Clinical significance of anti-NMDAR concurrent with glial or neuronal surface antibodies

Abnormal Brain MRI in Anti-NMDA Receptor Encephalitis: Clinical and Prognostic Implications

BACKGROUND AND OBJECTIVES

Abnormal brain MRI is associated with poor outcomes in anti-N-methyl-d-aspartate receptor encephalitis (NMDARE). We aimed to characterize the lesions on brain MRI in NMDARE and to assess the clinical and prognostic associations.

METHODS

This retrospective cohort study included patients with NMDARE identified at the French Reference Center for Autoimmune Encephalitis, with at least a one-year follow-up, and with available brain MRI results. In case of brain extralimbic lesion, the image files were reviewed when available. Clinical data were collected from medical records. Multivariable logistic regression analysis was used to study the outcomes at 2-year follow-up; recovery was defined as modified Rankin Scale score ≤1.

RESULTS

Among the 255 patients included, 37 (14.5%) had limbic hyperintensities and 41 (16.1%) had extralimbic lesions that included multiple sclerosis (MS)-like lesions (14/41, 34.1%); extensive lesions (5/41, 12.2%); and poorly demarcated fluffy lesions, either multifocal (10/41, 24.4%) or involving the cerebral cortex or cerebellum (6/41 each, 14.6%). Extralimbic lesions coexisting with limbic lesions (19/41 patients, 46.3%) were mostly fluffy lesions (11/19, 57.9%). Ten patients had overlapping demyelinating syndromes: 4 with MS, 4 with myelin oligodendrocyte glycoprotein-associated disorder, and 2 with neuromyelitis optica spectrum disorder; all had MS-like (7/10 patients) or extensive (3/10 patients) lesions, and none had fluffy lesions. Extralimbic lesions were associated with symptoms nontypical for NMDARE (23/41, 56.1%, p < 0.001), especially cerebellar ataxia (17/41, 41.5%) and motor impairment (12/41, 29.3%). At 2 years, patients with MS-like or extensive lesions had a lower recovery rate (5/12, 41.7%, and 1/4, 25%, respectively) compared with the patients without extralimbic lesions (124/162, 76.5%; p = 0.014 and p = 0.047, respectively). In multivariable analysis, MS-like lesions, but not hippocampal nor fluffy lesions, were associated with absence of recovery at 2 years (adjusted OR 0.1, 95% CI 0.03-0.42, p = 0.002; extensive lesions [n = 4] not included in the analysis).

DISCUSSION

Brain MRI lesions in NMDARE include limbic hyperintensities and 3 patterns of extralimbic lesions, which are associated with nontypical NMDARE symptoms. Moreover, MS-like and extensive lesions, but not fluffy nor hippocampal lesions, are associated with overlapping demyelinating syndromes and poor clinical outcomes at 2 years. These findings can have practical implications on the monitoring of patients with NMDARE.

Clinical and imaging features and treatment response of anti-NMDAR encephalitis combined with MOGAD

BACKGROUND

To investigate the clinical, imaging features, immunotherapy of anti-N-methyl-D-aspartate receptor encephalitis (NMDARE) combined with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD).

METHODS

A total of 124 patients with NMDARE and 86 patients with MOGAD were screened from an ongoing prospective cohort study (Clinical and Imaging Patterns of Neuroinflammation Diseases in China, CLUE). Ten NMDARE combined with MOGAD patients, were finally enrolled in this study. Clinical and imaging data and follow-up results characteristics were collected and analyzed.

RESULTS

In these 10 patients with NMDARE combined with MOGAD, 7 patients (70 %) showed recurrent courses. In all 26 episodes, 14 episodes (53.8 %) showed encephalitis-related symptoms, 6 episodes (23.1 %) showed demyelination-related symptoms, 6 episodes (23.1 %) showed both. The median CSF leukocytes were 13/μL (range 1-413) and the median protein was 0.43 g/L (range 0.22-0.70). MRI lesions were found involving the optic nerve (2/10), spinal cord (3/10), deep gray matter (3/10), cortex (6/10), subcortex (7/10), brainstem (5/10) and cerebellum (4/10). Leptomeningeal enhancement was found in 3 patients. All patients received high-dose intravenous methylprednisolone and immunoglobulin therapy during attacks. Seven patients received rituximab (RTX). The median annualized recurrence rate (ARR) reduced significantly following RTX treatments (z = -2.201, p = 0.028), and achieved good outcomes at the last follow-up visit (modified Rankin scale score ≤ 2).

CONCLUSION

NMDARE combined with MOGAD represents a unique characteristic of autoantibody-mediated encephalitis. Coexistence of NMDAR and MOG antibody may indicate high recurrence risk. RTX may be a relatively efficient therapeutic option.

Clinical characteristics of children with anti-N-methyl-D-aspartate receptor encephalitis with and without anti-myelin oligodendrocyte glycoprotein antibody

To analyze the clinical characteristics of an overlapping syndrome, MNOS, of anti-myelin oligodendrocyte glycoprotein antibody (MOG-Ab) coexisting with anti-N-methyl-D-aspartate receptor encephalitis (NMDARE) in children. We included patients with NMDARE at Children's Hospital of Chongqing Medical University between 2018 and 2022 and conducted a comparison between NMDARE with and without MOG-Ab. Among 163 patients with NMDARE, 15 individuals tested positive for MOG-Ab. The median age of MNOS was 11 years (IQR 8-13). Furthermore, 10 out of 15 were female. More than half of MNOS experienced a prior history of encephalitis or demyelinating disorders. Among ten patients with low MOG-Ab titers, two met the diagnostic criteria for MOGAD. All five patients with high MOG-Ab titers satisfied the criteria for MOGAD. A total of seven patients diagnosed with MOGAD presented with acute disseminated encephalomyelitis. The proportion of prodromal symptoms and brain lesions, the neutrophil counts, and the frequency of mycophenolate mofetil administration were significantly higher in MNOS compared to NMDARE patients without MOG-Ab (p < 0.05). The outcomes of MNOS were favorable and comparable to those observed in NMDARE. Nevertheless, MNOS demonstrated a higher tendency to relapse, with rates of 60.0% compared to 3.1% (p < 0.001).

CONCLUSION

Pediatric MNOS exhibited a high prevalence among females, particularly those with a prior history of MOGAD or encephalitis. MNOS had a favorable prognosis but with a high relapse rate. Coexisting MOG-Ab in pediatric MNOS may be pathogenic or a bystander, potentially correlating with antibody titers.

WHAT IS KNOWN

• Pediatric anti-N-methyl-D-aspartate receptor encephalitis (NMDARE) coexisting with anti-myelin oligodendrocyte glycoprotein antibody (MOG-Ab) generally has a favorable prognosis, albeit with a tendency to relapse. • Pediatric NMDARE coexisting with MOG-Ab may exhibit imaging features indicative of demyelination.

WHAT IS NEW

• Pediatric patients of MOG-Ab coexisting with NMDARE overlapping syndrome (MNOS) were predominantly observed in females, particularly those with a history of MOG-Ab-associated disorder (MOGAD) or encephalitis. • Compared with NMDARE patients, pediatric MNOS patients had higher neutrophil counts and more frequently exhibited abnormal MRI findings in the basal ganglia, insular lobe, temporal lobe, thalamus, and cerebellum.

Clinical characterization of diseases associated with anti-N-methyl-D-aspartate receptor encephalitis combined with anti-myelin oligodendrocyte glycoprotein antibodies in adults

OBJECTIVE

The aim of this study was to analyze the clinical characteristics of adult patients with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis combined with anti-myelin oligodendrocyte glycoprotein (MOG) antibodies.

METHODS

This was a non-randomized controlled study. Clinical data were collected from 17 patients with anti-NMDAR encephalitis combined with anti-MOG antibodies admitted to Xuanwu Hospital, Capital Medical University, from January 2020 to August 2024. As controls, 20 patients with NMDAR(+)/MOG(-) and 27 patients with MOG(+)/NMDAR(-) were selected.

RESULTS

The mean age of onset in the double-positive group was 33.47 ± 1.065 years, with a male-to-female ratio of 14:3. Significant differences were observed between the NMDAR(+)/MOG(+) group and the NMDAR(+)/MOG(-) group in terms of headache, lumbar puncture pressure, and cerebrospinal fluid (CSF) leukocyte counts (P < 0.05). Comparing the NMDAR(+)/MOG(+) group with the MOG(+)/NMDAR(-) group revealed significant differences in gender, headache, mental and behavioral abnormalities, limb twitching, loss of consciousness, cognitive impairment, speech impairment, visual impairment, limb numbness, cortical/sub-cortical white matter, brainstem lesions, OB type II, and CSF leukocyte counts (P < 0.05). No statistically significant differences were found in the comparison of CSF and serum antibody titers among the three groups (P > 0.05).

CONCLUSION

NMDAR and MOG antibodies can coexist in patients with autoimmune diseases, with a predominance of young male patients. The double-positive group exhibited more severe intracranial viral infections and a higher rate of intrathecal immunoglobulin synthesis in the central tissues. Compared to the double-positive group, NMDAR encephalitis alone presented with more similar clinical manifestations, while MOG-related disease demonstrated a higher likelihood of brainstem involvement.

Novel Meningoencephalomyelitis Associated With Vimentin IgG Autoantibodies

IMPORTANCE

Autoantibodies targeting astrocytes, such as those against glial fibrillary acidic protein (GFAP) or aquaporin protein 4, are crucial diagnostic markers for autoimmune astrocytopathy among central nervous system (CNS) autoimmune disorders. However, diagnosis remains challenging for patients lacking specific autoantibodies.

OBJECTIVE

To characterize a syndrome of unknown meningoencephalomyelitis associated with an astrocytic autoantibody.

DESIGN, SETTING, AND PARTICIPANTS

This retrospective case series study included samples collected from April 2021 to May 2024 at a tertiary referral hospital among patients with uncharacterized CNS autoimmune disorders and similar clinical and radiological features. Single-cell RNA sequencing (scRNA-seq) was performed on cerebrospinal fluid (CSF) cells of 2 index patients to identify the putative target antigen of the clonally expanded B cells. A comprehensive screening for additional patients was conducted using blinded cell-based and tissue-based assay. Candidate patients were followed up for a median (range) duration of 23 (5-31) months.

