The absence of antibodies in longitudinally extensive transverse myelitis may predict a more favourable prognosis

BACKGROUND

Isolated first episodes of longitudinally extensive transverse myelitis (LETM) have typically been associated with neuromyelitis optica spectrum disorder (NMOSD) or myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). However, in some cases, serological testing and screening for other aetiologies are negative, a condition referred to as double seronegative longitudinally extensive transverse myelitis (dsLETM).

OBJECTIVE

The objective of this study was to evaluate comparative outcomes of dsLETM, MOGAD-LETM and NMOSD-LETM.

METHODS

Cohort study of LETM cases seen in the UK NMOSD Highly Specialised Service between January 2008 and March 2022.

RESULTS

LETM = 87 cases were identified (median onset age = 46 years (15-85); median follow-up = 46 months (1-144); 47% NMOSD-LETM = 41 (aquaporin-4 antibodies (AQP4-IgG) positive = 36), 20% MOGAD-LETM = 17 and 33% dsLETM = 29). Despite similar Expanded Disability Status Scale (EDSS) at nadir, last EDSS was higher in AQP4-IgG and seronegative NMOSD-LETM (sNMOSD) (p = 0.006). Relapses were less common in dsLETM compared to AQP4-IgG NMOSD-LETM and sNMOSD-LETM (19% vs 60% vs 100%; p = 0.001). Poor prognosis could be predicted by AQP4-IgG (odds ratio (OR) = 38.86 (95% confidence interval (CI) = 1.36-1112.86); p = 0.03) and EDSS 3 months after onset (OR = 65.85 (95% CI = 3.65-1188.60); p = 0.005).

CONCLUSION

dsLETM remains clinically challenging and difficult to classify with existing nosological terminology. Despite a similar EDSS at nadir, patients with dsLETM relapsed less and had a better long-term prognosis than NMOSD-LETM.

Serum neurofilament and glial fibrillary acidic protein in idiopathic and seropositive transverse myelitis

BACKGROUND

Serum levels of neurofilament light chain (NfL) and glial fibrillary acidic protein (GFAP) reflect the disease activity and disability in central nervous system (CNS) demyelinating diseases. However, the clinical significance of NfL and GFAP in idiopathic transverse myelitis (iTM), an inflammatory spinal cord disease with unknown underlying causes, remains unclear. This study aimed to investigate NfL and GFAP levels in iTM and their association with the clinical parameters compared with those in TM with disease-specific antibodies such as anti-aquaporin 4 or myelin oligodendrocyte glycoprotein antibodies (sTM).

METHODS

We collected serum and clinical data of 365 patients with CNS inflammatory diseases from 12 hospitals. The serum NfL and GFAP levels were measured in patients with iTM (n = 37) and sTM (n = 39) using ultrasensitive single-molecule array assays. Regression analysis was performed to investigate the associations between serum levels of NfL and GFAP and the clinical parameters such as higher EDSS scores (EDSS ≥ 4.0).

RESULTS

Mean NfL levels were not significantly different between iTM (50.29 pg/ml) and sTM (63.18 pg/ml) (p = 0.824). GFAP levels were significantly lower in iTM (112.34 pg/ml) than in sTM (3814.20 pg/ml) (p = 0.006). NfL levels correlated with expanded disability status scale (EDSS) scores in sTM (p = 0.001) but not in iTM (p = 0.824). Disease duration also correlated with higher EDSS scores in sTM (p = 0.017).

CONCLUSION

NfL levels and disease duration correlated with EDSS scores in sTM, and GFAP levels could be a promising biomarker to differentiate iTM from sTM.

Neutrophil-to-lymphocyte ratio is an independent predictor for neurological disability in patients with idiopathic transverse myelitis

INTRODUCTION

The neutrophil-to-lymphocyte ratio (NLR) has been found to be useful in the prognostication of immune-mediated neurological disorders because it roughly reflects the systemic innate immune response compared to the adaptive immune response. However, studies on the validity of NLR in demyelinating disorders of the central nervous system have shown conflicting results. Therefore, we aimed to investigate NLR in the idiopathic transverse myelitis (ITM) cohort.

