Clinical analysis of adult MOG antibody-associated cortical encephalitis

Clinical features of recurrent MOG antibody-associated cortical encephalitis in adults

OBJECTIVE

To clarify the clinical features of recurrent myelin oligodendrocyte glycoprotein antibody-associated cortical encephalitis (MOGCE) in adults.

METHODS

We present an adult case of recurrent MOGCE and summarize the clinical symptoms, imaging findings, treatment and prognosis of this phenotype as per a systematic review of the literature.

RESULTS

We identified 9 adult patients with recurrent MOGCE. The mean age was 32 years, and 5/9 were male. Median time to recurrence was 6 months (range 2-36 months). The most common presentations of the first attack were headache (9/9), fever (8/9) and seizure (5/9). In most patients (6/9), presentations of recurrent attacks were different than those of the first attack. Relapses may affect more areas than the first attack, such as spine, brainstem, grey matter, and basal ganglia. All patients were seropositive for MOG antibodies during the first or second attack, with antibody titers ranging from 1:10 to 1:100. CSF white blood cell count and total protein were elevated in 6/9 patients. On MRI, 4/9 showed bilateral FLAIR hyperintense lesions, while 5/9 had unilateral lesions. Most patients demonstrated a positive response to treatment, and maintenance immunotherapy was added upon relapse.

CONCLUSION

The clinical presentation of recurrent MOGCE is atypical, and most patients had different symptoms upon recurrence compared to the first episode. Factors contributing to the likelihood of disease recurrence remain unclear. Most recurrent MOGCE patients respond well to immunotherapy, and require long-term immunotherapy after recurrence.

Pain and Headache in Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease

PURPOSE OF REVIEW

The purpose of this review is to evaluate the current knowledge and recent findings on different pain and headache presentations associated with Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease (MOGAD) disease.

RECENT FINDINGS

MOGAD is an inflammatory autoimmune disease affecting mostly the central nervous system, presenting with optic neuritis, transverse myelitis and other forms of inflammatory demyelination. Pain and headache in MOGAD have been recognized more recently and acute and chronic forms of pain can occur in both the adult and pediatric population. An important recent observation is that MOGAD can affect the peripheral nervous system, which can contribute to pain symptoms. Acute and chronic forms of pain have been described in MOGAD, including ocular pain, different types of headaches and neuropathies, involving the central and peripheral nervous system. Awareness of these types of pain in both the pediatric and adult population is crucial, to ensure timely diagnosis and treatment.

Increased Intracranial Pressure in Myelin-Oligodendrocyte Glycoprotein Antibody-Associated Disease

OBJECTIVES

To assess characteristics of increased intracranial pressure (ICP) in myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD).

METHODS

This is a multicenter retrospective review of 84 MOGAD cases at the University of Florida, Baylor College of Medicine, the University of California San Diego, and Providence Health and Services, Portland, Oregon, to identify cases with a documented increased opening pressure >25 cm H2O. A literature review was conducted to identify previously reported MOGAD cases with an opening pressure >25 cm H2O.

RESULTS

Of 28 MOGAD cases with available opening pressures, 6 (21.4%) patients (age: 5 to 36 y; 2/6 females) had documented increased ICP with an opening pressure of 26 to 46 cm H2O and optic nerve head edema on funduscopic examination. The increased ICP occurred in the setting of bilateral optic neuritis in all cases. In 5/6 patients, this was the initial presentation of the disorder. Anti-MOG titers were 1:40 (n = 1), 1:100 (n = 4), and 1:1000 (n = 1). In our literature review, we identified 13 additional MOGAD cases with ICP elevations in the setting of meningo-cortical presentations (n = 10), as well as bilateral optic neuritis (n = 3).

CONCLUSIONS

Increased ICP may occur in MOGAD and may be more common in patients with optic neuritis or meningoencephalitis.