EXPOSURES

scRNA-seq, autoantibody characterization, and testing.

MAIN OUTCOMES AND MEASURES

Detection of the autoantibody and characterization of the associated autoimmune meningoencephalomyelitis.

RESULTS

Fourteen candidate patients (10 [71%] female; median [IQR] age, 33 [23-41] years) were identified. Initially, CSF from 2 female patients with unknown encephalomyelitis showed astrocytic reactivity on rat tissue but was negative for GFAP IgG. A total of 17 of 37 clonally expanded B cell clonotypes (46%) in their CSF expressed IgG autoantibodies targeting the astrocytic intermediate filament protein vimentin. Subsequent screening identified 12 additional patients. These 14 patients shared a unique clinical profile characterized by relapsing courses and symptoms prominently involving the cerebellum, brainstem, and corticospinal tract (CST). All patients also exhibited elevated CSF protein and cells, intrathecal immunoglobulin synthesis, and magnetic resonance imaging (MRI) showing bilateral lesions on CST. Notably, 8 of 12 patients (67%) who received first-line immunotherapy at their first episode responded well. At the last follow-up, 11 patients (79%) experienced significant disability (modified Rankin Scale ≥3).

CONCLUSIONS AND RELEVANCE

In this case series, autoantibodies targeting the astrocytic intermediate filament protein vimentin were identified in patients with previously undifferentiated meningoencephalomyelitis and common radiographic features.

Case report: Overlapping syndrome of MOG-IgG associated optic neuritis and autoimmune encephalitis with co-existence of anti-NMDAR and anti-GABABR antibodies

We report a case of optic neuritis (ON) secondary to autoimmune encephalitis (AE) in a patient with concomitant antibodies to N-methyl-D-aspartate receptor (NMDAR), gamma-aminobutyric acid-B receptor (GABABR), and myelin oligodendrocyte glycoprotein (MOG). The patient exhibited a constellation of symptoms, including vision loss, seizures, mental and behavioral disorders, cognitive impairment, and speech abnormalities. At the two-year follow-up, the patient's symptoms had abated entirely. Overlap syndrome of triple autoimmune antibodies is rare and the coexistence of antibodies to NMDAR, GABABR and MOG has not been reported till now. This case report provides novel experience of diagnosis and treatment in autoimmune overlap syndromes.

MOGAD: A comprehensive review of clinicoradiological features, therapy and outcomes in 4699 patients globally

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is one of the most common antibody-mediated CNS disorders. Optimal diagnostic and prognostic biomarkers remain unclear. Our aim was to clarify these biomarkers and therapeutic outcomes internationally. We reviewed articles from 2007 to 2022 and identified 194 unique cohorts encompassing 4699 paediatric and adult patients from 31 countries. Where phenotypes were specified, the most common initial presentation overall was optic neuritis (ON; paediatric 34 %; adults 60 %), during which 71 % had papilloedema on fundoscopy. The most common phenotype at latest follow-up was relapsing ON (20 %). Only 47 % of patients with 6-24 months of follow-up exhibited a relapsing course, while this proportion was much higher (72 %) when follow-up was extended beyond 5 years. Despite a similar relapse rate, the time to first relapse was much shorter in paediatric than adult patients (6 vs 17 months). Adult MRI-Brain scans performed at onset were more frequently normal than in paediatric patients (50 % vs 27 %). Abnormal MRI scans showing involvement of deep grey matter, cortico-subcortical, periventricular lesions, leptomeningeal enhancement, H-shaped spinal cord lesions, and bilateral optic nerve abnormalities were more common in paediatric patients compared to adults. Conversely, adults demonstrated higher frequencies of eccentric spinal cord lesions and intraorbital involvement. CSF analysis demonstrated intrathecally restricted oligoclonal bands in 12 %, elevated protein in 35 %, and pleocytosis in 54 %. Peripapillary retinal nerve fibre layer (pRNFL) thickness, measured acutely, frequently demonstrated swelling (weighted-median 145 μm; normal 85-110). Most cohorts demonstrated notable pRNFL atrophy at latest follow-up (weighted-median 67 μm). pRNFL thickness was significantly lower when measured at or after six months following ON onset, compared to measurements taken within the first six months following ON onset (p < 0.001). Therapeutic and outcome data was available for 3031 patients with a weighted-median disease duration of 32 months. Acute immunotherapy was initiated in 97 %, and maintenance immunotherapy in 64 %, with considerable regional variation. Expanded Disability Status Scale (EDSS) scores and visual acuities improved from nadir to latest follow-up in most patients. A negative correlation was noted between follow-up pRNFL thickness and latest follow-up visual acuity (r = -0.56). Based on this unprecedented global aggregation of MOGAD patients, we reveal a higher proportion of relapsing patients than previously recognised. While commonly used measures like EDSS show significant recovery, they underestimate visual disability following optic neuritis, the most frequent clinical presentation. Our findings suggest that RNFL thickness, especially when measured at least 6 months post-ON, may serve as a more sensitive biomarker for long-term visual impairment.

Neuroglia in autoimmune encephalitis

Neuroglial cells play a crucial role in central nervous system (CNS) health and disease. Antibody-associated autoimmune encephalitis (AE) represents a group of inflammatory brain diseases with antibodies (Abs) against neuronal cell surface (e.g., anti-N-methyl-d-aspartate receptor (NMDAR), anti-leucine-rich glioma-inactivated 1 (LGI1), γ-aminobutyric acid (GABA) type A or B receptor (GABAA/BR)) or intracellular neuronal proteins. AE with Abs against glial antigens, e.g., myelin oligodendrocyte glycoprotein (MOG), glial fibrillary acidic protein (GFAP) are also described. Besides the known pathomechanisms with direct pathogenic effects of primary neuronal Abs and activation of innate (dendritic cells) and adaptive (B and T cells) immune systems, research findings suggest the involvement of glial cells including astrocytes, microglia, oligodendrocytes in the pathogenesis of Ab-associated AE, but only a limited number of studies is available. Neuropathologic findings showed reactive astrogliosis and microgliosis with microglial activation/proliferation, e.g., in anti-NMDAR and anti-LGI1 encephalitis. Direct effects of the GABAAR and NMDAR Abs on astrocytic receptors are discussed. Because of the primary involvement of B and T cells in the pathogenesis of Ab-associated AE it can be assumed that astrocytic and microglial activation is largely a response to the primary changes, but additional direct effects of Abs on astrocytic receptors are possible. Further research in this field is required to explore the exact role of glial cells in Ab-associated AE.

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.

Frequency, characteristics, and immunological accompaniments of ataxia in anti-NMDAR antibody-associated encephalitis

Introduction

Very rarely, adult NMDAR antibody-associated encephalitis (NMDAR-E) leads to persistent cerebellar atrophy and ataxia. Transient cerebellar ataxia is common in pediatric NMDAR-E. Immune-mediated cerebellar ataxia may be associated with myelin oligodendrocyte glycoprotein (MOG), aquaporin-4 (AQP-4), kelch-like family member 11 (KLHL11), and glutamate kainate receptor subunit 2 (GluK2) antibodies, all of which may co-occur in NMDAR-E. Here, we aimed to investigate the frequency, long-term outcome, and immunological concomitants of ataxia in NMDAR-E.

Methods

In this observational study, patients with definite NMDAR-E with a follow-up of >12 months were recruited from the GENERATE registry. Cases with documented ataxia were analyzed in detail.

Results

In 12 of 62 patients (19%), ataxia was documented. Bilateral cerebellar ataxia without additional focal CNS findings was found in four (one child and three adults); one of these was previously reported as a case with persistent cerebellar atrophy and ataxia. Two patients with bilateral cerebellar ataxia had additional focal neurological symptoms, optic neuritis and facial palsy. Two patients developed hemiataxia: one with diplopia suggesting brainstem dysfunction and the other probably resulting from cerebellar diaschisis due to contralateral status epilepticus. In all but the one developing cerebellar atrophy, cerebellar ataxia was transient and not associated with a worse long-term outcome. In all five patients with cerebellar ataxia tested, MOG, AQP-4, GluK2, and KLHL11 antibodies were negative. In two additional patients negative for both MOG and AQP-4 antibodies, ataxia was sensory and explained by cervical myelitis as part of multiple sclerosis (MS) manifesting temporal relation to NMDAR-E. One of the patients with bilateral ataxia with focal neurological deficits was also diagnosed with MS upon follow-up. Finally, in two patients, ataxia was explained by cerebral hypoxic damage following circulatory failure during an ICU stay with severe NMDAR-E.

Discussion

Ataxia of different types is quite common in NMDAR-E. Cerebellar ataxia in NMDAR-E is mostly transient. NMDAR-E followed by persistent ataxia and cerebellar atrophy is very rare. Cerebellar ataxia in NMDAR-E may not be explained by concomitant KLHL11, MOG, AQP-4, or GluK2 autoimmunity. Of note, ataxia in NMDAR-E may result from treatment complications and, most interestingly, from MS manifesting in temporal association with NMDAR-E.

Frequency of anti-MOG antibodies in serum and CSF of patients with possible autoimmune encephalitis: Results from a Brazilian multicentric study

INTRODUCTION

MOGAD encephalitis and ADEM share several clinical features with autoimmune encephalitis (AE) associated with antineuronal antibodies (ANeA); nonetheless, treatment and prognosis differ. Anti-MOG antibodies (abs) are not routinely tested in possible AE, and epidemiological studies on MOGAD encephalitis are scarce.

OBJECTIVES

To determine the frequency of anti-MOG abs in the serum and CSF in a cohort of possible AE and to compare the clinical characteristics of MOGAD patients and those with seropositive AE.

METHODS

481 patients with possible AE from the Brazilian Autoimmune Encephalitis Network underwent tissue-based assay and cell-based assay (CBA) for ANeA. Anti-MOG abs were assessed in serum and CSF with in-house CBA. Clinical and laboratory characteristics of MOGAD and seropositive AE patients were compared.