METHODS

We retrospectively analyzed the cohort data of patients with ITM between January 2006 and February 2020. The medical data of all patients with myelitis were reviewed to exclude patients with disease-associated myelopathy according to predefined exclusion criteria. The relationship between the natural log-transformed NLR (lnNLR) and the clinical, paraclinical, and imaging data was evaluated. Factors associated with neurological disability were analyzed using a linear mixed-effects model. Predictive factors for moderate-to-severe neurological disability (Expanded Disability Status Scale [EDSS] score ≥ 4) were investigated.

RESULTS

A total of 124 participants were included in the analysis. The lnNLR correlated with EDSS and lesion length. Linear mixed-effects analysis showed that age, lesion length, and lnNLR were independently associated with neurological disabilities. Multivariable logistic regression revealed that lnNLR (odds ratio [OR] = 4.266, 95% confidence interval [CI] = 1.220-14.912, p = 0.023) and lesion length (OR = 1.848, 95% CI = 1.249-2.734, p = 0.002) were independent predictive factors of the worst neurological disability.

CONCLUSION

NLR may be used as an independent prognostic factor for predicting poor neurological outcomes in patients with ITM.

Disease characteristics of idiopathic transverse myelitis with serum neuronal and astroglial damage biomarkers

Despite its close association with CNS inflammatory demyelinating disorders (CIDDs), pathogenic characteristics of idiopathic transverse myelitis (ITM) remain largely unknown. Here, we investigated serum levels of neurofilament light chain (sNfL) and glial fibrillary acidic protein (sGFAP) in patients with ITM to unravel the disease characteristics of ITM. We prospectively recruited 70 patients with ITM, 62 with AQP4 + NMOSD and 85 with RRMS-including 31 patients with acute TM attacks-along with 30 HCs. We measured sNfL and sGFAP levels using single-molecular arrays and compared these levels per lesion volume between the disease groups during attacks. Compared to HCs, ITM patients showed higher sNfL and sGFAP during acute attacks (sNfL: p < 0.001, sGFAP: p = 0.024), while those in remission (sNfL: p = 0.944, sGFAP: p > 0.999) did not, regardless of lesion extents and presence of multiple attacks. ITM patients demonstrated lower sGFAP/volume (p = 0.011) during acute attacks and lower sGFAP (p < 0.001) in remission compared to AQP4 + NMOSD patients. These findings suggest that both neuronal and astroglial damages occur in patients with acute ITM attacks at a similar level to those with RRMS, distinct from AQP4 + NMOSD. However, active neuroinflammatory process was not remarkable during remission in this cohort.

Glial fibrillary acidic protein as a biomarker in neuromyelitis optica spectrum disorder: a current review

INTRODUCTION

Neuromyelitis optica spectrum disorder (NMOSD) is a relapsing, often debilitating neuroinflammatory disease, whose predominant clinical manifestations are longitudinally extensive transverse myelitis and optic neuritis. About 80% of the patients with an NMOSD phenotype have pathogenic autoantibodies against the astrocyte water channel aquaporin-4 (AQP4-IgG). While therapeutic options for NMOSD have greatly expanded in recent years, well-established biomarkers for prognosis or treatment response are still lacking. Glial fibrillary acidic protein (GFAP) is mainly expressed in astrocytes and can be detected in cerebrospinal fluid (CSF) and blood of patients with NMOSD.

AREAS COVERED

Here, we comprehensively review the current knowledge on GFAP as a biomarker in NMOSD.

EXPERT OPINION

In patients with AQP4-IgG⁺ NMOSD, GFAP levels are elevated in CSF and serum during acute attacks and correlate with disability, consistent with the pathophysiology of this antibody-mediated astrocytopathy. Serum GFAP levels tend to be higher in AQP4-IgG⁺ NMOSD than in its differential diagnoses, multiple sclerosis, and myelin oligodendrocyte antibody-associated disease. Importantly, serum GFAP levels in AQP4-IgG⁺ NMOSD during remission may be predictive of future disease activity. Serial serum GFAP measurements are emerging as a biomarker to monitor disease activity in AQP4-IgG⁺ NMOSD and could have the potential for application in clinical practice.

