Retinal Optical Coherence Tomography in Neuromyelitis Optica

Diagnostic Value of Inter-Eye Difference Metrics on OCT for Myelin Oligodendrocyte Glycoprotein Antibody-Associated Optic Neuritis

BACKGROUND AND OBJECTIVES

The 2022 International Consortium for Optic Neuritis diagnostic criteria for optic neuritis (ON) include optical coherence tomography (OCT). The diagnostic value of intereye difference (IED) metrics is high for ON in patients with multiple sclerosis and aquaporin-4 antibody seropositive neuromyelitis optica spectrum disorders, but unknown in myelin oligodendrocyte glycoprotein antibody-associated ON (MOG-ON).

METHODS

A multicenter validation study was conducted on the published IED cutoff values (>4% or >4 μm in the macular ganglion cell and inner plexiform layer [mGCIP] or >5% or >5 μm in the peripapillary retinal nerve fiber layer [pRNFL]) in individuals with MOG-ON and age-matched and sex-matched healthy controls (HCs). Structural data were acquired with Spectralis spectral-domain OCT >6 months after ON. We calculated sensitivity, specificity, and receiver operating characteristics for both intereye percentage (IEPD) and absolute difference (IEAD).

RESULTS

A total of 66 individuals were included (MOG-ON N = 33; HCs N = 33). ON was unilateral in 20 and bilateral in 13 subjects. In the pooled analysis, the mGCIP IEPD was most sensitive (92%), followed by the mGCIP IEAD (88%) and pRNFL (84%). The same pattern was found for the specificity (mGCIP IEPD 82%, IEAD 82%; pRNFL IEPD 82%, IEAD 79%).In subgroup analyses, the diagnostic sensitivity was higher in subjects with unilateral ON (>99% for all metrics) compared with bilateral ON (61%-78%).

DISCUSSION

In individuals with MOG-ON, the diagnostic accuracy of OCT-based IED metrics for ON was high, especially of mGCIP IEPD.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that the intereye difference on OCT can distinguish between those with MOG and normal controls.

Relapse-Independent disease activity in neuromyelitis optica spectrum disorder: A systematic review

INTRODUCTION

Neuromyelitis Optica Spectrum Disorders (NMOSD) is a neuroinflammatory condition characterized by optic neuritis and transverse myelitis. While the current approach to NMOSD focuses on relapse-associated worsening (RAW), recent evidence indicates Relapse-Independent Disease Activity (RIDA) in patients.

METHOD

Databases including Embase, PubMed, Scopus, and Web of Sciences were systematically searched up to December 2023. No restrictions were applied. Inclusion criteria focused on studies reporting evidence of RIDA in NMOSD patients. Data extraction involved details such as study title, author, participant characteristics, treatment, evaluation methods, positive findings according to RIDA, and prevalence of findings in NMOSD patients. This study is conducted following the PRISMA guidelines with a registered protocol on PROSPERO (ID = CRD42023492352).

RESULT

Of 802 studies, 38 were included in the systematic review, covering 1881 NMOSD patients. AQP4-IGg status was positive in 90.6 % of the patients. Ocular findings indicative of RIDA were reported in 23 studies, including thinning of GCIPL, RNFL, GCC, and GCL layers, foveal and macular shape and volume abnormalities, vessel loss, and visual evoked potentials (VEPs) abnormalities. MRI findings supporting the RIDA were reported in 13 studies, including new lesion incidence and brain and spinal cord atrophy. Serum and CSF RIDA-supporting findings were reported in five studies, including elevation in sGFAP and sNFL. Biopsies and autopsies suggested inflammatory processes in relapse-free patients in 2 studies. The predominant manifestation of RIDA in NMOSD was identified in the visual system, suggesting the impaired retinal glial cells like Müller cells during the relapse-free period in NMOSD.

INTERPRETATION

Our systematic review provides valuable insights into RIDA in NMOSD. Establishing guidelines for the diagnosis and treatment of RIDA is crucial. Further studies are needed to provide robust evidence on RIDA in NMOSD patients.

NMOSD and MOGAD: an evolving disease spectrum

Neuromyelitis optica (NMO) spectrum disorder (NMOSD) is a relapsing inflammatory disease of the CNS, characterized by the presence of serum aquaporin 4 (AQP4) autoantibodies (AQP4-IgGs) and core clinical manifestations such as optic neuritis, myelitis, and brain or brainstem syndromes. Some people exhibit clinical characteristics of NMOSD but test negative for AQP4-IgG, and a subset of these individuals are now recognized to have serum autoantibodies against myelin oligodendrocyte glycoprotein (MOG) - a condition termed MOG antibody-associated disease (MOGAD). Therefore, the concept of NMOSD is changing, with a disease spectrum emerging that includes AQP4-IgG-seropositive NMOSD, MOGAD and double-seronegative NMOSD. MOGAD shares features with NMOSD, including optic neuritis and myelitis, but has distinct pathophysiology, clinical profiles, neuroimaging findings (including acute disseminated encephalomyelitis and/or cortical encephalitis) and biomarkers. AQP4-IgG-seronegative NMOSD seems to be a heterogeneous condition and requires further study. MOGAD can manifest as either a monophasic or a relapsing disease, whereas NMOSD is usually relapsing. This Review summarizes the history and current concepts of NMOSD and MOGAD, comparing epidemiology, clinical features, neuroimaging, pathology and immunology. In addition, we discuss new monoclonal antibody therapies for AQP4-IgG-seropositive NMOSD that target complement, B cells or IL-6 receptors, which might be applied to MOGAD in the near future.

Retinal Changes in Double-Antibody Seronegative Neuromyelitis Optica Spectrum Disorders

BACKGROUND AND OBJECTIVES

To systematically describe the clinical picture of double-antibody seronegative neuromyelitis optica spectrum disorders (DN-NMOSD) with specific emphasis on retinal involvement.

METHODS

Cross-sectional data of 25 people with DN-NMOSD (48 eyes) with and without a history of optic neuritis (ON) were included in this study along with data from 25 people with aquaporin-4 antibody seropositive neuromyelitis optica spectrum disorder (AQP4-NMOSD, 46 eyes) and from 25 healthy controls (HCs, 49 eyes) for comparison. All groups were matched for age and sex and included from the collaborative retrospective study of retinal optical coherence tomography (OCT) in neuromyelitis optica (CROCTINO). Participants underwent OCT with central postprocessing and local neurologic examination and antibody testing. Retinal neurodegeneration was quantified as peripapillary retinal nerve fiber layer thickness (pRNFL) and combined ganglion cell and inner plexiform layer thickness (GCIPL).

RESULTS

This DN-NMOSD cohort had a history of [median (inter-quartile range)] 6 (5; 9) attacks within their 5 ± 4 years since onset. Myelitis and ON were the most common attack types. In DN-NMOSD eyes after ON, pRNFL (p < 0.001) and GCIPL (p = 0.023) were thinner compared with eyes of HCs. Even after only one ON episode, DN-NMOSD eyes already had considerable neuroaxonal loss compared with HCs. In DN-NMOSD eyes without a history of ON, pRNFL (p = 0.027) and GCIPL (p = 0.022) were also reduced compared with eyes of HCs. However, there was no difference in pRNFL and GCIPL between DN-NMOSD and AQP4-NMOSD for the whole group and for subsets with a history of ON and without a history of ON-as well as between variances of retinal layer thicknesses.

DISCUSSION

DN-NMOSD is characterized by severe retinal damage after ON and attack-independent retinal neurodegeneration. Most of the damage occurs during the first ON episode, which highlights the need for better diagnostic markers in DN-NMOSD to facilitate an earlier diagnosis as well as for effective and early treatments. In this study, people with DN-NMOSD presented with homogeneous clinical and imaging findings potentially suggesting a common retinal pathology in these patients.