RESULTS

Of the 481 patients, 87 (18 %) had ANeA, and 17 (3.5 %) had anti-MOG abs. Three AE patients with anti-MOG abs and ANeA were excluded from further analysis. Anti-MOG abs were detected in 4 (1.2 %) of the 328 adults and 10 (6.5 %) of the 153 children. Of the 14 patients with MOGAD, nine had ADEM (mostly children), and five had encephalitis (including three adults). Only one patient with ADEM had anti-MOG abs exclusively in CSF. All patients with MOGAD encephalitis were seropositive for anti-MOG abs, and three had normal brain MRI. Patients with MOGAD had fewer behavioral changes (MOGAD 21 % x AE 96 %, p ≤ 0.0001) and movement disorders (MOGAD 42 % x AE 81 %, p = 0.0017) and more demyelinating symptoms, such as myelitis and optic neuritis (MOGAD 14 % x AE 0 %, p = 0.013).

CONCLUSION

Approximately 3.5 % of patients with possible AE harbor anti-MOG abs, and 0.9 % of the adults had MOGAD encephalitis. Anti-MOG abs were more frequent than other ANeAs regularly tested in AE. We provide evidence that MOGAD is a differential diagnosis in possible AE, even in adult patients with normal brain MRI, and that serum anti-MOG should be considered as an add-on diagnostic tool in AE among adults and pediatric patients.

MRI findings in autoimmune encephalitis

Autoimmune encephalitis encompasses a spectrum of conditions characterized by distinct clinical features and magnetic resonance imaging (MRI) findings. Here, we review the literature on acute MRI changes in the most common autoimmune encephalitis variants. In N-methyl-D-aspartate (NMDA) receptor encephalitis, most patients have a normal MRI in the acute stage. When lesions are present in the acute stage, they are typically subtle and non-specific white matter lesions that do not correspond with the clinical syndrome. In some NMDA receptor encephalitis cases, these T2-hyperintense lesions may be indicative of an NMDA receptor encephalitis overlap syndrome with simultaneous co-existence of multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD) or myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). Encephalitis with leucine-rich glioma-inactivated 1 (LGI1)-, contactin-associated protein-like 2 (CASPR2)- or glutamic acid decarboxylase (GAD)- antibodies typically presents as limbic encephalitis (LE) with unilateral or bilateral T2/fluid attenuated inversion recovery (FLAIR) hyperintensities in the medial temporal lobe that can progress to hippocampal atrophy. Gamma aminobutyric acid-B (GABA-B) receptor encephalitis also often shows such medial temporal hyperintensities but may additionally involve cerebellar lesions and atrophy. Gamma aminobutyric acid-A (GABA-A) receptor encephalitis features multifocal, confluent lesions in cortical and subcortical areas, sometimes leading to generalized atrophy. MRI is unremarkable in most patients with immunoglobulin-like cell adhesion molecule 5 (IgLON5)-disease, while individual case reports identified T2/FLAIR hyperintense lesions, diffusion restriction and atrophy in the brainstem, hippocampus and cerebellum. These findings highlight the need for MRI studies in patients with suspected autoimmune encephalitis to capture disease-specific changes and to exclude alternative diagnoses. Ideally, MRI investigations should be performed using dedicated autoimmune encephalitis imaging protocols. Longitudinal MRI studies play an important role to evaluate potential relapses and to manage long-term complications. Advanced MRI techniques and current research into imaging biomarkers will help to enhance the diagnostic accuracy of MRI investigations and individual patient outcome prediction. This will eventually enable better treatment decisions with improved clinical outcomes.

Case report: Autoimmune glial fibrillary acidic protein astrocytopathy with overlapping autoimmune syndrome

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy is a rare autoimmune disease, which is characterized by the immune system attacking astrocytes in the central nervous system, resulting in inflammation and damage to the nervous system. We reported a 41-year-old female patient with only drowsiness for 3 months, who was, otherwise, healthy with no other signs of meningoencephalitis or myelitis. There were no obvious abnormalities in her neurological and ophthalmic tests. Brain magnetic resonance imaging (MRI) plain scan + enhancement with the gadolinium contrast agent revealed patchy hypointensity on T1-weighted imaging, hyperintensity on T2-weighted imaging, hyperintensity on T2-weighted fluid-attenuated inversion recovery in the left basal ganglia, corona radiata, and local septum pellucida, with no enhancement in the enhanced lesions. Cerebrospinal fluid (CSF) revealed white blood cell count of 5.00 × 106/L, CSF protein of 828.53 mg/L, and glucose of 2.83 mmol/L. Aquaporin-4 (AQP4) antibody, N-methyl-D-aspartate receptor (NMDAR) antibody and GFAP antibody were all positive, whereas the remaining autoimmune encephalitis antibody tests were negative. Oncology screening [including head, chest, and whole-abdomen (involving the pelvic cavity) CT and tumor markers] did not reveal any obvious evidence of tumor presence. The patient received systemic treatment with high-dose intravenous injection of steroids combined with immunosuppressive agents, and the clinical and imaging features of the patients improved. To the best of our knowledge, reports on overlapping positivity of AQP4 antibody and NMDAR antibody in patients with GFAP astrocytopathy were still very rare. We hope to supplement the existing literature on this topic, review the relevant literature, and strive to increase the understanding toward GFAP astrocytopathy with overlapping autoimmune syndrome so as to enable early diagnosis and early treatment and to improve the clinical outcome of patients.

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.

Assessment of international MOGAD diagnostic criteria in patients with overlapping MOG-associated disease and multiple sclerosis phenotypes

BACKGROUND

The clinical spectrum and diagnosis of myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) has evolved in the setting of an optimized anti-MOG-IgG cell-based assay and expert consensus. The McDonald criteria for MS have been revised multiple times to improve the accuracy and specificity of diagnosis on a framework based on clinical presentation, MRI findings, and CSF results. While the uses of MS and MOGAD diagnostic criteria are helpful for typical cases, such utility for patients with overlapping clinical, laboratorial, and imaging features is unknown, posing diagnostic and management uncertainties.

OBJECTIVES

To report a multicenter cohort of patients with overlapping phenotypic features of MOGAD and MS and evaluate the application of new MOGAD diagnostic criteria.

METHODS

A collaborative retrospective cohort study was performed to identify patients with both positive serum anti-MOG-IgG and fulfillment of the MS revised 2017 McDonald criteria. Clinical and radiographic features of patients fulfilling inclusion criteria were reviewed longitudinally, including relapses, repeated MRI, and MOG-IgG testing in detail to allow the panel of expert opinion to assign to each case. The International MOGAD Panel proposed criteria were applied at onset and last follow-up to each case and compared to the expert author diagnosis assignment based on presentation, clinical and imaging features, and response to treatment.

RESULTS

Ten of 225 (4%) MOG-IgG seropositive cases met study inclusion criteria [seven of 10 were female; age at initial event: eight adults (mean age 26.8 years), two adolescents (mean age 14.5 years)]. AQP4-IgG was negative for all. Apart from serum titers of MOG-IgG, distinguishing clinical and radiographic features [i.e., clinical severity of the initial demyelinating event, radiographic features (optic nerve/spine/brain), and presence/absence of lesion normalization on serial scans] led to consensus of three separate classifications differing by degrees of shared features of MOGAD and MS. Patients were classified by expert panel into (1) Classic MOGAD even with MS-like, well-defined brain lesions, when severe events and most T2 lesions normalized (n = 5; MOG-IgG titers 1:100, 1:20, 1:160, 1:40, 1:200); (2) Classic RRMS included cases thought to have likely false positive or clinically irrelevant MOG-IgG, due to mild clinical events and no radiographic normalization of well-defined MS-like lesions (n = 3; MOG titers 1:20, 1:100, 1:40); (3) MOGAD and MS overlapping phenotype was defined by those with a combination of mild and severe clinical events, partial T2 lesion normalization, both well- and ill-defined lesions (n = 2; MOG titers 1:20, 1:100). The application of the International MOGAD Panel criteria categorized five patients (50%) in agreement with expert assignment. One additional patient was classified in agreement to assignment when MOGAD criteria were applied after serial MOG-IgG titers testing.

DISCUSSION

While the International MOGAD Panel diagnostic criteria have helped with accuracy for the diagnosis of this condition, in a group of patients seropositive for MOG-IgG with overlapping clinical and imaging features of RRMS criteria review may lead to increased accuracy. Serial serologies, repeated imaging, close attention to clinical course, and response to therapy are possible variables to consider for further refinement of MOGAD diagnostic criteria.

H-intensity scale score to estimate CSF GluN1 antibody titers with one-time immunostaining using a commercial assay

Introduction

Anti-NMDA receptor encephalitis is an autoimmune disorder caused by autoantibodies (abs) against the conformational epitope on GluN1 subunits. GluN1-abs have been determined with cell-based assay (CBA) co-expressing GluN1/GluN2 subunits. However, commercial fixed CBA expressing only GluN1 subunit has increasingly been used in clinical practice. The ab titers can be determined with serial dilutions, but its clinical significance remains unclear. We aimed to develop an H-intensity scale (HIS) score to estimate GluN1-ab titers in cerebrospinal fluid (CSF) with one-time immunostaining using both commercial CBA and immunohistochemistry and report its usefulness. "H" is the initial of a patient with high CSF GluN1-ab titers (1:2,048).

Methods

We first determined the reliability of CBA in 370 patients with suspected autoimmune encephalitis by comparing the results between commercial CBA and established assay in Dalmau's Lab. Then, we made positive control panels using the patient H's CSF diluted in a fourfold serial dilution method (1:2, 1:8, 1:32, 1:128, 1:512, and 1:2,048). Based on the panels, we scored the intensity of ab reactivity of 79 GluN1-ab-positive patients' CSF (diluted at 1:2) on a scale from 0 to 6 (with ≥1 considered positive). To assess inter-assay reliability, we performed immunostaining twice in 21 patients' CSF. We investigated an association between the score of CSF obtained at diagnosis and the clinical/paraclinical features.

Results

The sensitivity and specificity of CBA were 93.7% (95% CI: 86.0-97.3) and 98.6% (95% CI: 96.5-99.5), respectively. Linear regression analysis showed a good agreement between the scores of the first and second assays. Patients with a typical spectrum, need for mechanical ventilation support, autonomic symptoms/central hypoventilation, dyskinesias, speech dysfunction, decreased level of consciousness, preceding headache, ovarian teratoma, and CSF leukocyte count >20 cells/µL had a higher median HIS score than those without, but HIS score was not associated with sex, age at onset, or seizure. HIS score at diagnosis had a significant effect on 1-year functional status.

