Clinical spectrum and prognostic value of CNS MOG autoimmunity in adults

Alterations in the Retinal Vascular Network and Structure in Myelin Oligodendrocyte Glycoprotein Antibody-Associated Optic Neuritis: A Longitudinal OCTA Study

Purpose: To investigate the longitudinal microstructural and microvascular changes in patients with myelin oligodendrocyte glycoprotein antibody-associated optic neuritis (MOG-ON) without new attacks.Methods: We included 20 eyes of 12 MOG-ON patients without new attacks during the follow-up and 24 eyes of 12 age- and sex-matched healthy controls.Results: The BCVA, retinal vessels and structure were significantly lower in MOG-ON eyes than in healthy eyes(all P < .05). In MOG-ON eyes, the BCVA (p = .408) and mean deviation (p = .854) were not significantly decreased at the follow-up visit. However, there were small, significant decreases in parafoveal vessel density (p = .026), peripapillary vessel density (p = .008), and RNFL thickness (p = .03), but not GCIPL thickness (p = .107).Conclusions: Ongoing deterioration was observed in RNFL thickness and parafoveal and peripapillary vessel density, but not GCIPL thinning, in MOG-ON eyes without a new attack of ON.

Neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein associated disorder-optic neuritis: a comprehensive review of diagnosis and treatment

Optic neuritis (ON) is the most common cause of acute optic neuropathy in patients younger than 50 years of age and is most frequently idiopathic or associated with multiple sclerosis. However, the discovery of aquaporin-4 immunoglobulin G (IgG) and myelin oligodendrocyte glycoprotein (MOG)-IgG as biomarkers for two separate central nervous system inflammatory demyelinating diseases has revealed that neuromyelitis optica spectrum disorder (NMSOD) and MOG-IgG-associated disease (MOGAD) are responsible for clinically distinct subsets of ON. NMOSD-ON and MOGAD-ON both demonstrate tendencies for bilateral optic nerve involvement and often exhibit a relapsing course with the potential for devastating long-term visual outcomes. Early and accurate diagnosis is therefore essential. This review will summarize the current understanding of the clinical spectra of NMOSD and MOGAD, the radiographic and serological findings which support their diagnoses, and the current evidence behind various acute and long-term therapeutic strategies for ON related to these conditions. A particular emphasis is placed on a number of recent multi-centre randomized placebo-controlled trials, which provide the first level I evidence for long-term treatment of NMOSD.

Myelin oligodendrocyte glycoprotein antibody-associated disorders: clinical spectrum, diagnostic evaluation, and treatment options

Inflammatory or immune-mediated demyelinating central nervous system (CNS) syndromes include a broad spectrum of clinical phenotype and different overlapping diseases. Antibodies against myelin oligodendrocyte glycoprotein (MOG-Ab) have been found in some cases of these demyelinating diseases, particularly in children. MOG-Ab is associated with a wider clinical phenotype not limited to neuromyelitis optica spectrum disorder, with most patients presenting with optic neuritis, acute disseminated encephalomyelitis (ADEM) or ADEM-like encephalitis with brain demyelinating lesions, and/or myelitis. Using specific cell-based assays, MOG-Ab is becoming a potential biomarker of inflammatory demyelinating disorders of the CNS. A humoral immune reaction against MOG was recently found in monophasic diseases and recurrent/multiphasic clinical progression, particularly in pediatric patients. This review summarizes the data regarding MOG-Ab as an impending biological marker for discriminating between these diverse demyelinating CNS diseases and discusses recent developments, clinical applications, and findings regarding the immunopathogenesis of MOG-Ab-associated disorders.

Pregnancy in Patients With AQP4-Ab, MOG-Ab, or Double-Negative Neuromyelitis Optica Disorder

OBJECTIVE

To analyze the effects of pregnancy on neuromyelitis optica spectrum disorder (NMOSD) according to patients' serostatus and immunosuppressive therapy (IST).

METHODS

We performed a retrospective multicenter international study on patients with NMOSD. Patients were tested for aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) antibodies (Ab). Informative pregnancies were reported when NMOSD onset occurred before or during pregnancy or up to 12 months postpartum. The mean annualized relapse rate (ARR) was calculated for the 12 months before conception, for each trimester of pregnancy, and postpartum. Events such as miscarriage, abortion, and preeclampsia were reported. IST was considered if taken in the 3 months before or during pregnancy.

RESULTS

We included 89 pregnancies (46 with AQP4-Ab, 30 with MOG-Ab, and 13 without either Ab) in 58 patients with NMOSD. Compared to the prepregnancy period, the ARR was lower during pregnancy in each serostatus group and higher during the postpartum period in patients with AQP4-Ab (p < 0.01). Forty-eight percent (n = 31) of pregnancies occurred during IST and these patients presented fewer relapses during pregnancy and the 12 months postpartum than untreated patients (26% vs 53%, p = 0.04). Miscarriages occurred in 10 (11%) pregnancies, and were mainly in patients with AQP4-Ab (with or without IST) and a previous history of miscarriage. Preeclampsia was reported in 2 (2%) patients who were AQP4-Ab-positive.

CONCLUSION

We found a rebound in the ARR during the first postpartum trimester that was higher than the prepregnancy period only in AQP4-Ab-positive patients. Taking IST just before or during pregnancy reduces the risk of relapses in these conditions.

The long-term outcome of MOGAD: An observational national cohort study of 61 patients

BACKGROUND AND OBJECTIVE

The prognosis in myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is a matter of debate. Our aim was to assess the long-term outcomes of patients with MOGAD.

METHODS

We retrospectively analysed the clinical and paraclinical data of patients from the French nationwide observatory study NOMADMUS who tested positive for MOG antibodies (MOG-IgG) and who had clinical follow-up of at least 8 years from their first episode.

RESULTS

Sixty-one patients (median [range] age at onset 27 [3-69] years), with a median (mean; range) follow-up of 177 (212.8; 98-657) months, were included. Among 58 patients with a relapsing course, 26.3% relapsed in the first year after onset. Of the 61 patients, 90.2% experienced at least one episode of optic neuritis. At last visit, the median (mean; range) Expanded Disability Status Scale (EDSS) score was 1 (2.12; 0-7.5), 12.5% had an EDSS score ≥6 and 37.5% had an EDSS score ≥3. Of 51 patients with final visual acuity (VA) data available, 15.7% had VA ≤0.1 in at least one eye and 25.5% had VA ≤0.5 in at least one eye. Bilateral blindness (VA ≤0.1) was present in 5.9% of patients. Finally, 12.5% of patients presented bladder dysfunction requiring long-term urinary catheterization. No factor associated significantly with a final EDSS score ≥3 or with final VA ≤0.1 was found.

CONCLUSION

Overall long-term favourable outcomes were achieved in a majority of our patients, but severe impairment, in particular visual damage, was not uncommon.

Pain, depression, and quality of life in adults with MOG-antibody-associated disease

BACKGROUND AND PURPOSE

Myelin oligodendrocyte glycoprotein-antibody-associated disease (MOGAD) is an inflammatory autoimmune condition of the central nervous system. However, data on pain and depression have remained scarce. The aim of this study was to assess features of chronic pain and depression as well as their impact on health-related quality of life (hr-QoL) in MOGAD.

METHODS

Patients with MOGAD were identified in the Neuromyelitis Optica Study Group registry. Data were acquired by a questionnaire, including clinical, demographic, pain (PainDetect, Brief Pain Inventory-Short Form, McGill Pain Questionnaire-Short Form), depression (Beck Depression Inventory-II), and hr-QoL (Short Form-36 Health Survey) items.

RESULTS

Twenty-two of 43 patients suffered from MOGAD-related pain (11 nociceptive, eight definite neuropathic, three possible neuropathic) and 18 from depression. Patients with neuropathic pain had the highest pain intensity and most profound activities of daily living (ADL) impairment. Fifteen patients reported spasticity-associated pain, including four with short-lasting painful tonic spasms. Later disease onset, profound physical impairment, and depression were associated with chronic pain. Physical QoL was more affected in pain sufferers (p < 0.001) than in pain-free patients, being most severely reduced by neuropathic pain (p = 0.016). Pain severity, visual impairment, and gait impairment independently predicted lower physical QoL. Depression was the only factor reducing mental QoL. Twelve patients still suffering from moderate pain (pain severity 4.6 ± 2.3) received pain medication. Only four out of 10 patients with moderate to severe depression took antidepressants.