Patterns of cerebral damage in multiple sclerosis and aquaporin-4 antibody-positive neuromyelitis optica spectrum disorders-major differences revealed by non-conventional imaging

Multiple sclerosis and aquaporin-4 antibody neuromyelitis optica spectrum disorders are distinct autoimmune CNS disorders with overlapping clinical features but differing pathology. Multiple sclerosis is primarily a demyelinating disease with the presence of widespread axonal damage, while neuromyelitis optica spectrum disorders is characterized by astrocyte injury with secondary demyelination. Diagnosis is typically based on lesion characteristics observed on standard MRI imaging and antibody testing but can be challenging in patients with in-between clinical presentations. Non-conventional MRI techniques can provide valuable diagnostic information by measuring disease processes at the microstructural level. We used non-conventional MRI to measure markers of axonal loss in specific white matter tracts in multiple sclerosis and neuromyelitis optica spectrum disorders, depending on their relationship with focal lesions. Patients with relapsing-remitting multiple sclerosis (n = 20), aquaporin-4 antibody-associated neuromyelitis optica spectrum disorders (n = 20) and healthy controls (n = 20) underwent a 3T brain MRI, including T1-, T2- and diffusion-weighted sequences, quantitative susceptibility mapping and phase-sensitive inversion recovery sequence. Tractometry was used to differentiate tract fibres traversing through white matter lesions from those that did not. Neurite density index was assessed using neurite orientation dispersion and density imaging model. Cortical damage was evaluated using T1 relaxation rates. Cortical lesions and paramagnetic rim lesions were identified using phase-sensitive inversion recovery and quantitative susceptibility mapping. In tracts traversing lesions, only one out of 50 tracts showed a decreased neurite density index in multiple sclerosis compared with neuromyelitis optica spectrum disorders. Among 50 tracts not traversing lesions, six showed reduced neurite density in multiple sclerosis (including three in the cerebellum and brainstem) compared to neuromyelitis optica spectrum disorders. In multiple sclerosis, reduced neurite density was found in the majority of fibres traversing (40/50) and not traversing (37/50) white matter lesions when compared to healthy controls. A negative correlation between neurite density in lesion-free fibres and cortical lesions, but not paramagnetic rim lesions, was observed in multiple sclerosis (39/50 tracts). In neuromyelitis optica spectrum disorders compared to healthy controls, decreased neurite density was observed in a subset of fibres traversing white matter lesions, but not in lesion-free fibres. In conclusion, we identified significant differences between multiple sclerosis and neuromyelitis optica spectrum disorders corresponding to their distinct pathologies. Specifically, in multiple sclerosis, neurite density reduction was widespread across fibres, regardless of their relationship to white matter lesions, while in neuromyelitis optica spectrum disorders, this reduction was limited to fibres passing through white matter lesions. Further studies are needed to evaluate the discriminatory potential of neurite density measures in white matter tracts for differentiating multiple sclerosis from neuromyelitis optica spectrum disorders.

Retinal structural thicknesses reflect clinically relevant microstructural white matter abnormalities in neuromyelitis optica spectrum disorders

BACKGROUND

Thinning of retinal thickness seen on optical coherence tomography (OCT) is frequent in patients with neuromyelitis optica spectrum disorder (NMOSD). We explored the association between OCT metrics, MRI measurements and clinical outcomes in NMOSD.

METHODS

44 NMOSD and 60 controls underwent OCT and MR imaging. Mean peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell complex (GCC) thicknesses were measured. Diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI) was used to measure the white matter microstructural integrity. In NMOSD patients, Expanded Disability Status Scale (EDSS) was used to quantify disability. Visual acuity (VA) was also performed for all participants.

RESULTS

pRNFL thickness was positively associated with mean diffusivity in left posterior thalamic radiation (pp = 0.010) and axial kurtosis in inferior cerebellar peduncle (p = 0.023). Similarly, GCC thickness in NMOSD patients was positively associated with fractional anisotropy in right superior longitudinal fascicules (p = 0. 041) and axial kurtosis of left cerebellar peduncle (p = 0.011).

CONCLUSIONS

In NMOSD, pRNFL and GCC reflect integrity of clinically relevant white matter structures underlying the value of OCT metrics as markers of neuronaxonal loss and disability.

Efficacy and safety of mycophenolate mofetil for steroid reduction in neuromyelitis optica spectrum disorder: a prospective cohort study

Neuromyelitis optica spectrum disorder (NMOSD) is a rare autoimmune inflammatory disease that can affect multiple generations and cause complications with long-term prednisolone treatment. This study aimed to evaluate the efficacy and safety of mycophenolate mofetil (MMF) in preventing NMOSD relapse while reducing prednisolone dosage. The trial involved nine patients with NMOSD who received MMF along with prednisolone dose reduction. MMF was effective in achieving prednisolone dose reduction without relapse in 77.8% of patients, with a significant decrease in mean annualized relapse rate. All adverse events were mild. The findings suggest that MMF could be a viable treatment option for middle-aged and older patients who require steroid reduction.Clinical trial registration number: jRCT, jRCTs051180080. Registered February 27th, 2019-retrospectively registered, https://jrct.niph.go.jp/en-latest-detail/jRCTs051180080.

Trans-Synaptic Degeneration in the Visual Pathway in Patients With Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease

BACKGROUND AND OBJECTIVES

We aimed to assess the presence of retinal neurodegeneration independent of optic neuritis (ON) in myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) and to investigate the development of trans-synaptic anterograde degeneration in these patients after ON.

METHODS

Cross-sectional, retrospective study of 34 adult patients with MOGAD and 23 healthy controls (HC). Clinical, optical coherence tomography (OCT), and MRI data were collected. Peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell inner plexiform layer (GCIPL) were obtained using Heidelberg Spectralis. FreeSurfer7 was used to obtain the lateral geniculate nucleus (LGN), occipital volume fractions (to total estimated intracranial volume), and occipital cortical thickness. For the anterior visual pathway, the analysis was conducted using eyes, classified based on the history of ON (Eye-ON and Eye-NON) and compared with Eye-HC. The analysis of OCT and brain volumetric measures was conducted comparing MOGAD-ON, MOGAD-NON, and HC groups. The analysis of covariance with a Bonferroni-adjusted post hoc test was used to test differences between groups and linear regression analysis to evaluate OCT/MRI associations; age and sex were considered as covariates.

RESULTS

24 (70.5%) patients had a prior ON. Median pRNFL and GCIPL thickness (um) was significantly reduced in Eye-ON vs EyeNON and HC (pRNFL: 69.4 (17.3), 89.6 (13.7), 98.2 (11.7), p < 0.001; GCIPL: 55.8 (8.7), 67.39 (8.7), 72.6 (4.5), p < 0.001). pRNFL and GCIPL thickness had a negative correlation with the number of ON episodes (p = 0.025 and p = 0.031, respectively). LGN volume fraction was significantly lower in patients with MOGAD-ON than in HC (0.33 (0.05) vs 0.39 (0.04), p = 0.002). The occipital cortical thickness was lower in MOGAD-ON compared with MOGAD-NON and HC (p = 0.010). In patients with MOGAD-ON, pRNFL correlated with LGN volume (p = 0.006), occipital thickness (p = 0.002), and the medial occipital cortex (p = 0.002), but not the lateral occipital lobe.

DISCUSSION

Compared with HC, MOGAD-ON exhibits reduced retinal thickness, primarily influenced by the presence and the number of prior ON episodes. Moreover, MOGAD-ON demonstrates significant atrophy in the retinal, subcortical, and cortical regions of the visual pathway, distinguishing them from MOGAD-NON and HC. These findings suggest that in patients with MOGAD neurodegeneration is tightly correlated with damage to the involved pathway.

Retinal structure and vessel density changes in cerebral small vessel disease

Background

Cerebral small vessel disease (CSVD) attaches people's attention in recent years. In this study, we aim to explore retinal structure and vessel density changes in CSVD patients.

Methods

We collected information on retinal metrics assessed by optical coherence tomography (OCT) and OCT angiography and CSVD characters. Logistic and liner regression was used to analyze the relationship between retinal metrics and CSVD.

Results

Vessel density of superficial retinal capillary plexus (SRCP), foveal density- 300 length (FD-300), radial peripapillary capillary (RPC) and thickness of retina were significantly lower in CSVD patients, the difference only existed in the thickness of retina after adjusted relevant risk factors (OR (95% CI): 0.954 (0.912, 0.997), p = 0.037). SRCP vessel density showed a significant downward trend with the increase of CSVD scores (β: -0.087, 95%CI: -0.166, -0.008, p = 0.031). SRCP and FD-300 were significantly lower in patients with lacunar infarctions and white matter hypertensions separately [OR (95% CI): 0.857 (0.736, 0.998), p = 0.047 and OR (95% CI): 0.636 (0.434, 0.932), p = 0.020, separately].

Conclusion

SRCP, FD-300 and thickness of retina were associated with the occurrence and severity of total CSVD scores and its different radiological manifestations. Exploring CSVD by observing alterations in retinal metrics has become an optional research direction in future.

[Optical coherence tomography angiography in the diagnosis of multiple sclerosis]

PURPOSE

This study analyzes the main changes in retinal microcirculation in patients with multiple sclerosis (MS) and their relationship with the type of disease course.

MATERIAL AND METHODS

159 patients (318 eyes) were examined. The groups were formed according to the type of course and duration of MS: group 1 - 37 patients (74 eyes; 23.27%) with relapsing-remitting MS (RRMS) less than 1 year; group 2 - 47 patients (94 eyes; 29.56%) with RRMS from 1 year to 10 years; group 3 - 44 patients (86 eyes; 27.05%) with RRMS >10 years; group 4 - 32 patients (64 eyes; 20.12%) with secondary progressive MS (SPMS). Subgroups A and B were allocated within each group depending on the absence or presence of optic neuritis (ON). Patients underwent standard ophthalmological examination, including optical coherence tomography angiography (OCTA).