Discussion

The severity of disease and four of the six core symptoms were associated with higher GluN1-ab titers in CSF at diagnosis, which may play a role in poor 1-year functional status. An incomplete phenotype can be attributed to low CSF GluN1-ab titers.

Characteristics of cerebrospinal fluid oligoclonal band in anti-myelin oligodendrocyte glycoprotein (MOG) antibody associated disease

Objective

To analyze the immune parameters of cerebrospinal fluid (CSF) and oligoclonal band (OCB) type in patients with anti-myelin oligodendrocyte glycoprotein (MOG) antibody-associated diseases (MOGAD).

Methods

Patients who were seropositive for MOG-IgG and diagnosed with MOGAD according to the diagnosis criteria in the Department of Neurology, Huashan Hospital, Fudan University from December 2020 to June 2022 were retrospectively included in this study. Complete clinical data, blood and cerebrospinal fluid samples were collected from all the participants. Paired serum and CSF MOG-IgG and autoimmune encephalitis antibody were assayed by Cell Based Assay (CBA) based on transfected target antigens. Paired serum and CSF albumin and IgG were detected by turbidimetric scattering method, and OCB was detected by standard operation procedure as described.

Results

A total of 86 patients (44 males and 42 females) with MOGAD were included in this study, with a median age of 30 years (range: 5-82 years). Among all the patients, 73 patients showed OCB type I, 12 patients showed OCB type II, and one patient showed OCB type III. The overall positive rate of CSF-OCB in MOGAD patients was 15.1 %. The 24-h intrathecal synthesis rate of CSF in the OCB-positive group (n = 13) was higher than that in the OCB-negative group [n = 73, 0.62 (0.26) vs 5.11 (13.67), P = 0.003]. Subgroup analysis revealed that the positive rates of CSF-OCB in the single MOG group (n = 61) and the group combined with other antibodies (n = 25) were 14.8 % and 16.0 %, respectively. The incidence of meningoencephalitis (13/61 vs 13/25, P = 0.011) was significantly different between the two groups. The proportion of patients with high (≥1:32) or low (≤1:10) CSF MOG-IgG also showed significant difference in the group combined with other antibodies (P = 0.032). Optic neuritis was more common in the relapse course group (n = 49) than the monophasic course group (n = 37, P < 0.001) No significant diferences of CSF immune parameters were found in the MOG-IgGserum+/CSF- group and the MOG-IgGserum+/CSF + group, and the titer of MOG-IgG in the serum or CSF did not influence CSF immune parameters in different subgroups.

Conclusion

The overall positive rate of CSF-OCB in MOGAD patients was 15.1 %. The 24-h intrathecal synthesis rate of cerebrospinal fluid in the OCB-positive group was higher than that in the OCB-negative group. This study illustrated OCB characterization in MOGAD patients, and will shed light on the standardization of OCB test in the study of immune diseases.

Coexistence of anti-NMDAR and anti-IgLON5 antibodies in an autoimmune encephalitis patient: The first case report

Background

The coexistence of autoimmune encephalitis (AE) with multiple neural auto-antibodies is of great clinical significance because overlying antibodies may cause superposition or variation of clinical syndrome, which increases the difficulty of diagnosis and treatment of the disease. To the best of our knowledge, the coexistence of anti-N-methyl d-aspartate Receptor (NMDAR) and anti-IgLON5 antibodies in AE has not been published previously.

Case presentation

A 38-year-old female patient presented to our hospital due to headache and abnormal psychiatric behavior. Based on her clinical manifestations (psychiatric and behavioral abnormalities, involuntary limb movements, and sleep disorders) and laboratory assessment results (positive human leukocyte antigen (HLA)-DQB1*05:01 haplotype, anti-NMDAR, and anti-IgLON5 antibodies), she was diagnosed as AE with coexisting anti-NMDAR and anti-IgLON5 antibodies. After treatment with intravenous methylprednisolone and immunoglobulin, as well as plasmapheresis, her symptoms gradually improved with exception for the sleep disorders. Although oral prednisone acetate and mycophenolate mofetil were continued after discharge, her symptoms of sleep disorders did not improve at 6-month follow-up.

Conclusion

This is the first case of AE co-existing with anti-NMDAR and anti-IgLON5 antibodies. Co-existence of neural auto-antibodies should be considered when patients present with overlapping or atypical symptoms. Special attention should be paid to the treatment of these patients as some anti-IgLON5 encephalitis patients may not benefit from immunotherapy treatment.

New insights into neuropathology and pathogenesis of autoimmune glial fibrillary acidic protein meningoencephalomyelitis

Anti-glial fibrillary acidic protein (GFAP) meningoencephalomyelitis (autoimmune GFAP astrocytopathy) is a new autoimmune central nervous system (CNS) disease diagnosable by the presence of anti-GFAP autoantibodies in the cerebrospinal fluid and presents as meningoencephalomyelitis in the majority of patients. Only few neuropathological reports are available and little is known about the pathogenic mechanisms. We performed a histopathological study of two autopsies and nine CNS biopsies of patients with anti-GFAP autoantibodies and found predominantly a lymphocytic and in one autopsy case a granulomatous inflammatory phenotype. Inflammatory infiltrates were composed of B and T cells, including tissue-resident memory T cells. Although obvious astrocytic damage was absent in the GFAP-staining, we found cytotoxic T cell-mediated reactions reflected by the presence of CD8+/perforin+/granzyme A/B+ cells, polarized towards astrocytes. MHC-class-I was upregulated in reactive astrocytes of all biopsies and two autopsies but not in healthy controls. Importantly, we observed a prominent immunoreactivity of astrocytes with the complement factor C4d. Finally, we provided insight into an early phase of GFAP autoimmunity in an autopsy of a pug dog encephalitis that was characterized by marked meningoencephalitis with selective astrocytic damage with loss of GFAP and AQP4 in the lesions.Our histopathological findings indicate that a cytotoxic T cell-mediated immune reaction is present in GFAP autoimmunity. Complement C4d deposition on astrocytes could either represent the cause or consequence of astrocytic reactivity. Selective astrocytic damage is prominent in the early phase of GFAP autoimmunity in a canine autopsy case, but mild or absent in subacute and chronic stages in human disease, probably due to the high regeneration potential of astrocytes. The lymphocytic and granulomatous phenotypes might reflect different stages of lesion development or patient-specific modifications of the immune response. Future studies will be necessary to investigate possible implications of pathological subtypes for clinical disease course and therapeutic strategies.

Anti-aquaporin-4 immunoglobulin G/anti-myelin oligodendrocyte glycoprotein immunoglobulin G double-positive paraneoplastic neurological syndrome in a patient with triple-negative breast cancer

We report a rare case of paraneoplastic neurological syndrome with dual seropositivity of anti-aquaporin-4 and myelin oligodendrocyte glycoprotein antibodies in a 40 year-old woman with metastatic triple-negative breast cancer. She received multiple lines of anti-neoplastic treatment, including immunotherapy with pembrolizumab, as well as cytotoxic chemotherapy. Paraneoplastic meningoencephalomyelitis developed 2 years after diagnosis of breast cancer and 1 year after discontinuation of immunotherapy with pembrolizumab. She first developed longitudinally extending transverse myelitis followed by left optic neuritis and meningoencephalitis with new enhancing lesions in the brain and spinal leptomeninges. Cerebrospinal fluid analysis during both episodes showed normal glucose and protein, and elevated white blood cell count. Cytology was negative for malignancy. Cerebrospinal fluid was positive for neuromyelitis optica immunoglobulin G antibody anti-aquaporin-4, and autoimmune myelopathy panel was positive for myelin oligodendrocyte glycoprotein antibody. The patient had significant clinical and radiographic improvement after completion of five cycles of plasmapheresis followed by intravenous immunoglobulin. She did not have recurrence of paraneoplastic syndrome with maintenance rituximab every 6 months and daily low-dose prednisone. She succumbed to progressive systemic metastatic disease 4.5 years after her breast cancer diagnosis. This case shows that these antibodies can occur concurrently and cause clinical features, such as both neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein antibody disease, in a patient with a singular type of cancer. We highlight the importance of testing for paraneoplastic etiology in cancer patients with radiographic menigoencephalomyelitis or meningitis with atypical symptoms of meningeal carcinomatosis and/or cerebrospinal fluid profile negative for leptomeningeal carcinomatosis.

Myelin oligodendrocyte glycoprotein antibody and N-methyl-d-aspartate receptor antibody overlapping syndrome: insights from the recent case reports

The overlapping of two or more types of neural autoantibodies in one patient has increasingly been documented in recent years. The coexistence of myelin oligodendrocyte glycoprotein (MOG) and N-methyl-d-aspartate receptor (NMDAR) antibodies is most common, which leads to a unique condition known as the MOG antibody and NMDAR antibody overlapping syndrome (MNOS). Here, we have reviewed the pathogenesis, clinical manifestations, paraclinical features, and treatment of MNOS. Forty-nine patients with MNOS were included in this study. They were young males with a median onset age of 23 years. No tumors were observed in the patients, and 24 of them reported prodromal symptoms. The most common clinical presentations were psychiatric symptoms (35/49) and seizures (25/49). Abnormalities on magnetic resonance imaging involved the brainstem (11/49), cerebellum (9/49), and parietal lobe (9/49). Most patients mostly responded to immunotherapy and had a good long-term prognosis. However, the overall recurrence rate of MNOS was higher than that of mono antibody-positive diseases. The existence of concurrent NMDAR antibodies should be suspected in patients with MOG antibody-associated disease having psychiatric symptoms, seizures, movement disorders, or autonomic dysfunction. Similarly, serum MOG antibody testing should be performed when patients with anti-NMDAR encephalitis present with atypical clinical manifestations, such as visual impairment and limb weakness, and neuroradiological findings, such as optic nerve, spinal cord, or infratentorial involvement or meningeal enhancement. Early detection of the syndrome and prompt treatment can be beneficial for these patients, and maintenance immunosuppressive therapy is recommended due to the high overall recurrence rate of the syndrome.