Clinical Analysis of MOG Antibody-Associated Disease Overlapped With Anti-NMDA Receptor Encephalitis: A Long-Term Retrospective Study

To summarise the clinical characteristics, radiological features, treatments and prognosis of patients with myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) overlapped with NMDA receptor (NMDAR) encephalitis. We retrospectively analysed patients who exhibited dual positivity for MOG antibodies and NMDAR antibodies in serum/CSF from Jan 2018 to Jun 2023. Ten patients with MOGAD and NMDAR encephalitis were enrolled. The median age of initial attacks was 23 (range: 10-43) years old. Common symptoms were cortical encephalopathies (8/10), focal neurological deficits (4/10), as well as other presentations including headache, fever, optic neuritis and transverse myelitis. CSF pleocytosis was general (9/10, median 63.9 cells/μl). Lesions on brain MRI included brainstem (37.5%), cerebral cortex (33.3%), basal ganglia (25.0%) and hippocampus (20.8%). The average follow-up duration was 25.4 months. 10/10 patients developed more than one relapse attacks, with MOG positivity before (10%), simultaneous (40%) or after anti-NMDAR encephalitis (50%). Most patients (7/10) had good response to first-line therapy but experienced next relapse with an average interval of 6.7 (range: 2-14) months. We conducted initial analysis of lymphocyte subsets in these patients, which revealed that CD3+ and CD4 + T cells increased after immunosuppressants medication (p < 0.01 and p < 0.05, respectively). We concluded that MOGAD overlapping with NMDAR encephalitis presents a distinct clinical phenotype which differs from either MOGAD or NMDAR encephalitis. Brainstem in combination with cortical lesions might be warning signs for this overlapping syndrome. Due to the high recurrent rates, we recommend early diagnosis and timely treatment with efficient immunosuppressants at onset.

Clinical features of adult patients with positive NMDAR-IgG coexisting with MOG-IgG

INTRODUCTION

This study was designed to analyze clinical and radiographic features of adult patients coexisting with NMDAR-IgG and MOG-IgG.

METHODS

Eleven adult patients coexisting with NMDAR-IgG and MOG-IgG were collected from Xiangya Hospital, Central South University, between June 2017 and December 2021. Fifty-five patients with anti-NMDAR encephalitis and 49 with MOG-AD were served as controls.

RESULTS

Onset age was 27 (IQR 20-34) years old. Seizures and psychotic symptoms were prominent symptoms. Ten of eleven patients presented abnormal T2/FLAIR hyperintensity, mainly involving the cortex, brainstem, and optic nerve. Compared with the NMDAR IgG ( +)/MOG IgG ( -) group, the NMDAR IgG ( +)/MOG IgG ( +) group showed more ataxia symptoms (27.3% vs. 3.6%, P = 0.037), while more T2/FLAIR hyperintensity lesions were found in the brainstem (54.5% vs. 7.3%, P < 0.001) and optic nerve (27.3% vs. 1.8%, P = 0.011) with more abnormal MRI patterns (90.9% vs. 41.8%, P = 0.003). In comparison with the NMDAR IgG ( -)/MOG IgG ( +) group, the NMDAR IgG ( +)/MOG IgG ( +) group had more seizures (72.7% vs. 24.5%, P = 0.007) and mental symptoms (45.5% vs. 0, P < 0.001). The NMDAR IgG ( +)/MOG IgG ( +) group tended to be treated with corticosteroids alone (63.6% vs. 20.0%, P = 0.009), more prone to recur (36.5% vs. 7.3%, P = 0.028) and lower mRS score (P = 0.036) at the last follow-up than pure anti-NMDAR encephalitis.

CONCLUSION

The symptoms of the NMDAR IgG ( +)/MOG IgG ( +) group were more similar to anti-NMDAR encephalitis, while MRI patterns overlapped more with MOG-AD. Detecting both NMDAR-IgG and MOG-IgG maybe warranted in patients with atypical encephalitis symptoms and demyelinating lesions in infratentorial regions.

Myelin Oligodendrocyte Glycoprotein-Antibody Associated Disease: An Updated Review of the Clinical Spectrum, Pathogenetic Mechanisms and Therapeutic Management

Clinical syndromes associated with antibodies against myelin oligodendrocyte glycoprotein (MOG) are now recognized as a distinct neurological disease entity, and are gaining increasing attention. The pathogenic mechanisms underlying MOG-antibody disease (MOGAD) remain incompletely understood. Case series, facilitated by registries, and observational studies over the past few years have shed increasing light on the clinical aspects and therapeutic approaches of MOGAD. MOGAD may manifest with a variety of clinical syndromes, including acute disseminated encephalomyelitis (ADEM), autoimmune encephalitis, optic neuritis (ON) and transverse myelitis (TM). MOGAD can be either monophasic or relapsing. This review aims to provide a comprehensive updated description of the clinical spectrum, paraclinical features, and prognosis of MOG-antibody disease, as well as summarize its therapeutic considerations. Randomized clinical trials, standardized diagnostic criteria and treatment guidelines are the steps forward.

