Differing Structural and Functional Patterns of Optic Nerve Damage in Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorder

Brain-Derived Neurotrophic Factor Val66Met is Associated with Variation in Cortical Structure in Healthy Aging Subjects

Aging is associated with progressive brain atrophy and declines in learning and memory, often attributed to hippocampal or cortical deterioration. The role of brain-derived neurotrophic factor (BDNF) in modulating the structural and functional changes in the brain and visual system, particularly in relation to BDNF Val66Met polymorphism, remains underexplored. In this present cross-sectional observational study, we aimed to assess the effects of BDNF polymorphism on brain structural integrity, cognitive function, and visual pathway alterations. A total of 108 older individuals with no evidence of dementia and a mean (SD) age of 67.3 (9.1) years were recruited from the Optic Nerve Decline and Cognitive Change (ONDCC) study cohort. The BDNF Met allele carriage had a significant association with lower entorhinal cortex volume (6.7% lower compared to the Val/Val genotype, P = 0.02) and posterior cingulate volume (3.2% lower than the Val/Val group, P = 0.03), after adjusting for confounding factors including age, sex and estimated total intracranial volumes (eTIV). No significant associations were identified between the BDNF Val66Met genotype and other brain volumetric or diffusion measures, cognitive performances, or vision parameters except for temporal retinal nerve fibre layer thickness. Small but significant correlations were found between visual structural and functional, cognitive, and brain morphological metrics. Our findings suggest that carriage of BDNF Val66Met polymorphism is associated with lower entorhinal cortex and posterior cingulate volumes and may be involved in modulating the cortical morphology along the aging process.

Multi-registry analysis of patients with multiple sclerosis and neuromyelitis optica to improve capture of demographic data and compare visual outcomes

IMPORTANCE

The American Academy of Neurology Axon Registry® provides real-world data for patients with multiple sclerosis and neuro-myelitis optica. However, some data are incomplete (e.g. demographics) and some relevant outcomes are not systematically captured in neurology documentation (e.g. visual acuity). The American Academy of Ophthalmology IRIS® Registry (Intelligent Research in Sight) contains demographic and visual function data that may complement Axon Registry-derived data to enhance understanding of real-world visual outcomes in neurological disease.

OBJECTIVE

To combine Axon Registry and IRIS Registry data to reduce missingness of demographic information and characterize visual outcomes in patients with multiple sclerosis and neuro-myelitis optica.

DESIGN

Cross-sectional study.

SETTING

Outpatient neurology and ophthalmology clinical practices.

PARTICIPANTS

Patients participating in both registries between January 1, 2014 through December 10, 2021 were included if they had repeat ICD-9/10 codes for with multiple sclerosis or neuro-myelitis optica in the Axon registry.

EXPOSURE

Diagnosis (multiple sclerosis or neuro-myelitis optica).

MAIN OUTCOME AND MEASURE

Age, sex, race and ethnicity were assessed in the individual registries and classified as conflicting, missing, or not missing in the combined data set. The IRIS Registry contributed visual acuity data.

RESULTS

Among 60,316 patients with multiple sclerosis and 1,068 patients with neuro-myelitis optica in the Axon Registry, 14,085 and 252 had temporal overlap in the IRIS Registry. Combining data reduced missing or conflicting data for race and ethnicity by 15-19 % (absolute reduction, all p ≤ 0.0005), but not age (p = 1.0) or gender (p = 0.08). 10,907 patients with MS and 142 with NMO had visual acuity data in the IRIS Registry. Visual acuity averaged between eyes was worse in patients with NMO after adjusting for age and gender (0.17 logMAR, 95 %CI 0.12,0.21, p < 0.0005).

CONCLUSION AND RELEVANCE

Using data from two registries reduced missing data for race and ethnicity and enabled examination of outcomes captured in the IRIS Registry for conditions that are diagnosed more frequently in the Axon Registry, demonstrating the utility of a multi-registry analysis.

Optical Coherence Tomography Angiography: Revolutionizing Clinical Diagnostics and Treatment in Central Nervous System Disease

Optical coherence tomography angiography (OCTA), as a new generation of non-invasive and efficient fundus imaging technology, can provide non-invasive assessment of vascular lesions in the retina and choroid. In terms of anatomy and development, the retina is referred to as an extension of the central nervous system (CNS). CNS diseases are closely related to changes in fundus structure and blood vessels, and direct visualization of fundus structure and blood vessels provides an effective "window" for CNS research. This has important practical significance for identifying the characteristic changes of various CNS diseases on OCTA in the future, and plays a key role in promoting early screening, diagnosis, and monitoring of disease progression in CNS diseases. This article reviews relevant fundus studies by comparing and summarizing the unique advantages and existing limitations of OCTA in various CNS disease patients, in order to demonstrate the clinical significance of OCTA in the diagnosis and treatment of CNS diseases.

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.

The Association of APOE ε4 Allele with Retinal Layer Thickness and Microvasculature in Older Adults: Optic Nerve Decline and Cognitive Change Study

PURPOSE

To investigate the relationship between the apolipoprotein E (APOE) ε4 allele and retinal structural and vascular characteristics in older adult participants from several research studies. We also studied the relationship between these structural and vascular characteristics with multifocal visual evoked potential (mfVEP) indices, neuropsychological parameters and MRI brain volumes in these participants.

METHODS

In this study, 109 participants with a mean (SD) age of 67.1 (9.0) years were recruited. Participants were classified as APOE ε4 carriers or non-carriers based on the presence or absence of the ε4 allele. Baseline measurements included peripapillary retinal nerve fibre layer optical coherence tomography (RNFL OCT), and OCT-angiography (OCT-A) for evaluation of the retinal layer thickness and vessel density (VD) parameters. A multifocal visual evoked potential (mfVEP) test, including amplitude and latency, was used to assess the visual pathway function. Finally, cognitive function was evaluated using a battery of neuropsychological tests. OCT-A images were analysed in ImageJ to quantify VD in the superficial and deep vascular plexus and the size of the foveal avascular zone (FAZ). The relationship between carriers of APOE ε4 allele and these ocular parameters was analysed using generalised estimating equation (GEE) models and data adjusted for age, sex and inter-eye differences as within-subject variables (p < 0.05).

RESULTS

Twenty-four participants were APOE ε4 carriers. Temporal RNFL thickness was decreased in APOE ε4 carriers (p < 0.01). Vessel density between carriers and non-carriers was not significantly different at either the superficial or deep level. The FAZ area was significantly smaller in ε4 carriers in both superficial (p < 0.01) and deep layers (p < 0.003).

CONCLUSIONS

Retinal abnormalities were present in participants with increased genetic risk of dementia due to presence of the ε4 allele. These findings provide preliminary evidence for their potential role in the diagnosis of dementia.

B cell targeted therapies in inflammatory autoimmune disease of the central nervous system

Cumulative evidence along several lines indicates that B cells play an important role in the pathological course of multiple sclerosis (MS), neuromyelitisoptica spectrum disorders (NMOSD) and related CNS diseases. This has prompted extensive research in exploring the utility of targeting B cells to contain disease activity in these disorders. In this review, we first recapitulate the development of B cells from their origin in the bone marrow to their migration to the periphery, including the expression of therapy-relevant surface immunoglobulin isotypes. Not only the ability of B cells to produce cytokines and immunoglobulins seems to be essential in driving neuroinflammation, but also their regulatory functions strongly impact pathobiology. We then critically assess studies of B cell depleting therapies, including CD20 and CD19 targeting monoclonal antibodies, as well as the new class of B cell modulating substances, Bruton´s tyrosinekinase (BTK) inhibitors, in MS, NMOSD and MOGAD.

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.