RESULTS

A decrease in the vessel density (wiVD) and perfusion density (wiPD) in the macular and peripapillary regions was revealed, progressing with the duration of the disease and with its transition to the progressive type. The minimum values were observed in patients with SPMS (group 4), with the most pronounced in the subgroup with ON (wiVD = 16.06±3.65 mm/mm2, wiPD = 39.38±9.46%, ppwiPD = 44.06±3.09%, ppwiF = 0.41±0.05).

CONCLUSION

OCTA provides the ability to detect subclinical vascular changes and can be considered a comprehensive, reliable method for early diagnosis and monitoring of MS progression.

Update on the diagnosis and treatment of neuromyelitis optica spectrum disorders (NMOSD) - revised recommendations of the Neuromyelitis Optica Study Group (NEMOS). Part II: Attack therapy and long-term management

This manuscript presents practical recommendations for managing acute attacks and implementing preventive immunotherapies for neuromyelitis optica spectrum disorders (NMOSD), a rare autoimmune disease that causes severe inflammation in the central nervous system (CNS), primarily affecting the optic nerves, spinal cord, and brainstem. The pillars of NMOSD therapy are attack treatment and attack prevention to minimize the accrual of neurological disability. Aquaporin-4 immunoglobulin G antibodies (AQP4-IgG) are a diagnostic marker of the disease and play a significant role in its pathogenicity. Recent advances in understanding NMOSD have led to the development of new therapies and the completion of randomized controlled trials. Four preventive immunotherapies have now been approved for AQP4-IgG-positive NMOSD in many regions of the world: eculizumab, ravulizumab - most recently-, inebilizumab, and satralizumab. These new drugs may potentially substitute rituximab and classical immunosuppressive therapies, which were as yet the mainstay of treatment for both, AQP4-IgG-positive and -negative NMOSD. Here, the Neuromyelitis Optica Study Group (NEMOS) provides an overview of the current state of knowledge on NMOSD treatments and offers statements and practical recommendations on the therapy management and use of all available immunotherapies for this disease. Unmet needs and AQP4-IgG-negative NMOSD are also discussed. The recommendations were developed using a Delphi-based consensus method among the core author group and at expert discussions at NEMOS meetings.

Delimiting MOGAD as a disease entity using translational imaging

The first formal consensus diagnostic criteria for myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) were recently proposed. Yet, the distinction of MOGAD-defining characteristics from characteristics of its important differential diagnoses such as multiple sclerosis (MS) and aquaporin-4 antibody seropositive neuromyelitis optica spectrum disorder (NMOSD) is still obstructed. In preclinical research, MOG antibody-based animal models were used for decades to derive knowledge about MS. In clinical research, people with MOGAD have been combined into cohorts with other diagnoses. Thus, it remains unclear to which extent the generated knowledge is specifically applicable to MOGAD. Translational research can contribute to identifying MOGAD characteristic features by establishing imaging methods and outcome parameters on proven pathophysiological grounds. This article reviews suitable animal models for translational MOGAD research and the current state and prospect of translational imaging in MOGAD.

A comprehensive review of the advances in neuromyelitis optica spectrum disorder

Neuromyelitis optica spectrum disorder (NMOSD) is a rare relapsing neuroinflammatory autoimmune astrocytopathy, with a predilection for the optic nerves and spinal cord. Most cases are characterised by aquaporin-4-antibody positivity and have a relapsing disease course, which is associated with accrual of disability. Although the prognosis in NMOSD has improved markedly over the past few years owing to advances in diagnosis and therapeutics, it remains a severe disease. In this article, we review the evolution of our understanding of NMOSD, its pathogenesis, clinical features, disease course, treatment options and associated symptoms. We also address the gaps in knowledge and areas for future research focus.

The OSCAR-MP Consensus Criteria for Quality Assessment of Retinal Optical Coherence Tomography Angiography

BACKGROUND AND OBJECTIVES

Optical coherence tomography angiography (OCTA) is a noninvasive high-resolution imaging technique for assessing the retinal vasculature and is increasingly used in various ophthalmologic, neuro-ophthalmologic, and neurologic diseases. To date, there are no validated consensus criteria for quality control (QC) of OCTA. Our study aimed to develop criteria for OCTA quality assessment.

METHODS

To establish criteria through (1) extensive literature review on OCTA artifacts and image quality to generate standardized and easy-to-apply OCTA QC criteria, (2) application of OCTA QC criteria to evaluate interrater agreement, (3) identification of reasons for interrater disagreement, revision of OCTA QC criteria, development of OCTA QC scoring guide and training set, and (4) validation of QC criteria in an international, interdisciplinary multicenter study.

RESULTS

We identified 7 major aspects that affect OCTA quality: (O) obvious problems, (S) signal strength, (C) centration, (A) algorithm failure, (R) retinal pathology, (M) motion artifacts, and (P) projection artifacts. Seven independent raters applied the OSCAR-MP criteria to a set of 40 OCTA scans from people with MS, Sjogren syndrome, and uveitis and healthy individuals. The interrater kappa was substantial (κ 0.67). Projection artifacts were the main reason for interrater disagreement. Because artifacts can affect only parts of OCTA images, we agreed that prior definition of a specific region of interest (ROI) is crucial for subsequent OCTA quality assessment. To enhance artifact recognition and interrater agreement on reduced image quality, we designed a scoring guide and OCTA training set. Using these educational tools, 23 raters from 14 different centers reached an almost perfect agreement (κ 0.92) for the rejection of poor-quality OCTA images using the OSCAR-MP criteria.

DISCUSSION

We propose a 3-step approach for standardized quality control: (1) To define a specific ROI, (2) to assess the occurrence of OCTA artifacts according to the OSCAR-MP criteria, and (3) to evaluate OCTA quality based on the occurrence of different artifacts within the ROI. OSCAR-MP OCTA QC criteria achieved high interrater agreement in an international multicenter study and is a promising QC protocol for application in the context of future clinical trials and studies.

Subclinical damage to the contralateral eye in unilateral optic neuritis: A longitudinal study

BACKGROUND

Early detection of subclinical injuries can lead to a correct diagnosis and help control the advancement of the condition. This study aims to investigate the presence of subclinical damage and silent progression to the contralateral eye's visual function and structure in patients experiencing their first episode of unilateral optic neuritis (ON).

METHODS

Fifty patients with first-onset unilateral ON were enrolled in this study. Based on etiology, they were classified as having neuromyelitis optica spectrum disorder-related ON (NMOSD-ON), myelin oligodendrocyte glycoprotein antibody-associated ON (MOG-ON), idiopathic ON (IDON), or multiple sclerosis-related ON (MS-ON). These cases were followed up for one year to determine whether there was any silent progression of visual function and structure in the contralateral non-ON (NON) eye. A gender- and age-matched healthy control (HC) group was included to compare the differences in visual function and structure between the patients with NON eyes and the HC group.

RESULTS

Within two weeks of onset, best-corrected visual acuity (BCVA; P = 0.008), mean deviation (MD) of the visual field (VF) (P = 0.001), and peripapillary retinal nerve fiber layer (pRNFL; P = 0.019) thickness were significantly worse in the NMOSD-NON patients than those in the HC group, while there were no differences in the pRNFL and the ganglion cell-inner plexiform layer (GCIPL) thicknesses and quadrant thicknesses (P > 0.05) of the groups. IDON-NON only showed subclinical damage in VF (P = 0.001) and temporal pRNFL (P = 0.042), while the BCVA, VF, and optic nerve structure (pRNFL, GCIPL) of the MOG-NON patients showed no subclinical damage (P > 0.05). In addition, the one-year follow-up of each NON eye type showed that there was no silent progression in NMOSD-NON, MOG-NON, or IDON-NON. A pairwise comparison of the different types of NON eyes revealed no statistical differences (P > 0.05).

CONCLUSION

Among the patients with unilateral ON, NMOSD-NON and IDON-NON resulted in subclinical damage to the visual function and structure of the contralateral eye within two weeks of onset, whereas MOG-NON did not show any subclinical damage to visual function or structure. Furthermore, these subclinical damages did not show any silent progression during the one-year follow-up period.

Glial autoantibody prevalence in Chinese optic neuritis with onset after age 45: clinical factors for diagnosis

Purpose

As glial autoantibody testing is not yet available in some areas of the world, an alternative approach is to use clinical indicators to predict which subtypes of middle-aged and elderly-onset optic neuritis (ON) have manifested.

Method

This study was a single-center hospital-based retrospective cohort study. Middle-aged and elderly-onset ON patients (age > 45 years) who had experienced the first episode of ON were included in this cohort. Single- and multi-parametric diagnostic factors for middle-aged and elderly-onset myelin oligodendrocyte glycoprotein immunoglobulin-associated ON (MOG-ON) and aquaporin-4 immunoglobulin-related ON (AQP4-ON) were calculated.