The case report of MOG and NMDAR IgG double positive encephalitis treated with subcutaneous ofatumumab

The phenotypic spectrum of myelin oligodendrocyte glycoprotein (MOG)- IgG-associated disorders (MOGAD) has broadened in the past few years, and atypical phenotypes are increasingly recognized. Isolated seizures and MRI-negative brainstem and cerebellar symptoms or encephalitis have rarely been reported as a feature of MOGAD and represent a diagnostic challenge. Meanwhile, the coexistence of MOG IgG and other CNS autoimmune antibodies is infrequent. We report a patient presented with isolated epileptic onset, relapsed with MRI-negative brainstem symptoms and MRI-negative encephalitis. He was positive for MOG IgG throughout the disease course while concomitant NMDAR IgG was not detected positive until second relapse. He showed decreasing response to conventional first-line therapy. The last relapse was during a COVID-19 epidemic with limited inpatient resources. Fortunately, he was ultimately controlled on subcutaneous ofatumumab, a novel fully humanized anti-CD20 mAb. This is the first report about subcutaneous ofatumumab treatment in MOG and NMDAR IgG double positive encephalitis with 12-month follow-up, depicting its potential as a therapeutic option.

[Absence of cortical lesions after the first seizure in a patient with anti-myelin oligodendrocyte glycoprotein-associated cortical encephalitis]

A 31-year-old man developed headache and generalized convulsions. At the time of the first seizure, there was no distinct MRI abnormality. He was admitted to the hospital with repeated seizures, left-sided hemiparesis, and left-sided neglect. He had a slight fever, elevated cerebrospinal fluid (CSF) pressure, and increased CSF cell count with predominance of mononuclear cells. A repeat MRI scan on day 8 after the recurrent seizure showed cortical edema in the right cerebral hemisphere on fluid-attenuated inversion recovery (FLAIR), abnormal high signal on DWI, and decreased apparent diffusion coefficient. The patient was diagnosed with aseptic meningoencephalitis and treated with antiviral drugs and methylprednisolone pulse therapy. Serum anti-myelin oligodendrocyte glycoprotein (MOG) antibody was subsequently detected, and prednisolone was added to treat the FLAIR-hyperintense lesions in anti-MOG antibody associated encephalitis with seizures (FLAMES). It is important to identify the clinical picture and typical images of FLAMES to allow early treatment.

Meta-analysis of the effectiveness of relapse prevention therapy for myelin-oligodendrocyte glycoprotein antibody-associated disease

BACKGROUND

Approximately 40% of adults and 30% of children with Myelin-oligodendrocyte glycoprotein antibody-associated disease (MOGAD) experience a relapsing course, but the optimal relapse prevention therapy remains unclear. A meta- analysis was conducted to investigate the efficacy of azathioprine (AZA), mycophenolate mofetil (MMF), rituximab (RTX), maintenance intravenous immunoglobulin (IVIG), and tocilizumab (TCZ) in prevention of attacks in MOGAD.

METHODS

English and Chinese-language articles published from January 2010 to May 2022 were searched in PubMed, Embase, Web of Science, Cochrane, Wanfang Data, China National Knowledge Infrastructure (CNKI), and China Science and Technology Journal Database (CQVIP). Studies with fewer than three cases were excluded. Meta-analysis of the relapse-free rate, the change of annualized relapse rate (ARR)and Expanded Disability Status Scale (EDSS) scores before and after treatment, and an age subgroup analysis was performed.