Case report: Overlapping anti-AMPAR encephalitis with anti-IgLON5 disease post herpes simplex virus encephalitis

Autoimmune encephalitis (AE) is the result of an autoimmune process that occurs as a rapidly advancing encephalopathy. Autoimmune encephalitis was commonly linked to herpes simplex virus 1 (HSV-1) as the most frequently identified virus. The main areas affected by this invasion are the temporal lobe, frontal lobe, and limbic system. Limbic encephalitis is a highly uncommon occurrence involving anti-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) encephalitis and anti-IgLON family member 5 (IgLON5) disease, both belonging to the rare category. As far as we know, this is the first report showing that a patient diagnosed with AMPAR encephalitis overlapped with anti-IgLON5 disease post herpes simplex virus encephalitis (HSE), which helps to broaden the range of this uncommon autoimmune disease. We recommend autoantibody testing in all patients with HSE, particularly those involving neurological relapses or progression.

Clinical characteristics of Chinese pediatric patients positive for anti-NMDAR and MOG antibodies: a case series

Introduction

The cases of MOG-AD (MOG antibody-associated disorder) and anti-NMDAR encephalitis overlapping syndrome (MNOS) are rare, especially among pediatric patients, and their clinical understanding is limited. This study aimed to investigate the clinical manifestations, imaging findings, treatments, and prognosis of Chinese pediatric patients who tested positive for anti-NMDAR and MOG antibodies.

Methods

This retrospective study enrolled 10 MNOS pediatric patients, 50 MOG-AD (anti-NMDAR antibody-negative), and 81 anti-NMDAR encephalitis (MOG antibody-negative) pediatric patients who were admitted from July 2016 to June 2022 and used their clinical data for comparison.

Results

The MNOS patients had a significantly lower incidence of psycho-behavioral abnormalities and involuntary movements than anti-NMDAR antibody (+)/MOG antibody (-) patients and had a significantly higher incidence of sleep disorders, seizures, and psycho-behavioral abnormalities than MOG antibody (+)/anti-NMDAR antibody (-) patients. The MNOS patients had a significantly higher incidence of MRI abnormalities than the anti-NMDAR antibody (+)/MOG antibody (-) patients, while there was no significant difference in the incidence between the MNOS patients and the MOG antibody (+)/anti-NMDAR antibody (-) patients. No significant difference was seen in the initial mRS score between the three groups of patients. The anti-NMDAR antibody (+)/MOG antibody (-) patients had a higher rate of admission to the ICU, a longer length of in-hospital stay, and a higher rate of introduction to second-line treatment than the other two groups of patients. No significant difference was seen in the mRS score at the last follow-up and in the disease recurrence rate between the three groups. All these patients respond well to immunosuppressive therapy.

Discussion

In the presence of psycho-behavioral abnormalities, sleep disorders, and frequent seizures in MOG-AD patients or demyelinating symptoms of the central nervous system or demyelinating lesions on head MRI in anti-NMDAR encephalitis patients, the coexistence of MOG and anti-NMDAR antibodies should be considered and would suggest a diagnosis of MNOS for these patients. Immunotherapy is effective among these patients and should be given possibly earlier.

Optimizing the diagnostic performance of neural antibody testing for paraneoplastic and autoimmune encephalitis in clinical practice

The detection of neural antibodies in patients with paraneoplastic and autoimmune encephalitis has majorly advanced the diagnosis and management of neural antibody-associated diseases. Although testing for these antibodies has historically been restricted to specialized centers, assay commercialization has made this testing available to clinical chemistry laboratories worldwide. This improved test accessibility has led to reduced turnaround time and expedited diagnosis, which are beneficial to patient care. However, as the utilization of these assays has increased, so too has the need to evaluate how they perform in the clinical setting. In this chapter, we discuss assays for neural antibody detection that are in routine use, draw attention to their limitations and provide strategies to help clinicians and laboratorians overcome them, all with the aim of optimizing neural antibody testing for paraneoplastic and autoimmune encephalitis in clinical practice.

Glial Fibrillary Acidic Protein Autoimmunity After Aseptic Meningitis: A Report of 2 Cases

OBJECTIVES

We describe 2 patients with glial fibrillary acidic protein (GFAP) autoimmunity secondary to aseptic viral meningitis or meningoencephalomyelitis.

METHODS

This study involved a retrospective chart review.

RESULTS

Two female patients, 45 and 55 years of age, developed aseptic meningoencephalomyelitis or meningitis; in one patient, it was likely caused by herpes simplex virus 2. The patients were recovering from the infectious condition when they, 51 and 5 days after onset, had new symptoms with detection of GFAP antibodies in the CSF; CSF and serum samples from the initial lumbar punctures had been negative for GFAP antibodies. Both patients recovered with steroid treatment (in one case, plus rituximab; in the other, plus azathioprine) including resolution of MRI and CSF abnormalities.

DISCUSSION

These 2 patients had GFAP autoimmunity secondary to viral meningoencephalomyelitis or meningitis. This suggests that GFAP astrocytopathy might not always be a primary disease entity; it may follow another brain injury that triggers this autoimmune response.

Pediatric anti-NMDAR encephalitis with demyelination on brain MRI: A single center study

OBJECTIVE

To explore the clinical characteristics, immunotherapy response, and prognosis of pediatric anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis associated with demyelination on brain magnetic resonance (MRI).

METHODS

We retrospectively reviewed the medical records of children diagnosed with anti-NMDAR encephalitis in our hospital between January 2016 and December 2021. All children with evidence of demyelination on brain MRI were included.

RESULTS

A total of 183 anti-NMDAR encephalitis children were included; 8.7 % (16/183) of them had demyelination on brain MRI. Nine were positive for myelin oligodendrocyte glycoprotein (MOG)-IgG, while two were positive for both MOG-IgG and glial fibrillary acidic protein (GFAP)-IgG. Four patients had a history of acquired demyelinating syndromes and encephalitis, respectively, while nine (56.3 %) had atypical symptoms of anti-NMDAR encephalitis. All children had supratentorial demyelination on brain MRI; four of them had additional infratentorial lesions. All children received first-line immunotherapy; four were administered repeated first-line immunotherapy and/or rituximab because of poor initial response. During the follow-up, 37.5 % (6/16) of the children relapsed, but all responded well to immunotherapy. There were no significant differences in mRS score before immunotherapy, response to first-line immunotherapy, and long-term prognosis between anti-NMDAR encephalitis children with and without demyelination. However, patients with demyelination were more likely to have a history of acquired demyelinating syndromes or unexplained cortical encephalitis and to relapse.

CONCLUSION

Pediatric anti-NMDAR encephalitis can co-occur with demyelination and has a high rate of MOG-IgG positivity. A history of acquired demyelinating syndromes or unexplained cortical encephalitis and atypical symptoms may indicate demyelination in children with anti-NMDAR encephalitis. Pediatric anti-NMDAR encephalitis with demyelination is more likely to relapse and needs a closer follow-up. However, it remains unknown whether more intensive immunotherapy is required in these patients.

Detection of High-Risk Paraneoplastic Antibodies against TRIM9 and TRIM67 Proteins

OBJECTIVE

Co-occurring anti-tripartite motif-containing protein 9 and 67 autoantibodies (TRIM9/67-IgG) have been reported in only a very few cases of paraneoplastic cerebellar syndrome. The value of these biomarkers and the most sensitive methods of TRIM9/67-IgG detection are not known.

METHODS

We performed a retrospective, multicenter study to evaluate the cerebrospinal fluid and serum of candidate TRIM9/67-IgG cases by tissue-based immunofluorescence, peptide phage display immunoprecipitation sequencing, overexpression cell-based assay (CBA), and immunoblot. Cases in which TRIM9/67-IgG was detected by at least 2 assays were considered TRIM9/67-IgG positive.

RESULTS

Among these cases (n = 13), CBA was the most sensitive (100%) and revealed that all cases had TRIM9 and TRIM67 autoantibodies. Of TRIM9/67-IgG cases with available clinical history, a subacute cerebellar syndrome was the most common presentation (n = 7/10), followed by encephalitis (n = 3/10). Of these 10 patients, 70% had comorbid cancer (7/10), 85% of whom (n = 6/7) had confirmed metastatic disease. All evaluable cancer biopsies expressed TRIM9 protein (n = 5/5), whose expression was elevated in the cancerous regions of the tissue in 4 of 5 cases.

INTERPRETATION

TRIM9/67-IgG is a rare but likely high-risk paraneoplastic biomarker for which CBA appears to be the most sensitive diagnostic assay. ANN NEUROL 2023;94:1086-1101.

Anti-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor encephalitis developed after ovarian cancer cytoreduction surgery: a case report and literature review

BACKGROUND

Anti-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) encephalitis, a rare subtype of autoimmune encephalitis (AE), is often found associated with tumors such as thymoma, lung cancer, ovarian tumors, and breast cancer, and the tumors were generally detected during the screening process after the encephalitis initiated. The tumor is considered a trigger of AE, but the mechanism remains unclear.

CASE PRESENTATION

A 53-year-old woman presented short-term memory loss two days after the primary cytoreduction for high-grade serous ovarian cancer (HGSOC, FIGO stage IC3). Cell-based assay found AMPAR CluA2 IgG positive in both serum (1:3.2) and cerebrospinal fluid (1:32). Moreover, mild AMPAR GluA1 and strong GluA2 expressions were also found positive in the paraffin sections of ovarian tumor tissue, indicating the ovarian cytoreduction surgery might stimulate the release of receptor antigens into the circulation system. The patient's condition deteriorated within two weeks, developing consciousness and autonomic dysfunction, leading to ICU admission. With oral steroids, intravenous immunoglobulin, plasmapheresis, and rituximab treatment, the patient's consciousness markedly improved after three months.

CONCLUSION

We presented the first case of anti-AMPAR encephalitis developed right after the primary cytoreduction of a patient with HGSOC and retrieved paraneoplastic anti-AMPAR encephalitis cases (n = 66). Gynecologists should pay attention to patients who develop cognitive dysfunction or psychiatric symptoms shortly after the ovarian tumor resection and always include AE in the differentiation diagnosis.

