyte glycoprotein (MOG)-IgG associated disorders are increasingly recognized as a distinct disease entity. However, diagnostic sensitivity and specificity of serum MOG-IgG as well as recommendations for testing are still debated. Between October 2015 and July 2017 we tested serum MOG-IgG in 91 adult patients (49 females) with a demyelinating event (DE) not fulfilling 2010 McDonald criteria for MS at sampling, negative for neuromyelitis optica (NMO)-IgG and followed-up for at least 12 months. We assessed the sensitivity and specificity of a live-cell MOG-IgG assay for each final diagnosis at last follow-up, for the 2018 international recommendations for MOG-IgG testing, and for other combinations of clinical and laboratory characteristics. Clinical presentations included acute myelitis (n = 48), optic neuritis (n = 36), multifocal encephalomyelitis (n = 4), and brainstem syndrome (n = 3). Twenty-four patients were MOG-IgG positive. Sensitivity and specificity of MOG-IgG test applied to the 2018 international recommendations were 28.4% and 86.7%, while they were 42.1% and 88.6% when applied to DE of unclear aetiology as defined above with two or more among: 1_no periventricular and juxtacortical MS-like lesions on brain MRI; 2_longitudinally extensive MRI optic nerve lesion; 3_no CSF-restricted oligoclonal bands; 4_CSF protein > 50 mg/dl. Simplified requirements compared to those currently proposed for MOG-IgG testing could facilitate the applicability of the assay in the diagnosis of adults with DEs of unclear aetiology. Unlabelled Image • There's still uncertainty about diagnostic sensitivity and specificity of serum MOG-IgG • This is an observational study including 91 patients with a demyelinaing event of unclear aetiology, 24 MOG-IgG positive • We evaluated sensitivity and specificity of simplified requirements for MOG-IgG testing • These requirements are easily applicable compared to previous indications for testing [ABSTRACT FROM AUTHOR]