RESULTS

A total of 41 studies were included. Three were prospective cohort studies, one was an ambispective cohort study, and 37 were retrospective cohort studies or case series. Eleven, eighteen, eighteen, eight, and two studies were included in the meta-analysis for relapse-free probability after AZA, MMF, RTX, IVIG, and TCZ therapy, respectively. The proportions of patients without relapse after AZA, MMF, RTX, IVIG, and TCZ were 65% [95% confidence interval (CI):49%-82%]), 73% (95%CI:62%-84%), 66% (95%CI:55%-77%), 79% (95%CI:66%-91%), and 93% (95%CI:54%-100%), respectively. The relapse-free rate did not significantly differ between the children and adults treated with each medication. Six, nine, ten, and three studies were included in the meta-analysis for the change of ARR before and after AZA, MMF, RTX, and IVIG therapy, respectively. ARR was significantly decreased after AZA, MMF, RTX, and IVIG therapy with a mean reduction of 1.58 (95%CI: [-2.29--0.87]), 1.32 (95%CI: [-1.57--1.07]), 1.01 (95%CI: [-1.34--0.67]), and 1.84 (95%CI: [-2.66--1.02]), respectively. The change in ARR did not significantly differ between children and adults.

CONCLUSIONS

AZA, MMF, RTX, maintenance IVIG, and TCZ all reduce the risk of relapse in both pediatric and adult patients with MOGAD. The literatures included in the meta-analysis were mainly retrospective studies, so large randomized prospective clinical trials are needed to compare the efficacy of different treatments.

Anti-MOG Antibody-Associated Unilateral Cortical Encephalitis with Bilateral Meningeal Involvement: A Case Report

A 27-year-old Han Chinese woman presented with fever, headache, lethargy, and difficulty in expression. Magnetic resonance imaging (MRI) detected extensive hyperintensity of the left-sided frontoparietal, temporal, occipital, and insular cortices via fluid-attenuated inversion recovery (FLAIR) imaging. Post-contrast MRI revealed linear enhancement in the frontoparietal, temporal, and occipital sulci bilaterally. The detection of anti-myelin oligodendrocyte glycoprotein (MOG) was positive in the cerebrospinal fluid (CSF) and serum. The patient was diagnosed with anti-MOG antibody-associated unilateral cortical encephalitis with bilateral meningeal involvement. The patient received low doses of intravenous dexamethasone followed by oral prednisone, which was tapered until withdrawal. The treatment significantly improved the patient's symptoms. A one-month follow-up showed that the patient gradually resumed her normal lifestyle. No further relapse was recorded after a one-year follow-up. MRI performed almost a year after the initial symptom onset showed that the FLAIR signal had decreased in the left insular lobe, and the abnormal cortical signal of the FLAIR in the original left frontotemporal occipital lobe had disappeared. Thus, we report a rare case of anti-MOG antibody encephalitis (unilateral cortical encephalitis with bilateral meningeal involvement) in an adult patient. This study provides a reference for the clinical diagnosis and treatment of MOG antibody-associated unilateral cortical encephalitis.

Cerebral Cortical Encephalitis in Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease

Cerebral cortical encephalitis (CCE) is a recently described myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) phenotype. In this observational retrospective study, we characterized 19 CCE patients (6.7% of our MOGAD cohort). Headache (n = 15, 79%), seizures (n = 13, 68%), and encephalopathy (n = 12, 63%) were frequent. Magnetic resonance imaging revealed unilateral (n = 12, 63%) or bilateral (n = 7, 37%) cortical T2 hyperintensity and leptomeningeal enhancement (n = 17, 89%). N-Methyl-D-aspartate receptor autoantibodies coexisted in 2 of 15 tested (13%). CCE pathology (n = 2) showed extensive subpial cortical demyelination (n = 2), microglial reactivity (n = 2), and inflammatory infiltrates (perivascular, n = 1; meningeal, n = 1). Most received high-dose steroids (n = 17, 89%), and all improved, but 3 had CCE relapses. This study highlights the CCE spectrum and provides insight into its pathogenesis. ANN NEUROL 2023;93:297-302.

Clinical characteristic of myelin oligodendrocyte glycoprotein antibody associated cortical encephalitis in adults and outcomes following glucocorticoid therapy

Objective

To describe the clinical and radiological features, as well as outcomes following glucocorticoid therapy and recurrence in adults suffering from cortical encephalitis associated with myelin oligodendrocyte glycoprotein (MOG) antibody.