Seroprevalence of anti-myelin oligodendrocyte glycoprotein antibodies in adults with myelitis

Although myelitis is the second most common presentation in adults with myelin oligodendrocyte glycoprotein (MOG) antibody‐associated disease (MOGAD), studies on MOG‐IgG seroprevalence in patients with myelitis episodes are sparse. Herein, we investigated MOG‐IgG seroprevalence in Korean adults who exhibited myelitis since 2017. Among 151 adults with acute myelitis, 11 (7.3%) tested positive for MOG‐IgG by the initial screening and 10 (6.6%) patients were finally diagnosed with MOGAD during the study period. This study is the first to provide data on MOG‐IgG seroprevalence in adults with myelitis and supports the clinical utility and importance of MOG‐IgG testing in myelitis episodes.

Clinical and Radiological Features of Myelin Oligodendrocyte Glycoprotein-Associated Myelitis in Adults

Antibodies against myelin oligodendrocyte glycoprotein (MOG-IgG) have recently been established as a biomarker for MOG-antibody-associated disease (MOGAD), which is a distinct demyelinating disease of the central nervous system. Among the diverse clinical phenotypes of MOGAD, myelitis is the second-most-common presentation in adults, followed by optic neuritis. While some features overlap, there are multiple reports of distinctive clinical and radiological features of MOG-IgG-associated myelitis, which are useful for differentiating MOGAD from both multiple sclerosis and neuromyelitis optica spectrum disorder. In this review we summarize the clinical and radiographic characteristics of MOG-IgG-associated myelitis with a particular focus on adult patients.

Magnetic resonance imaging in neuromyelitis optica spectrum disorder

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory disease of the central nervous system (CNS) associated with antibodies to aquaporin-4 (AQP4), which has distinct clinical, radiological and pathological features, but also has some overlap with multiple sclerosis and myelin oligodendrocyte glycoprotein (MOG) antibody associated disease. Early recognition of NMOSD is important because of differing responses to both acute and preventive therapy. Magnetic resonance (MR) imaging has proved essential in this process. Key MR imaging clues to the diagnosis of NMOSD are longitudinally extensive lesions of the optic nerve (more than half the length) and spinal cord (three or more vertebral segments), bilateral optic nerve lesions and lesions of the optic chiasm, area postrema, floor of the IV ventricle, periaqueductal grey matter, hypothalamus and walls of the III ventricle. Other NMOSD-specific lesions are denoted by their unique morphology: heterogeneous lesions of the corpus callosum, 'cloud-like' gadolinium (Gd)-enhancing white matter lesions and 'bright spotty' lesions of the spinal cord. Other lesions described in NMOSD, including linear periventricular peri-ependymal lesions and patch subcortical white matter lesions, may be less specific. The use of advanced MR imaging techniques is yielding further useful information regarding focal degeneration of the thalamus and optic radiation in NMOSD and suggests that paramagnetic rim patterns and changes in normal appearing white matter are specific to MS. MR imaging is crucial in the early recognition of NMOSD and in directing testing for AQP4 antibodies and guiding immediate acute treatment decisions. Increasingly, MR imaging is playing a role in diagnosing seronegative cases of NMOSD.

Review of approved NMO therapies based on mechanism of action, efficacy and long-term effects

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Neuromyelitis optica (NMO - including NMO spectrum disorders [NMOSD]) is a devastating disease.

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Up until recently, there was no proven agent to treat to prevent relapses.

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We now have three agents indicated for the treatment of NMO.

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We might suggest the following sequence – 1st line using eculizumab for rapid efficacy and stabilization without effect on the acquired immune system followed by satrilizumab (long term immunomodulation).

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Reserve inebilizumab (immunosuppressant) for breakthrough disease and salvage the severe with AHSCBMT.

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In NMO, control the complement, transition to modulation, and reserve suppression – and salvage the severe with AHSCBMT.