Use of retinal optical coherence tomography to differentiate suspected neuromyelitis optica spectrum disorder from multiple sclerosis: A cross-sectional study

BACKGROUND

Retinal optical coherence tomography (OCT) can differentiate definite NMOSD (dNMOSD) from multiple sclerosis (MS), but has not been evaluated in patients with a high clinical suspicion of NMOSD and not fulfilling the current consensus diagnostic criteria, referred in this paper as "potential" NMOSD (pNMOSD).

AIM

To compare the retinal OCT measurements between patients with pNMOSD, dNMOSD, MS, and reference healthy controls (HC).

MATERIAL AND METHODS

In this cross-sectional study, clinical and demographic characteristics, as well as OCT measurements of peripapillary retinal nerve fiber layer (pRNFL), inner nuclear layer (INL), macular retinal nerve fiber layer (mRNFL), outer nuclear layer (ONL) ganglion cell/inner plexiform layer (GCIPL), and macular volume (MV) were compared between groups. Mixed-effects regression models adjusting for within-patient inter-eye correlations, controlling for age, gender, disease duration and history of optic neuritis per eye were explored. Subgroup analyses were performed on eyes with previous optic neuritis.

RESULTS

234 eyes (20 pNMOSD, 33 dNMOSD, 138 MS, and 43 HC) were included. Controlling for age, gender, disease duration, and history of optic neuritis per eye, pNMOSD eyes showed decreased GCIPL, pRNFL, mRNFL and MV thicknesses, similar to eyes with dNMOSD, but significantly thinner than MS and HC subjects' eyes. Similar results were obtained for the pRNFL, mRNFL, GCIPL, INL and MV thickness in the subgroup analysis exploring only eyes with history of optic neuritis (12 pNMOSD, 15 dNMOSD, and 27 MS).

CONCLUSION

Retinal OCT measurements in patients with pNMOSD were similar to dNMOSD, but significantly lower than patients with MS and healthy controls. This suggests that retinal OCT measures could be helpful markers supportive of NMOSD diagnosis and should be explored in larger studies as a valuable addition to the current consensus diagnostic criteria.

Different visual evoked potentials in neuromyelitis optica spectrum disorder-related optic neuritis and idiopathic demyelinating optic neuritis: a prospective longitudinal analysis

Background

To investigate different visual evoked potential (VEP) patterns in neuromyelitis optica spectrum disorder-related optic neuritis (NMOSD-ON) and idiopathic demyelinating optic neuritis (IDON).

Methods

This was a longitudinal, prospective, case-control study. Eighty-four Chinese patients with acute optic neuritis were enrolled, including 26 NMOSD-ON patients and 58 IDON patients. All the patients underwent best-corrected visual acuity (BCVA) and full-field pattern reversal VEP recordings at the onset, 1 month, 3 months, and 6 months.

Results

Within 15′ checks, the NMOSD-ON patients had more severe VEP amplitude reduction at 6 months (2.39 ± 4.63 μV vs. 6.96 ± 8.88 μV, P = 0.034). However, the IDON patients showed more frequently normal VEP response at 3 months (24.0% vs. 4.5%, P = 0.017), and only prolonged P100 peak latency with normal amplitude (L) at 6 months (30.0% vs. 57.8%, P = 0.048). Within 60′ checks, no significant difference in VEP parameters between the two groups was found at each follow-up (P > 0.05).

Conclusions

The NMOSD-ON patients showed more severe axonal damage and worse axonal recovery than the IDON patients. VEP elicited by smaller check size was more sensitive to visual pathway abnormality in NMOSD-ON.

Immunopathology of the Optic Nerve in Multiple Sclerosis

Optic neuritis, a primary clinical manifestation commonly observed in multiple sclerosis (MS) is a major factor leading to permanent loss of vision. Despite decreased vision (optic neuritis), diplopia, and nystagmus, the immunopathology of the optic nerve in MS is unclear. Here, we have characterised the optic nerve pathology in a large cohort of MS cases (n=154), focusing on the immune responses in a sub-cohort of MS (n=30) and control (n=6) cases. Immunohistochemistry was used to characterise the myeloid (HLA-DR, CD68, Iba1, TMEM119, P2RY12) and adaptive immune cells (CD4, CD8, CD138) in the parenchyma, perivascular spaces, and meninges in optic nerve tissues from MS and control cases. Of the 154 MS cases, 122 (79%) reported visual problems of which 99 (81%) optic nerves showed evidence of damage. Of the 31 cases with no visual disturbances, 19 (61%) showed evidence of pathology. A pattern of myeloid cell activity and demyelination in the optic nerve was similar to white matter lesions in the brain and spinal cord. In the optic nerves, adaptive immune cells were more abundant in the meninges close to active and chronic active lesions, and significantly higher compared to the parenchyma. Similar to brain tissues in this Dutch cohort, B-cell follicles in the meninges were absent. Our study reveals that optic nerve pathology is a frequent event in MS and may occur in the absence of clinical symptoms.

Optic Neuritis-Independent Retinal Atrophy in Neuromyelitis Optica Spectrum Disorder

BACKGROUND

A limited number of studies have investigated the presence of ongoing disease activity independent of clinical relapses in neuromyelitis optica spectrum disorder (NMOSD), and data are conflicting. The objective of our study was to examine whether patients with aquaporin-4 (AQP4)-IgG seropositive NMOSD exhibit progressive retinal neuroaxonal loss, independently of optic neuritis (ON) attacks.

METHODS

In this single-center, longitudinal study, 32 AQP4-IgG+ NMOSD patients and 48 healthy controls (HC) were followed with serial spectral-domain optical coherence tomography and visual acuity (VA) assessments. NMOSD patients with ON less than 6 months before baseline were excluded, whereas data from patients with ON during follow-up were censored at the last visit before ON. VA worsening was defined as a decrease in monocular letter acuity ≥5 letters for high-contrast VA and ≥7 letters for low-contrast VA. Analyses were performed with mixed-effects linear regression models adjusted for age, sex, and race.

RESULTS

The median follow-up duration was 4.2 years (interquartile range: 1.8-7.5). Relative to HC, NMOSD eyes had faster peripapillary retinal nerve fiber layer (pRNFL) (β = -0.25 µm/year faster, 95% confidence interval [CI]: -0.45 to -0.05, P = 0.014) and GCIPL thinning (β = -0.09 µm/year faster, 95% CI: -0.17 to 0, P = 0.05). This difference seemed to be driven by faster pRNFL and GCIPL thinning in NMOSD eyes without a history of ON compared with HC (GCIPL: β = -0.15 µm/year faster; P = 0.005; pRNFL: β = -0.43 µm/year faster, P < 0.001), whereas rates of pRNFL (β: -0.07 µm/year, P = 0.53) and GCIPL (β = -0.01 µm/year, P = 0.90) thinning did not differ between NMOSD-ON and HC eyes. Nine NMOSD eyes had VA worsening during follow-up.

CONCLUSIONS

In this longitudinal study, we observed progressive pRNFL and GCIPL atrophy in AQP4-IgG+ NMOSD eyes unaffected by ON. These results support that subclinical involvement of the anterior visual pathway may occur in AQP4-IgG+ NMOSD.

Structural and functional markers of optic nerve damage in myelin oligodendrocyte glycoprotein antibody-associated optic neuritis

Background

Optic neuritis (ON) occurs in immune-mediated disorders including multiple sclerosis (MS), aquaporin-4 antibody-positive (AQP4) neuromyelitis optica spectrum disorder (AQP4-NMOSD) and myelin oligodendrocyte glycoprotein (MOG) antibody-associated demyelination (MOGAD). Accurate determination of aetiology is critical for appropriate treatment and prognostication.

Objective

To evaluate demyelination and axonal loss in MOG-ON to facilitate differentiation from MS-ON and AQP4-ON.

Methods

15 MOGAD patients with previous ON (25 eyes) underwent multifocal visual evoked potential (mfVEP) recordings and optical coherence tomography scans. Comparison was made to previously reported MS patients (n = 67, 69 eyes) and AQP4-NMOSD patients (n = 15, 23 eyes) with prior ON and healthy controls (n = 37, 74 eyes).