CONCLUSIONS

Being highly prevalent, pain and depression strongly affect QoL and ADL in MOGAD. Both conditions remain insufficiently controlled in real-life clinical practice.

NfL levels predominantly increase at disease onset in MOG-Abs-associated disorders

The unpredictable course and uncertain impact of relapses make treatment strategies of anti-myelin oligodendrocyte glycoprotein antibodies associated disorders (MOGAD) challenging. We analysed neurofilament light chain levels (NfL) in onset and follow-up sera of 18 patients with MOGAD to clarify the timing of axonal damage. In comparison with disease onset values (median 8.9 pg/mL, range 1.8-97), NfL levels remained stable or decreased in most follow-up measurements (n=52, median 6.7 pg/mL, range 0.2-207), including those measured on relapses. The predominant axonal damage occurs during onset, which could be the main driving factor of final disability, with subsequent relevant clinical and therapeutic implications.

Clinical spectrum, treatment and outcome of myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease in children: a tertiary care experience

Anti-myelin oligodendrocyte glycoprotein antibodies have been associated with a wide range of clinical presentations including monophasic and relapsing disease courses. Lack of a definitive marker for predicting further relapses and the final diagnoses complicates the clinical follow-up and treatment decisions for patients with the first episode. This study retrospectively analyzed the clinical spectrum, treatment protocols and outcome of nine children with MOG antibody-associated demyelinating disease. Diagnoses at first presentation were acute disseminated encephalomyelitis (ADEM) in six cases (67%), optic neuritis in two cases (22%), and clinically isolated syndrome in one case (11%). The disease remained monophasic in five (56%) cases. All cases with a monophasic disease course were negative for anti-MOG antibody titers in the third month. The initial diagnosis of all relapsing cases was ADEM. Three of the four cases with a relapsing disease course were available for anti-MOG antibody testing at the third month and all were positive, however, antibody titers at the sixth month were inconsistent. Cases with a relapsing disease course had no further attacks after monthly intravenous immunoglobulin treatment. Relapsing disease course is not rare in childhood MOG-antibody associated demyelinating disease. Monthly IVIG treatment may be a good alternative for the long-term treatment of relapsing cases with a low side effect profile. Anti-MOG antibody serostatus at remission periods should be interpreted cautiously. Further studies are needed to better understand and predict the clinical course of pediatric patients with MOG-antibody associated diseases.

Neuromyelitis optica spectrum disorders and myelin oligodendrocyte glycoprotein antibody-associated disease: current topics

PURPOSE OF REVIEW

We reviewed present topics on neuromyelitis optica spectrum disorders (NMOSD) and myelin oligodendrocyte glycoprotein (MOG)-antibody-associated disease (MOGAD).

RECENT FINDINGS

The number of NMOSD-related publications have increased year by year after the discovery of aquaporin 4 (AQP4)-antibody, and those on MOGAD started to surge since 2012-2013. Recent clinic-epidemiological surveys in NMOSD suggest that some racial differences in the prevalence and the clinical course. At present, experts feel the 2015 diagnostic criteria of AQP4-antibody-seronegative NMOSD should be revised. Randomized controlled trials of monoclonal antibodies in NMOSD have demonstrated a significant risk reduction of relapse, especially in AQP4-antibody-positive cases. Meanwhile, the efficacy in seronegative NMOSD was unclear. MOGAD can show NMO and other clinical phenotypes, but the clinical manifestations and frequencies are different in children and adults. One pathological study has suggested that MOGAD is distinct from AQP4-antibody-positive NMOSD, but may share some features with multiple sclerosis and acute disseminated encephalomyelitis. Immunosuppressive therapy can reduce relapse in MOGAD, but, unlike AQP4-antibody-positive NMOSD, some MOGAD patients treated with rituximab experience relapses despite a complete B-cell depletion.

SUMMARY

Our understanding and therapy of AQP4-antibody-positive NMOSD has made a significant progress, and recent research has identified challenges in seronegative NMOSD and MOGAD.

Comparison of clinical characteristics and prognoses in patients with different AQP4-Ab and MOG-Ab serostatus with neuromyelitis optica spectrum disorders

BACKGROUND

At present, patients positive for aquaporin-4 antibody (AQP4-Ab) or myelin oligodendrocyte glycoprotein antibody (MOG-Ab) are diagnosed as neuromyelitis optica spectrum disorder (NMOSD) and MOG-Ab-associated diseases, respectively. However, some patients who meet the diagnostic criteria for NMOSD and show demyelination of the central nervous system cannot be clearly classified.

METHODS

We performed a prospective cohort study to evaluate the clinical characteristics and prognoses of double-seronegative patients with NMOSD.

RESULTS

A total of 594 patients were included in the cohort, including 26 patients with MOG-Ab, 517 with AQP4-Ab, and 51 with double seronegativity. Compared to AQP4-Ab-positive patients, double-seronegative patients experienced less severe clinical attacks (51.0% vs. 78.1%; P^corr < 0.01), either visual (23.5% vs. 42.6%; P^corr = 0.024) or motor attacks (39.2% vs. 59.8%; P^corr = 0.015), and had a better median Expand Disability Status Scale (EDSS) score at the last follow-up (2.0 vs. 3.0; P^corr = 0.012) and a lower proportion of disability (11.8% vs. 30.9%; P^corr = 0.015). Furthermore, lower risks of visual and motor disability were also observed by Kaplan-Meier analyses (P = 0.031 and 0.038, respectively). Both the MOG-Ab and double-seronegative groups had lower frequencies of severe clinical attacks, especially motor attacks, better EDSS scores at the last visit, and a lower proportion of disability than was found in the AQP4-Ab group (all P values and corrected P values <0.05).

CONCLUSIONS

In patients who met the diagnostic criteria for NMOSD, compared with AQP4-Ab-seropositive patients, double-seronegative and MOG-Ab-seropositive patients had less severe clinical attacks and better prognoses, including lower EDSS scores and a lower proportion of disability.

Fever is a common onset feature of MOG-IgG associated disorders (MOGAD)

BACKGROUND

Fever is a deceptive feature of autoimmune disorders. Although cases of MOG-IgG associated disorders (MOGAD) were rarely associated with fever, this association was not specifically described.

METHODS

We report a case of MOGAD revealed by weeks of fever and meningitis. We reviewed the current literature to describe the association between fever and MOGAD.

RESULTS

We analyzed 146 cases from the literature including ours. Fever was associated with 39% of MOGAD attacks and lasted more than a week in 74%. Fever was strongly associated with brain and spinal cord attacks, and with meningitis.

CONCLUSION

Among the various features of MOGAD, fever is a highly prevalent associated symptom that should be kept in mind.

Myelin Oligodendrocyte Glycoprotein (MOG) Antibody Positive Patients in a Multi-Ethnic Canadian Cohort

Introduction: Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease is a recently described central nervous system (CNS) inflammatory disorder with phenotypic overlap with Neuromyelitis Optica Spectrum Disorder (NMOSD). NMOSD seronegative patients, and those with limited forms of the disorder, become suspects for MOG antibody-associated disease. We describe a multi-ethnic population with MOG antibody seropositivity from the University of British Columbia MS/NMO clinic. Methods: AQP4-antibody seronegative patients presenting 2005-2016 with CNS inflammatory disease suspicious for NMOSD, as well as 20 MS controls, were retrospectively tested for MOG-IgG1 antibodies by live cell-based assay at Oxford Autoimmune Neurology Diagnostic Laboratory (UK) and by a commercial fixed cell-based assay at MitogenDx (Calgary, Canada). Additional MOG seropositive cases were identified through routine clinical interaction (2016-2018) using one of these laboratories. Clinical data was reviewed retrospectively. Results: Retrospective testing identified 21 MOG seropositives (14 by live assay only, 3 by fixed assay only and 4 by both) representing 14% of the "NMOSD suspects" cohort. One multiple sclerosis (MS) control serum was MOG seropositive. Twenty additional MOG positive cases were identified prospectively. Of 42 patients (27 female), median disease onset age was 29 years (range 3-62; 9 pediatric cases), 20 (47%) were non-Caucasian, and 3 (7%) had comorbid autoimmune disease. Most common onset phenotypes were optic neuritis (23, 55%; 8 bilateral) and myelitis (9, 21%; 6 longitudinally extensive) Three of the patients in our cohort experienced cortical encephalitis; two presented with seizures. Onset was moderate-severe in 64%, but 74% had good response to initial steroid therapy. Cumulative relapse probability for the MOG positive group at 1 year was 0.428 and at 4 years was 0.628. Most had abnormal brain imaging, including cortical encephalitis and poorly demarcated subcortical and infratentorial lesions. Few "classic MS" lesions were seen. Optic nerve lesions (frequently bilateral) were long and predominantly anterior, but 5 extended to the chiasm. Spinal cord lesions were long and short, with involvement of multiple spinal regions simultaneously, including the conus medullaris. Conclusions: Our MOG seropositive patients display phenotypes similar to previous descriptions, including cortical lesions with seizures and conus medullaris involvement. Many patients relapsed, predominantly in a different CNS location from onset. Serologic data from two different cell-based antibody assays highlight the discrepancies between live and fixed testing for MOG antibodies.