Importance

Neuromyelitis optica (NMO - including NMO spectrum disorders [NMOSD]) is a devastating disease. Eighty-three percent of patients with transverse myelitic (TM) attacks and 67% of patients with optic neuritis (ON) attacks have no or a partial recovery.

Observations

Up until recently, there was no proven agent to treat to prevent relapses. The neuro-immunological community had a dearth of indicated agents for NMOSD. We now have three agents indicated for the treatment of NMO including (eculizumab [Soliris®]), an anti-C5 complement inhibitor, satralizumab (ENSRYNG®), a monoclonal antibody against the IL-6 receptor (IL-6R) that blocks B cell antibody production and inebilizumab (Uplinza®), a monoclonal antibody that binds to the B-cell surface antigen CD19 with subsequent B and plasmablast cell lymphocytolysis with decreasing antibody production. Autologous hematopoietic stem cell bone marrow transplantation (AHSCBMT) has also been used. How do we sequence NMO therapies with the understanding of the acuteness and severity of the disease, the individual mechanism of action (MOA) and rapidity of onset of action, onset of efficacy and long-term safety of each agent?

Conclusions and Relevance

We might suggest the following sequence – 1st line using eculizumab for rapid efficacy and stabilization without effect on the acquired immune system followed by satrilizumab (long term immunomodulation). Reserve inebilizumab (immunosuppressant) for breakthrough disease and salvage the severe with AHSCBMT. In NMO, control the complement, transition to modulation, and reserve suppression – and salvage the severe with AHSCBMT.

Outcome and risk of recurrence in a large cohort of idiopathic longitudinally extensive transverse myelitis without AQP4/MOG antibodies

Background

Longitudinally extensive transverse myelitis (LETM) is classically related to aquaporin (AQP4)-antibodies (Ab) neuromyelitis optica spectrum disorders (NMOSD) or more recently to myelin oligodendrocyte glycoprotein (MOG)-Ab associated disease. However, some patients remain negative for any diagnosis, despite a large work-up including AQP4-Ab and MOG-Ab. Data about natural history, disability outcome, and treatment are limited in this group of patients.

We aimed to (1) describe clinical, biological, and radiological features of double seronegative LETM patients; (2) assess the clinical course and identify prognostic factors; and (3) assess the risk of recurrence, according to maintenance immunosuppressive therapy.

Methods

Retrospective evaluation of patients with a first episode of LETM, tested negative for AQP-Ab and MOG-Ab, from the French nationwide observatory study NOMADMUS.

Results

Fifty-three patients (median age 38 years (range 16–80)) with double seronegative LETM were included. Median nadir EDSS at onset was 6.0 (1–8.5), associated to a median EDSS at last follow-up of 4.0 (0–8). Recurrence was observed in 24.5% of patients in the 18 following months, with a median time to first relapse of 5.7 months. The risk of recurrence was lower in the group of patients treated early with an immunosuppressive drug (2/22, 9%), in comparison with untreated patients (10/31, 32%).

Conclusions

A first episode of a double seronegative LETM is associated to a severe outcome and a high rate of relapse in the following 18 months, suggesting that an early immunosuppressive treatment may be beneficial in that condition.

Neuromyelitis optica spectrum disorders: Features of aquaporin-4, myelin oligodendrocyte glycoprotein and double-seronegative-mediated subtypes

The new diagnostic classification of neuromyelitis optica spectrum disorder (NMOSD) in 2015 highlights the central role of biomarkers, such as antibodies against aquaporin-4 (AQP4-Ab), in diagnosis. Also, in approximately 20-25% of patients without AQP4-Ab (NMOSD^AQP4-) the presence of an antibody directed against myelin oligodendrocyte glycoprotein (MOG) characterizes a specific population of NMOSD patients (NMOSD^MOG+), according to their demographic and clinical data and prognoses. While double-seronegative cases (NMOSD^NEG) have not been fully described, they may correspond to the very first patients with opticospinal demyelination reported by Devic and Gault in 1894. The present report reviews the current knowledge of the pathophysiology and clinical features of NMOSD^AQP4+, NMOSD^MOG+ and NMOSD^NEG patients, and also discusses the relationship between the extended spectrum of MOG disease and NMOSD^MOG+. Finally, the current treatments for acute relapses and relapse prevention are described, with a focus on serological-based therapeutic responses and the promising new therapeutic targets.