Results

MOG-ON patients had less retinal nerve fibre layer (RNFL) loss than AQP4-ON patients (p < 0.05) and less mfVEP latency prolongation than MS-ON patients (p < 0.01). Number of ON episodes in MOGAD was associated with reduced RNFL thickness (global, p = 0.07; temporal, p < 0.001) and mfVEP amplitude (p < 0.001). There was no abnormality in non-ON eyes.

Conclusions

Our study demonstrated a distinct pattern of damage in MOG-ON compared to AQP4-ON and MS-ON. ON in MOGAD produces less axonal loss than AQP4-NMOSD. Damage accumulates with relapses, supporting the role of maintenance immunosuppression to induce remission. Compared to MS, MOGAD causes less demyelination.

Evidence for and against subclinical disease activity and progressive disease in MOG antibody disease and neuromyelitis optica spectrum disorder

Myelin oligodendrocyte glycoprotein antibody disease (MOGAD) and aquaporin-4 IgG seropositive neuromyelitis optica spectrum disorder (AQP4-IgG+ NMOSD) are generally considered to be relapsing disorders, without clinical progression or subclinical disease activity outside of clinical relapses, in contrast to multiple sclerosis (MS). With advances in the diagnosis and treatment of these conditions, prolonged periods of remission without relapses can be achieved, and the question of whether progressive disease courses can occur has re-emerged. In this review, we focus on studies exploring evidence for and against relapse-independent clinical progression and/or subclinical disease activity in patients with MOGAD and AQP4-IgG+ NMOSD.

A comparative study of alteration in retinal layer segmentation alteration by SD-OCT in neuromyelitis optica spectrum disorders: A systematic review and meta-analysis

Background

To evaluate the feature of different retinal layer segmentation in neuromyelitis optica spectrum disorders (NMOSD) with spectral-domain optical coherence tomography (SD-OCT) and to compare it with that in multiple sclerosis (MS), healthy controls (HC), and idiopathic optic neuritis (ION).

Methods

We retrieved four electronic databases, including Pubmed, Embase, Cochrane Library, and Web of Science from inception to September 1st, 2021. A meta-analysis was performed to compare different retinal layer segmentation thicknesses between patients with or without a history of optic neuritis (ON) in NMOSD and the control group, including patients with MS, HC, and ION.

Results

Forty-two studies were included and the interval between the last ON onset and examination was greater than 3 months. Compared with that in HC eyes, the loss of retinal nerve fiber layer (RNFL) and macular ganglion cell and inner plexiform layer (GC-IPL) was serious in NMOSD eye especially after ON. Moreover, compared with that in ION eyes or MS-related-ON eyes, the injury to the peripapillary retinal nerve fiber layer (pRNFL) was severe in NMOSD-related-ON eyes. In addition, the correlation coefficient between pRNFL and prognostic visual acuity was 0.43. However, the one-arm study revealed the inner nuclear layer (INL) was thickened in NMOSD-related-ON eyes compared with HC eyes.

Conclusions

Inclusion of the RNFL and macular GC-IPL is recommended for monitoring disease progression and attention should be paid to changes in the INL.

Optical coherence tomography monitoring and diagnosing retinal changes in multiple sclerosis

This study explores the use of optical coherence tomography (OCT) to monitor and diagnose multiple sclerosis (MS). The analysis of reduced total macular volume and peripapillary retinal nerve fiber layer thinning are shown. The severity of these defects increases as MS progresses, reflecting the progressive degeneration of nerve fibers and retinal ganglion cells. The OCT parameters are noninvasive, sensitive indicators that can be used to assess the progression of neurodegeneration and inflammation in MS.

Multifocal visual evoked potential evaluation for diagnosis of acute optic neuritis and for prediction of visual outcome and ganglion cell layer thinning following optic neuritis

BACKGROUND

While damage to the optic nerve following optic neuritis (ON) is readily quantifiable, the evaluation of prognosis for visual function and neuroaxonal loss in the acute ON is challenging.

OBJECTIVE

The objective of this study is to investigate the value of multifocal visual evoked potential (mfVEP) in acute ON, diagnostically for acute ON and prognostically for visual outcome and subsequent ganglion cell/inner plexiform layer thickness (GCLIPLt).

METHODS

A prospective cohort study of mfVEP and full-field visual evoked potential (ffVEP) in acute, unilateral ON (onset < 31 days) was conducted. Comparisons with healthy controls (n = 30) and association analysis with follow-up optical coherence tomography (OCT) measurements (of the GCLIPLt) and visual function (Sloan low-contrast visual acuity (LCVA)) were conducted.

RESULTS

Seventy-nine ON patients were included (mean: 17 days from onset). Excluding measurements with conduction block, ffVEP (n = 54) and mfVEP (n = 44) showed sensitivities of 89% and 84% to a specificity of 97%. 65/79 patients were re-examined (mean: 200 days follow-up). mfVEP amplitude and latency inter-eye asymmetry in acute ON correlated with GCLIPLt (r = 0.587 and Spearman's ρ = 0.597, for both, p < 0.001). mfVEP amplitude correlated with LCVA inter-eye asymmetry at follow-up (r = 0.421, p < 0.001), mfVEP latency did not.

CONCLUSION

mfVEP may support the prognostic evaluation of acute ON patients and prove valuable in future neuroprotective and remyelinating trials. In acute ON, the increase in diagnostic value of mfVEP to ffVEP may be limited due to widespread conduction block.

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.

Impaired motion perception is associated with functional and structural visual pathway damage in multiple sclerosis and neuromyelitis optica spectrum disorders

Background:

Decreased motion perception has been suggested as a marker for visual pathway demyelination in optic neuritis (ON) and/or multiple sclerosis (MS).

Objectives:

To examine the influence of neuro-axonal damage on motion perception in MS and neuromyelitis optica spectrum disorders (NMOSD).

Methods:

We analysed motion perception with numbers-from-motion (NFM), visual acuity, (multifocal (mf)) VEP, optical coherence tomography in patients with MS (n = 38, confirmatory cohort n = 43), NMOSD (n = 13) and healthy controls (n = 33).

Results:

NFM was lower compared with controls in MS (B = −12.37, p < 0.001) and NMOSD (B = −34.5, p < 0.001). NFM was lower in ON than in non-ON eyes (B = −30.95, p = 0.041) in NMOSD, but not MS. In MS and NMOSD, lower NFM was associated with worse visual acuity (B = −139.4, p < 0.001/B = −77.2, p < 0.001) and low contrast letter acuity (B = 0.99, p = 0.002/B = 1.6, p < 0.001), thinner peripapillary retinal nerve fibre layer (B = 1.0, p < 0.001/ B = 0.92, p = 0.016) and ganglion cell/inner plexiform layer (B = 64.8, p < 0.001/B = 79.5, p = 0.006), but not with VEP P100 latencies. In the confirmatory MS cohort, lower NFM was associated with thinner retinal nerve fibre layer (B = 1.351, p < 0.001) and increased mfVEP P100 latencies (B = −1.159, p < 0.001).

Conclusions:

Structural neuro-axonal visual pathway damage is an important driver of motion perception impairment in MS and NMOSD.

Optical coherence tomography angiography helps distinguish multiple sclerosis from AQP4-IgG-seropositive neuromyelitis optica spectrum disorder

INTRODUCTION

The aim was to characterize the optical coherence tomography (OCT) angiography measures in patients with multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) and to evaluate their disease discrimination capacity.

METHODS

Patients with MS (n = 83) and AQP4-IgG-seropositive NMOSD (n = 91) with or without a history of optic neuritis, together with healthy controls (n = 34), were imaged. The main outcome measures were peripapillary retinal nerve fiber layer (pRNFL) thickness, macular ganglion cell-inner plexiform layer (GC-IPL) thickness, macular vessel density (VD), and perfusion density (PD) in the superficial capillary plexus. Diagnostic accuracy was assessed using the area under the receiver operating characteristics curve.