Bilateral symmetrical deep gray matter involvement and leptomeningeal enhancement in a child with MOG-IgG-associated encephalomyelitis

Background

Currently, myelin oligodendrocyte glycoprotein (MOG)-IgG-associated encephalomyelitis (MOG-EM) is regarded as an independent inflammatory demyelinating disease. Magnetic resonance imaging (MRI) abnormalities occur in 44.4% of patients with MOG-EM. However, symmetrical deep gray matter involvement with leptomeningeal enhancement is rarely described in the literature.

Case presentation

A 3-year-old boy was admitted to our hospital because of acute onset fever, headache, vomiting and disturbance of consciousness. Neurological examination showed somnolence, neck stiffness and positive Kernig’s sign. Brain MRI demonstrated bilateral symmetrical lesions in the basal ganglia and thalamus as well as diffuse leptomeningeal enhancement along the sulci of bilateral hemisphere. Cerebrospinal fluid analysis demonstrated increased cell count (7 cells/mm3, mononuclear cells dominant) and protein (1.17 g/L) without glucose and chloride abnormality. Work-up for infectious and autoimmune causes, serum MOG IgG was positive by cell based assay. Therefore, a diagnosis of MOG-EM was established according to the international recommendatory criteria in 2018. He was administrated with intravenous methylprednisolone followed by oral corticosteroids and had recovered completely within 1 week.

Conclusions

In the setting of meningoencephalitis-like clinical presentation with bilateral symmetrical deep gray matter involvement, MOG-EM should be distinguished from other infectious and autoimmune disorders, such as Epstein-Barr virus (EBV) encephalitis, Japanese encephalitis and Anti-NMDA receptor (NMDAR) encephalitis. Besides, aseptic meningitis associated with leptomeningeal enhancement may be an atypical phenotype of MOG-EM.

What percentage of AQP4-ab-negative NMOSD patients are MOG-ab positive? A study from the Argentinean multiple sclerosis registry (RelevarEM)

BACKGROUND

Myelin oligodendrocyte glycoprotein antibodies (MOG-ab) have been described in aquaporin-4-antibodies(AQP4-ab)-negative neuromyelitis optica spectrum disorder (NMOSD) patients. We aimed to evaluate the percentage of AQP4-ab-negative NMOSD patients who are positive for MOG-ab in a cohort of Argentinean patients included in RelevarEM (Clinical Trials registry number NCT03375177).

METHODS

RelevarEM is a longitudinal, strictly observational multiple sclerosis (MS) and NMOSD registry in Argentina. Of 3031 consecutive patients (until March 2020), 165 patients with phenotype of suspected NMOSD, whose relevant data for the purpose of this study were available, were included. Data on demographic, clinical, paraclinical and treatment in AQP4-ab (positive, negative and unknown) and MOG-ab (positive and negative) patients were evaluated.

RESULTS

A total of 165 patients (79 AQP4-Ab positive, 67 AQP4-Ab negative and 19 unknown) were included. Of these, 155 patients fulfilled the 2015 NMOSD diagnostic criteria. Of 67 AQP4-Ab-negative patients, 36 (53.7%) were tested for MOG-Ab and 10 of them (27.7%) tested positive. Serum AQP4-ab levels were tested by means of cell-based assay (CBA) in 48 (35.2%), based on tissue-based indirect immunofluorescence assays in 58 (42.6%) and enzyme-linked immunosorbent assay in 4 (2.9%). All MOG-ab were tested by CBA. Optic neuritis (90%) was the most frequent symptom at presentation and optic nerve lesions the most frequent finding (80%) in neuroimaging of MOG-ab-associated disease. Of these, six (60%) patients were under immunosuppressant treatments at latest follow-up.

CONCLUSION

We observed that 27.7% (10/36) of the AQP4-ab-negative patients tested for MOG-ab were positive for this antibody, in line with results from other world regions.

MRI Characteristics of NMO, MOG and MS Related Optic Neuritis

Acute isolated optic neuritis can be the initial presentation of demyelinating inflammatory central nervous system disease related to multiple sclerosis (MS), neuromyelitis optica (NMO) or myelin oligodendrocyte glycoprotein antibody disease (MOG-AD). In addition to the well-characterized brain and spinal cord imaging features, important and characteristic differences in the radiologic appearance of the optic nerves in these disorders are being described, and magnetic resonance imaging (MRI) of the optic nerves is becoming an essential tool in the differential diagnosis of optic neuritis. Whereas typical demyelinating optic neuritis is a relatively mild and self-limited disease, atypical optic neuritis in NMO and MOG-AD is potentially much more vision-threatening and merits a different treatment approach. Thus, differentiation based on MRI features may be particularly important during the first attack of optic neuritis, when antibody status is not yet known. This review discusses the optic nerve imaging in the major demyelinating disorders with an emphasis on clinically relevant differences that can help clinicians assess and manage these important neuro-ophthalmic disorders. It also reviews the utility of optic nerve MRI as a prognostic indicator in acute optic neuritis.

B cell depletion therapies in autoimmune disease: advances and mechanistic insights

In the past 15 years, B cells have been rediscovered to be not merely bystanders but rather active participants in autoimmune aetiology. This has been fuelled in part by the clinical success of B cell depletion therapies (BCDTs). Originally conceived as a method of eliminating cancerous B cells, BCDTs such as those targeting CD20, CD19 and BAFF are now used to treat autoimmune diseases, including systemic lupus erythematosus and multiple sclerosis. The use of BCDTs in autoimmune disease has led to some surprises. For example, although antibody-secreting plasma cells are thought to have a negative pathogenic role in autoimmune disease, BCDT, even when it controls the disease, has limited impact on these cells and on antibody levels. In this Review, we update our understanding of B cell biology, review the results of clinical trials using BCDT in autoimmune indications, discuss hypotheses for the mechanism of action of BCDT and speculate on evolving strategies for targeting B cells beyond depletion.

Anti-MOG associated disorder-Clinical and radiological characteristics compared to AQP4-IgG+ NMOSD-A single-center experience

BACKGROUND

The discovery of two immunoglobulin G (IgG) antibodies against aquaporin 4 (anti-AQP4) and myelin oligodendrocyte glycoprotein (anti-MOG) has led to the distinction of the disorders anti-AQP4 immunoglobulin G positive neuromyelitis spectrum disorder (AQP4-IgG+ NMOSD) and anti-MOG associated disorder (MOGAD). Different clinical and radiological features have been proposed to distinguish these two demyelinating CNS diseases.

METHODS

This is a single-center retrospective review at the University of Florida (UF) including all patients with the diagnostic code ICD G36 ("other acute disseminated demyelination") from October 2015 to January 2020 (n=141) and all charts included in the clinical NMOSD database of the UF Division of Neuroimmunology (n=36). A total of 151 cases were reviewed for presence of anti-MOG and anti-AQP4 antibodies and NMOSD diagnostic criteria. Differences in MOGAD and AQP4-IgG+ NMOSD were compared.