Concurrent NMDAR and GFAP Antibody Encephalitis During Pregnancy

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an autoimmune antibody encephalitis, commonly affecting young women with comorbid ovarian teratoma. It typically presents with alteration of consciousness, psychosis, movement disorders eventually deteriorating with seizures, dysautonomia and central hypoventilation requiring critical level of care that may last weeks to months. Removal of teratoma and immunosuppressant therapy support can led to a dramatic recovery.To our knowledge, this is the first illustrated case in the literature of a pregnant woman presenting with concurrent autoimmune NMDAR and anti-glial gibrillary acidic protein(GFAP) antibody encephalitis in the setting of an ovarian teratoma. Despite the teratoma removal and receiving various forms of immunosuppressant therapy, a meaningful neurological improvement was observed following the delivery. After a prolonged hospitalisation and recovery period, the patient and her offspring made an excellent recovery highlighting the significance of early diagnosis and management.

Long-term efficacy and safety of different corticosteroid courses plus mycophenolate mofetil for autoimmune encephalitis with neuronal surface antibodies without tumor

Objective

To compare the efficacy and safety of different-course corticosteroids plus mycophenolate mofetil (MMF) as maintenance therapy in autoimmune encephalitis (AE) with neuronal surface antibodies (NSAbs) without tumor and explore the optimal course of corticosteroids.

Methods

Fifty-five patients with definite AE without tumor were enrolled consecutively between June 2015 and November 2020 and retrospectively divided three groups according to the course of treatment with corticosteroid, i.e., a group of patients with a course of 3-6 months (Group 3-6mo), 6-12 months (Group 6-12mo), and >12 months (Group >12mo). Demographic data, clinical manifestation and ancillary tests results were recorded. The dosage and courses of corticosteroid treatment, the recovery of neurological function, the occurrence of adverse effects, and relapses were followed up.

Results

A total of 55 patients were included in the final analysis. The numbers of patients in Group 3-6 mo, Group 6-12 mo, and Group >12 mo was 14, 17, and 24, respectively. A significantly higher proportion of patients in Group >12 mo showed a decreased level of consciousness at the onset (12, 50%) than in Group 3-6 mo and Group 6-12 mo (2,14.3%; 3, 17.6%) (p = 0.033). The incidence of MRI abnormalities was significantly higher in Group 6-12 mo and Group >12 mo (10, 58.8%; 16, 66.7%) than in Group 3-6 mo (3, 21.4%) (P=0.023). Ordinal regression analysis indicated that decreased level of consciousness was associated with the course of corticosteroid (OR=3.838, 95% CI: 1.103-13.323, P=0.035). No significant difference was observed between the three groups regarding the cumulative dose of corticosteroids administered during the first three months of long-term treatment (P>0.05). Additionally, no significant difference in the cumulative dosage of corticosteroids was found between patients in Group 6-12 months and Group >12 months during the first 6 months after beginning long-term treatment. The mRS scores of the three groups were not statistically significant before and after first-line treatment or at the last follow-up. Bonferroni multiple comparison test indicated that the mRS scores of patients in Group 6-12 months and Group >12 months were not statistically significant at 3 months and 12 months after the start of long-term treatment. During the follow-up, 50 (90.9%) patients achieved satisfactory neurological function (mRS score ≤2). Five patients (9.1%) experienced a first relapse and 2 of them were overlapped with both anti-NMDA receptor and glial antibodies. The incidence of adverse effects was significantly higher in Group >12 mo (17, 70.8%) than in Group 3-6 mo (3, 21.4%) and Group 6-12 mo (5, 29.4%) (P=0.003).

Conclusions

The beneficial effects of oral corticosteroid treatment may do not persist beyond 12 months and may even contribute to an increased incidence of adverse effects. In order to optimize the effectiveness and safety of treatment, we recommend a corticosteroid course of 3-12 months. Patients with reduced levels of consciousness may be more inclined to choose longer courses of corticosteroids for long-term treatment. Patients with an "overlapping syndrome" may require more intense immunotherapy to prevent relapse.

AMPA and NMDA receptor antibody autoimmune encephalitis preceded by ocular myasthenia gravis: a case report

BACKGROUND

α-Amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA) and N-methyl-D-aspartate (NMDA) receptors mediate excitatory neurotransmission in the brain and may be targeted by autoantibodies, leading to autoimmune synaptic encephalitis (AE). AE can be associated with other autoimmune diseases. However, the cooccurrence of anti-AMPA and NMDA receptor AE together with myasthenia gravis (MG) is unusual.

CASE PRESENTATION

A 24-year-old previously healthy male presented with seronegative ocular MG, the diagnosis of which was supported by single-fiber electrophysiology findings. Three months later, he developed AE, initially being positive for AMPA receptor antibodies and subsequently for NMDA receptor antibodies. No underlying malignancy was found. In response to aggressive immunosuppressive treatment, he recovered (modified Rankin Scale (mRS) score change from 5 to 1). Despite some cognitive problems at the 1-year follow-up, which were not revealed using the mRS, he was able to return to his studies.

CONCLUSIONS

AE may coexist with other autoimmune disorders. Patients with seronegative MG, including ocular MG, may develop autoimmune encephalitis with more than one cell-surface antibody.

Diagnosis of myelin oligodendrocyte glycoprotein antibody-associated disease: International MOGAD Panel proposed criteria

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.

AMPAR autoimmunity: Neurological and oncological accompaniments and co-existing neural autoantibodies

α -amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor (AMPAR) encephalitis is rare but treatable. We reviewed the clinical and autoantibody profiles of 52 AMPAR-IgG-positive patients (median age 48 years [range 12-81]; 38 female) identified at the Mayo Clinic neuroimmunology laboratory. Main presentation was encephalitis; symptoms other than encephalitis associated with co-existing antibodies (p = 0.004). A tumor was found in 33/44; mostly thymoma. Most patients had partial (14/29) or complete (11/29) immunotherapy response. Thirty-one patients had at least one co-existing antibody that predicted thymoma in paraneoplastic patients (p = 0.008). In conclusion, in AMPAR encephalitis co-existing antibodies predict clinical presentation other than encephalitis and thymoma.

Non-infectious meningitis and CNS demyelinating diseases: A conceptual review

Many cases of aseptic meningitis or meningoencephalitis, unresponsive to antimicrobial treatments, have been reported recently in patients with established/new-onset central nervous system (CNS) inflammatory demyelinating diseases (CNSIDDs). Given the higher probability of infectious etiologies, CNSIDDs are rarely considered among the differentials in meningitis or meningoencephalitis cases. We gathered and tabulated cases of non-infectious, steroid-responsive meningitis or meningoencephalitis associated with neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein-associated disease (MOGAD). This conceptual review highlights the need to bolster routine infectious workups with immunological workups in cases of meningoencephalitis or meningitis where potential autoimmune etiologies can be suspected. Although differentiating CNSIDDs with meningeal involvement from infectious meningitis may not substantially affect acute treatment strategies, long-term management and follow-up of the two are entirely different. We also discuss future research directions and hypotheses on how CNSIDDs may be associated with meningitis-like presentations, e.g. overlapping glial fibrillary acidic protein astrocytopathy or autoimmune encephalitis, alterations in regulatory T-helper cells function, and undetected viral agents.

Neuronal surface antigen-specific immunostaining pattern on a rat brain immunohistochemistry in autoimmune encephalitis

A variety of neuronal surface (NS) antibodies (NS-Ab) have been identified in autoimmune encephalitis (AE). Tissue-based assay (TBA) using a rodent brain immunohistochemistry (IHC) is used to screen NS-Ab, while cell-based assay (CBA) to determine NS antigens. Commercial rat brain IHC is currently available but its clinical relevance remains unclear. Immunostaining patterns of NS antigens have not been extensively studied yet. To address these issues, we assessed a predictive value of "neuropil pattern" and "GFAP pattern" on commercial IHC in 261 patients, and characterized an immunostaining pattern of 7 NS antigens (NMDAR, LGI1, GABAaR, GABAbR, AMPAR, Caspr2, GluK2). Sensitivity and specificity of "neuropil pattern" for predicting NS-Ab were 66.0% (95% CI 55.7-75.3), and 98.2% (95% CI 94.8-99.6), respectively. False-positive rate was 1.8% (3/164) while false-negative rate was 34.0% (33/97). In all 3 false-positive patients, neuropil-like staining was attributed to high titers of GAD65-Ab. In 33 false-negative patients, NMDAR was most frequently identified (n=18 [54.5%], 16/18 [88.9%] had low titers [< 1:32]), followed by GABAaR (n=5). Of 261 patients, 25 (9.6%) had either GFAP (n=21) or GFAP-mimicking pattern (n=4). GFAP-Ab were identified in 21 of 31 patients examined with CBA (20 with GFAP pattern, 1 with GFAP-mimicking pattern). Immunostaining pattern of each NS antigen was as follows: 1) NMDAR revealed homogenous reactivity in the dentate gyrus molecular layer (DG-ML) with less intense dot-like reactivity in the cerebellar granular layer (CB-GL); 2) both GABAaR and GluK2 revealed intense dot-like reactivity in the CB-GL, but GABAaR revealed homogenous reactivity in the DG-ML while GluK2 revealed intense reactivity along the inner layer of the DG-ML; and 3) LGI1, Caspr2, GABAbR, and AMPAR revealed intense reactivity in the cerebellar ML (CB-ML) but LGI1 revealed intense reactivity along the middle layer of the DG-ML. Whereas, Caspr2, GABAbR, and AMPAR revealed similar reactivity in the DG-ML but some difference in other regions. TBA is useful not only for screening NS- or GFAP-Ab but also for estimating NS antigens; however, negative results should be interpreted cautiously because "neuropil pattern" may be missed on commercial IHC when antibody titers are low. Antigen-specific immunoreactivity is a useful biomarker of AE.

[Clinical features of autoimmune glial fibrillary acidic protein astrocytopathy in children: an analysis of 34 cases]

OBJECTIVES

To study the clinical features of children with autoimmune glial fibrillary acidic protein astrocytopathy (GFAP-A).

METHODS

A retrospective analysis was performed on the medical data of 34 children with GFAP-A who attended the Department of Neurology, Children's Hospital of Chongqing Medical University, from January 2020 to February 2022. The medical data included clinical manifestations, cerebrospinal fluid features, imaging examination results, treatment, and prognosis.