MOG-IgG-Associated Optic Neuritis, Encephalitis, and Myelitis: Lessons Learned From Neuromyelitis Optica Spectrum Disorder

Antibodies against myelin oligodendrocyte glycoprotein (MOG-IgG) have been found in some cases diagnosed as seronegative neuromyelitis optica spectrum disorder (NMOSD). MOG-IgG allowed the identification of a subgroup with a clinical course distinct from that of NMOSD patients who are seropositive for aquaporin-4-IgG antibodies. MOG-IgG is associated with a wider clinical phenotype, not limited to NMOSD, with the majority of cases presenting with optic neuritis (ON), encephalitis with brain demyelinating lesions, and/or myelitis. Therefore, we propose the term MOG-IgG-associated Optic Neuritis, Encephalitis, and Myelitis (MONEM). Depending on the clinical characteristics, these patients may currently be diagnosed with NMOSD, acute disseminated encephalomyelitis, pediatric multiple sclerosis, transverse myelitis, or ON. With specific cell-based assays, MOG-IgG is emerging as a potential biomarker of inflammatory disorders of the central nervous system. We review the growing body of evidence on MONEM, focusing on its clinical aspects.

Central nervous system neuroinflammatory disorders in Asian/Pacific regions

PURPOSE OF REVIEW

The discovery of aquaporin-4 (AQP4) antibodies with high specificity for neuromyelitis optica spectrum disorder (NMOSD) has induced tremendous changes in the approach and management of central nervous system (CNS) neuroinflammatory disorders. Owing to the increasing availability of the AQP4 antibody assay and evolution of diagnostic criteria for multiple sclerosis and NMOSD, recent studies have reevaluated CNS neuroinflammatory disorders. This review describes recent advances in the understanding of CNS neuroinflammatory disorders in Asian/Pacific regions.

RECENT FINDINGS

Although multiple sclerosis prevalence is lower in Asian countries than in Western countries, the overall clinical features of multiple sclerosis are comparable between these countries. Hospital-based studies have reported that the frequency of NMOSD is higher in Asian populations (22-42%) than in white populations (2-26%). Despite improvements in the AQP4 antibody assay, AQP4 antibodies are not detected in certain patients with NMOSD. Recently, myelin oligodendrocyte glycoprotein (MOG) antibodies have been identified in AQP4 antibody-negative patients with the NMOSD phenotype, and the clinical features differ slightly between MOG antibody-positive patients and AQP4 antibody-positive patients.

SUMMARY

The understanding of CNS neuroinflammatory disorders in Asian/Pacific regions continues to evolve owing to the discovery of new biological markers and recognition of broader clinical phenotypes.

Pattern Recognition of the Multiple Sclerosis Syndrome

During recent decades, the autoimmune disease neuromyelitis optica spectrum disorder (NMOSD), once broadly classified under the umbrella of multiple sclerosis (MS), has been extended to include autoimmune inflammatory conditions of the central nervous system (CNS), which are now diagnosable with serum serological tests. These antibody-mediated inflammatory diseases of the CNS share a clinical presentation to MS. A number of practical learning points emerge in this review, which is geared toward the pattern recognition of optic neuritis, transverse myelitis, brainstem/cerebellar and hemispheric tumefactive demyelinating lesion (TDL)-associated MS, aquaporin-4-antibody and myelin oligodendrocyte glycoprotein (MOG)-antibody NMOSD, overlap syndrome, and some yet-to-be-defined/classified demyelinating disease, all unspecifically labeled under MS syndrome. The goal of this review is to increase clinicians’ awareness of the clinical nuances of the autoimmune conditions for MS and NMSOD, and to highlight highly suggestive patterns of clinical, paraclinical or imaging presentations in order to improve differentiation. With overlay in clinical manifestations between MS and NMOSD, magnetic resonance imaging (MRI) of the brain, orbits and spinal cord, serology, and most importantly, high index of suspicion based on pattern recognition, will help lead to the final diagnosis.