RESULTS

Of the 151 reviewed patient charts, 11 were consistent with MOGAD and 43 with AQP4-IgG+ NMOSD. Patients with MOGAD were significantly younger at symptom onset compared to patients with AQP4-IgG+ NMOSD (14 [1-33] years vs. 37 [6-82] years; p=0.005). In comparison with AQP4-IgG+ NMOSD, optic neuritis in MOGAD was more frequently associated with bilateral optic nerve involvement: (6/11 [54.5%] vs. 6/43 [13.9%]; p=0.009) and fundoscopic presence of optic disc edema (5/11 [45.5%] vs. 3/43 [7%]; p=0.006). Perineuritis was a common radiological feature in MOGAD (present in 4 cases). In case of myelitis, there was more frequent involvement of the conus medullaris in MOGAD (4/11 [36.4%] vs. 2/43 [4.7%]; p=0.012). Symptomatic cerebral syndrome with supratentorial white matter lesions was seen in MOGAD patients with pediatric onset (pediatric onset: 4/6 [66.7%] vs. adult onset: 0/5 [0%]. In MOGAD, evidence for combined central and peripheral demyelination and increased intracranial pressure was present in one patient each. A preceding inciting event (illness/postpartum) was more frequently identifiable in MOGAD (4/11 [36.4%] vs. 4/43 [7%]; p=0.045). Disability as calculated on the Expanded Disability Status Scale was less severe in MOGAD compared to AQP-IgG+ NMOSD (most severe presentation: 5 [2-7] vs. 7 [1-10]; p=0.015; most recent assessment: 2 [0-5] vs. 5 [0-10]; p=0.045) and patients were more likely to respond to treatment of acute attacks with corticosteroids and/or plasmapheresis (Clinical Global Impression-Global Change scale: 1 [1-4] vs. 3 [1-6]; p=0.001).

INTERPRETATION

The study confirms that simultaneous bilateral optic neuritis, presence of optic disc edema, transverse myelitis with conus involvement and a less severe disease course are distinctive features of MOGAD.

Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease: Current Insights into the Disease Pathophysiology, Diagnosis and Management

Myelin oligodendrocyte glycoprotein (MOG)-associated disease (MOGAD) is a rare, antibody-mediated inflammatory demyelinating disorder of the central nervous system (CNS) with various phenotypes starting from optic neuritis, via transverse myelitis to acute demyelinating encephalomyelitis (ADEM) and cortical encephalitis. Even though sometimes the clinical picture of this condition is similar to the presentation of neuromyelitis optica spectrum disorder (NMOSD), most experts consider MOGAD as a distinct entity with different immune system pathology. MOG is a molecule detected on the outer membrane of myelin sheaths and expressed primarily within the brain, spinal cord and also the optic nerves. Its function is not fully understood but this glycoprotein may act as a cell surface receptor or cell adhesion molecule. The specific outmost location of myelin makes it a potential target for autoimmune antibodies and cell-mediated responses in demyelinating processes. Optic neuritis seems to be the most frequent presenting phenotype in adults and ADEM in children. In adults, the disease course is multiphasic and subsequent relapses increase disability. In children ADEM usually presents as a one-time incident. Luckily, acute immunotherapy is very effective and severe disability (ambulatory and visual) is less frequent than in NMOSD. A critical element of reliable diagnosis is detection of pathogenic serum antibodies MOG with accurate, specific and sensitive methods, preferably with optimized cell-based assay (CBA). MRI imaging can also help in differentiating MOGAD from other neuro-inflammatory disorders. Reports on randomised control trials are limited, but observational open-label experience suggests a role for high-dose steroids and plasma exchange in the treatment of acute attacks, and for immunosuppressive therapies, such as steroids, oral immunosuppressants and rituximab as maintenance treatment. In this review, we present up-to-date clinical, immunological, radiographic, histopathological data concerning MOGAD and summarize the practical aspects of diagnosing and managing patients with this disease.

Interleukin-6 inhibition with tocilizumab for relapsing MOG-IgG associated disorder (MOGAD): A case-series and review

BACKGROUND

Myelin oligodendrocyte glycoprotein-immunoglobulin G (MOG-IgG) associated disorder (MOGAD) is a CNS demyelinating disease distinct from neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis. Some patients with MOGAD exhibit a highly-relapsing and steroid-dependent disease course for which optimal treatment is unknown. Interleukin-6 (IL-6) plays an important pathobiologic role in NMOSD with aquaporin-4 antibodies and preliminary data suggest similar mechanisms of CNS damage may occur in MOGAD.

OBJECTIVE

To summarize our experience with and all current literature on the use of tocilizumab, an IL-6 inhibitor, for highly-relapsing MOGAD along with the underlying immunopathologic rationale.

METHODS

This is a single-center report from a U.S. military tertiary referral hospital of all patients with clinically, radiographically, and serologically confirmed MOGAD who were treated with tocilizumab compiled with data from five other case series/reports from tertiary referral centers. The main outcomes of interest were reduction in annualized relapse rate and required dose of oral prednisone for symptomatic management.

RESULTS

Ten total patients with relapsing MOGAD who were treated with intravenous or subcutaneous tocilizumab were identified. At our institution, a 20 year-old female with a 9-year history of highly-relapsing and steroid dependent MOGAD was treated with tocilizumab. In 28 months of follow up, she had no clinical relapses and was able to discontinue corticosteroids. Another 35 year-old female at our institution with a 10-year history of highly-relapsing and steroid dependent MOGAD was treated with tocilizumab for 6 months. Tocilizumab therapy was associated with relapse freedom, resolution of eye pain, and ability to discontinue corticosteroids. When compiled with data from all other case reports of relapsing MOGAD treated with tocilizumab, there have been zero clinical or radiographic relapses in 10 patients over an average treatment duration of 28.6 months.

CONCLUSIONS

Tocilizumab is an IL-6 inhibitor that may be a promising therapeutic option for patients with relapsing MOGAD that has not responded to other immunotherapies. Our results support a key role for IL-6-related mechanisms in MOGAD disease activity. Its safety and tolerability profile, both in our own experience and based on its use for other FDA approved conditions, may even justify its use a first line therapy in select patients. Further research is needed to establish the safety and efficacy of IL-6 inhibition in MOGAD.

Clinical and Radiological Features of Adult Onset Bilateral Medial Frontal Cerebral Cortical Encephalitis With Anti-myelin Oligodendrocyte Glycoprotein Antibody

Objective: To clarify the clinical and radiological features of adult onset anti-myelin oligodendrocyte glycoprotein (MOG) antibody-associated bilateral medial frontal cerebral cortical encephalitis (BFCCE). Methods: We systematically reviewed the literature for patients with anti-MOG antibody-associated BFCCE. Patients who were also positive for other encephalitis-related autoantibodies were excluded from the study. The frequency of several characteristic neurological symptoms and lesion distributions were analyzed. Results: We identified six patients with anti-MOG antibody-associated BFCCE. Among them, 6/6 had headache, 4/6 had fever, 3/6 had seizure, 2/6 had paraparesis, 2/6 had lethargy, and 2/6 had memory disturbance. CSF pleocytosis was observed in 5/6 patients, while CSF myelin basic protein was not elevated in any of the six patients. On brain MRI, 6/6 had bilateral medial frontal cortical lesions, 3/6 had corpus callosum lesions, and 3/6 had leptomeningeal enhancements. Most of the lesions were distributed in the territory of the anterior cerebral artery (ACA). Conclusion: Our results indicate that anti-MOG antibody-associated BFCCE presents with characteristic clinical symptoms and MRI findings, which might reflect lesion formation in the ACA territory.

MOG-IgG- versus AQP4-IgG-Positive Optic Neuritis in Thailand: Clinical Characteristics and Long-Term Visual Outcomes Comparison

Purpose

To compare demographic data, clinical and radiological characteristics, treatment, and long-term visual outcomes between myelin oligodendrocyte glycoprotein autoantibody-positive optic neuritis (MOG-IgG + ON) and aquaporin-4 autoantibody-positive optic neuritis (AQP4-IgG + ON) in Thailand.

Patients and Methods

We included individuals who were diagnosed with either MOG-IgG + ON or AQP4-IgG + ON over an 11-year period. Demographic data, clinical and radiological characteristics at ON presentation, treatment, and long-term visual outcomes were retrospectively collected.

Results

There were 16 patients (28 eyes) and 43 patients (59 eyes) in the MOG-IgG + ON and AQP4-IgG + ON groups, respectively. AQP4-IgG + ON occurred predominantly in female patients whereas MOG-IgG + ON-affected female patients and male patients equally (p < 0.001). Prior or concurrent non-ON demyelinating events were more often observed at AQP4-IgG + ON onset (p < 0.001). At ON presentation, bilaterality and the presence of optic disc edema were predominantly found in the MOG-IgG + ON group (bilaterality: 80% vs 8%, MOG-IgG + ON vs AQP4-IgG + ON patients, respectively (p < 0.001); presence of optic disc edema: 92.3% vs 36.6%, MOG-IgG + ON- vs AQP4-IgG + ON-affected eyes, respectively (p < 0.001)). There was no statistically significant difference in age at ON onset, nadir visual acuity (VA), presence of pain, segmental enhancement, and total enhanced segments of the anterior visual pathways. At the last follow-up, immunosuppressive drugs were used more often in the AQP4-IgG + ON group (43.7% vs 74.4%, MOG-IgG + ON vs AQP4-IgG + ON, respectively; p < 0.027). Remarkably better final VA was achieved in MOG-IgG + ON-affected eyes (median: 0.0 vs 0.4 logMAR, MOG-IgG + ON- vs AQP4-IgG + ON-affected eyes, respectively; p < 0.001).