RESULTS

The median age of onset was 8.4 (range 1.9-14.9) years for the 34 children with GFAP-A. The main clinical manifestations included headache (50%, 17/34), fever (47%, 16/34), visual impairment (47%, 16/34), and disturbance of consciousness (44%, 15/34). Abnormal cerebrospinal fluid results were observed in 19 children (56%, 19/34), among whom 8 children had positive autoantibody. The children with overlap syndrome had significantly higher recurrence rate and rate of use of immunosuppressant than those without overlap syndrome (P<0.05). About 77% (24/31) of the children had good response to immunotherapy, and only 1 child had poor prognosis.

CONCLUSIONS

Children with GFAP-A often have non-specific clinical symptoms and show good response to immunotherapy. Children with overlap syndrome have a high recurrence rate, and early application of immunosuppressants may help to prevent recurrence and alleviate symptoms.

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.

Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease (MOGAD) in Chile: lessons learned from challenging cases

BACKGROUND

Anti-Myelin Oligodendrocyte Glycoprotein (MOG) Antibody Associated Disease (MOGAD) is an emerging disorder recognized as a clinical entity distinct from Multiple Sclerosis and Aquaporin-4-positive Neuromyelitis Optica Spectrum Disorders (NMOSD-AQP4+), and its phenotypic spectrum continues to expand. Most information about its clinical course has emerged from retrospective studies, and treatment response both in acute and chronic-relapsing disease is still limited. We aimed to describe the clinical and paraclinical characteristics of monophasic and relapsing, paediatric and adult patients with MOGAD under regular clinical care in Chile, highlighting some challenging cases that are far from being considered benign.

METHODS

Observational, retrospective, and prospective longitudinal multicentre study including patients with positive serum MOG-IgG assessed by cell-based assay.

RESULTS

We include 35 patients, 71% women, median age at onset 30 years (range 1-68), 23% had paediatric onset, with a median disease-duration 24 months (range 12-348). In the whole cohort, the most frequent symptoms at onset were isolated optic neuritis (ON) (34%) and myelitis (22%). Encephalitis with seizures or encephalomyelitis was the most common presentation in paediatric-onset patients 75% (n = 6), compared to 11% (n = 3) of the adult-onset patients (p < 0.001). A relapsing course was observed in 34%, these patients were younger (25 vs. 34 years, p = 0.004) and with a longer disease duration (64 vs. 6 months, p = 0.004) compared to monophasic patients. Two patients developed encephalitis with seizures/status epilepticus, with concomitant positive CSF anti-NMDAR-IgG. Chronic immunotherapy was ever prescribed in 77%, the most frequent was rituximab (35%). Relapses under chronic immunotherapy occurred in 5/27 patients (18.5%), two of them under rituximab, one paediatric patient who started combined therapy with monthly IVIG and one adult patient that switched to satralizumab plus mycophenolate. The median EDSS at the last follow-up was 1.5 (range 0-6.0).

CONCLUSION

In Chile, patients with MOGAD exhibit a wide spectrum of clinical presentations at disease onset and during relapses. Close monitoring is needed, particularly in younger patients with short follow-up periods.

[Clinical features and modern diagnostic criteria of the disease associated with myelin oligodendrocyte glycoprotein antibody disease]

Demyelinating disease of the central nervous system associated with antibodies to myelin oligodendrocyte glycoprotein (MOGAD) has been proposed to be distinguished from neuromyelitis optica spectrum disorders (NMOSD) into a separate nosological form. The basis for the recognition of nosological independence was the presence of clinical features of this disease and the detection of a specific biomarker in the blood serum of patients - IgG class antibodies to MOG. The article summarizes the current data on the clinical and radiological phenotypes of MOGAD in children and adults and the features of the course of the disease. The requirements for the laboratory diagnosis of the disease and diagnostic criteria for MOGAD proposed by an international group of experts in 2023 are given.

Epilepsy, Immunity and Neuropsychiatric Disorders

Several studies have focused on the emerging role of immunity and inflammation in a wide range of neurological disorders. Autoimmune diseases involving central nervous system share well defined clinical features including epileptic seizures and additional neuropsychiatric symptoms, like cognitive and psychiatric disturbances. The growing evidence about the role of immunity in the pathophysiologic mechanisms underlying these conditions lead to the concept of autoimmune epilepsy. This relatively-new term has been introduced to highlight the etiological and prognostic implications of immunity in epileptogenesis. In this review, we aim to discuss the role of autoimmunity in epileptogenesis and its clinical, neurophysiological, neuroimaging and therapeutic implications. Moreover, we wish to address the close relationship between immunity and additional symptoms, particularly cognitive and psychiatric features, which deeply impact clinical outcomes in these patients. To assess these aspects, we first analyzed Rasmussen's encephalitis. Subsequently, we have covered autoimmune encephalitis, particularly those associated with autoantibodies against surface neuronal antigens, as these autoantibodies express a direct immune-mediated mechanism, different from those against intracellular antigens. Then, we discussed the connection between systemic immune disorders and neurological manifestations. This review aims to highlight the need to expand knowledge about the role of inflammation and autoimmunity in the pathophysiology of neurological disorders and the importance to early recognize these clinical entities. Indeed, early identification may result in faster recovery and a better prognosis.

[Clinical characteristics and short-term outcomes of autoimmune encephalitis in adults]

OBJECTIVE

To characterize clinical, paraclinical features and short-term outcomes in different types of autoimmune encephalitis (AE) in a one-center cohort of Russian patients, as well as to evaluate the frequency and significance of the joint expression of antineuronal and anti-glial antibodies (Abs) in AE.

MATERIAL AND METHODS

Forty-one patients were diagnosed with AE at the Research Center of Neurology from November 2020 to December 2022. Demographic, clinical characteristics, results of laboratory tests, MRI of brain, treatment and outcomes of disease were analyzed. The analysis of Abs to glial antigens (myelin-oligodendrocyte glycoprotein - MOG, glial fibrillar acidic protein - GFAP, aquaporin 4 - AQP-4) was performed by indirect immunofluorescence assay (Euroimmun, Germany).

RESULTS

In 24 (58.5%) patients was established definite AE, confirmed by specific Abs detection; in 2 (4.9%) - definite limbic encephalitis, in 15 (36.6%) - seronegative probable AE (including 3 cases of Hashimoto's encephalitis). GFAP-Abs in cerebrospinal fluid (CSF) were detected only in two patients - with clinical and MRI-picture of autoimmune GFAP-astrocytopathy (A-GFAP-A). GFAP- and MOG-Abs in the blood were detected in 25.7% and 6%, respectively, AQP-4-Abs were not detected. There were no correlations between co-expression with glial Abs and clinical characteristics. Systemic and antithyroid Abs were present in 15% and 31%, respectively. Paraneoplastic AE accounted for 22%. For the first time in the Russian population, 2 cases of A-GFAP-A, 6 cases of AE associated with COVID-19 were described. The most common first syndrome were epileptic seizure (34%), psychiatric (29%) and cognitive (14%) disorders. Relapses of AE was observed in 22%. Inflammatory changes in CSF were detected in 41%, focal changes on MRI in 68%. First-line immune therapy was performed in all patients, 85% of cases received pulse therapy with methylprednisolone. Second-line immune therapy (rituximab or cyclophosphamide intravenously) was performed in 19.5%, 78% of patients achieved significant improvement during treatment (scores ≤2 on the modified Rankin scale).

CONCLUSIONS

The results allow us to consider COVID-19 as a trigger of AE. The absence of detection of GFAP-Abs in CSF in patients with other types of AE contributes to the confirmation of the specificity of GFAP-seropositivity of CSF for the diagnosis of A-GFAP-A. The expression of GFAP- and MOG-Abs in AE can serve as confirmation of the immuno-mediated etiology of the disease, which is especially important for the AE diagnosis in the absence of antineuronal Abs.

Motor symptoms in nonparaneoplastic CNS disorders associated with neural antibodies

Motor symptoms are common, and sometimes predominant, in almost all nonparaneoplastic CNS disorders associated with neural antibodies. These CNS disorders can be classified into five groups: (1) Autoimmune encephalitis with antibodies against synaptic receptors, (2) cerebellar ataxias associated with neuronal antibodies that mostly target intracellular antigens. (3) Stiff-person syndrome and progressive encephalomyelitis with rigidity and myoclonus which have antibodies against glutamic acid decarboxylase and glycine receptor, respectively. Both diseases have in common the presence of predominant muscle stiffness and rigidity. (4) Three diseases associated with glial antibodies. Two present motor symptoms mainly due to the involvement of the spinal cord: neuromyelitis optica spectrum disorders with aquaporin-4 antibodies and myelin oligodendrocyte glycoprotein antibody-associated disease. The third disorder is the meningoencephalitis associated with glial fibrillar acidic protein antibodies which frequently also presents a myelopathy. (5) Two antibody-related diseases which are characterized by prominent sleep dysfunction: anti-IgLON5 disease, a disorder that frequently presents a variety of movement disorders, and Morvan syndrome associated with contactin-associated protein-like 2 antibodies and clinical manifestations of peripheral nerve hyperexcitability. In this chapter, we describe the main clinical features of these five groups with particular emphasis on the presence, frequency, and types of motor symptoms.

Anti-NMDA receptor encephalitis and MOG-associated demyelination - a case report with long-term follow-up and a systematic review

BACKGROUND

Overlap syndromes of anti-NMDA receptor encephalitis and MOG-mediated demyelination have been reported. In this case we provide a long-term longitudinal follow-up of clinical and imaging characteristics as well as of antibody dynamics.

CASE PRESENTATION

We report a 32-year-old male patient who presented with psychosis, decreased consciousness and movement disorders and was tested positive for anti-NMDA receptor antibodies. Forty-four months after symptom onset and diagnosis of autoimmune encephalitis, he suffered from relapse. At this time, the patient developed anti-MOG and anti-Caspr2 antibodies. Treatment with plasmapheresis, steroids and rituximab eventually led to substantial clinical and radiological improvement. Anti-Caspr2 antibodies persisted, anti-NMDA receptor antibodies decreased, while anti-MOG antibodies turned negative again.