Myelin Oligodendrocyte Glycoprotein: Deciphering a Target in Inflammatory Demyelinating Diseases

Myelin oligodendrocyte glycoprotein (MOG), a member of the immunoglobulin (Ig) superfamily, is a myelin protein solely expressed at the outermost surface of myelin sheaths and oligodendrocyte membranes. This makes MOG a potential target of cellular and humoral immune responses in inflammatory demyelinating diseases. Due to its late postnatal developmental expression, MOG is an important marker for oligodendrocyte maturation. Discovered about 30 years ago, it is one of the best-studied autoantigens for experimental autoimmune models for multiple sclerosis (MS). Human studies, however, have yielded controversial results on the role of MOG, especially MOG antibodies (Abs), as a biomarker in MS. But with improved detection methods using different expression systems to detect Abs in patients' samples, this is meanwhile no longer the case. Using cell-based assays with recombinant full-length, conformationally intact MOG, several recent studies have revealed that MOG Abs can be found in a subset of predominantly pediatric patients with acute disseminated encephalomyelitis (ADEM), aquaporin-4 (AQP4) seronegative neuromyelitis optica spectrum disorders (NMOSD), monophasic or recurrent isolated optic neuritis (ON), or transverse myelitis, in atypical MS and in N-methyl-d-aspartate receptor-encephalitis with overlapping demyelinating syndromes. Whereas MOG Abs are only transiently observed in monophasic diseases such as ADEM and their decline is associated with a favorable outcome, they are persistent in multiphasic ADEM, NMOSD, recurrent ON, or myelitis. Due to distinct clinical features within these diseases it is controversially disputed to classify MOG Ab-positive cases as a new disease entity. Neuropathologically, the presence of MOG Abs is characterized by MS-typical demyelination and oligodendrocyte pathology associated with Abs and complement. However, it remains unclear whether MOG Abs are a mere inflammatory bystander effect or truly pathogenetic. This article provides deeper insight into recent developments, the clinical relevance of MOG Abs and their role in the immunpathogenesis of inflammatory demyelinating disorders.

Short segment myelitis as a first manifestation of neuromyelitis optica spectrum disorders

BACKGROUND

Some patients with neuromyelitis optica spectrum disorders (NMOSD) present with spinal cord lesions extending fewer than three vertebral segments (short transverse myelitis, STM), hindering an early diagnosis.

OBJECTIVE

We investigated the frequency and imaging characteristics of STM lesions in patients presenting with myelitis as an initial manifestation of NMOSD.

METHODS

Patients seen at three referral hospitals in Korea between June 2005 and March 2015 who met the following inclusion criteria were recruited for review: seropositivity for aquaporin-4 antibody, initial presentation with myelitis and spinal cord magnetic resonance imaging (MRI) performed within 1 month of initial myelitis onset.

RESULTS

Of the 76 enrolled patients, 65 (85.5%) collectively had 69 longitudinally extensive transverse myelitis lesions, while the remaining 11 (14.5%) had a total of 15 STM lesions. Of the 15 STM lesions, 5 spanned 2.5 vertebral segments, 6 were continuous over two segments, 3 showed a length of 1.5 segments and 1 was confined to a single segment. On axial imaging, all of the STM lesions involved the central grey matter.

CONCLUSION

These MRI findings suggested that STM does not preclude the possibility of an NMOSD diagnosis.