Conclusion

Compared with AQP4-IgG + ON, MOG-IgG + ON tended to present with bilaterality and optic disc edema and demonstrated better visual outcomes.

State of the Art and Future Challenges in Multiple Sclerosis Research and Medical Management: An Insight into the 5th International Porto Congress of Multiple Sclerosis

The 5th International Porto Congress of Multiple Sclerosis took place between the 14th and 16th of February 2019 in Porto, Portugal. Its intensive programme covered a wide-range of themes-including many of the hot topics, challenges, pitfalls and yet unmet needs in the field of multiple sclerosis (MS)-led by a number of well-acknowledged world experts. This meeting review summarizes the talks that took place during the congress, which focussed on issues in MS as diverse as the development and challenges of progressive MS, epidemiology, differential diagnosis, medical management, molecular research and imaging tools.

Case Report: Myelin Oligodendrocyte Glycoprotein Antibody-Associated Relapse With COVID-19

A 39-year-old lady with relapsing myelin oligodendrocyte glycoprotein antibody (MOG-IgG) associated disease developed coryzal symptoms, malaise, sweating, and postural dizziness. Six days later she presented with painful progressive right visual loss consistent with optic neuritis. COVID-19 was confirmed by nasopharyngeal swab and MOG-IgG serological reversion was noted. Visual function improved following steroids and plasma exchange. This case highlights a possible causal association between inflammation due to COVID-19 and a relapse of MOG-IgG associated disease. It also highlights the clinical relevance of reporting MOG-IgG titers in MOG-IgG associated disease.

Variability of cerebrospinal fluid findings by attack phenotype in myelin oligodendrocyte glycoprotein-IgG-associated disorder

BACKGROUND

The variability in cerebrospinal fluid (CSF) findings of myelin oligodendrocyte glycoprotein-IgG-associated disorder (MOGAD) is not fully elucidated.

OBJECTIVE AND METHODS

We retrospectively analyzed 203 attack-associated CSFs from Mayo Clinic patients (2000-2019) with MOGAD.

RESULTS

White-blood-cell (>5/mm³) elevation was less with clinically isolated optic neuritis (23%), compared to myelitis, brain/brainstem attacks, or combinations thereof (>70%), p<0.0001. CSF pleocytosis in optic neuritis was more common in patients with coexisting asymptomatic brain and/or spine MRI T2-lesions (53%) than in those without (16%), p=0.005. Abnormal CSF oligoclonal bands ranged from 1% (optic neuritis) to 18% (brain/brainstem attacks). CSF pleocytosis was less common after immunotherapy.

CONCLUSIONS

CSF findings in MOGAD vary by attack phenotype and preceding treatment.

Neural Antibody Testing in Patients with Suspected Autoimmune Encephalitis

Background

Autoimmunity is an increasingly recognized cause of encephalitis with a similar prevalence to that of infectious etiologies. Over the past decade there has been a rapidly expanding list of antibody biomarker discoveries that have aided in the identification and characterization of autoimmune encephalitis. As the number of antibody biomarkers transitioning from the research setting into clinical laboratories has accelerated, so has the demand and complexity of panel-based testing. Clinical laboratories are increasingly involved in discussions related to test utilization and providing guidance on which testing methodologies provide the best clinical performance.

Content

To ensure optimal clinical sensitivity and specificity, comprehensive panel-based reflexive testing based on the predominant neurological phenotypic presentation (e.g., encephalopathy) is ideal in the workup of cases of suspected autoimmune neurological disease. Predictive scores based on the clinical workup can aid in deciding when to order a test. Testing of both CSF and serum is recommended with few exceptions. Appropriate test ordering and interpretation requires an understanding of both testing methodologies and performance of antibody testing in different specimen types.

Summary

This review discusses important considerations in the design and selection of neural antibody testing methodologies and panels. Increased collaboration between pathologists, laboratorians, and neurologists will lead to improved utilization of complex autoimmune neurology antibody testing panels.

[Aquaporin-4 and Myelin Oligodendrocyte Glycoprotein Antibody-Associated Optic Neuritis: Diagnosis and Treatment]

Optic neuritis (ON) is a frequent manifestation of aquaporin-4 (AQP4) antibody-mediated neuromyelitis optica spectrum disorders (NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated encephalomyelitis (MOG-EM; also termed MOG antibody-associated disorders, MOGAD). The past few years have seen major advances in the diagnosis and treatment of these two relatively new entities: international diagnostic criteria for NMOSD and MOG-EM have been proposed, improved antibody assays developed, and consensus recommendations on the indications and methodology of serological testing published. Very recently, the results of four phase III trials assessing new treatment options for NMOSD have been presented. With eculizumab, a monoclonal antibody inhibiting complement factor C5, for the first time a relapse-preventing long-term treatment for NMOSD - which has so far mostly been treated off-label with rituximab, azathioprine, and other immunosuppressants - has been approved. Data from recent retrospective studies evaluating treatment responses in MOG-ON suggest that rituximab and other immunosuppressants are effective also in this entity. By contrast, many drugs approved for the treatment of multiple sclerosis (MS) have been found to be either ineffective or to cause disease exacerbation (e.g., interferon-β). Recent studies have shown that not only NMOSD-ON but also MOG-ON usually follows a relapsing course. If left untreated, both disorders can result in severe visual deficiency or blindness, though MOG-ON seems to have a better prognosis overall. Acute attacks are treated with high-dose intravenous methylprednisolone and, in many cases, plasma exchange (PEX) or immunoadsorption (IA). Early use of PEX/IA may prevent persisting visual loss and improve the long-term outcome. Especially MOG-ON has been found to be frequently associated with flare-ups, if steroids are not tapered, and to underlie many cases of "chronic relapsing inflammatory optic neuropathy" (CRION). Both NMOSD-ON and MOG-ON are often associated with simultaneous or consecutive attacks of myelitis and brainstem encephalitis; in contrast to earlier assumptions, supratentorial MRI brain lesions are a common finding and do not preclude the diagnosis. In this article, we review the current knowledge on the clinical presentation, epidemiology, diagnosis, and treatment of these two rare yet important differential diagnoses of both MS-associated ON und idiopathic autoimmune ON.

Anti-MOG-associated demyelinating disorders: two sides of the same coin

BACKGROUND

Anti-myelin oligodendrocyte glycoprotein antibody-associated disorders (MOGAD) are new emerging diseases with heterogeneous course, treatment, response, and prognosis.

CASE REPORT

We herein present 2 cases with antibodies to MOG, one with a cerebellar/brainstem monophasic syndrome which partially improved after treatment, and the other with an optic neuritis onset then relapsed with cortical encephalitis and presented a subsequent complete recovery. We further discuss elements possibly associated with disease heterogeneity and influencing treatment choices.

CONCLUSIONS

MOGAD is an extremely variable disease which can relapse and accumulate disability over time. An early diagnosis and correct timely treatment is fundamental to improve clinical outcome.

Serial Anti-Myelin Oligodendrocyte Glycoprotein Antibody Analyses and Outcomes in Children With Demyelinating Syndromes

Question

Are antibodies to myelin oligodendrocyte glycoprotein (MOG) associated with relapses in children with acquired demyelination?

Findings

In this cohort study including 274 children with acquired demyelinating syndrome, anti-MOG antibodies were found in approximately 30% of children at presentation; they were more frequent in children with acute disseminated encephalomyelitis or younger than 11 years and were rarely present in children meeting multiple sclerosis diagnostic criteria. Neither presence of anti-MOG antibodies at onset nor their subsequent persistence were strongly associated with relapsing disease.

Meaning

While common in children with demyelination, anti-MOG antibodies should not be used to adjudicate long-term immunomodulatory therapy in the absence of clinical relapsing disease.