Results

From January 2016 to January 2020, there were 81 patients with middle-aged and elderly-onset ON, including 32 (39.5%) AQP4-ON cases, 19 (23.5%) MOG-ON cases, and 30 (37.0%) Seronegative-ON cases. Bilateral involvement (47.4%, P = 0.025) was most common in the MOG-ON group. The presence of other concomitant autoimmune antibodies (65.6%, P = 0.014) and prior neurological history (37.5%, P = 0.001) were more common in the AQP4-ON group. The MOG-ON group had the best follow-up best-corrected visual acuity (BCVA) (89.5% ≤ 1.0 LogMAR, P = 0.001). The most sensitive diagnostic factors for middle-aged and elderly-onset MOG-ON were 'follow-up VA ≤ 0.1 logMAR' (sensitivity 0.89), 'bilateral involvement or follow-up VA ≤ 0.1 logMAR' (sensitivity 0.95), 'bilateral involvement or without neurological history' (sensitivity 1.00), and 'follow-up VA ≤ 0.1 logMAR or without neurological history' (sensitivity 1.00), and the most specific factor was 'bilateral involvement' (specificity 0.81). The most sensitive diagnostic factors for middle-aged and elderly-onset AQP4-ON were 'unilateral involvement' (sensitivity 0.88), 'unilateral involvement or neurological history' (sensitivity 0.91), and 'unilateral involvement or other autoimmune antibodies' (sensitivity 1.00), and the most specific factor was neurological history (specificity 0.98).

Conclusion

Based on our cohort study of middle-aged and elderly-onset ON, MOG-ON is less prevalent than AQP4-ON and Seronegative-ON. Using multiple combined parameters improves the sensitivity and negative predictive value for diagnosing middle-aged and elderly-onset MOG-ON and AQP4-ON. These combined parameters can help physicians identify and treat middle-aged and elderly-onset ON early when glial autoantibody status is not available.

The neuro-ophthalmological manifestations of NMOSD and MOGAD-a comprehensive review

Optic neuritis (ON) is one of the most frequently seen neuro-ophthalmic causes of vision loss worldwide. Typical ON is often idiopathic or seen in patients with multiple sclerosis, which is well described in the landmark clinical trial, the Optic Neuritis Treatment Trial (ONTT). However, since the completion of the ONTT, there has been the discovery of aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) antibodies, which are biomarkers for neuromyelitis optica spectrum disorder (NMOSD) and MOG antibody-associated disease (MOGAD), respectively. These disorders are associated with atypical ON that was not well characterised in the ONTT. The severity, rate of recurrence and overall outcome differs in these two entities requiring prompt and accurate diagnosis and management. This review will summarise the characteristic neuro-ophthalmological signs in NMOSD and MOGAD, serological markers and radiographic findings, as well as acute and long-term therapies used for these disorders.

Predicting the final clinical phenotype after the first attack of optic neuritis

BACKGROUND AND OBJECTIVES

To evaluate the factors determining the final clinical phenotype after an initial isolated attack of optic neuritis (ON). ON could be an isolated event or the initial presentation of a chronic neuroimmunological condition.

METHODS

This was a retrospective analysis of patients presenting to University Hospitals Cleveland Medical Center for an initial, isolated attack of ON. Final clinical phenotypes were idiopathic ON, multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), myelin oligodendrocyte glycoprotein associated disease (MOGAD), or secondary ON (e.g. neurosarcoidosis). Several potential predictors at the time of initial presentation were compared among the different phenotypes to determine early predictors. Categorical variables were compared using Pearson χ2 or Fisher's exact test, and continuous variables were compared using independent t-test.

RESULTS

Sixty-four patients met criteria (average age 41.3 ± 13.3, 78.1% females). Average time to final diagnosis was 8.3 months, and average follow-up was 47 months. The final phenotypes were MS (22, 34%), idiopathic ON (14, 22%), MOGAD (11, 17%), NMOSD (10, 16%), and secondary ON (7, 11%). White race, unilateral ON, short segment hyperintensity on orbital MRI, classical demyelination on brain MRI, and not requiring PLEX were associated with MS. Older age, poor steroid responsiveness, and requiring PLEX were associated with NMOSD. African American race, bilateral ON, papillitis on fundoscopy, long segment hyperintensity on orbital MRI, and normal brain MRI were associated with MOGAD. Normal or thinned retinal nerve fiber layer on OCT, short segment hyperintensity on orbital MRI, and normal brain MRI were associated with idiopathic ON.

CONCLUSION

The final clinical phenotype may be predictable at the time of initial ON presentation. This requires a careful evaluation of patient demographics, treatment response, funduscopic findings, OCT, and orbital and brain MRIs. Utilizing early predictors in clinical practice could better inform prognosis and management decisions.

Update on the diagnosis and treatment of neuromyelits optica spectrum disorders (NMOSD) - revised recommendations of the Neuromyelitis Optica Study Group (NEMOS). Part I: Diagnosis and differential diagnosis

The term 'neuromyelitis optica spectrum disorders' (NMOSD) is used as an umbrella term that refers to aquaporin-4 immunoglobulin G (AQP4-IgG)-positive neuromyelitis optica (NMO) and its formes frustes and to a number of closely related clinical syndromes without AQP4-IgG. NMOSD were originally considered subvariants of multiple sclerosis (MS) but are now widely recognized as disorders in their own right that are distinct from MS with regard to immunopathogenesis, clinical presentation, optimum treatment, and prognosis. In part 1 of this two-part article series, which ties in with our 2014 recommendations, the neuromyelitis optica study group (NEMOS) gives updated recommendations on the diagnosis and differential diagnosis of NMOSD. A key focus is on differentiating NMOSD from MS and from myelin oligodendrocyte glycoprotein antibody-associated encephalomyelitis (MOG-EM; also termed MOG antibody-associated disease, MOGAD), which shares significant similarity with NMOSD with regard to clinical and, partly, radiological presentation, but is a pathogenetically distinct disease. In part 2, we provide updated recommendations on the treatment of NMOSD, covering all newly approved drugs as well as established treatment options.

Optical coherence tomography angiography measurements in multiple sclerosis: a systematic review and meta-analysis

BACKGROUND AND OBJECTIVES

Recent literature on multiple sclerosis (MS) demonstrates the growing implementation of optical coherence tomography-angiography (OCT-A) to discover potential qualitative and quantitative changes in the retina and optic nerve. In this review, we analyze OCT-A studies in patients with MS and examine its utility as a surrogate or precursor to changes in central nervous system tissue.

METHODS

PubMed and EMBASE were systematically searched to identify articles that applied OCT-A to evaluate the retinal microvasculature measurements in patients with MS. Quantitative data synthesis was performed on all measurements which were evaluated in at least two unique studies with the same OCT-A devices, software, and study population compared to controls. A fixed-effects or random-effects model was applied for the meta-analysis based on the heterogeneity level.

RESULTS

The study selection process yielded the inclusion of 18 studies with a total of 1552 evaluated eyes in 673 MS-associated optic neuritis (MSON) eyes, 741 MS without optic neuritis (MSNON eyes), and 138 eyes without specification for the presence of optic neuritis (ON) in addition to 1107 healthy control (HC) eyes. Results indicated that MS cases had significantly decreased whole image superficial capillary plexus (SCP) vessel density when compared to healthy control subjects in the analyses conducted on Optovue and Topcon studies (both P < 0.0001). Likewise, the whole image vessel densities of deep capillary plexus (DCP) and radial peripapillary capillary (RPC) were significantly lower in MS cases compared to HC (all P < 0.05). Regarding optic disc area quadrants, MSON eyes had significantly decreased mean RPC vessel density compared to MSNON eyes in all quadrants except for the inferior (all P < 0.05). Results of the analysis of studies that used prototype Axsun machine revealed that MSON and MSNON eyes both had significantly lower ONH flow index compared to HC (both P < 0.0001).

CONCLUSIONS

This systematic review and meta-analysis of the studies reporting OCT-A measurements of people with MS confirmed the tendency of MS eyes to exhibit reduced vessel density in the macular and optic disc areas, mainly in SCP, DCP, and RPC vessel densities.

Diagnostic value of intereye difference metrics for optic neuritis in aquaporin-4 antibody seropositive neuromyelitis optica spectrum disorders

BACKGROUND

The novel optic neuritis (ON) diagnostic criteria include intereye differences (IED) of optical coherence tomography (OCT) parameters. IED has proven valuable for ON diagnosis in multiple sclerosis but has not been evaluated in aquaporin-4 antibody seropositive neuromyelitis optica spectrum disorders (AQP4+NMOSD). We evaluated the diagnostic accuracy of intereye absolute (IEAD) and percentage difference (IEPD) in AQP4+NMOSD after unilateral ON >6 months before OCT as compared with healthy controls (HC).