RESULTS

Compared with patients with MS, those with NMOSD had a significantly smaller average thickness of the pRNFL and GC-IPL (80.0 [59.0; 95.8] μm versus 92.0 [80.2; 101] μm, p < .001; 68.0 [56.0; 81.0] μm, versus 74.5 [64.2; 81.0] μm, p < .001) and significantly smaller whole VD and PD areas (15.6 [12.6; 17.0] mm^-1 versus 16.7 [14.8; 17.7] mm^-1 , p < .001; 0.38 [0.31; 0.42] mm^-1 versus 0.40 [0.37; 0.43] mm^-1 , p < .01). The combination of structural parameters (average thickness of the pRNFL and GC-IPL) with microvascular parameters (temporal-inner quadrant of VD, temporal-inner, nasal-inferior, and nasal-outer quadrant of PD) was revealed to have a good diagnostic capability for discriminating between NMOSD and MS.

CONCLUSIONS

OCT angiography reveals different structural and microvascular retinal changes in MS and AQP4-IgG-seropositive NMOSD. These combined structural and microvascular parameters might be promising biomarkers for disease diagnosis.

Structure-Function Relationship of Retinal Ganglion Cells in Multiple Sclerosis

The retinal ganglion cells (RGC) may be considered an easily accessible pathophysiological site of degenerative processes in neurological diseases, such as the RGC damage detectable in multiple sclerosis (MS) patients with (HON) and without a history of optic neuritis (NON). We aimed to assess and interrelate RGC functional and structural damage in different retinal layers and retinal sites. We included 12 NON patients, 11 HON patients and 14 healthy controls for cross-sectional multifocal pattern electroretinography (mfPERG) and optical coherence tomography (OCT) measurements. Amplitude and peak times of the mfPERG were assessed. Macula and disc OCT scans were acquired to determine macular retinal layer and peripapillary retinal nerve fiber layer (pRNFL) thickness. In both HON and NON patients the foveal N2 amplitude of the mfPERG was reduced compared to controls. The parafoveal P1 peak time was significantly reduced in HON only. For OCT, parafoveal (pfGCL) and perifoveal (pGCL) ganglion cell layer thicknesses were decreased in HON vs. controls, while pRNFL in the papillomacular bundle sector (PMB) showed reductions in both NON and HON. As the mfPERG derived N2 originates from RGC axons, these findings suggest foveal axonal dysfunction not only in HON, but also in NON patients.

Recent advances on optic nerve magnetic resonance imaging and post-processing

The optic nerve is known to be one of the largest nerve bundles in the human central nervous system. There have been many studies of optic nerve imaging and post-processing that have provided insights into pathophysiology of optic neuritis related to multiple sclerosis and neuromyelitis optica spectrum disorder, glaucoma, and Leber's hereditary optic neuropathy. There are many challenges in optic nerve imaging, due to the morphology of the nerve through its course to the optic chiasm, its mobility due to eye movements and the high signal from cerebrospinal fluid and orbital fat surrounding the optic nerve. Recently, many advanced and fast imaging sequences have been used with post-processing techniques in attempts to produce higher resolution images of the optic nerve for evaluating various diseases. Magnetic resonance imaging (MRI) is one of the most common imaging methodologies for the optic nerve. This review paper will focus on recent MRI advances in optic nerve imaging and explain several post-processing techniques being used for analysis of optic nerve images. Finally, some challenges and potential for future optic nerve studies will be discussed.

Alleviation of extensive visual pathway dysfunction by a remyelinating drug in a chronic mouse model of multiple sclerosis

Visual deficits are among the most prevalent symptoms in patients with multiple sclerosis (MS). To understand deficits in the visual pathway during MS and potential treatment effects, we used experimental autoimmune encephalomyelitis (EAE), the most commonly used animal model of MS. The afferent visual pathway was assessed in vivo using optical coherence tomography (OCT), electroretinography (ERG), and visually evoked cortical potentials (VEPs). Inflammation, demyelination, and neurodegeneration were examined by immunohistochemistry ex vivo. In addition, an immunomodulatory, remyelinating agent, the estrogen receptor β ligand chloroindazole (IndCl), was tested for its therapeutic potential in the visual pathway. EAE produced functional deficits in visual system electrophysiology, including suppression of ERG and VEP waveform amplitudes and increased signal latencies. Therapeutic IndCl rescued overall visual system latency by VEP but had little impact on amplitude or ERG findings relative to vehicle. Faster VEP conduction in IndCl-treated mice was associated with enhanced myelin basic protein signal in all visual system structures examined. IndCl preserved retinal ganglion cells (RGCs) and oligodendrocyte density in the prechiasmatic white matter, but similar retinal nerve fiber layer thinning by OCT was noted in vehicle and IndCl-treated mice. Although IndCl differentially attenuated leukocyte and astrocyte staining signal throughout the structures analyzed, axolemmal varicosities were observed in all visual fiber tracts of mice with EAE irrespective of treatment, suggesting impaired axonal energy homeostasis. These data support incomplete functional recovery of VEP amplitude with IndCl, as fiber tracts displayed persistent axon pathology despite remyelination-induced decreases in latencies, evidenced by reduced optic nerve g-ratio in IndCl-treated mice. Although additional studies are required, these findings demonstrate the dynamics of visual pathway dysfunction and disability during EAE, along with the importance of early treatment to mitigate EAE-induced axon damage.

Interferon-β Is Less Effective Than Other Drugs in Controlling the Rate of Retinal Ganglion Cell Loss in MS

Objective

To investigate the association between disease-modifying therapies (DMTs) and the rate of progressive retinal ganglion cell (RGC) and nerve fiber loss in MS.

Methods

One hundred five relapsing-remitting patients with MS were followed annually for a median of 4.0 years using optical coherence tomography. Twenty-five healthy subjects were also included as normal controls. The rates of global peripapillary retinal nerve fiber layer (pRNFL), temporal RNFL (tRNFL), and ganglion cell inner plexiform layer (GCIPL) thinning were analyzed according to DMT type using a linear mixed-effects model. Optic radiation lesion volume was measured on brain MRI and included as a covariate to minimize the effects of retrograde transsynaptic degeneration.

Results

The annual rates of RNFL and GCIPL thinning were higher in patients treated with “platform” therapies (interferon-β and glatiramer acetate) compared with DMTs of higher clinical efficacy (including fingolimod, dimethyl fumarate, natalizumab, alemtuzumab, rituximab, and ocrelizumab) (difference = −0.22 μm/y, p = 0.02 for pRNFL; difference = −0.34 μm/y, p = 0.009 for tRNFL; and difference = −0.16 μm/y, p = 0.005 for GCIPL). Based on an analysis of individual treatments (interferon-β, glatiramer acetate, fingolimod, and natalizumab), interferon-β was associated with inferior RGC preservation, relative to the other drugs. No effect difference was found between glatiramer acetate, fingolimod, and natalizumab.

Conclusions

Progressive loss of RGCs in patients with MS is more pronounced in patients treated with interferon-β than other DMTs. This finding may have implications for DMT selection in MS.

Classification of Evidence

This study provides Class IV evidence that for patients with MS, treatment with interferon-β compared with other DMTs leads to a more pronounced rate of retinal ganglion cell loss.

Differential patterns of parafoveal and peripapillary vessel density in multiple sclerosis and neuromyelitis optica spectrum disorder

BACKGROUND

To compare intraocular microvascular alterations between patients with multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD) using optical coherence tomography angiography (OCT-A).