Importance

Identifying the course of demyelinating disease associated with myelin oligodendrocyte glycoprotein (MOG) autoantibodies is critical to guide appropriate treatment choices.

Objective

To characterize serial anti-MOG antibody serologies and clinical and imaging features at presentation and during follow-up in an inception cohort of prospectively monitored children with acquired demyelination.

Design, Setting, and Participants

In this prospective cohort study, study participants were recruited from July 2004 to February 2017 through the multicenter Canadian Pediatric Demyelinating Disease Study. Inclusion criteria included (1) incident central nervous system demyelination, (2) at least 1 serum sample obtained within 45 days from onset, and (3) complete clinical information. Of 430 participants with acquired demyelinating syndrome recruited, 274 were included in analyses. Of 156 excluded participants, 154 were excluded owing to missing baseline samples and 2 owing to incomplete clinical information. Data were analyzed from May to October 2018.

Main Outcomes and Measures

Presence of anti-MOG antibodies was blindly assessed in serial samples collected over a median of 4 years. Clinical, magnetic resonance imaging, and cerebrospinal fluid features were characterized at presentation, and subsequent disease course was assessed by development of new brain magnetic resonance imaging lesions, total lesion volume at last evaluation, annualized relapse rates, Expanded Disability Status Scale score and visual functional score at 4 years, and any disease-modifying treatment exposure.

Results

Of the 274 included participants, 140 (51.1%) were female, and the median (interquartile range) age of all participants was 10.8 (6.2-13.9) years. One-third of children were positive for anti-MOG antibodies at the time of incident demyelination. Clinical presentations included a combination of optic neuritis, transverse myelitis, and acute disseminated encephalomyelitis for 81 of 84 anti-MOG antibody–positive children (96%). Brain lesions were present in 51 of 76 anti-MOG antibody–positive participants (67%), but magnetic resonance imaging characteristics differed with age at presentation. Complete resolution of baseline lesions was observed in 26 of 49 anti-MOG antibody–positive participants (53%). On serial serum analysis, 38 of 67 participants (57%) who were seropositive at onset became seronegative (median time to conversion, 1 year). Among all participants who were positive for anti-MOG antibodies at presentation, clinical relapses occurred in 9 of 24 children (38%) who remained persistently seropositive and in 5 of 38 children (13%) who converted to seronegative status.

Conclusions and Relevance

Myelin oligodendrocyte glycoprotein antibodies are common in children with acquired demyelinating syndrome and are transient in approximatively half of cases. Even when persistently positive, most anti-MOG antibody–positive children experience a monophasic disease. The presence of anti-MOG antibodies at the time of incident demyelination should not immediately prompt the initiation of long-term immunomodulatory therapy.

Myelin oligodendrocyte glycoprotein-antibody-associated disorder: a new inflammatory CNS demyelinating disorder

BACKGROUND AND AIMS

Myelin oligodendrocyte glycoprotein (MOG) is an oligodendrocytopathy resulting in demyelination. We aimed to determine the frequency of MOG-associated disorders (MOGAD), its various clinical phenotypes, and imaging characteristics.

METHODS

All patients with MOGAD were included. Description of the various clinical phenotypes, investigation profile, therapeutic response, differences between pediatric and adult-onset neurological disorders, determination of poor prognostic factors was done.

RESULTS

The study population consisted of 93 (M:F = 45:48) (Pediatric:40, Adult-onset:47, Late-onset:7) patients with a median age of 21 years. Among the 263 demyelinating episodes; 45.8% were optic neuritis (ON), 22.8% were myelopathy, 17.1% were brainstem, 7.6% were acute demyelinating encephalomyelitis(ADEM), 4.2% were opticomyelopathy and 2.3% with cerebral manifestations. There was exclusive vomiting in 24.7% prior to onset of clinical syndrome, none of them had area postrema involvement. ADEM was exclusively seen in pediatric patients. Poor prognostic indicators included: (i) incomplete recovery from an acute attack, (b) brainstem syndrome, (c) ADEM with incomplete recovery, (d) MRI suggestive of leukodystrophy pattern, (e) severe ON, (f) ADEMON.

CONCLUSIONS

The Spectrum of MOG-associated disorders is wider affecting the brain (grey and white matter) and the meninges. There are various clinical phenotypes and MRI patterns, recognition of which may help in the determination of therapeutic strategies, and long-term prognosis.

Neuromyelitis optica spectrum disorders

The disease concept of Neuromyelitis Optica Spectrum Disorders(NMOSD) has undergone a significant change over the last two decades including the detection of Myelin Oligodendrocyte Glycoprotein(MOG) antibody in patients who are seronegative for aquaporin-4 antibody. Aquaporin-4 antibody positive NMOSD is now regarded as an immune astrocytopathy. Conversely, MOG antibody associated disease is known to target myelin rather than astrocytes, leading to an NMOSD syndrome with distinct clinical and radiological features. Incorporation of clinical features like area postrema syndrome, brainstem syndrome, diencephalic syndrome and cortical manifestations as core clinical characteristics into the revised diagnostic criteria has widened the clinical spectrum of NMOSD. With the development of these criteria, it is possible to make the diagnosis at an earlier stage so that effective immunosuppression can be instituted promptly for a better long-term prognosis. Newer therapeutic agents have been introduced for aquaporin-4 seropositive NMOSD disease; however, challenges remain in treating seronegative disease because of limited treatment options.

Biomarkers in Rare Demyelinating Disease of the Central Nervous System

Rare neurological diseases are a heterogeneous group corresponding approximately to 50% of all rare diseases. Neurologists are among the main specialists involved in their diagnostic investigation. At the moment, a consensus guideline on which neurologists may base clinical suspicion is not available. Moreover, neurologists need guidance with respect to screening investigations that may be performed. In this respect, biomarker research has emerged as a particularly active field due to its potential applications in clinical practice. With respect to autoimmune demyelinating diseases of the Central Nervous System (CNS), although these diseases occur in the frame of organ-specific autoimmunity, pathology of the disease itself is orchestrated among several anatomical and functional compartments. The differential diagnosis is broad and includes, but is not limited to, rare neurological diseases. Multiple Sclerosis (MS) needs to be differentially diagnosed from rare MS variants, Acute Disseminated Encephalomyelitis (ADEM), the range of Neuromyelitis Optica Spectrum Disorders (NMOSDs), Myelin Oligodendrocyte Glycoprotein (MOG) antibody disease and other systemic inflammatory diseases. Diagnostic biomarkers may facilitate timely diagnosis and proper disease management, preventing disease exacerbation due to misdiagnosis and false treatment. In this review, we will describe advances in biomarker research with respect to rare neuroinflammatory disease of the CNS.

E.U. paediatric MOG consortium consensus: Part 1 - Classification of clinical phenotypes of paediatric myelin oligodendrocyte glycoprotein antibody-associated disorders

Over the past few years, increasing interest in the role of autoantibodies against myelin oligodendrocyte glycoprotein (MOG-abs) as a new candidate biomarker in demyelinating central nervous system diseases has arisen. MOG-abs have now consistently been identified in a variety of demyelinating syndromes, with a predominance in paediatric patients. The clinical spectrum of these MOG-ab-associated disorders (MOGAD) is still expanding and differs between paediatric and adult patients. This first part of the Paediatric European Collaborative Consensus emphasises the diversity in clinical phenotypes associated with MOG-abs in paediatric patients and discusses these associated clinical phenotypes in detail. Typical MOGAD presentations consist of demyelinating syndromes, including acute disseminated encephalomyelitis (ADEM) in younger, and optic neuritis (ON) and/or transverse myelitis (TM) in older children. A proportion of patients experience a relapsing disease course, presenting as ADEM followed by one or multiple episode(s) of ON (ADEM-ON), multiphasic disseminated encephalomyelitis (MDEM), relapsing ON (RON) or relapsing neuromyelitis optica spectrum disorders (NMOSD)-like syndromes. More recently, the disease spectrum has been expanded with clinical and radiological phenotypes including encephalitis-like, leukodystrophy-like, and other non-classifiable presentations. This review concludes with recommendations following expert consensus on serologic testing for MOG-abs in paediatric patients, the presence of which has consequences for long-term monitoring, relapse risk, treatments, and for counselling of patient and families. Furthermore, we propose a clinical classification of paediatric MOGAD with clinical definitions and key features. These are operational and need to be tested, however essential for future paediatric MOGAD studies.