METHODS

Twenty-eight AQP4+NMOSD after unilateral ON (NMOSD-ON), 62 HC and 45 AQP4+NMOSD without ON history (NMOSD-NON) were recruited by 13 centres as part of the international Collaborative Retrospective Study on retinal OCT in Neuromyelitis Optica study. Mean thickness of peripapillary retinal nerve fibre layer (pRNFL) and macular ganglion cell and inner plexiform layer (GCIPL) were quantified by Spectralis spectral domain OCT. Threshold values of the ON diagnostic criteria (pRNFL: IEAD 5 µm, IEPD 5%; GCIPL: IEAD: 4 µm, IEPD: 4%) were evaluated using receiver operating characteristics and area under the curve (AUC) metrics.

RESULTS

The discriminative power was high for NMOSD-ON versus HC for IEAD (pRNFL: AUC 0.95, specificity 82%, sensitivity 86%; GCIPL: AUC 0.93, specificity 98%, sensitivity 75%) and IEPD (pRNFL: AUC 0.96, specificity 87%, sensitivity 89%; GCIPL: AUC 0.94, specificity 96%, sensitivity 82%). The discriminative power was high/moderate for NMOSD-ON versus NMOSD-NON for IEAD (pRNFL: AUC 0.92, specificity 77%, sensitivity 86%; GCIP: AUC 0.87, specificity 85%, sensitivity 75%) and for IEPD (pRNFL: AUC 0.94, specificity 82%, sensitivity 89%; GCIP: AUC 0.88, specificity 82%, sensitivity 82%).

CONCLUSIONS

Results support the validation of the IED metrics as OCT parameters of the novel diagnostic ON criteria in AQP4+NMOSD.

Retina thickness in clinically affected and unaffected eyes in patients with aquaporin-4 immunoglobulin G antibody seropositive neuromyelitis optica spectrum disorders: a systematic review and meta-analysis

BACKGROUND AND PURPOSE

Retina thickness has been studied in patients with neuromyelitis optica spectrum disorders (NMOSD) without distinguishing serostatus and limited data are available in unaffected eyes. We aimed to investigate retina thickness in eyes of aquaporin-4 immunoglobulin G antibody seropositive (AQP4-IgG⁺) NMOSD patients with optic neuritis (AQP4-ON) and without (AQP4-NON).

METHODS

Eligible studies were identified by searching PubMed and Embase. Mean difference (MD, μm) with corresponding 95% confidence interval (CI) was pooled with random-effect models. The primary measures were average thickness of peripapillar retinal nerve fiber layer (pRNFL) centered on optic disc and the combination of ganglion cell layer and inner plexiform layer (GCIPL) at macula.

RESULTS

We included 21 studies enrolling 787 AQP4-IgG⁺ NMOSD patients. Compared with healthy control, pRNFL was thinner in eyes of AQP4-ON (- 32.78, 95% CI [- 36.24, - 29.33]) and AQP4-NON (- 2.76, 95% CI [- 3.94, - 1.58]), so was GICPL in AQP4-ON (-21.38, 95% CI [- 24.01, - 18.74]) and AQP4-NON (95% CI - 2.96, [- 3.91, - 2.00]). Compared with multiple sclerosis with ON, AQP4-ON had thinner pRNFL (- 13.56, 95%CI [- 16.51, - 10.60]) and GCIPL (- 9.12, 95% CI [- 11.88, - 6.36]). AQP4-ON and myelin oligodendrocyte glycoprotein antibody-associated demyelination with ON (MOG-ON) had similar pRNFL (0.59, 95% CI [- 6.61, 7.79]) and GCIPL thickness (- 0.55, 95% CI [- 2.92, 1.82]). AQP4-NON had similar pRNFL and GCIPL thickness to MOG-NON and multiple sclerosis without ON.

CONCLUSIONS

The average thickness of pRNFL and GICPL decreased both in AQP4-ON and AQP4-NON eyes. AQP4-ON eyes had a similar level of pRNFL and GICPL thinning to MOG-ON eyes, so did AQP4-NON to MOG-NON eyes.

Volumetric brain changes in MOGAD: A cross-sectional and longitudinal comparative analysis

BACKGROUND

Relatively little is known about how global and regional brain volumes changes in myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) compare with Multiple Sclerosis (MS), Neuromyelitis optica spectrum disorder (NMOSD), and healthy controls (HC).

OBJECTIVE

To compare global and regional brain volumes in MOGAD, MS, NMOSD, and HC cross-sectionally as well as longitudinally in a subset of patients.

METHODS

We retrospectively reviewed all adult MOGAD and NMOSD patients with brain MRI performed in stable remission and compared them with MS patients and HC. Volumetric parameters were assessed using the FDA-approved icobrain software. adjusted for age and sex.

RESULTS

Twenty-four MOGAD, 47 NMOSD, 40 MS patients, and 37 HC were included in the cross-sectional analyses. Relative to HC, the age-adjusted whole brain (WB) volume was significantly lower in patients with MOGAD (p=0.0002), NMOSD (p=0.042), and MS (p=0.01). Longitudinal analysis of a subset of 8 MOGAD, 22 NMOSD, and 34 MS patients showed a reduction in the WB and cortical gray matter (CGM) volumes over time in all three disease groups, without statistically significant differences between groups. The MOGAD group had a greater loss of thalamic volume compared to MS (p=0.028) and NMOSD (p=0.023) and a greater loss of hippocampal volumes compared to MS (p=0.007).

CONCLUSIONS

Age-adjusted WB volume loss was evident in all neuroinflammatory conditions relative to HC in cross-sectional comparisons. In longitudinal analyses, MOGAD patients had a higher thalamic atrophy rate relative to MS and NMOSD, and a higher hippocampal atrophy rate relative to MS. Larger studies are needed to validate these findings and to investigate their clinical implications.

Berlin Registry of Neuroimmunological entities (BERLimmun): protocol of a prospective observational study

BACKGROUND

Large-scale disease overarching longitudinal data are rare in the field of neuroimmunology. However, such data could aid early disease stratification, understanding disease etiology and ultimately improve treatment decisions. The Berlin Registry of Neuroimmunological Entities (BERLimmun) is a longitudinal prospective observational study, which aims to identify diagnostic, disease activity and prognostic markers and to elucidate the underlying pathobiology of neuroimmunological diseases.

METHODS

BERLimmun is a single-center prospective observational study of planned 650 patients with neuroimmunological disease entity (e.g. but not confined to: multiple sclerosis, isolated syndromes, neuromyelitis optica spectrum disorders) and 85 healthy participants with 15 years of follow-up. The protocol comprises annual in-person visits with multimodal standardized assessments of medical history, rater-based disability staging, patient-report of lifestyle, diet, general health and disease specific symptoms, tests of motor, cognitive and visual functions, structural imaging of the neuroaxis and retina and extensive sampling of biological specimen.

DISCUSSION

The BERLimmun database allows to investigate multiple key aspects of neuroimmunological diseases, such as immunological differences between diagnoses or compared to healthy participants, interrelations between findings of functional impairment and structural change, trajectories of change for different biomarkers over time and, importantly, to study determinants of the long-term disease course. BERLimmun opens an opportunity to a better understanding and distinction of neuroimmunological diseases.

Visual function and disability are associated with microcystic macular edema, macular and peripapillary vessel density in patients with neuromyelitis optica spectrum disorder

Purpose

To assess macular and peripapillary vessel density and neurodegeneration in eyes with and without microcystic macular edema (MME) in neuromyelitis optica spectrum disorder (NMOSD) patients while investigating their association with visual impairment and disease disability.

Methods

This is a cross-sectional study. A total of 52 eyes from 29 NMOSD patients were recruited, including 8 eyes with MME from 7 patients. Optical coherence tomography angiography (OCTA) images were analyzed to quantify the radial papillary capillary density (RPCD), and the density of macular microvascular network in both the superficial retinal capillary plexus (SRCP) and the deep retinal capillary plexus (DRCP). Thicknesses of the neural retinal layers centered on the fovea and the optic nerve head were also collected by OCT. Best-corrected visual acuity (BCVA) and Expanded Disability Status Scale (EDSS) scores were assessed for all patients. Microvascular densities and retinal sublayer thicknesses were compared among groups, and correlations of these vascular and structural parameters with BCVA and EDSS scores were determined.

Results

Patients with NMOSD and MME had significantly decreased visual acuity and worse EDSS score than patients without MME (P = 0.01 and 0.002, respectively). The vessel density in SRCP and RPCD were significantly lower in eyes with MME and ON compared to that of eyes with ON but without MME and eyes without MME or ON. Impairment of visual acuity and disease severity were significantly negatively associated with the reduction of SRCP vessel density and RPCD but were not related to DRCP vessel density.

Conclusions

MME were correlated with worse visual impairment and disability in NMOSD patients. Sparse SRCP vessel density and RPCD were observed in NMOSD MME eyes and correlated with worse BCVA and EDSS scores.