CONCLUSION

We provide long-term longitudinal follow-up of a patient with anti-NMDA receptor encephalitis who developed triple antibody positivity at the time of relapse. Antibody dynamics were associated with clinical disease course.

Anti-NMDAR encephalitis with GFAPα IgG: a case report

Background

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is an inflammatory disease of the central nervous system (CNS) in which antibodies within the serum and cerebrospinal fluid (CSF) target NMDA receptors. Glial fibrillary acidic protein (GFAP) astrocytopathy is an autoimmune disease affecting the central nervous system (CNS). Meningoencephalitis can affect any anatomical region rostrocaudally, from the optic nerve to the spinal cord. The clinical implications of NMDAR antibodies overlapping with other antibodies against glial or neuronal cell surface proteins have not been investigated.

Case presentation

A 35-year-old male presented with headaches along with amnesia, slurred and awkward speech, psychiatric symptoms, cognitive decline, and insomnia. His medical history revealed ankylosing spondylitis for six months. Ancillary findings included CSF pleocytosis and elevated protein levels. T2-weighted fluid attenuation inversion recovery was used to image high-intensity lesions of the bilateral paraventricular, radiate corona, semioval centre, and right subcortical regions. The CSF was positive for NMDAR and GFAP antibodies through transfected cell-based assays. A diagnosis of anti-GFAP encephalitis was made, although the prominent clinical features were of anti-NMDAR encephalitis.

Conclusions

Herein, we describe a case of anti-NMDAR encephalitis with overlapping symptoms of GFAP antibody positivity. Patients with unusual symptoms of anti-NMDAR encephalitis should also be tested for anti-GFAP antibodies. However, because this was a single case study, caution should be exercised when interpreting the observations. Since the patient was diagnosed with autoimmune encephalitis, intravenous methylprednisolone was administered, which yielded a positive outcome.

MOGAD Involving Cranial Neuropathies: A Case Report and Review of Literature

Myelin-oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is an autoimmune-mediated demyelinating disease of the central nervous system (CNS). Patients with MOGAD may develop any combination of optic neuritis (ON), myelitis, brainstem syndrome and encephalitis. Reports of MOGAD with cranial nerve involvement are rare. Herein, we report a MOGAD patient with cranial neuropathies. In addition, we summarized the clinical features of the previously reported six MOG-IgG-positive cases with cranial nerve involvement and discussed the underlying mechanisms of MOGAD involving cranial nerves. Cranial neuropathy is an emerging phenotype in MOGAD, which has characteristics of both central and peripheral nervous system (PNS) involvement, with the trigeminal nerve being the most commonly affected nerve. MOG antibody testing in patients with cranial neuropathies is warranted, and immunotherapy is advocated when the risk of relapse is high. Although higher antibody titers and persistently positive serological test results are predictive of disease recurrence, the long-term outcomes of MOG-IgG-positive patients with cranial neuropathies remain largely unknown.

A case of GFAP-IgG positivity followed by anti-NMDAR encephalitis

Background

In recent years, there have been an increasing number of reports on overlapping antibodies in autoimmune encephalitis (AE). There are various types of overlapping antibodies, but the clinical significance of each type is not yet clear. Glial antibodies, such as MOG, AQP4, and especially NMDAR, can be detected in patients with AE. However, little is known about the overlapping antibodies of anti-glial fibrillary acidic protein (GFAP), and only a few case reports have described this overlap.

Case presentation

The patient was a 7-year-old girl with recurrent intermittent fever and seizures, and viral encephalitis was diagnosed at the beginning of the disease. She was discharged after treatment with acyclovir, high-dose immunoglobulins, and valproic acid as an antiseizure medication. Subsequently, the patient still had occasional seizures and abnormal behavior, and the anti-NMDAR antibody test was positive (1:3.2). She was treated with high-dose methylprednisolone and antiseizure therapy. Approximately half a year later, the patient experienced fever and seizures again, serum GFAP IgG was 1:100, and a head MRI indicated new lesions. Improvement was achieved after repeated high-dose methylprednisolone and continuous prednisone anti-inflammatory therapy.

Conclusions

Anti-NMDAR encephalitis combined with GFAP-IgG is uncommon, and repeated tests for AE-associated antibodies may be required in patients with recurrent encephalitis. Compared with cerebrospinal fluid antibody-positive children, serum GFAP IgG-positive children should be comprehensively diagnosed according to their clinical manifestations. It is worth considering whether overlapping antibody syndrome can still be an issue for patients with AE who recover and have negative antibodies after a few months if disease recurrence and new antibodies are detected.

Autoimmune diseases and cancers overlapping with myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD): A systematic review

Background

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) has various similarities with AQP4-IgG-seropositive Neuromyelitis Optica Spectrum Disorder (AQP4-IgG + NMOSD) in terms of clinical presentations, magnetic resonance imaging (MRI) findings, and response to treatment. But unlike AQP4-IgG + NMOSD, which is known to coexist with various autoimmune diseases and cancers, an association of MOGAD with these conditions is less clear.

Methods

We conducted a systematic search in PubMed, Scopus, Web of Science, and Embase based on the preferred reporting items for systematic reviews and meta-analysis (PRISMA). Duplicates were removed using Mendeley 1.19.8 (USA production) and the citations were uploaded into Covidence systematic review platform for screening.

Results

The most common autoimmune disease overlapping with MOGAD was anti-N-Methyl-D-Aspartate receptor encephalitis (anti-NMDAR-EN), followed by autoimmune thyroid disorders, and the most common autoantibody was antinuclear antibody (ANA), followed by AQP4-IgG (double-positive MOG-IgG and AQP4-IgG). A few sporadic cases of cancers and MOG-IgG-associated paraneoplastic encephalomyelitis were found.

Conclusion

Unlike AQP4-IgG + NMOSD, MOGAD lacks clustering of autoimmune diseases and autoantibodies associated with systemic and organ-specific autoimmunity. Other than anti-NMDAR-EN and perhaps AQP4-IgG + NMOSD, the evidence thus far does not support the need for routine screening of overlapping autoimmunity and neoplasms in patients with MOGAD.

Novelties in Autoimmune and Paraneoplastic Cerebellar Ataxias: Twenty Years of Progresses

Major advances in our knowledge concerning autoimmune and paraneoplastic cerebellar ataxias have occurred in the last 20 years. The discovery of several neural antibodies represents an undeniable contribution to this field, especially those serving as good biomarkers of paraneoplastic neurological syndromes and those showing direct pathogenic effects. Yet, many patients still lack detectable or known antibodies, and also many antibodies have only been reported in few patients, which makes it difficult to define in detail their clinical value. Nevertheless, a notable progress has additionally been made in the clinical characterization of patients with the main neural antibodies, which, although typically present with a subacute pancerebellar syndrome, may also show either hyperacute or chronic onsets that complicate the differential diagnoses. However, prodromal and transient features could be useful clues for an early recognition, and extracerebellar involvement may also be highly indicative of the associated antibody. Moreover, important advances in our understanding of the pathogenesis of cerebellar ataxias include the description of antibody effects, especially those targeting cell-surface antigens, and first attempts to isolate antigen-specific T-cells. Furthermore, genetic predisposition seems relevant, although differently involved according to cancer association, with particular HLA observed in non-paraneoplastic cases and genetic abnormalities in the tumor cells in paraneoplastic ones. Finally, immune checkpoint inhibitors used as cancer immunotherapy may rarely induce cerebellar ataxias, but even this undesirable effect may in turn serve to shed some light on their physiopathology. Herein, we review the principal novelties of the last 20 years regarding autoimmune and paraneoplastic cerebellar ataxias.

Coexistence of Myelin Oligodendrocyte Glycoprotein Immunoglobulin G and Neuronal or Glial Antibodies in the Central Nervous System: A Systematic Review

Background: Myelin oligodendrocyte glycoprotein immunoglobulin G (MOG-IgG) has been considered a diagnostic marker for patients with demyelinating disease, termed “MOG-IgG associated disorder” (MOGAD). Recently, the coexistence of MOG-IgG and other neuronal or glial antibodies has attracted extensive attention from clinicians. In this article, we systematically review the characteristics of MOG-IgG-related antibody coexistence syndrome. Methods: Two authors independently searched PubMed for relevant studies published before October 2021. We also manually searched the references of each related article. The appropriateness of the included studies was assessed by reading the titles, abstracts, and full texts if necessary. Results: Thirty-five relevant publications that met our inclusion criteria were finally included, of which fourteen were retrospective studies and twenty-one were case reports. A total of 113 patients were reported to show the coexistence of MOG-IgG and neuronal or glial antibodies. Additionally, 68.14% of patients were double positive for MOG-IgG and N-Methyl-D-Aspartate Receptor-IgG (NMDAR-IgG), followed by 23.01% of patients who were double positive for MOG-IgG and aquaporin4-IgG (AQP4-IgG). Encephalitis was the predominant phenotype when MOG-IgG coexisted with NMDAR-IgG, probably accompanied by imaging features of demyelination. Patients with dual positivity for MOG-IgG and AQP4-IgG experienced more severe disease and more frequent relapses. The coexistence of MOG-IgG and antibodies other than NMDAR-IgG and AQP4-IgG was extremely rare, and the clinical presentations were diverse and atypical. Except for patients who were double positive for MOG-IgG and AQP4-IgG, most patients with multiple antibodies had a good prognosis. Conclusions: MOG-IgG may coexist with neuronal or glial antibodies. Expanded screening for neuronal or glial antibodies should be performed in patients with atypical clinical and radiological features.

Autoantibody Encephalitis: Presentation, Diagnosis, and Management

Autoantibody encephalitis causes distinct clinical syndromes involving alterations in mentation, abnormal movements, seizures, psychiatric symptoms, sleep disruption, spasms, and neuromyotonia. The diagnoses can be confirmed by specific antibody tests, although some antibodies may be better detected in spinal fluid and others in serum. Each disorder conveys a risk of certain tumors which may inform diagnosis and be important for treatment. Autoantibodies to receptors and other neuronal membrane proteins are generally thought to be pathogenic and result in loss of function of the targets, so understanding the pharmacology of the receptors may inform our understanding of the syndromes. Patients may be profoundly ill but the syndromes usually respond to immune therapy, although there are differences in the types of immune therapy that are thought to be most effective for the various disorders.