Methods

The clinical information of nine adult patients suffering from cortical encephalitis associated with MOG antibody admitted to the Affiliated Brain Hospital of Nanjing Medical University from 2020 to 2022 was systematically reviewed. The clinical symptoms, laboratory data, imaging results, outcomes following glucocorticoid therapy and recurrence were evaluated.

Result

A total of 9 patients positive for MOG antibody and suffering from cortical encephalitis were included in our study (55.6% men, median age 29 years, 15-57 years). The most common clinical symptoms included headache (77.8%), fever (66.7%), and generalized seizures (55.6%). Some patients also experienced limb shaking (22.2%), leg numbness (22.2%), transient motor aphasia (11.1%), and vision loss (11.1%). The main features of cerebrospinal fluid () examination were increased intracranial pressure, pleocytosis, and elevated cerebrospinal fluid (CSF) protein. In addition, N-methyl-D-aspartate receptor (NMDAR) and MOG antibodies were found in the CSF of 3 patients, and NMDAR, MOG, and glial fibrillary acidic protein antibodies were found in the CSF of 1 patient. All patients were subjected to magnetic resonance imaging (MRI) and the images of eight of them showed T2 and/flair image hyperintense lesions, three showed meningeal or lesion enhancement and four showed white matter lesions, which were mostly located in the midline structures (75%). All patients received glucocorticoid therapy in the acute phase and in remission, and eight of them received an intravenous high dose of methylprednisolone, including one patient who received a simultaneous immunoglobulin therapy. One patient was treated with low-dose prednisolone tablets. Seven (77.8%) patients were wholly recovered at discharge, and 2 (22.2%) patients were left with slight symptoms. During the median 9-month follow-up (range: 2-36 months), 2 (22.2%) patients developed recurrence.

Conclusion

The clinical manifestations of adult MOG antibody-associated cortical encephalitis were significantly different from those of the typical MOG antibody-associated disease (MOGAD). Patients in the acute phase of the disease were prone to show signs similar to central nervous system infection, requiring clinicians to have the ability to recognize the disease to avoid misdiagnosis. In addition, seizures were common in MOG antibody-related encephalitis, and the type of seizures was age-related. Brain MRI results showed that the distribution of cerebral cortex lesions was closely related to the classification of cortical encephalitis. Based on the patient's response to the treatment, glucocorticoid therapy was effective against MOG antibody-associated cortical encephalitis, which is consistent with the treatment response and clinical prognosis of MOGAD. Therefore, our opinion was that MOG antibody might be the "responsible antibody" in MOG antibody-associated cortical encephalitis, although further studies are needed to confirm this hypothesis.

FLAIR-hyperintense lesions in anti-MOG-associated encephalitis with seizures overlaying anti-N-methyl-D-aspartate receptor encephalitis: a case report and literature review

Background

FLAIR-hyperintense lesions in anti-MOG-associated encephalitis with seizures (FLAMES) has been identified increasingly frequently in recent years. However, this rare MOG antibody disease may coexist with anti-N-methyl-D-aspartate receptor encephalitis (anti-NMDARe), in an overlap syndrome with unknown clinical features and prognosis.

Methods

We report a new case of this overlap syndrome and present a systematic review of similar cases in the literature to provide information on the clinical presentation, MRI features, EGG abnormalities, treatment, and prognosis of patients with this rare syndrome.

Results

A total of 12 patients were analyzed in the study. The most common clinical manifestations of FLAMES overlaid with anti-NMDARe were epilepsy (12/12), headache (11/12), and fever (10/12). Increases in intracranial pressure (median: 262.5 mmH₂O, range: 150-380 mmH₂O), cerebrospinal fluid (CSF) leukocyte count (median: 128×10⁶/L, range: 1-610×10⁶/L), and protein level (median: 0.48 g/L) were also observed. The median CSF anti-NMDAR antibody titer was 1:10 (1:1-1:32), while the median serum MOG antibody titer was 1:32 (1:10-1:1024). Seven cases exhibited unilateral cortical FLAIR hyperintensity, and five cases (42%) had bilateral cortical FLAIR hyperintensity, including four cases involving the bilateral medial frontal lobes. Of the 12 patients, five showed lesions at other sites (e.g., the brainstem, corpus callosum, or frontal orbital gyrus) before or after the development of cortical encephalitis. EEG showed slow waves in four cases, spike-slow waves in two cases, an epileptiform pattern in one case, and normal waves in two cases. The median number of relapses was two. Over a mean follow-up period of 18.5 months, only one patient experienced residual visual impairment, while the remaining 11 patients had good prognoses.