Diagnostik der Neuromyelitis-optica-Spektrum-Erkrankung (NMOSD) und der MOG-Antikörper-assoziierten Erkrankung (MOGAD)

Die Aquaporin-4-Antikörper-positive Neuromyelitis-optica-Spektrum-Erkrankung (engl. NMOSD) und die Myelin-Oligodendrozyten-Glykoprotein-Antikörper-assoziierte Erkrankung (engl. MOGAD) sind Autoimmunerkrankungen des zentralen Nervensystems. Typische Erstmanifestationen sind bei Erwachsenen Optikusneuritis und Myelitis. Eine Beteiligung auch von Hirn und Hirnstamm, spätestens im weiteren Verlauf, ist häufig. Während die NMOSD nahezu immer schubförmig verläuft, nimmt die MOGAD gelegentlich einen monophasischen Verlauf. Die Differenzialdiagnostik ist anspruchsvoll und stützt sich auf u. a. auf radiologische und serologische Befunde. Die Abgrenzung von der häufigeren neuroinflammatorischen Erkrankung, Multiple Sklerose (MS), ist von erheblicher Bedeutung, da sich Behandlung und langfristige Prognose von NMOSD, MOGAD und MS wesentlich unterscheiden. Die vielfältigen Symptome und die umfangreiche Diagnostik machen eine enge Zusammenarbeit zwischen Ophthalmologie, Neurologie und Radiologie erforderlich. Dieser Artikel gibt einen Überblick über typische MRT-Befunde und die serologische Antikörperdiagnostik bei NMOSD und MOGAD. Zwei illustrative Fallberichte aus der ärztlichen Praxis ergänzen die Darstellung.

Structure-function correlates of vision loss in neuromyelitis optica spectrum disorders

Optic neuritis (ON) in neuromyelitis optica spectrum disorders (NMOSD) regularly leads to more profound vision loss compared to multiple sclerosis (MS) and myelin-oligodendrocyte-glycoprotein-antibody associated disease (MOGAD). Here we investigate ON-related vision loss in NMOSD compared to MS and MOGAD in order to identify neuroaxonal and retinal contributors to visual dysfunction. In this retrospective study we included patients with aquaporin-4-antibody seropositive NMOSD (n = 28), MOGAD (n = 14), MS (n = 29) and controls (n = 14). We assessed optic nerve damage and fovea morphometry by optical coherence tomography. Visual function was assessed as high (HCVA) and low contrast visual acuity (LCVA), and visual fields' mean deviation (MD). In all diseases, lower visual function was associated with peripapillary retinal nerve fiber layer (pRNFL) and ganglion cell and inner plexiform layer (GCIP) thinning following a broken stick model, with pRNFL and GCIP cutoff point at ca. 60 µm. HCVA loss per µm pRNFL and GCIP thinning was stronger in NMOSD compared with MOGAD. Foveal inner rim volume contributed to MD and LCVA in NMOSD eyes, only. Together these data supports that visual dysfunction in NMOSD is associated with neuroaxonal damage beyond the effect seen in MS and MOGAD. A primary retinopathy, respectively Müller cell pathology, may contribute to this effect.

Retinal thickness changes in different subfields reflect the volume change of cerebral white matter hyperintensity

Purpose

To investigate the relationship between the retinal thickness in different subfields and the volume of white matter hyperintensity (WMH), with the hope to provide new evidence for the potential association between the retina and the brain.

Methods

A total of 185 participants aged over 40 years were included in our study. Magnetic resonance imaging (MRI) was used to image the WMH, and WMH volume was quantitatively measured by a specific toolbox. The thickness of the total retina, the retinal nerve fiber layer (RNFL), and the ganglion cell and inner plexiform layer (GCIP) was measured by optical coherence tomography (OCT) in nine subfields. The association between retinal thickness and WMH volume was demonstrated using binary logistic regression and Pearson correlation analysis.

Results

Participants were divided into two groups by the WMH volume (‰, standardized WMH volume) median. In the quartile-stratified binary logistic regression analysis, we found that the risk of higher WMH volume showed a positive linear trend correlation with the thickness of total retina (95% CI: 0.848 to 7.034; P for trend = 0.044)/ GCIP (95% CI: 1.263 to 10.549; P for trend = 0.038) at the central fovea, and a negative linear trend correlation with the thickness of nasal inner RNFL (95% CI: 0.086 to 0.787; P for trend = 0.012), nasal outer RNFL (95% CI: 0.058 to 0.561; P for trend = 0.004), and inferior outer RNFL (95% CI: 0.081 to 0.667; P for trend = 0.004), after adjusting for possible confounders. Correlation analysis results showed that WMH volume had a significant negative correlation with superior outer RNFL thickness (r = −0.171, P = 0.02) and nasal outer RNFL thickness (r = −0.208, P = 0.004).

Conclusion

It is suggested that central fovea and outer retina thickness are respectively associated with WMH volume. OCT may be a biological marker for early detection and longitudinal monitoring of WMH.

Diagnosis and classification of optic neuritis

There is no consensus regarding the classification of optic neuritis, and precise diagnostic criteria are not available. This reality means that the diagnosis of disorders that have optic neuritis as the first manifestation can be challenging. Accurate diagnosis of optic neuritis at presentation can facilitate the timely treatment of individuals with multiple sclerosis, neuromyelitis optica spectrum disorder, or myelin oligodendrocyte glycoprotein antibody-associated disease. Epidemiological data show that, cumulatively, optic neuritis is most frequently caused by many conditions other than multiple sclerosis. Worldwide, the cause and management of optic neuritis varies with geographical location, treatment availability, and ethnic background. We have developed diagnostic criteria for optic neuritis and a classification of optic neuritis subgroups. Our diagnostic criteria are based on clinical features that permit a diagnosis of possible optic neuritis; further paraclinical tests, utilising brain, orbital, and retinal imaging, together with antibody and other protein biomarker data, can lead to a diagnosis of definite optic neuritis. Paraclinical tests can also be applied retrospectively on stored samples and historical brain or retinal scans, which will be useful for future validation studies. Our criteria have the potential to reduce the risk of misdiagnosis, provide information on optic neuritis disease course that can guide future treatment trial design, and enable physicians to judge the likelihood of a need for long-term pharmacological management, which might differ according to optic neuritis subgroups.

Optical Coherence Tomography in Chronic Relapsing Inflammatory Optic Neuropathy, Neuromyelitis Optica and Multiple Sclerosis: A Comparative Study

Purpose: To examine the optical coherence tomography (OCT) features of the retina in patients with chronic relapsing inflammatory optic neuropathy (CRION) and compare them with those of neuromyelitis optica spectrum disorder (NMOSD), relapsing-remitting multiple sclerosis (RRMS) with and without optic neuritis (ON), and healthy controls (HC). Methods: In this retrospective cross-sectional study, we used spectral domain OCT to evaluate the retinal structure of 14 participants with CRION, 22 with NMOSD, 40 with RRMS with unilateral ON, and 20 HC. The peripapillary retinal nerve fiber layer (pRNFL), total macular volume (TMV), and papillomacular bundle (PMB) were measured, and intra-retinal segmentation was performed to obtain the retinal nerve fiber (RNFL), ganglion cell (GCL), inner plexiform (IPL), inner nuclear (INL), outer plexiform (OPL) and outer nuclear (ONL) layer volumes. Results: The global pRNFL [39.33(±1.8) µm] and all its quadrants are significantly thinner in CRION compared with all other groups (p < 0.05). CRION patients have decreased volumes of TMV, RNFL, GCL, and IPL compared with all other groups (p < 0.05). Conclusion: Severe thinning in pRNFL and thinning in intra-retinal segments of IPL, GCL, RNFL, and TMV could be helpful in differentiating CRION from NMOSD and RRMS.

Serum glial fibrillary acidic protein correlates with retinal structural damage in aquaporin-4 antibody positive neuromyelitis optica spectrum disorder

BACKGROUND

Aquaporin-4 immunoglobulin-G positive (AQP4-IgG⁺) neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune astrocytopathy associated with optic neuritis (ON). Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is an oligodendrocytopathy with a similar phenotype. Serum glial fibrillary acidic protein (sGFAP), an astrocyte-derived protein, is associated with disease severity in AQP4-IgG⁺ NMOSD. Serum neurofilament light (sNfL) indicates neuroaxonal damage. The objective was to investigate the association of sGFAP and sNfL with subclinical afferent visual system damage in clinically stable AQP4-IgG⁺ NMOSD and MOGAD patients.

METHODS

In this cross-sectional study, clinically stable patients with AQP4-IgG⁺ NMOSD (N = 33) and MOGAD (N = 16), as diseased controls, underwent sGFAP and sNfL measurements by single molecule array, retinal optical coherence tomography and visually evoked potentials.

RESULTS

Higher sGFAP concentrations were associated with thinner ganglion cell-inner plexiform layer (β (95% confidence interval (CI)) = -0.75 (-1.23 to -0.27), p = 0.007) and shallower fovea (average pit depth: β (95%CI) = -0.59 (-0.63 to -0.55), p = 0.020) in NMOSD non-ON eyes. Participants with pathological P100 latency had higher sGFAP (median [interquartile range]: 131.32 [81.10-179.34] vs. 89.50 [53.46-121.91] pg/ml, p = 0.024). In MOGAD, sGFAP was not associated with retinal structural or visual functional measures.