METHODS

Sixty patients were included in the study, 23 MS patients (36 eyes) and 37 NMOSD patients (47 eyes), all with a history of optic neuritis (ON). All subjects underwent comprehensive ophthalmic examinations, OCT-A, and high-definition-OCT imaging. OCT-A was used to measure the vessel density of the superficial and deep retinal capillary plexus (SRCP and DRCP) in the macular area and the radial peripapillary capillary (RPC) segment. Age, spherical equivalent, and gender were adjusted for in the analyses.

RESULTS

Patients with NMOSD showed significantly decreased vessel density of the SRCP (average, p = 0.0007; superior, p = 0.0009; inferior, p = 0.0002) and RPC segment (average, p < 0.0001; superior, p = 0.0004; inferior, p = 0.0052; temporal, p < 0.0001; nasal, p = 0.0001) compared to the MS patients. Parafoveal and peripapillary vessel density was significantly associated with the OCT parameters in both the MS and NMOSD patients. Parafoveal and peripapillary vessel density in the MS patients was significantly associated with visual function, including visual acuity and visual field defects, whereas only peripapillary vessel density was significantly associated with visual function in the NMOSD patients.

CONCLUSION

We demonstrated parafoveal and peripapillary vascular alterations between MS and NMOSD patients that varied in degree and pattern. We also found associations between vessel density and structural and functional parameters in MS and NMOSD patients. Further studies are needed to facilitate a greater understanding of the pathogenesis and its association with vascular alterations in these disorders.

The contribution of multifocal visual evoked potentials in patients with optic neuritis and multiple sclerosis: a review

Purpose

To review the evidence on the usefulness of the multifocal visual evoked potential (mfVEP) test in patients with optic neuritis (ON) and/or multiple sclerosis (MS).

Methods

We critically review key published evidence on the use of mfVEP in ON/MS patients and its association with other functional and structural tests.

Results

Multifocal VEP tests are useful in detecting abnormality in patients with ON/MS and monitor the progression of lesions (remyelination, atrophy). In addition, mfVEP has good correlation with conventional visual evoked potential (VEP), standard automated perimetry, optical coherence tomography and magnetic resonance imaging. In patients with ON, mfVEP might be useful in predicting the risk of conversion to MS.

Evidence of subclinical quantitative retinal layer abnormalities in AQP4-IgG seropositive NMOSD

BACKGROUND

Prior studies have suggested that subclinical retinal abnormalities may be present in aquaporin-4 immunoglobulin G (AQP4-IgG) seropositive neuromyelitis optica spectrum disorder (NMOSD), in the absence of a clinical history of optic neuritis (ON).

OBJECTIVE

Our aim was to compare retinal layer thicknesses at the fovea and surrounding macula between AQP4-IgG+ NMOSD eyes without a history of ON (AQP4-nonON) and healthy controls (HC).

METHODS

In this single-center cross-sectional study, 83 AQP4-nonON and 154 HC eyes were studied with spectral-domain optical coherence tomography (OCT).

RESULTS

Total foveal thickness did not differ between AQP4-nonON and HC eyes. AQP4-nonON eyes exhibited lower outer nuclear layer (ONL) and inner photoreceptor segment (IS) thickness at the fovea (ONL: -4.01 ± 2.03 μm, p = 0.049; IS: -0.32 ± 0.14 μm, p = 0.029) and surrounding macula (ONL: -1.98 ± 0.95 μm, p = 0.037; IS: -0.16 ± 0.07 μm, p = 0.023), compared to HC. Macular retinal nerve fiber layer (RNFL: -1.34 ± 0.51 μm, p = 0.009) and ganglion cell + inner plexiform layer (GCIPL: -2.44 ± 0.93 μm, p = 0.009) thicknesses were also lower in AQP4-nonON compared to HC eyes. Results were similar in sensitivity analyses restricted to AQP4-IgG+ patients who had never experienced ON in either eye.

CONCLUSIONS

AQP4-nonON eyes exhibit evidence of subclinical retinal ganglion cell neuronal and axonal loss, as well as structural evidence of photoreceptor layer involvement. These findings support that subclinical anterior visual pathway involvement may occur in AQP4-IgG+ NMOSD.

Early diagnosis of multiple sclerosis by OCT analysis using Cohen's d method and a neural network as classifier

BACKGROUND

The consequences of inflammation, demyelination, axonal degeneration and neuronal loss in the central nervous system, typical of the development of multiple sclerosis (MS), are manifested in thinning of the retina and optic nerve. The purpose of this work is to diagnose early-stage MS patients based on analysis of retinal layer thickness obtained by swept-source optical coherence tomography (SS-OCT).

METHOD

OCT (Triton® SS-OCT device -Topcon, Tokyo, Japan-) recordings were obtained from 48 control subjects and 48 recently diagnosed MS patients. The following thicknesses were measured on a 45 × 60 grid: retinal nerve fibre layer (RNFL), ganglion cell layer (GCL+), GCL++, retinal thickness and choroid. Using Cohen's d effect size, it was determined the regions and layers with greatest capacity to discriminate between control subjects and patients. Points exceeding the threshold set were used as inputs for an automatic classifier: support vector machine and feed-forward neural network.

RESULTS

In MS at clinical onset the layer with greatest discriminant capacity is GCL++ [AUC = 0.83] which exhibits a horseshoe-like macular topographic distribution. It is followed by retina, GCL+ and RNFL; choroidal thicknesses do not provide discriminatory capacity. Using a neural network as a classifier between controls and MS patients, obtains sensitivity of 0.98 and specificity of 0.98.

CONCLUSIONS

This work suggest that OCT may serve as an important complementary role to other clinical tests, particularly regarding neurodegeneration. It is possible to characterise structural alterations in retina and diagnose early-stage MS with high degree of accuracy using OCT and artificial neural networks.

Efficacy of plasma exchange in acute attacks of neuromyelitis optica spectrum disorders: A systematic review and meta-analysis

BACKGROUND

Plasma exchange (PE) has usually to be considered as a rescue therapy when intravenous corticosteroids is insufficient in acute attacks of neuromyelitis optica spectrum disorders (NMOSD). The efficacy of PE has not been quantified. This system review and meta-analysis was aimed to evaluate the efficacy of PE therapy in acute attacks of NMOSD.

METHODS

Studies evaluating the efficacy of PE in patients with NMOSD were identified from PubMed and Embase. Changes of Expanded Disability Status Scale (EDSS) score between before and after PE therapy, and the rate of response to PE, were defined as the main efficacy outcomes. Meta-regression was performed to identify the sources of heterogeneity. Subgroup meta-analysis were performed based on the interval of initiation PE after attack onset and AQP4-IgG serostatus of patients.

RESULTS

Twenty-four studies containing 528 patients with NMOSD were included in this meta-analysis. As a rescue therapy when patients failed to respond to intravenous corticosteroids (PE rescue), PE treatment resulted in a reduction in the mean EDSS score by 1.69 (95% CI: 0.88-2.50), with a response rate of 75%(95%CI: 66%-83%). As a first-line therapy being used alone or simultaneously with intravenous corticosteroids (PE first-line), PE resulted in a reduction in the mean EDSS score by 2.34 (95% CI: 1.69-2.98), with a response rate of 71%(95%CI: 44%-93%). Overall, PE resulted in a reduction in the mean EDSS score by 1.83 (95% CI: 1.19-2.47), with a response rate of 74% (95%CI: 66%-82%). Subgroup analysis suggested that earlier PE initiation and AQP4-IgG seronegative patients seemed to be associated with a superior response to PE therapy.

CONCLUSION

Plasma exchange, whether used as rescue or as first-line therapy, is an effective therapeutic method in patients during acute attacks of NMOSD.

Update on neuromyelitis optica spectrum disorder

PURPOSE OF REVIEW

Neuromyelitis optica spectrum disorder is an autoimmune disease that causes optic neuritis and transverse myelitis. Attacks can cause severe neurological damage leading to blindness and paralysis. Understanding of the immunopathogenesis of this disease has led to major breakthroughs in diagnosis and treatment. In the past 18 months, three successful phase 3 clinical trials have been published using targeted approaches to preventing relapses.