Conclusion

FLAMES alone is difficult to distinguish from overlap syndrome based on clinical features. However, FLAMES with bilateral medial frontal lobe involvement suggests the presence of the overlap syndrome.

An update on biologic treatments for neuromyelitis optica spectrum disorder

INTRODUCTION

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune disease of the central nervous system mediated by antibodies targeting the aquaporin-4 (AQP4) water channel expressed on astrocytes. The binding of specific antibodies to AQP4 causes complement-dependent cytotoxicity, leading to inflammation and demyelination. Several recent phase 2 and 3 randomized placebo-controlled trials showed the efficacy and safety of monoclonal antibody therapies targeting B-cells, interleukin-6 receptor, and complement.

AREAS COVERED

Current biologic treatments for NMOSD and developments therein, and unresolved issues in NMOSD treatment.

EXPERT OPINION

New biologic treatments demonstrate high efficacy and good safety for patients with AQP4-IgG-positive NMOSD. The optimal therapeutics for seronegative NMOSD, pediatric patients, and female patients who are pregnant or wish to be are unclear, and further research is needed. Also, real-world studies of new biological agents and the data on the durability of their beneficial effects and their long-term safety are required. Effective rescue therapy for an acute attack is critical given permanent disability in NMOSD is attack-related, and biologic agents that treat acute attack are emerging. If such treatments are to become widely applied, studies on the most cost-effective treatment strategies are needed.

Myelin oligodendrocyte glycoprotein antibody-associated aseptic meningitis without neurological parenchymal lesions: A novel phenotype

BACKGROUND

Myelin oligodendrocyte glycoprotein (MOG) antibodies mediate inflammatory demyelinating diseases of the central nervous system. This study aimed to understand the clinical characteristics of MOG antibody-associated aseptic meningitis (MOGAM).

METHODS

Here, we report the cases of two children with MOGAM. A systematic literature review was conducted and included patients who had MOGAM only, without neurological parenchymal lesions. The clinical characteristics that may have affected the outcome were statistically analyzed.

RESULTS

We reviewed 12 cases of MOGAM; male: female = 9: 3. Prolonged fever lasting over 7 days (11/12) was the most frequent symptom, followed by headache (10/12), vomiting (5/12), and seizures (4/12). None of the patients had focal neurological manifestations or parenchymal lesions on imaging. Cerebrospinal fluid (CSF) leukocytosis was observed in all patients (12/12), and blood leukocytosis and elevated CSF pressure was observed in all patients who had corresponding results (9/9 and 4/4, respectively). Seizures occurrence was lower than that of MOG antibody-associated cortical encephalitis. Seven cases progressed to other MOG antibody-associated diseases (MOGADs) in the later phase of MOGAM. Patients who did not progress to other MOGADs had a shorter disease duration from onset to the initiation of intravenous methylprednisolone than those who did. All the patients achieved full recovery after steroid treatment. One patient had relapses.

CONCLUSIONS

MOGAM without inflammatory demyelination is a rare but distinct phenotype of MOGAD, with fewer clinical manifestations mimicking bacterial or viral meningitis/encephalomeningitis. Delayed diagnosis and treatment may induce the progression to other severe MOGADs. Early recognition of this unique autoimmune aseptic meningitis may contribute to early diagnosis, treatment, and better outcomes.