CONCLUSIONS

The association of sGFAP with structural and functional markers of afferent visual system damage in absence of ON suggests that sGFAP may be a sensitive biomarker for chronic disease severity in clinically stable AQP4-IgG⁺ NMOSD.

Non-vasogenic cystoid maculopathies

Besides cystoid macular edema due to a blood-retinal barrier breakdown, another type of macular cystoid spaces referred to as non-vasogenic cystoid maculopathies (NVCM) may be detected on optical coherence tomography but not on fluorescein angiography. Various causes may disrupt retinal cell cohesion or impair retinal pigment epithelium (RPE) and Müller cell functions in the maintenance of retinal dehydration, resulting in cystoid spaces formation. Tractional causes include vitreomacular traction, epiretinal membranes and myopic foveoschisis. Surgical treatment does not always allow cystoid space resorption. In inherited retinal dystrophies, cystoid spaces may be part of the disease as in X-linked retinoschisis or enhanced S-cone syndrome, or occur occasionally as in bestrophinopathies, retinitis pigmentosa and allied diseases, congenital microphthalmia, choroideremia, gyrate atrophy and Bietti crystalline dystrophy. In macular telangiectasia type 2, cystoid spaces and cavitations do not depend on the fluid leakage from telangiectasia. Various causes affecting RPE function may result in NVCM such as chronic central serous chorioretinopathy and paraneoplastic syndromes. Non-exudative age macular degeneration may also be complicated by intraretinal cystoid spaces in the absence of fluorescein leakage. In these diseases, cystoid spaces occur in a context of retinal cell loss. Various causes of optic atrophy, including open-angle glaucoma, result in microcystoid spaces in the inner nuclear layer due to a retrograde transsynaptic degeneration. Lastly, drug toxicity may also induce cystoid maculopathy. Identifying NVCM on multimodal imaging, including fluorescein angiography if needed, allows guiding the diagnosis of the causative disease and choosing adequate treatment when available.

Neuromyelitis Optica Spectrum Disorder: From Basic Research to Clinical Perspectives

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory disease of the central nervous system characterized by relapses and autoimmunity caused by antibodies against the astrocyte water channel protein aquaporin-4. Over the past decade, there have been significant advances in the biologic knowledge of NMOSD, which resulted in the IDENTIFICATION of variable disease phenotypes, biomarkers, and complex inflammatory cascades involved in disease pathogenesis. Ongoing clinical trials are looking at new treatments targeting NMOSD relapses. This review aims to provide an update on recent studies regarding issues related to NMOSD, including the pathophysiology of the disease, the potential use of serum and cerebrospinal fluid cytokines as disease biomarkers, the clinical utilization of ocular coherence tomography, and the comparison of different animal models of NMOSD.

Longitudinal retinal changes in MOGAD

OBJECTIVE

Patients with myelin oligodendrocyte glycoprotein antibody (MOG-IgG) associated disease (MOGAD) suffer from severe optic neuritis (ON) leading to retinal neuro-axonal loss, which can be quantified by optical coherence tomography (OCT). We assessed whether ON-independent retinal atrophy can be detected in MOGAD.

METHODS

Eighty MOGAD patients and 139 healthy controls (HC) were included. OCT data was acquired with 1) Spectralis spectral domain OCT (MOGAD (N=66) and HC (N=103)) and 2) Cirrus HD-OCT (MOGAD (N=14) and HC (N=36)). Macular combined ganglion cell and inner plexiform layer (GCIPL) and peripapillary retinal nerve fibre layer (pRNFL) were quantified.

RESULTS

At baseline, GCIPL and pRNFL were lower in MOGAD eyes with a history of ON (MOGAD-ON) compared with MOGAD eyes without a history of ON (MOGAD-NON) and HC (p<0.001). MOGAD-NON eyes had lower GCIPL volume compared to HC (p<0.001) in the Spectralis, but not in the Cirrus cohort. Longitudinally (follow-up up to 3 years), MOGAD-ON with ON within the last 6-12 months before baseline exhibited greater pRNFL thinning than MOGAD-ON with an ON >12 months ago (p<0.001). The overall MOGAD cohort did not exhibit faster GCIPL thinning compared with HC.

INTERPRETATION

Our study suggests the absence of attack-independent retinal damage in MOGAD. Yet, ongoing neuroaxonal damage or oedema resolution seems to occur for up to 12 months after ON, which is longer than what has been reported with other ON forms. These findings support that the pathomechanisms underlying optic nerve involvement and the evolution of OCT retinal changes after ON is distinct in MOGAD. This article is protected by copyright. All rights reserved.

Optic neuritis: A South African hospital-based prospective study protocol

Background

Optic neuritis is a relatively common disease with an estimated lifetime risk of 0.6 per 1000; the estimated prevalence is 1–5 per 100 000/year. It occurs because of inflammation of the optic nerve from a variety of causes. The diagnosis of the disorder is established clinically and current literature is predominantly based on white patients from high-income countries. Optic neuritis presents differently in black patients compared to white patients. This study aims to assess the presentation and outcome of optic neuritis patients in a South African setting.

Methods

This is a prospective, hospital-based cohort study that will enrol patients with optic neuritis presenting to either the neurology department at Chris Hani Baragwanath Academic Hospital or the ophthalmology department at St John Eye Hospital, both in Johannesburg, South Africa. The specific aetiologies, clinical presentation and radiological findings will be studied, and the patient’s course over one year will be documented in three-monthly follow-up visits. A specific group of patients with Neuromyelitis Optica Spectrum Disorders (NMOSD) and Myelin Oligodendrocyte Glycoprotein Associated Disorders (MOGAD) optic neuritis will be followed up for 5 years at yearly intervals.

Discussion

This study represents one of the few cohort studies in Sub-Saharan Africa that seeks to investigate optic neuritis. Our hope is that it will lead to better insights regarding the presentation, course and outcome of this condition. We will also analyse the data with a view of developing a predictive model for good visual outcome.

Intraretinal Layer Segmentation Using Cascaded Compressed U-Nets

Reliable biomarkers quantifying neurodegeneration and neuroinflammation in central nervous system disorders such as Multiple Sclerosis, Alzheimer's dementia or Parkinson's disease are an unmet clinical need. Intraretinal layer thicknesses on macular optical coherence tomography (OCT) images are promising noninvasive biomarkers querying neuroretinal structures with near cellular resolution. However, changes are typically subtle, while tissue gradients can be weak, making intraretinal segmentation a challenging task. A robust and efficient method that requires no or minimal manual correction is an unmet need to foster reliable and reproducible research as well as clinical application. Here, we propose and validate a cascaded two-stage network for intraretinal layer segmentation, with both networks being compressed versions of U-Net (CCU-INSEG). The first network is responsible for retinal tissue segmentation from OCT B-scans. The second network segments eight intraretinal layers with high fidelity. At the post-processing stage, we introduce Laplacian-based outlier detection with layer surface hole filling by adaptive non-linear interpolation. Additionally, we propose a weighted version of focal loss to minimize the foreground-background pixel imbalance in the training data. We train our method using 17,458 B-scans from patients with autoimmune optic neuropathies, i.e., multiple sclerosis, and healthy controls. Voxel-wise comparison against manual segmentation produces a mean absolute error of 2.3 μm, outperforming current state-of-the-art methods on the same data set. Voxel-wise comparison against external glaucoma data leads to a mean absolute error of 2.6 μm when using the same gold standard segmentation approach, and 3.7 μm mean absolute error in an externally segmented data set. In scans from patients with severe optic atrophy, 3.5% of B-scan segmentation results were rejected by an experienced grader, whereas this was the case in 41.4% of B-scans segmented with a graph-based reference method. The validation results suggest that the proposed method can robustly segment macular scans from eyes with even severe neuroretinal changes.

Aquaporin-4 prevents exaggerated astrocytosis and structural damage in retinal inflammation

Abstract

Aquaporin-4 (AQP4) is the molecular target of the immune response in neuromyelitis optica (NMO) that leads to severe structural damage in the central nervous system (CNS) and in the retina. Conversely, AQP4 might be upregulated in astrocytes as a compensatory event in multiple sclerosis. Thus, the functional relevance of AQP4 in neuroinflammation needs to be defined. Here, we tested the role of AQP4 in the retina in MOG(35–55)-induced experimental autoimmune encephalomyelitis (EAE) using optical coherence tomography (OCT), OCT angiography, immunohistology, flow cytometry, and gene expression analysis in wild-type and Aqp4^–/– mice. No direct infiltrates of inflammatory cells were detected in the retina. Yet, early retinal expression of TNF and Iba1 suggested that the retina participated in the inflammatory response during EAE in a similar way in wild-type and Aqp4^–/– mice. While wild-type mice rapidly cleared retinal swelling, Aqp4^–/– animals exhibited a sustainedly increased retinal thickness associated with retinal hyperperfusion, albumin extravasation, and upregulation of GFAP as a hallmark of retinal scarring at later stages of EAE. Eventually, the loss of retinal ganglion cells was higher in Aqp4^–/– mice than in wild-type mice. Therefore, AQP4 expression might be critical for retinal Müller cells to clear the interstitial space from excess vasogenic edema and prevent maladaptive scarring in the retina during remote inflammatory processes of the CNS.