RECENT FINDINGS

Updates in epidemiology, imaging, quality of life and treatment for acute relapse and prevention have been published in the past 18 months. Epidemiology studies are distinguishing patients based on their antigen specificity for aquaporin-4 and myelin oligodendrocyte glycoprotein, which are increasingly recognized as separate immunological conditions. Imaging by MRI and optical coherence tomography continue to be developed as tools to distinguish neuromyelitis optica spectrum disorders (NMOSD) from other diseases. This is especially relevant as the recent clinical trials showed differences in response between aquaporin-4 seropositive and seronegative patients. The three drugs that were tested for prevention of NMOSD relapses were eculizumab, inebilizumab, and satralizumab. All of the trials were worldwide, placebo-controlled, double-masked studies that demonstrated a clear benefit with each approach.

SUMMARY

Recent research in NMOSD has resulted in improved diagnosis and approved treatments.

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

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

Multiple sclerosis in ophthalmology: beyond optic neuritis

Disorders of the visual system are one of the main features of multiple sclerosis (MS), and have a great impact on the quality of life of patients. Although optic neuritis is the most frequent manifestation, there are other ophthalmological processes not related to neuritis, a knowledge of which is very useful in the management of patients with MS. These abnormalities are described, grouped into impairments of the afferent pathway, efferent pathway, or upper cerebral areas. Additionally, the main ophthalmological side effects of the drugs currently used in the control of MS are described.

The relationship between aquaporin-4 antibody status and visual tract integrity in neuromyelitis optica spectrum disorders: A visual evoked potential study

BACKGROUND

Optic neuritis (ON) is one of the hallmark symptomatic features of neuromyelitis optica spectrum disorders (NMOSD). The majority of patients with NMOSD present highly specific autoantibodies against aquaporin-4 (AQP4). A number of studies have reported poor visual acuity outcomes in individuals with AQP4 seropositive NMOSD, but no such relationship has been found with regard to visual evoked potentials (VEP) parameters such as the amplitude and latency of the P100 component. In this paper, we aimed (i) to describe VEP responses in patients with NMOSD; (ii) to analyze those results based on a scoring system; and (iii) to investigate the association between the VEPs and AQP4 antibody status.

METHODS

We retrospectively analysed the VEP responses of 40 patients with a diagnosis of NMOSD (according to the 2015 IPND criteria), including 16 with AQP4-postive status (AQP4[+]) and 24 with AQP4-negative status (AQP4[-]). In the first step, we measured the P100 peak latency and P100-N2 peak-to-peak amplitude in each patient. In the second, we converted these measures to the VEP score (0-10) using the scoring proposed by Jung et al. (2008). All recordings were performed using the same VEP device and testing protocol.

RESULTS

Abnormal VEPs were recorded in 25 of 40 patients (62.6%). Of these, 17 (42.5%) had prolonged P100 latency, and 8 (20%) had no response detected in at least one eye. The patients with ON as the initial relapse symptom had significantly higher median VEP scores than those who experienced the longitudinally extensive transverse myelitis (LETM) at the disease onset (7.0 [in-terquar-tile range (IQR), 2.0-8.0] vs. 0.0 [IQR, 0.0-4.0], p<0.001). A lack of VEP response in at least one eye was detected more frequently in the AQP4[+] group than the AQP4[-] group (7/16 vs. 1/24, p<0.005). Logistic regression model controlling for age, gender, disease duration, and the type of relapse at onset showed an independent impact of AQP4[+] status (OR=35.45, p = 0.018) on the higher rate of absent VEP responses. In the entire group of patients (n = 40), those with AQP4[+] showed a small tendency towards a higher median VEP score (4.0 [IQR, 0.0-7.8] vs. 1.0 [IQR, 0.0-4.0], p = 0.304). Among individuals with abnormal responses (n = 25), the patients with AQP4[+] had significantly higher median VEP scores (7.0 [IQR, 4.0-8.5] vs. 3.0 [IQR, 1.0-7.0], p = 0.034) and more common bilateral involvement of the optic tracts (80% vs. 40%, p = 0.048) than those who were seronegative for anti-AQP4 antibody. A median regression analysis model controlling for age, gender, disease duration, type of onset, and number of relapses in last 12 months showed an independent association between the AQP4-positive status and a higher VEP score in patients with NMOSD (t = 2.882, df=2, p = 0.007).

CONCLUSION

VEP study remains a useful tool in the assessment of NMOSD patients. Due to the high prevalence of absent VEPs in NMOSD patients, the scoring system appears to be more applicable for the precise analysis of VEP recordings. There is a positive association between the AQP-positive serostatus and the poorer outcome in VEP responses, especially in patients with severe impairment of the optic nerve(s).

Chronic demyelination exacerbates neuroaxonal loss in patients with MS with unilateral optic neuritis

Objective

To examine the effect of chronic demyelination in the optic nerve of patients with MS on progressive loss of retinal ganglion cell (RGC) axons.

Methods

Progressive retinal nerve fiber layer (RNFL) loss, as measured by optical coherence tomography, was longitudinally examined in 51 patients with MS with a history of unilateral optic neuritis (ON) and 25 normal controls. Patients were examined annually with a median of 4-year follow-up. Pairwise intereye comparison was performed between ON and fellow non-ON (NON) eyes of patients with MS using the linear mixed-effects model and survival analysis. The latency asymmetry of multifocal visual evoked potential (mfVEP) was used to determine the level of demyelination in the optic nerve.

Results

Although both ON and NON eyes demonstrate significantly faster loss of RGC axons compared with normal subjects, ON eyes with severe chronic demyelination show accelerated thinning in the RNFL in the temporal sector of the optic disc (temporal RNFL [tRNFL]) compared with fellow eyes (evidenced by both the linear mixed-effects model and survival analysis). Furthermore, progressive tRNFL thinning is associated with the degree of optic nerve demyelination and reflects the topography of pathology in the optic nerve. More rapid axonal loss in ON eyes is also functionally evidenced by mfVEP amplitude reduction, which correlates with the level of optic nerve demyelination.

Conclusions

Although the effect of demyelination on axonal survival has been demonstrated in experimental studies, our results provide first clinically meaningful evidence that chronic demyelination is associated with progressive axonal loss in human MS.

Optimization of spectral domain optical coherence tomography and visual evoked potentials to identify unilateral optic neuritis

BACKGROUND

Optic neuritis is a common manifestation of multiple sclerosis and frequently the presenting sign. The diagnosis of MS is heavily based on MRI findings but the latter is relatively insensitive in detecting optic nerve lesions. Identification of optic nerve lesion using ancillary tools such spectral-domain optical coherence tomography (SDOCT) by measuring the retinal nerve fiber layer (RNFL) and ganglion cell-inner plexiform layer (GCIPL), and visual-evoked potentials latencies (VEP) may facilitate early diagnosis and treatment of multiple sclerosis.

OBJECTIVE

To determine the optimal of SDOCT measures in RFNL and GCIPL and the VEP latency value for the identification of a prior symptomatic optic nerve lesion.

METHODS

Thirty patients with diagnosed clinically with optic neuritis and fifty healthy control subjects were tested with SDOCT and VEP and the sensitivity, specificity, negative and positive predictive values of optimal values from healthy controls and optic neuritis patients were determined of for the identification unilateral optic nerve lesion.

RESULTS

The inter-eye GCIPL difference of 3.5 µm is highly sensitive (100%) and specific (98%) in identifying unilateral optic nerve lesion, while lowest 5th percentile normal GCIPL threshold values of 71 µm was highly sensitive (100%) but less specific (83.3%). The inter-eye RNFL difference of 5.5 µm had a sensitivity of 70% and specificity of 90% in identifying optic nerve lesion while the lower 5th percentile normal RNFL value of 92.3 µm was poorly sensitive (40%). Finally, the 95th percentile normal VEP latency of 104.50 milliseconds had sensitivity of 80% and specificity of 76% in identifying optic nerve lesion.