Disease Type- and Status-Specific Alteration of CSF Metabolome Coordinated with Clinical Parameters in Inflammatory Demyelinating Diseases of CNS

Central nervous system (CNS) inflammatory demyelinating diseases (IDDs) are a group of disorders with different aetiologies, characterized by inflammatory lesions. These disorders include multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), and idiopathic transverse myelitis (ITM). Differential diagnosis of the CNS IDDs still remains challenging due to frequent overlap of clinical and radiological manifestation, leading to increased demands for new biomarker discovery. Since cerebrospinal fluid (CSF) metabolites may reflect the status of CNS tissues and provide an interfacial linkage between blood and CNS tissues, we explored multi-component biomarker for different IDDs from CSF samples using gas chromatography mass spectrometry-based metabolite profiling coupled to multiplex bioinformatics approach. We successfully constructed the single model with multiple metabolite variables in coordinated regression with clinical characteristics, expanded disability status scale, oligoclonal bands, and protein levels. The multi-composite biomarker simultaneously discriminated four different immune statuses (a total of 145 samples; 54 MS, 49 NMOSD, 30 ITM, and 12 normal controls). Furthermore, systematic characterization of transitional metabolic modulation identified relapse-associated metabolites and proposed insights into the disease network underlying type-specific metabolic dysfunctionality. The comparative analysis revealed the lipids, 1-monopalmitin and 1-monostearin were common indicative for MS, NMOSD, and ITM whereas fatty acids were specific for the relapse identified in all types of IDDs.

Evaluation of the 2015 diagnostic criteria for neuromyelitis optica spectrum disorder

OBJECTIVE

To evaluate the application of the 2015 International Panel for NMO Diagnosis (IPND) criteria to consecutive cases of neuromyelitis optica spectrum disorder (NMOSD) in a large cohort of individuals with CNS inflammatory diseases.

METHODS

In total, 594 patients with CNS inflammatory diseases were included. Rigorous confirmation of the patients' aquaporin-4 immunoglobulin G antibodies (AQP4-IgG) status throughout the disease duration (mean 9.2 ± 5.7 years) using repeated assays, including ELISA and cell-based assay, was performed.

RESULTS

A total of 252 patients fulfilled the IPND criteria (AQP4-IgG positive: 226 [90%], AQP4-IgG negative: 26 [10%]). Of these, 136 (54%) patients met the 2006 neuromyelitis optica criteria. When we assumed an unknown AQP4-IgG status in the confirmed NMOSD group with AQP4-IgG, 162 of 226 (72%) patients with AQP4-IgG were classified as having NMOSD by the IPND criteria. The majority of patients were diagnosed with NMOSD within 2 years of onset (73%) or after a second attack (72%). Acute myelitis (83%) and optic neuritis (65%) were the most common clinical features throughout the disease duration. Optic neuritis (42%) was the most common initial manifestation, followed by acute myelitis (38%) and area postrema syndrome (14%).

CONCLUSIONS

The IPND criteria well-reflected the broader clinical spectrum of NMOSD and markedly improved the diagnostic yield compared to the previous criteria, even in patients with an unknown AQP4-IgG status.

Antibodies to myelin oligodendrocyte glycoprotein in aquaporin 4 antibody seronegative longitudinally extensive transverse myelitis: Clinical and prognostic implications

Objective:

We aimed to investigate the frequency and clinical significance of antibodies to myelin oligodendrocyte glycoprotein (MOG-abs) in patients who presented with a first episode of seronegative aquaporin 4 antibody (AQP4-ab) longitudinally extensive transverse myelitis (LETM).

Methods:

Epidemiological, clinical, and paraclinical data of 56 patients from three European centres were analysed. Patients were retrospectively tested for MOG-abs and AQP4-abs, by cell-based assays.

Findings:

Thirteen (23.2%) patients were MOG-ab positive. Among the 56 patients, six (10.7%) converted to neuromyelitis optica (NMO), one (1.8%) to multiple sclerosis (MS), nine (16.1%) had recurrent LETM, and 40 (71.4%) remained as monophasic LETM. Compared with seronegative patients, those with MOG-abs were younger (median: 32.5 vs 44 years; p=0.007), had cerebrospinal fluid pleocytosis more frequently (94% vs 45%, p=0.003) and had better outcome (median Expanded Disability Status Scale (EDSS) 2.0 vs 3.0, p=0.027). MOG-ab positive patients also showed an increase risk of optic neuritis relapse and NMO conversion ( p=0.010).

Conclusion:

Patients with MOG-abs in AQP4-ab seronegative LETM have clinical distinctive features, higher risk of optic neuritis relapses, and better outcome than patients seronegative.