Key messages

Genetic ablation of AQP4 leads to a functional derangement of the retinal gliovascular unit with retinal hyperperfusion during autoimmune CNS inflammation.

Genetic ablation of AQP4 results in a structural impairment of the blood retina barrier with extravasation of albumin during autoimmune CNS inflammation.

Eventually, the lack of AQP4 in the retina during an inflammatory event prompts the exaggerated upregulation of GFAP as a hallmark of scarring as well as loss of retinal ganglion cells.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00109-022-02202-6.

Astrocytic outer retinal layer thinning is not a feature in AQP4-IgG seropositive neuromyelitis optica spectrum disorders

BACKGROUND

Patients with anti-aquaporin-4 antibody seropositive (AQP4-IgG+) neuromyelitis optica spectrum disorders (NMOSDs) frequently suffer from optic neuritis (ON) leading to severe retinal neuroaxonal damage. Further, the relationship of this retinal damage to a primary astrocytopathy in NMOSD is uncertain. Primary astrocytopathy has been suggested to cause ON-independent retinal damage and contribute to changes particularly in the outer plexiform layer (OPL) and outer nuclear layer (ONL), as reported in some earlier studies. However, these were limited in their sample size and contradictory as to the localisation. This study assesses outer retinal layer changes using optical coherence tomography (OCT) in a multicentre cross-sectional cohort.

METHOD

197 patients who were AQP4-IgG+ and 32 myelin-oligodendrocyte-glycoprotein antibody seropositive (MOG-IgG+) patients were enrolled in this study along with 75 healthy controls. Participants underwent neurological examination and OCT with central postprocessing conducted at a single site.

RESULTS

No significant thinning of OPL (25.02±2.03 µm) or ONL (61.63±7.04 µm) were observed in patients who were AQP4-IgG+ compared with patients who were MOG-IgG+ with comparable neuroaxonal damage (OPL: 25.10±2.00 µm; ONL: 64.71±7.87 µm) or healthy controls (OPL: 24.58±1.64 µm; ONL: 63.59±5.78 µm). Eyes of patients who were AQP4-IgG+ (19.84±5.09 µm, p=0.027) and MOG-IgG+ (19.82±4.78 µm, p=0.004) with a history of ON showed parafoveal OPL thinning compared with healthy controls (20.99±5.14 µm); this was not observed elsewhere.

CONCLUSION

The results suggest that outer retinal layer loss is not a consistent component of retinal astrocytic damage in AQP4-IgG+ NMOSD. Longitudinal studies are necessary to determine if OPL and ONL are damaged in late disease due to retrograde trans-synaptic axonal degeneration and whether outer retinal dysfunction occurs despite any measurable structural correlates.

Retinal inter-eye difference and atrophy progression in multiple sclerosis diagnostics

BACKGROUND

The visual system could be included in the diagnostic criteria for multiple sclerosis (MS) to demonstrate dissemination in space (DIS) and dissemination in time (DIT).

OBJECTIVE

To investigate the diagnostic value of retinal asymmetry in MS.

METHODS

A prospective, longitudinal study in individuals with MS (n=151) and healthy controls (n=27). Optical coherence tomography (OCT) was performed at 0, 2 and 4 years. Macular ganglion cell and inner plexiform layer (mGCIPL) thickness was determined as well as measures for retinal asymmetry: the inter-eye percentage difference (IEPD) and inter-eye absolute difference (IEAD). Receiver operator characteristics curves were plotted and the area under the curve (AUC) was calculated for group comparisons of the mGCIPL, IEPD, IEAD and atrophy rates.

RESULTS

The diagnostic accuracy of both the IEPD and IEAD for differentiating bilateral and unilateral MS optic neuritis was high and stable over time (AUCs 0.88-0.93). The IEPD slightly outperformed the IEAD. Atrophy rates showed low discriminatory abilities for differentiating MS from controls (AUC 0.49-0.58).

CONCLUSION

The inter-eye differences of the mGCIPL have value for demonstration of DIS but in individuals with longstanding MS not for DIT. This may be considered as a test to detect DIS in future diagnostic criteria. Validation in a large prospective study in people presenting with symptoms suggestive of MS is required.

What's new in neuromyelitis optica spectrum disorder treatment?

Optic neuritis, an optic nerve inflammatory disease presenting with acute unilateral or bilateral visual loss, is one of the core symptoms of neuromyelitis optica spectrum disorder (NMOSD). The diagnosis of NMOSD-related optic neuritis is challenging, and it is mainly based on clinical presentation, optical coherence tomography, magnetic resonance imaging scans, and the status of serum aquaporin-4 antibodies. In the pathogenesis, aquaporin-4 antibodies target astrocytes in the optic nerves, spinal cord and some specific regions of the brain eliciting a devastating autoimmune response. Current pharmacological interventions are directed against various steps within the immunological response, notably the terminal complement system, B-cells, and the pro-inflammatory cytokine Interleukin 6 (IL6). Conventional maintenance therapies were off-label uses of the unspecific immunosuppressants azathioprine and mycophenolate mofetil as well as the CD20 specific antibody rituximab and the IL6 receptor specific antibody tocilizumab. Recently, four phase III clinical trials demonstrated the safety and efficacy of the three novel biologics eculizumab, inebilizumab, and satralizumab. These monoclonal antibodies are directed against the complement system, CD19 B-cells and the IL6 receptor, respectively. All three have been approved for NMOSD in the US and several other countries worldwide and thus provide convincing treatment options.

Sparser macula microvasculature in neuromyelitis optica spectrum disorder occurs independently of optic neuritis

PURPOSE

To evaluate the macula microvascular perfusion in neuromyelitis optica spectrum disorder (NMOSD) patients and assess the correlation with their clinical features.

METHODS

35 aquaporin-4 seropositive NMOSD patients (38 NMOSD eyes without optic neuritis, NMOSD-NON, and 32 NMOSD eyes with optic neuritis) and 35 healthy controls (HC) were included in our study. Swept-source optical coherence tomography angiography (SS-OCTA) was used to image and segment the macula microvasculature into the inner macula vascular complex (IVC), superficial vascular plexus (SVC), and deep vascular plexus (DVC). An inbuilt software within the OCTA tool was used to measure the microvascular perfusion in these two plexuses.

RESULTS

NMOSD eyes without optic neuritis showed sparser (P < 0.05) IVC and SVC compared with healthy controls; NMOSD eyes with optic neuritis showed significantly sparser (P < 0.001) IVC, SVC, and DVC when compared with healthy controls respectively. NMOSD eyes with optic neuritis showed significantly sparser IVC (P = 0.002), SVC (P = 0.001) and DVC (P = = 0.040) when compared with eyes without optic neuritis.

CONCLUSIONS

Microvascular impairment in NMOSD patients occurs independently of ON. Microvascular impairment is associated with reduced visual acuity and frequency of ON.

Retinal optical coherence tomography and magnetic resonance imaging in neuromyelitis optica spectrum disorders and MOG-antibody associated disorders: an updated review

INTRODUCTION

Neuromyelitis optica spectrum disorders (NMOSD) and myelin oligodendrocyte glycoprotein IgG antibody-associated disorders (MOGAD) comprise two groups of rare neuroinflammatory diseases that cause attack-related damage to the central nervous system (CNS). Clinical attacks are often characterized by optic neuritis, transverse myelitis, and to a lesser extent, brainstem encephalitis/area postrema syndrome. Retinal optical coherence tomography (OCT) is a non-invasive technique that allows for in vivo thickness quantification of the retinal layers. Apart from OCT, magnetic resonance imaging (MRI) plays an increasingly important role in NMOSD and MOGAD diagnosis based on the current international diagnostic criteria. Retinal OCT and brain/spinal cord/optic nerve MRI can help to distinguish NMOSD and MOGAD from other neuroinflammatory diseases, particularly from multiple sclerosis, and to monitor disease-associated CNS-damage.

AREAS COVERED

This article summarizes the current status of imaging research in NMOSD and MOGAD, and reviews the clinical relevance of OCT, MRI and other relevant imaging techniques for differential diagnosis, screening and monitoring of the disease course.

EXPERT OPINION

Retinal OCT and MRI can visualize and quantify CNS damage in vivo, improving our understanding of NMOSD and MOGAD pathology. Further efforts on the standardization of these imaging techniques are essential for implementation into clinical practice and as outcome parameters in clinical trials.