CONCLUSIONS

The inter-eye GCIPL difference is a powerful index for identifying unilateral optic nerve lesion, while the inter-eye RNFL difference and 95th percentile normal VEP latency had very good sensitivity and specificity. These measures can be useful in the evaluation of the first demyelinating event of MS and therefor can facilitate early diagnosis and therapy.

Clinical and radiologic approach to 'typical' versus antibody-related optic neuritis

PURPOSE OF REVIEW

Optic neuritis is an autoimmune optic neuropathy that has been associated with multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD), and more recently antimyelin oligodendrocyte glycoprotein (anti-MOG)-positive disorder. At initial presentation, it is often difficult to differentiate these entities given their significant overlap in clinical presentation and MRI findings. This review summarizes the distinguishing clinical and radiological features of MS, NMOSD, and anti-MOG disorders to help clinicians accurately diagnose and manage patients affected by these conditions.

RECENT FINDINGS

Antiaquaporin-4 (AQP4) and more recently anti-MOG antibodies are both associated with central nervous system demyelinating diseases that often initially present with optic neuritis. Serologic testing now allows for a new classification of these overlapping conditions that can help to differentiate 'typical' optic neuritis that is often associated with MS from 'atypical' optic neuritis associated with NMOSD and anti-MOG-positive disorder.

SUMMARY

Optic neuritis associated with MS, NMOSD, and anti-MOG-positive disease can have a similar clinical presentation. However, some clinical and radiologic findings can help clinicians to differentiate these entities so that they can be properly managed to optimize visual prognosis.

Association Between BDNF Val66Met Polymorphism and Optic Neuritis Damage in Neuromyelitis Optica Spectrum Disorder

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune inflammatory disease of the central nervous system (CNS). The purpose of the study was to examine the association between the brain-derived neurotrophic factor (BDNF) Val66Met genotype and structural and functional optic nerve damage in the eyes of NMOSD patients. A total of 17 NMOSD subjects (34 eyes) were included in the study and were divided into subgroups based on optic neuritis (ON) history and BDNF Val66Met polymorphisms. The mean (range) age was 47.8 (23–78) years, and the mean (SD) disease duration was 7.4 (2–39) years. All participants had undergone optical coherence tomography (OCT) scans for global retinal nerve fiber layer (gRNFL) and ganglion cell-inner plexiform layer (GCIPL) thickness and multifocal visual evoked potential (mfVEP) test for amplitude and latency. BDNF Val66Met polymorphisms were genotyped in all participants. OCT and mfVEP changes were compared between two genotype groups (Met carriers vs. Val homozygotes) by using the generalised estimating equation (GEE) models. The BDNF Val66Met polymorphism was significantly associated with more severe nerve fiber layer damage and axonal loss in ON eyes of NMOSD subjects. Met carriers had more significantly reduced GCIPL (P = 0.002) and gRNFL (P < 0.001) thickness as well as more delayed mfVEP latency (P = 0.008) in ON eyes. No association was found between Val66Met variants and non-ON (NON)-eye of the participants. These findings suggest that the BDNF Val66Met polymorphism may be associated with optic nerve damage caused by acute ON attacks in NMOSD patients.

Visual Outcomes of Plasma Exchange Treatment of Steroid-Refractory Optic Neuritis: A Retrospective Monocentric Analysis

Introduction

In acute inflammatory optic neuritis (ON) as a typical onset of multiple sclerosis (MS), only few studies have investigated plasma exchange (PLEX) as a sequential treatment after insufficient response to high-dose intravenous glucocorticosteroids. Therefore, we aimed to investigate treatment outcome on visual acuity (VA) with PLEX in patients with steroid-refractory ON.

Methods

In our retrospective monocentric study, medical records were screened for patients with acute ON as their first relapse with sequential MS diagnosis or with an established MS diagnosis from the Bern University Hospital (Switzerland) that were treated with PLEX between 2016 and 2018 due to lacking steroid response. VA prior to steroid administration, and before and after PLEX were assessed and compared using the Friedman multiple comparison test.

Results

In total, 18 patients were included in the analysis. Interval from symptom onset to PLEX was 20.3 days (mean, 95% CI 14.8-25.9). Relevant functional improvement (VA of ≥0.5, after a mean of 15.9 (13.3-18.5) days after start of PLEX) was detected in 16/18 (88.9%) with a significant amelioration as compared to VA before glucocorticosteroids and before PLEX (p < 0.0001). VA improvement at a later time point (38.1 weeks, 25.2-51.0) was present in 15/16 (93.8%) patients. No serious adverse events were detected. PLEX could be performed via peripheral access in 13/18 patients (72.2%).

Conclusion

Our study demonstrates significant improvements of VA with PLEX in a cohort of MS patients with steroid-refractory ON. High response rates may be due to the timely treatment initiation. Despite the small sample size, our data support the early use of PLEX in steroid-refractory ON with a favorable safety profile.

Plasma Exchange as a First Line Therapy in Acute Attacks of Neuromyelitis Optica Spectrum Disorders

Background and Aims:

Neuromyelitis optica spectrum disorder (NMOSD) is a demyelinating disorder of central nervous system with deleterious effects. At present Intravenous corticosteroids are used for the relapse as the first line of treatment, but with only a class evidence III-IV. Having an underlying humoral immune mechanism in the pathogenesis of NMOSD and as it is rightly said that “Time is Cord and Eyes”, delaying the time to start plasma exchange (PLEX) awaiting favorable outcome in response to corticosteroids is detrimental for the patient. Hence, PLEX may be a promising first line therapeutic approach in the management of severe attacks of NMOSD. The aim of this study is to evaluate the efficacy of PLEX as the first line of treatment for the acute attacks in patients with NMOSD that is being largely used as an add-on therapy for more than 10 years, and also to define the time opportunity window for the starting of PLEX.

Methods:

The study analysed the therapeutic efficacy and safety profile of PLEX as a first line therapy in 30 patients diagnosed with NMOSD over a period of 30 months. PLEX was performed using a Hemonetics Mobile Collection System plus machine with due written consent including the risks and benefits of the treatment that is being proposed to the patient/relative in their own language.

Results:

A total of 30 patients were analysed, out of which 16 were females and rest males. 85% of the patients were in the age group of 25-35 years. All the patients had severe Expanded Disability Status Scale (EDSS) scores at the baseline, and 73.33% showed significant improvement following PLEX. The only predictor of good outcome was the time to PLEX i.e shorter delay betters the outcome.

Conclusion:

The study ascertained the importance of early PLEX as a therapeutic intervention in severe attacks of NMOSD irrespective of their Anti-Aquaporin 4 (AQP4) antibody status.

Sex-Specific Effect of BDNF Val66Met Genotypes on the Progression of Open-Angle Glaucoma

Purpose

To investigate whether the brain-derived neurotrophic factor (BDNF) Val66Met genotype is associated with the rate of progression of open-angle glaucoma (OAG).

Methods

In this retrospective cohort study, 148 OAG patients (292 eyes) were enrolled with a median follow-up period of 5.3 (range, 1.1-8.6) years. All participants had undergone regular clinical examinations by using spectral-domain optical coherence tomography (SD-OCT) scans and Humphrey (SITA) visual field tests. BDNF Val66Met polymorphisms were genotyped in all participants. Longitudinal visual field and retinal nerve fiber layer (RNFL) changes were compared between Met carriers (n = 68, 135 eyes) and Val homozygotes (n = 80, 157 eyes) by using the generalized estimating equations (GEE) model and Kaplan-Meier survival analysis.

