Optic neuritis and autoimmune optic neuropathies: advances in diagnosis and treatment

MOG Antibody Disease: Nuances in Presentation, Diagnosis, and Management

PURPOSE OF REVIEW

Myelin oligodendrocyte glycoprotein antibody disease (MOGAD) is a distinct neuroinflammatory condition characterized by attacks of optic neuritis, transverse myelitis, and other demyelinating events. Though it can mimic multiple sclerosis and neuromyelitis optica spectrum disorder, distinct clinical and radiologic features which can discriminate these conditions are now recognized. This review highlights recent advances in our understanding of clinical manifestations, diagnosis, and treatment of MOGAD.

RECENT FINDINGS

Studies have identified subtleties of common clinical attacks and identified more rare phenotypes, including cerebral cortical encephalitis, which have broadened our understanding of the clinicoradiologic spectrum of MOGAD and culminated in the recent publication of proposed diagnostic criteria with a familiar construction to those diagnosing other neuroinflammatory conditions. These criteria, in combination with advances in antibody testing, should simultaneously lead to wider recognition and reduced incidence of misdiagnosis. In addition, recent observational studies have raised new questions about when to treat MOGAD chronically, and with which agent. MOGAD pathophysiology informs some of the relatively unique clinical and radiologic features which have come to define this condition, and similarly has implications for diagnosis and management. Further prospective studies and the first clinical trials of therapeutic options will answer several remaining questions about the peculiarities of this condition.

MOG antibody-associated optic neuritis

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is a demyelinating disorder, distinct from multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD). MOGAD most frequently presents with optic neuritis (MOG-ON), often with characteristic clinical and radiological features. Bilateral involvement, disc swelling clinically and radiologically, and longitudinally extensive optic nerve hyperintensity with associated optic perineuritis on MRI are key characteristics that can help distinguish MOG-ON from optic neuritis due to other aetiologies. The detection of serum MOG immunoglobulin G utilising a live cell-based assay in a patient with a compatible clinical phenotype is highly specific for the diagnosis of MOGAD. This review will highlight the key clinical and radiological features which expedite diagnosis, as well as ancillary investigations such as visual fields, visual evoked potentials and cerebrospinal fluid analysis, which may be less discriminatory. Optical coherence tomography can identify optic nerve swelling acutely, and atrophy chronically, and may transpire to have utility as a diagnostic and prognostic biomarker. MOG-ON appears to be largely responsive to corticosteroids, which are often the mainstay of acute management. However, relapses are common in patients in whom follow-up is prolonged, often in the context of early or rapid corticosteroid tapering. Establishing optimal acute therapy, the role of maintenance steroid-sparing immunotherapy for long-term relapse prevention, and identifying predictors of relapsing disease remain key research priorities in MOG-ON.

Moving towards a new era for the treatment of neuromyelitis optica spectrum disorders

Neuromyelitis optica spectrum disorders (NMOSD) include a rare group of autoimmune conditions that primarily affect the central nervous system. They are characterized by inflammation and damage to the optic nerves, brain and spinal cord, leading to severe vision impairment, locomotor disability and sphynteric disturbances. In the majority of cases, NMOSD arises due to specific serum immunoglobulin G (IgG) autoantibodies targeting aquaporin 4 (AQP4-IgG), which is the most prevalent water-channel protein of the central nervous system. Early diagnosis and treatment are crucial to manage symptoms and prevent long-term disability in NMOSD patients. NMOSD were previously associated with a poor prognosis. However, recently, a number of randomized controlled trials have demonstrated that biological therapies acting on key elements of NMOSD pathogenesis, such as B cells, interleukin-6 (IL-6) pathway, and complement, have impressive efficacy in preventing the occurrence of clinical relapses. The approval of the initial drugs marks a revolutionary advancement in the treatment of NMOSD patients, significantly transforming therapeutic options and positively impacting their prognosis. In this review, we will provide an updated overview of the key immunopathological, clinical, laboratory, and neuroimaging aspects of NMOSD. Additionally, we will critically examine the latest advancements in NMOSD treatment approaches. Lastly, we will discuss key aspects regarding optimization of treatment strategies and their monitoring.

Optic Neuritis in a Pediatric Patient with Kikuchi-Fujimoto Disease: A Case Report and Review of the Literature

Kikuchi-Fujimoto disease (KFD), also known as histiocytic necrotizing lymphadenitis, is a rare, benign, and self-limiting condition characterized by lymph node inflammation. While KFD is rarely associated with ocular manifestations, our case report highlights bilateral optic neuritis in a 13-year-old male patient with KFD. We also provide a comprehensive review of similar cases in the literature.

Visual Function Improvement after Plasma Exchange Therapy for Acute Optic Neuritis in Neuromyelitis Optica Spectrum Disorders: Case Series and Review

OBJECTIVE

Neuromyelitis optica (NMO) and neuromyelitis optica spectrum disorder (NMOSD) are autoimmune-mediated central nervous system disorders distinguished by the presence of serum aquaporine-4 IgG antibody (AQP4-Ab). The clinical panel comprises severe optic neuritis (ON) and transverse myelitis, which can result in incomplete recovery and a high risk of recurrence.