Meningo-cortical manifestations of myelin oligodendrocyte glycoprotein antibody-associated disease: Review of a novel clinico-radiographic spectrum

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is an inflammatory demyelinating disease that is distinct from multiple sclerosis. Initial manifestations of MOGAD that were reported in the literature included optic neuritis, myelitis, brainstem demyelination and encephalitis, with emphasis placed on acute disseminated encephalomyelitis (ADEM) as the primary encephalitic presentation. In 2017, however, Ogawa et al. described four patients with seizures, unilateral cortical hyperintensities on brain magnetic resonance imaging T2-fluid-attenuated inversion recovery sequences, and anti-MOG positivity, indicating a potentially novel form of encephalitis in MOGAD. In 2019, we systematically reviewed the literature to better characterize this unique syndrome, which we referred to as unilateral cortical FLAIR-hyperintense Lesions in Anti-MOG-associated Encephalitis with Seizures (FLAMES). Subsequently, anti-MOG positivity in patients with a variety of cortical and meningeal disease presentations has been reported, indicating a broader spectrum of meningo-cortical manifestations in MOGAD that we review herein.

Case report: Overlapping syndrome mimicking infectious meningoencephalitis in a patient with coexistent MOG, NMDAR, mGluR5 antibody positivity

A 38-year-old Chinese Han man presented with fever, headache and difficulty in language expression. The initial cerebrospinal fluid (CSF) analysis revealed lymphocytic-predominant pleocytosis with a normal glucose level, and magnetic resonance imaging (MRI) showed extensive cortical edema in left cerebral hemisphere. He received the antiviral treatment. However, one week later, he developed psychomotor agitation and seizures. Lumbar puncture was performed again and further testing for autoantibodies was conducted in both the CSF and serum. His CSF was positive for anti-myelin oligodendrocyte glycoprotein (MOG), anti-N-methyl-D-aspartate receptor (NMDAR) and anti-metabotropic glutamate receptor 5 (mGluR5) antibodies. He was diagnosed with overlapping syndrome of MOG antibody-related cerebral cortical encephalitis and anti-NMDAR, anti-mGluR5 autoimmune encephalitis. He received intravenous methylprednisolone and immunoglobulin, followed by oral prednisone and mycophenolate mofetil. His psychomotor agitation and seizures were relieved, and he gradually recovered his language expression ability. We reported for the first time a case that was positive for coexistent MOG, NMDAR, mGluR5 antibodies, which was initially misdiagnosed as infectious meningoencephalitis. This case widens the clinical spectrum of the overlapping syndrome recently reported.

Seizures and epilepsy in multiple sclerosis, aquaporin 4 antibody-positive neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein antibody-associated disease

Seizure is one of the manifestations of central nervous system (CNS) inflammatory demyelinating diseases, which mainly include multiple sclerosis (MS), aquaporin 4 antibody-positive neuromyelitis optica spectrum disorder (AQP4-NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). "Acute symptomatic seizures secondary to MS / AQP4-NMOSD / MOGAD" occur in the acute phase of the diseases, and are more frequent in MOGAD. In contrast, recurrent non-provoked seizures, mainly attributed to "autoimmune-associated epilepsy", occur in the non-acute phase of the diseases. Seizures in MS / AQP4-NMOSD / MOGAD mostly have a focal-onset. MS patients with concomitant systemic infections, an earlier onset and a higher disease activity are more likely to have seizures, whereas factors such as higher MS severity, the presence of status epilepticus and cortical damage indicate a greater risk of developing epilepsy. In MOGAD, cerebral cortical encephalitis, acute disseminated encephalomyelitis (ADEM)-like phenotypes (predominately ADEM and multiphasic disseminated encephalomyelitis) indicate a higher seizure risk. Multiple relapses with ADEM-like phenotypes predict epilepsy in pediatrics with MOGAD. Pathophysiologically, acute symptomatic seizures in MS are associated with neuronal hyperexcitability secondary to inflammation and demyelination. Chronic epilepsy in MS is largely due to gliosis, neuronal dysfunction and synaptic abnormalities. The mainstay of treatment for seizures secondary to MS / AQP4-NMOSD / MOGAD include immunotherapy along with antiseizure medications. This critical review discusses the most-updated evidence on epidemiology, clinical correlates, and inflammatory mechanisms underlying seizures and epilepsy in MS / AQP4-NMOSD / MOGAD. Treatment cautions including drug-drug interactions and the impact of treatments on the other are outlined. We also highlight pitfalls and challenges in managing such patients and future research perspectives to address unsolved questions.