Optic neuritis classification in 2021

Autoantibody profile (MOG-IgG-positivity, AQP4-IgG-positivity, and double-seronegativity) as an outcome predictor after optic neuritis

BACKGROUND

Optic neuritis (ON) is the leading cause of optic neuropathy among young adults. Approximately 45 % of these patients have autoantibodies, and their possible clinical and prognostic implications have not been completely elucidated.

OBJECTIVE

We aimed to assess the visual outcome and its predictors in a cohort of patients with optic neuritis as a clinically isolated syndrome according to their antibody profile: AQP4-IgG-positivity, MOG-IgG-positivity, and double-seronegativity (SN).

METHODS AND MATERIAL

This cohort study used partial retrospective data collection from the neuroimmunology outpatient clinic of the University of São Paulo Hospital, including consecutive cases of isolated inflammatory ON. All samples were tested for MOG and AQP4 antibodies using in-house cell-based assays in live HEK-293 cells. This study was conducted following the STROBE guidelines.

RESULTS

Forty-seven consecutive patients were included in this study. The number of patients with visual acuity (VA) worse than 20/200 during acute attacks was similar among the three groups. However, severe long-term disability (20/200) was less frequent in patients with MOG-IgG (AQP4-IgG group: 58 %, MOG-IgG group: 15 %, SN group: 54 %; p = 0.029). After adjusting for age and attack severity, MOG-IgG status was associated with a 30.9 % higher relative VA improvement (95 %CI 7.5 - 54.3 %, p = 0.011) than the other subgroups.

CONCLUSIONS

Severe visual acuity disability was less frequent in the MOG-IgG group than in the AQP4-IgG and SN groups. Positivity for these antibodies was the only predictor of long-term VA in patients with isolated ON (single or recurrent).

Can volumetric analysis of the brain help diagnose isolated optic neuritis?

Isolated optic neuritis is a single episode inflammatory optic neuropathy. This condition, which affects the optimal function of the optic nerve, is not associated with neurological or systemic diseases. Our study aimed to compare patients with isolated optic neuritis and normal healthy individuals in terms of the cerebrum, cerebellum and hippocampus volumes by using the "volBrain Online MRI Brain Volumetry System" program. Persons diagnosed with isolated optic neuritis (n = 16) and persons without any disease (n = 16) were included in the study. VolBrain was used to process the MRI data and, the findings were compared with Mann-Whitney U test. Values with a p-value <0.05 were considered statistically significant. The cerebrum white matter volumes in the total brain and in the right-left hemispheres of the brain were statistically significantly lower in the optic neuritis group (p = 0.029; p = 0.050; p = 0.029, respectively). In the segmental cerebellum analysis, the left side lobule VIIIB, the total and right-left side lobule IX volumes were statistically significantly higher (p = 0.022; p = 0.014; p = 0.029; p = 0.018, respectively). In total, lobule I-II volume was statistically significantly lower in the optic neuritis group (p = 0.046). In the segmental hippocampus analysis, the right side CA2-CA3, the total and right-left side SR-SL-SM volumes were statistically significantly lower in the optic neuritis group (p = 0.039; p = 0.050; p = 0.016, respectively). There are neurodegenerative changes in brain volume in patients with isolated optic neuritis. Although volBrain alone is not sufficient to diagnose isolated optic neuritis, it provides quantitative data that can be used as a complementary diagnostic method.

Pathogenic role of autoantibodies at the ependyma in autoimmune disorders of the central nervous system

Ependymal cells make up the epithelial monolayer that lines the brain ventricles and the spinal cord central canal that are filled with cerebrospinal fluid. The ependyma has several functions, including regulating solute exchange between the cerebrospinal fluid and parenchyma, controlling microcirculation of cerebrospinal fluid via coordinated ciliary beating, and acting as a partial barrier. Dysregulation of these functions can lead to waste clearance impairment, cerebrospinal fluid accumulation, hydrocephalus, and more. A role for ependymal cells in a variety of neurological disorders has been proposed, including in neuromyelitis optica and multiple sclerosis, two autoimmune demyelinating diseases of the central nervous system, where periventricular damage is common. What is not known is the mechanisms behind how ependymal cells become dysregulated in these diseases. In neuromyelitis optica, it is well established that autoantibodies directed against Aquaporin-4 are drivers of disease, and it has been shown recently that these autoantibodies can drive ependymal cell dysregulation. We propose a similar mechanism is at play in multiple sclerosis, where autoantibodies targeting a glial cell protein called GlialCAM on ependymal cells are contributing to disease. GlialCAM shares high molecular similarities with the Epstein-Barr virus (EBV) protein EBNA1. EBV has recently been shown to be necessary for multiple sclerosis initiation, yet how EBV mediates pathogenesis, especially in the periventricular area, remains elusive. In this perspective article, we discuss how ependymal cells could be targeted by antibody-related autoimmune mechanisms in autoimmune demyelinating diseases and how this is implicated in ventricular/periventricular pathology.