E.U. paediatric MOG consortium consensus: Part 2 - Neuroimaging features of paediatric myelin oligodendrocyte glycoprotein antibody-associated disorders

Imaging plays a crucial role in differentiating the spectrum of paediatric acquired demyelinating syndromes (ADS), which apart from myelin oligodendrocyte glycoprotein antibody associated disorders (MOGAD) includes paediatric multiple sclerosis (MS), aquaporin-4 antibody neuromyelitis optica spectrum disorders (NMOSD) and unclassified patients with both monophasic and relapsing ADS. In contrast to the imaging characteristics of children with MS, children with MOGAD present with diverse imaging patterns which correlate with the main demyelinating phenotypes as well as age at presentation. In this review we describe the common neuroradiological features of children with MOGAD such as acute disseminated encephalomyelitis, optic neuritis, transverse myelitis, AQP4 negative NMOSD. In addition, we report newly recognized presentations also associated with MOG-ab such as the 'leukodystophy-like' phenotype and autoimmune encephalitis with predominant involvement of cortical and deep grey matter structures. We further delineate the features, which may help to distinguish MOGAD from other ADS and discuss the future role of MR-imaging in regards to treatment decisions and prognosis in children with MOGAD. Finally, we propose an MRI protocol for routine examination and discuss new imaging techniques, which may help to better understand the neurobiology of MOGAD.

E.U. paediatric MOG consortium consensus: Part 4 - Outcome of paediatric myelin oligodendrocyte glycoprotein antibody-associated disorders

There is increasing knowledge on the role of antibodies against myelin oligodendrocyte glycoprotein (MOG-abs) in acquired demyelinating syndromes and autoimmune encephalitis in children. Better understanding and prediction of outcome is essential to guide treatment protocol decisions. Therefore, this part of the Paediatric European Collaborative Consensus provides an oversight of existing knowledge of clinical outcome assessment in paediatric MOG-ab-associated disorders (MOGAD). The large heterogeneity in disease phenotype, disease course, treatment and follow-up protocols is a major obstacle for reliable prediction of outcome. However, the clinical phenotype of MOGAD appears to be the main determinant of outcome. Patients with a transverse myelitis phenotype in particular are at high risk of accruing neurological disability (motor and autonomic), which is frequently severe. In contrast, having a single episode of optic neuritis any time during disease course is broadly associated with a lower risk of persistent disability. Furthermore, MOG-ab-associated optic neuritis often results in good functional visual recovery, although retinal axonal loss may be severe. The field of cognitive and behavioural outcome and epilepsy following demyelinating episodes has not been extensively explored, but in recent studies acute disseminated encephalomyelitis (-like) phenotype in the young children was associated with cognitive problems and epilepsy in long-term follow-up. In conclusion, main domains of importance in determining clinical outcome in paediatric MOGAD are visual, motor, autonomic and cognitive function. A standardised evaluation of these outcome domains in all children is of importance to allow adequate rehabilitation and follow-up.

Acute and subacute myelopathy

Myelopathy is a term referring to any pathologic process affecting the spinal cord, and encompasses a broad spectrum of etiologies. The first step is to categorize myelopathy, according to the time to reach maximum deficit. Myelopathies are commonly classified as acute, subacute or chronic, for which the etiologies are totally different. Myelopathy is considered acute when the symptoms progress to their nadir in maximum 21 days after onset. Due to heterogeneity in pathogenesis, and the overlap in the clinical and imaging presentation among etiologies, acute myelopathy is considered as a diagnostic dilemma. A simple and efficient algorithm for timely identification of the underlying cause is thus useful. In this review, we provide a simplified approach for the differential diagnosis among all causes of acute myelopathies, and describe the principal clinical and imaging features of the main etiologies in adults, including recently characterized antibody-mediated myelitis, and its mimics.

Brain structural and functional alterations in MOG antibody disease

BACKGROUND

The impact of myelin oligodendrocyte glycoprotein antibody disease (MOGAD) on brain structure and function is unknown.

OBJECTIVES

The aim of this study was to study the multimodal brain MRI alterations in MOGAD and to investigate their clinical significance.

METHODS

A total of 17 MOGAD, 20 aquaporin-4 antibody seropositive neuromyelitis optica spectrum disorders (AQP4 + NMOSD), and 28 healthy controls (HC) were prospectively recruited. Voxel-wise gray matter (GM) volume, fractional anisotropy (FA), mean diffusivity (MD), and degree centrality (DC) were compared between groups. Clinical associations and differential diagnosis were determined using partial correlation and stepwise logistic regression.

RESULTS

In comparison with HC, MOGAD had GM atrophy in frontal and temporal lobe, insula, thalamus, and hippocampus, and WM fiber disruption in optic radiation and anterior/posterior corona radiata; DC decreased in cerebellum and increased in temporal lobe. Compared to AQP4 + NMOSD, MOGAD presented lower GM volume in postcentral gyrus and decreased DC in cerebellum. Hippocampus/parahippocampus atrophy associated with Expanded Disability Status Scale (R = -0.55, p = 0.04) and California Verbal Learning Test (R = 0.62, p = 0.031). The differentiation of MOGAD from AQP4 + NMOSD achieved an accuracy of 95% using FA in splenium of corpus callosum and DC in occipital gyrus.

CONCLUSION

Distinct structural and functional alterations were identified in MOGAD. Hippocampus/parahippocampus atrophy associated with clinical disability and cognitive impairment.

Clinical Features and Risk of Relapse in Children and Adults with Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease

OBJECTIVE

The main objective was to compare clinical features, disease course, and myelin oligodendrocyte glycoprotein (MOG) antibody (Ab) dynamics between children and adults with MOG-Ab-associated disease (MOGAD).

METHODS

This retrospective multicentric, national study included 98 children and 268 adults with MOGAD between January 2014 and September 2019. Cox regression model for recurrent time-to-event data and Kaplan-Meier curves for time to antibody negativity were performed for the objectives.

RESULTS

Isolated optic neuritis was the most frequent clinical presentation in both children (40.8%) and adults (55.9%, p = 0.013), and acute disseminated encephalomyelitis syndrome was more frequent in children (36.7% vs 5.6%, p < 0.001). Compared to adults, children displayed better recovery (Expanded Disability Status Scale ≥ 3.0 at last follow-up reached only by 10 of 97 [10.3%] vs 66/247 [26.7%], p < 0.001). In the multivariate analysis, adults were at higher risk of relapse than children (hazard ratio = 1.41, 95% confidence interval [CI] = 1.12-1.78, p = 0.003). At 2 years, 64.2% (95% CI = 40.9-86.5) of nonrelapsing children became MOG-Ab negative compared to 14.1% (95% CI = 4.7-38.3) of relapsing children (log-rank p < 0.001), with no differences observed in adults (log-rank p = 0.280).

INTERPRETATION

MOGAD patients differ in the clinical presentation at onset, showing an age-related shift in the clinical features across age groups. Compared to children, adults have a higher risk of relapse and worse functional recovery. Finally, children with monophasic disease become MOG-Ab negative earlier than relapsing children, but this is not true in adults. Considering these differences, management and treatment guidelines should be considered independently in children and adults. ANN NEUROL 2021;89:30-41.

Detection of MOG-IgG by cell-based assay: moving from discovery to clinical practice

Myelin oligodendrocyte glycoprotein (MOG) is a unique CNS-specific mammalian protein that is expressed on the surface of compact myelin and oligodendrocyte cell bodies. MOG is an accessible target for autoantibodies, associated with immune-mediated demyelination in the central nervous system. The identification of MOG reactive immunoglobulin G antibodies (MOG-IgG) helps to distinguish a subgroup of patients from multiple sclerosis and other CNS disorders, reducing the risk of clinical misdiagnosis. The development of the cell-based assays (CBA) improved the detection of clinically meaningful MOG-IgG binding to conformational MOG expressed in the cell membrane surface. In this review, we describe factors that impact on the results of CBA, such as MOG conformation, protein glycosylation, addition of fluorescent tags, serum dilution, secondary antibodies, and data interpretation.

Evaluation of diagnostic criteria and red flags of myelin oligodendrocyte glycoprotein encephalomyelitis in a clinical routine cohort

Aims

Myelin oligodendrocyte glycoprotein antibodies (MOG‐IgG) have been proposed to define “MOG encephalomyelitis” (MOG‐EM), with published diagnostic and “red flag” criteria. We aimed to evaluate these criteria in a routine clinical setting.