Results

There was no significant difference in mean rates of progression for the two genotypes. However, there was a significant association between the Val66Met genotypes and slower OAG progression, as suggested by a higher rate of global RNFL loss in Val/Val homozygotes (P = 0.008) in the long-term survival analysis. The effect demonstrated a degree of sex specificity, with the significant difference present only in females (P = 0.016) but not males. Similar sexual dimorphism was presented in superior (P = 0.005 in females, P = 0.38 in males) and inferior (P = 0.004 in females, P = 0.41 in males) RNFL loss. No significant difference was observed in visual field parameters.

Conclusions

Our results suggested that carriage of Met allele reduces the rate of long-term OAG progression. However, the fact that this effect is observed only in females indicates BDNF Val66Met influences the progression rate of OAG in a sex-specific manner.

Subclinical neurodegeneration in multiple sclerosis and neuromyelitis optica spectrum disorder revealed by optical coherence tomography

BACKGROUND

Neuroretinal atrophy is associated with whole-brain atrophy and disease activity in multiple sclerosis (MS). Recent findings support that subclinical visual pathway involvement might also occur in neuromyelitis optica spectrum disorders (NMOSDs).

OBJECTIVE

The objective of this study is to assess retinal thinning in MS and NMOSD and its association with disease activity.

METHODS

In total, 27 NMOSD and 54 propensity-score-matched MS patients underwent optical coherence tomography, visual acuity, and visual-evoked potentials at 2.4 years apart, in addition to routine clinical and magnetic resonance imaging (MRI) assessment. We excluded eyes with acute optic neuritis.

RESULTS

In NMOSD, we detected peripapillary retinal nerve fiber layer (pRNFL) thinning in patients with disease activity during follow-up (-0.494 µm/year), but not in stable patients (-0.012 µm/year). Macular ganglion cell-inner plexiform layer (GCIPL) thinning occurred instead in all patients (-0.279 µm/year). Relapsing-remitting multiple sclerosis (RRMS) meeting NEDA-3 criteria had no pRNFL or GCIPL thinning during follow-up. Active-disease RRMS and progressive MS, both active and stable, displayed pRNFL (-0.724, -0.586, -0.556 µm/year, respectively) and GCIPL loss.

CONCLUSION

In MS, neuroretinal atrophy was associated with disease activity but occurred in progressive MS even when achieving NEDA-3 criteria. In NMOSD, pRNFL thinning was associated with non-ocular relapses due to a spreading of inflammatory activity. GCIPL thinning was found in all patients, supporting a primary retinal pathology targeting AQP4-rich structures.

In vivo structural and functional assessment of optic nerve damage in neuromyelitis optica spectrum disorders and multiple sclerosis

Early detection of neuromyelitis optica spectrum disorders (NMOSD), especially after optic neuritis, a presenting manifestation commonly observed also in multiple sclerosis (MS), is crucial for timely treatment and prognosis. Integrated visual pathway assessment with optical coherence tomography (OCT) and visual evoked potentials (VEP) may help in this task, showing in vivo different pathophysiological backgrounds. We evaluated combined VEP and OCT in a cross-sectional, single-centre study assessing 50 consecutive NMOSD patients, 57 MS patients and 52 healthy controls. After optic neuritis, VEP were more frequently absent in NMOSD compared to MS; most NMOSD eyes with recordable VEP showed prolonged latency, but extreme latency delays were less common than in MS. OCT showed predominantly axonal involvement in NMOSD, with 88% eyes (95% CI: 69-97%) displaying retinal nerve fibre layer thickness <60 µm even after first optic neuritis episode. Accuracy of OCT was further enhanced by combination with VEP into a new Z-score derived OCT-VEP index, measuring prevalence of axonal damage or demyelination. Our results suggest that integrated optic nerve assessment may elucidate differences in optic neuritis pathophysiology; conduction slowing with relatively preserved nerve fibre layer suggests MS, while severe neuroaxonal loss after optic neuritis, often hindering VEP response, characterizes NMOSD.

A computer-aided diagnosis of multiple sclerosis based on mfVEP recordings

Introduction

The aim of this study is to develop a computer-aided diagnosis system to identify subjects at differing stages of development of multiple sclerosis (MS) using multifocal visual-evoked potentials (mfVEPs). Using an automatic classifier, diagnosis is performed first on the eyes and then on the subjects.

Patients

MfVEP signals were obtained from patients with Radiologically Isolated Syndrome (RIS) (n = 30 eyes), patients with Clinically Isolated Syndrome (CIS) (n = 62 eyes), patients with definite MS (n = 56 eyes) and 22 control subjects (n = 44 eyes). The CIS and MS groups were divided into two subgroups: those with eyes affected by optic neuritis (ON) and those without (non-ON).

Methods

For individual eye diagnosis, a feature vector was formed with information about the intensity, latency and singular values of the mfVEP signals. A flat multiclass classifier (FMC) and a hierarchical classifier (HC) were tested and both were implemented using the k-Nearest Neighbour (k-NN) algorithm. The output of the best eye classifier was used to classify the subjects. In the event of divergence, the eye with the best mfVEP recording was selected.

Results

In the eye classifier, the HC performed better than the FMC (accuracy = 0.74 and extended Matthew Correlation Coefficient (MCC) = 0.68). In the subject classification, accuracy = 0.95 and MCC = 0.93, confirming that it may be a promising tool for MS diagnosis.

Conclusion

In addition to amplitude (axonal loss) and latency (demyelination), it has shown that the singular values of the mfVEP signals provide discriminatory information that may be used to identify subjects with differing degrees of the disease.

Evidence of Müller Glial Dysfunction in Patients with Aquaporin-4 Immunoglobulin G-Positive Neuromyelitis Optica Spectrum Disorder

PURPOSE

To compare functional and structural changes in the retina in patients with aquaporin-4 immunoglobulin G (AQP4-IgG)-positive neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS).

DESIGN

Cross-sectional study; biochemical study of human retinas.

PARTICIPANTS

A total of 181 participants, including 22 consecutive patients (44 eyes) with NMOSD, 131 patients (262 eyes) with multiple sclerosis (MS), and 28 normal subjects (56 eyes). In addition, 8 eyeballs from healthy donors were used for biochemical analysis.

METHODS

Full-field electroretinography (ERG) and spectral-domain OCT were performed in all the subjects. Topography of AQP4 expression and Müller glial distribution were analyzed using Western blotting and immunohistochemistry.

MAIN OUTCOME MEASURES

Full-field ERG parameters, including amplitudes and peak times. Tissue volume of each of the retinal layers at the fovea by OCT segmentation. Levels of AQP4 expression at different retinal regions.

RESULTS

The b-wave amplitude was significantly reduced in patients with AQP4-IgG+ NMOSD in scotopic ERGs (compared with AQP4-IgG- subjects, patients with MS, and normal controls) but not in photopic ERGs. Further analysis showed that this b-wave change was mainly caused by reduction of the slow PII component, suggesting specific Müller cell dysfunction. We also found thinning of specific retinal layers at the fovea in patients with AQP4-IgG+ NMOSD, in the Henle fiber outer nuclear layer (HFONL) and the inner segment (IS) layer, but not in the inner nuclear layer (INL), outer plexiform layer (OPL), or outer segment (OS) layer. Furthermore, there was a significant association between foveal HFONL-IS complex thinning and scotopic b-wave amplitude reduction (P = 0.005∼0.01, fixed-effects model). Western blotting demonstrated that Müller cell-specific AQP4 was expressed at a higher level at the fovea than the peripheral retina. Immunohistochemical studies revealed that the specific foveal thinning reflected the topography of AQP4 expression and Müller glial distribution in the human macula.

CONCLUSIONS

This study provides in vivo structural and functional evidence of Müller glial dysfunction in eyes of patients with AQP4-IgG+ NMOSD. Topography of retinal structural change is supported by distribution of Müller cells and patterns of AQP4 expression. The study suggests that visual electrophysiology and retinal imaging could be useful biomarkers to assess the potential retinal astrocytopathy in NMOSD.