The Treatment of Acute Optic Neuritis

Despite the high incidence of optic neuritis (ON), and the growing number of therapeutic options for the long-term treatment of diseases associated with ON including multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD) and MOG antibody associated disease (MOGAD), there are still only limited therapeutic options for treating an acute event of optic neuritis. These include steroids, plasma exchange (PLEX) and intravenous immunoglobulin (IVIG). High-dose steroids remain the mainstay of acute treatment. However, evidence is emerging that when optic neuritis is accompanied with certain atypical features that suggest a more unfavorable outcome this mandates special consideration such as early addition of other therapeutic agents or tapering the steroid very slowly. This review will distinguish between typical and atypical neuritis and discuss acute treatment options.

The Acute Optic Neuritis Network (ACON): Study protocol of a non-interventional prospective multicenter study on diagnosis and treatment of acute optic neuritis

Optic neuritis (ON) often occurs at the presentation of multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD), and myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD). The recommended treatment of high-dose corticosteroids for ON is based on a North American study population, which did not address treatment timing or antibody serostatus. The Acute Optic Neuritis Network (ACON) presents a global, prospective, observational study protocol primarily designed to investigate the effect of time to high-dose corticosteroid treatment on 6-month visual outcomes in ON. Patients presenting within 30 days of the inaugural ON will be enrolled. For the primary analysis, patients will subsequently be assigned into the MS-ON group, the aquapotin-4-IgG positive ON (AQP4-IgG+ON) group or the MOG-IgG positive ON (MOG-IgG+ON) group and then further sub-stratified according to the number of days from the onset of visual loss to high-dose corticosteroids (days-to-Rx). The primary outcome measure will be high-contrast best-corrected visual acuity (HC-BCVA) at 6 months. In addition, multimodal data will be collected in subjects with any ON (CIS-ON, MS-ON, AQP4-IgG+ON or MOG-IgG+ON, and seronegative non-MS-ON), excluding infectious and granulomatous ON. Secondary outcomes include low-contrast best-corrected visual acuity (LC-BCVA), optical coherence tomography (OCT), magnetic resonance imaging (MRI) measurements, serum and cerebrospinal fluid (CSF) biomarkers (AQP4-IgG and MOG-IgG levels, neurofilament, and glial fibrillary protein), and patient reported outcome measures (headache, visual function in daily routine, depression, and quality of life questionnaires) at presentation at 6-month and 12-month follow-up visits. Data will be collected from 28 academic hospitals from Africa, Asia, the Middle East, Europe, North America, South America, and Australia. Planned recruitment consists of 100 MS-ON, 50 AQP4-IgG+ON, and 50 MOG-IgG+ON. This prospective, multimodal data collection will assess the potential value of early high-dose corticosteroid treatment, investigate the interrelations between functional impairments and structural changes, and evaluate the diagnostic yield of laboratory biomarkers. This analysis has the ability to substantially improve treatment strategies and the accuracy of diagnostic stratification in acute demyelinating ON.

Trial registration

ClinicalTrials.gov, identifier: NCT05605951.

Visual fields and optical coherence tomography (OCT) in neuro-ophthalmology: Structure-function correlation

Visual field (VF) testing is an essential component of the neurological examination. The differential diagnosis of VF defects depends on relating this measure of afferent visual function to the structure of the visual pathway and optical coherence tomography (OCT) is an invaluable tool for detailed structural evaluation of the optic nerve and retina. This review describes the ways in which interpretation of VF and OCT can be used together to increase the accuracy of the localization of lesions along the visual pathway. Lesions of the anterior visual pathway (originating in ganglion cells or nerve fibre layer of the retina or optic nerve) will typically produce defects that respect the horizontal midline, reflecting the arcuate path of the ganglion cell axons as they travel to the optic nerve. OCT of peripapillary retinal nerve fibre layer and ganglion cell complex (GCC) will typically demonstrate irreversible thinning in compressive and demyelinating lesions affecting anterior visual pathway. Chiasmal lesions produce highly localizable VF defects (junctional scotoma and bitemporal hemianopia) which correspond to the thinning of nasal portion of GCC. Lesions of the optic tract result in incongruous homonymous hemianopia on VF with corresponding hemianopic thinning on GCC developing within months. Lesions affecting optic radiations usually produce more congruous homonymous VF defects and can also produce homonymous thinning on GCC, however, this takes much longer to develop as trans-synaptic degeneration at the lateral geniculate body must occur.