Methods

We retrospectively analyzed patients with borderline/positive MOG‐IgG and applied the diagnostic and red flag criteria to determine likelihood of MOG‐EM diagnosis. Para‐/clinical parameters were described and analyzed with chi‐square test.

Results

In total, 37 patients fulfilled MOG‐EM diagnostic criteria (female‐to‐male ratio: 1.6:1, median onset age: 28.0 years [IQR 18.5‐40.5], n = 8 with pediatric onset). In 24/37, red flags were present, predominantly MOG‐IgG at assay cutoff and/or MRI lesions suggestive of multiple sclerosis (MS). As proposed in the consensus criteria, these patients should rather be described as “possible” MOG‐EM. Of these, we classified 13 patients as “unlikely” MOG‐EM in the presence of the red flag “borderline MOG‐IgG” with negative MOG‐IgG retest or coincidence of ≥1 additional red flag. This group mainly consisted of patients diagnosed with MS (n = 11). Frequency of cerebrospinal fluid (CSF‐)—specific oligoclonal bands (OCB) is significantly lower in definite vs possible and unlikely MOG‐EM (P = .0005).

Conclusion

Evaluation of diagnostic and red flag criteria, MOG‐IgG retesting (incl. change of assay), and CSF‐specific OCB are relevant in clinical routine cohorts to differentiate MOG‐EM from MS.

MRI characteristics of MOG-Ab associated disease in adults: An update

Our knowledge of the radiological spectrum of myelin oligodendrocyte glycoprotein antibody associated disease (MOGAD) is growing rapidly. An update on the radiological features of the disease, and its evolution is thus necessary. Magnetic resonance imaging (MRI) has an increasingly important role in the differential diagnosis of MOGAD particularly from aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder (AQP4-NMOSD), and multiple sclerosis (MS). Differentiating these conditions is of prime importance because the management is different between the three inflammatory diseases, and thus could prevent further attack-related disability. Therefore, identifying the MRI features suggestive of MOGAD has diagnostic and prognostic implications. We herein review optic nerve, spinal cord and the brain MRI findings from MOGAD adult patients, and compare them to AQP4-NMOSD and MS.

AQP4-IgG and MOG-IgG Related Optic Neuritis-Prevalence, Optical Coherence Tomography Findings, and Visual Outcomes: A Systematic Review and Meta-Analysis

Background: Optic neuritis (ON) is a cardinal manifestation of multiple sclerosis (MS), aquaporin-4 (AQP4)-IgG-, and myelin oligodendrocyte glycoprotein (MOG)-IgG-associated disease. However, the prevalence of AQP4-IgG seropositivity and MOG-IgG seropositivity in isolated ON is unclear, and studies comparing visual outcomes and optical coherence tomography (OCT)-derived structural retinal measures between MS-ON, AQP4-ON, and MOG-ON eyes are limited by small sample sizes. Objectives: (1) To assess the prevalence of AQP4-IgG and MOG-IgG seropositivity among patients presenting with isolated ON; (2) to compare visual outcomes and OCT measures between AQP4-ON, MOG-ON, and MS-ON eyes. Methods: In this systematic review and meta-analysis, a total of 65 eligible studies were identified by PubMed search. Statistical analyses were performed with random effects models. Results: In adults with isolated ON, AQP4-IgG seroprevalence was 4% in non-Asian and 27% in Asian populations, whereas MOG-IgG seroprevalence was 8 and 20%, respectively. In children, AQP4-IgG seroprevalence was 0.4% in non-Asian and 15% in Asian populations, whereas MOG-IgG seroprevalence was 47 and 31%, respectively. AQP4-ON eyes had lower peri-papillary retinal nerve fiber layer (pRNFL; -11.7 μm, 95% CI: -15.2 to -8.3 μm) and macular ganglion cell + inner plexiform layer (GCIPL; -9.0 μm, 95% CI: -12.5 to -5.4 μm) thicknesses compared with MS-ON eyes. Similarly, pRNFL (-11.2 μm, 95% CI: -21.5 to -0.9 μm) and GCIPL (-6.1 μm, 95% CI: -10.8 to -1.3 μm) thicknesses were lower in MOG-ON compared to MS-ON eyes, but did not differ between AQP4-ON and MOG-ON eyes (pRNFL: -1.9 μm, 95% CI: -9.1 to 5.4 μm; GCIPL: -2.6 μm, 95% CI: -8.9 to 3.8 μm). Visual outcomes were worse in AQP4-ON compared to both MOG-ON (mean logMAR difference: 0.60, 95% CI: 0.39 to 0.81) and MS-ON eyes (mean logMAR difference: 0.68, 95% CI: 0.40 to 0.96) but were similar in MOG-ON and MS-ON eyes (mean logMAR difference: 0.04, 95% CI: -0.05 to 0.14). Conclusions: AQP4-IgG- and MOG-IgG-associated disease are important diagnostic considerations in adults presenting with isolated ON, especially in Asian populations. Furthermore, MOG-IgG seroprevalence is especially high in pediatric isolated ON, in both non-Asian and Asian populations. Despite a similar severity of GCIPL and pRNFL thinning in AQP4-ON and MOG-ON, AQP4-ON is associated with markedly worse visual outcomes.

Differences in Advanced Magnetic Resonance Imaging in MOG-IgG and AQP4-IgG Seropositive Neuromyelitis Optica Spectrum Disorders: A Comparative Study

Aims: To explore differences in advanced brain magnetic resonance imaging (MRI) characteristics between myelin oligodendrocyte (MOG) immunoglobulin (IgG) and aquaporin-4 (AQP4) IgG seropositive (+) neuromyelitis optica spectrum disorders (NMOSD).

Methods: 33 AQP4-IgG and 18 MOG-IgG seropositive NMOSD patients and 61 healthy control (HC) subjects were included. All 112 participants were scanned with the same standardized MRI-protocol on a 3-Tesla MRI-scanner. Brain volume and diffusion tensor imaging (DTI) parameters were assessed.

Results: MOG-IgG+ patients showed reduced parallel diffusivity within white matter tracts compared to HC whereas AQP4-IgG+ showed no significant brain parenchymal damage in DTI analysis. AQP4-IgG+ patients showed reduced whole brain volumes and reduced volumes of several deep gray matter structures compared to HC whereas MOG-IgG+ patients did not show reduced brain or deep gray matter volumes compared to HC.

Conclusions: Microstructural brain parenchymal damage in MOG-IgG+ patients was more pronounced than in AQP4-IgG+ patients, compared with HC, whereas normalized brain volume reduction was more severe in AQP4-IgG+ patients. Longitudinal imaging studies are warranted to further investigate this trend in NMOSD. Our results suggest that MOG-IgG+ and AQP4-IgG+ NMOSD patients differ in cerebral MRI characteristics. Advanced MRI analysis did not help to differentiate between MOG-IgG+ and AQP4-IgG+ patients in our study.

Treatment of MOG-IgG-associated disorder with rituximab: An international study of 121 patients

OBJECTIVE

To assess the effect of anti-CD20 B-cell depletion with rituximab (RTX) on relapse rates in myelin oligodendrocyte glycoprotein antibody-associated disorder (MOGAD).

METHODS

Retrospective review of RTX-treated MOGAD patients from 29 centres in 13 countries. The primary outcome measure was change in relapse rate after starting rituximab (Poisson regression model).

RESULTS

Data on 121 patients were analysed, including 30 (24.8%) children. Twenty/121 (16.5%) were treated after one attack, of whom 14/20 (70.0%) remained relapse-free after median (IQR) 11.2 (6.3-14.1) months. The remainder (101/121, 83.5%) were treated after two or more attacks, of whom 53/101 (52.5%) remained relapse-free after median 12.1 (6.3-24.9) months. In this 'relapsing group', relapse rate declined by 37% (95%CI=19-52%, p<0.001) overall, 63% (95%CI=35-79%, p = 0.001) when RTX was used first line (n = 47), and 26% (95%CI=2-44%, p = 0.038) when used after other steroid-sparing immunotherapies (n = 54). Predicted 1-year and 2-year relapse-free survival was 79% and 55% for first-line RTX therapy, and 38% and 18% for second-/third-line therapy. Circulating CD19+B-cells were suppressed to <1% of total circulating lymphocyte population at the time of 45/57 (78.9%) relapses.

CONCLUSION

RTX reduced relapse rates in MOGAD. However, many patients continued to relapse despite apparent B-cell depletion. Prospective controlled studies are needed to validate these results.