METHODS

This study aimed to evaluate the visual outcomes of three patients with severe acute ON in NMOSD that was non-responsive to intravenous methylprednisolone (IVMP), who received plasma exchange therapy (PLEX). We included three patients (P1, P2 and P3) with severe acute ON who had no improvement after IVMP treatment and were admitted to the ophthalmology department at the Emergency University Hospital Bucharest from January 2022 to September 2023. All three patients with ON were diagnosed in accordance with the criteria described by the Optic Neuritis Treatment Trial. All the subjects were experiencing their first attack.

RESULTS

The mean recruitment age was 35.3 ± 7.71. All patients were seropositive for the AQP4 antibody. All patients were tested for serum myelin oligodendrocyte glycoprotein (MOG) antibody but only one showed a positive test (P3). Lesions visible in orbital MRI indicated the involvement of retrobulbar, canalicular and/or intracranial segments. All three subjects had no response or incomplete remission after an IVMP protocol (5 days of 1000 mg intravenous methylprednisolone in sodium chloride 0.9%). The mean time from onset of optic neuritis to PLEX was 37.6 days. The PLEX treatment protocol comprised five cycles of plasma exchange treatment over 10 days, with a plasma exchange session every other day. An amount of 1 to 1.5 volumes of circulating plasma were dialyzed for 2-4 h. At 1 month after the completion of PLEX therapy, BCVA and VF parameters were improved in all three patients.

CONCLUSION

The treatment of ON remains subject to debate and is somewhat controversial. Plasma exchange must be considered as a rescue therapy when IVMP is insufficient for AQP4-ON patients. This study revealed that PLEX treatment effectively improves the visual outcomes of patients experiencing their first attack of severe acute isolated ON after high-dose IVMP treatment. This study suggests that PLEX may be associated with improved visual outcomes in NMOSD acute optic neuritis.

Applying the 2022 optic neuritis criteria to noninflammatory optic neuropathies with optic nerve T2-hyperintensity: an observational study

INTRODUCTION

Recent diagnostic criteria for optic neuritis include T2-hyperintensity of the optic nerve (ON), even without associated contrast enhancement. However, isolated ON-T2-hyperintensity is a nonspecific finding found in any optic neuropathy or severe retinopathy. We applied the 2022 optic neuritis diagnostic criteria to a cohort of patients with noninflammatory optic neuropathy and ON-T2-hyperintensity in at least one eye, to assess the rate of optic neuritis misdiagnosis using these criteria.

METHODS

Retrospective study of consecutive patients who underwent brain/orbit MRI with/without contrast between 07/01/2019 and 06/30/2022. Patients with ON-T2-hyperintensity in at least one eye were included. The 2022 optic neuritis diagnostic criteria were applied to patients with noninflammatory optic neuropathies who had an ophthalmologic examination available for review.

RESULTS

Of 150 patients included, 85/150 had compressive optic neuropathy; 32/150 had glaucoma; 12/150 had papilledema; 8/150 had hereditary (3), radiation-induced (3), nutritional (1), traumatic (1) optic neuropathies (none fulfilled the criteria); 13/150 had ischemic optic neuropathy and 4 fulfilled the criteria as definite optic neuritis due to contrast enhancement of the ON head. Seven additional patients would have satisfied the diagnostic criteria if red flags for alternative diagnoses had been overlooked.

DISCUSSION

The application of the 2022 optic neuritis diagnostic criteria in patients with noninflammatory optic neuropathy and ON-T2-hyperintensity in at least one ON resulted in misdiagnosis of optic neuritis in only 4 patients because of ON head enhancement, all with nonarteritic anterior ischemic optic neuropathy. Neuro-ophthalmologic evaluation and exclusion of the ON head as a location in the MRI criteria would have prevented optic neuritis misdiagnosis in our study.

Challenges in Diagnosis and Therapeutic Strategies in Late-Onset Multiple Sclerosis

Multiple sclerosis (MS) is a chronic inflammatory and degenerative demyelinating disease of the central nervous system of unknown etiology, which affects individuals in their early adulthood. However, nearly 5-10% of people with MS can be diagnosed at ages above 50 years old, referred to as late-onset multiple sclerosis (LOMS). Some studies have reported a distinctive presentation, clinical course, and prognosis for LOMS, implicating a different diagnostic and therapeutic approach for this population. Furthermore, similar manifestations between LOMS and other age-related conditions may lead to potential misdiagnosis and diagnostic delays, and a higher burden of multimorbidity associated with aging can further complicate the clinical picture. This review aims to explore the clinical characteristics, the disease course, and the differential diagnosis of LOMS and addresses therapeutic considerations for this population.

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 structural and microvascular deterioration independent of optic neuritis in aquaporin-4 antibody-positive neuromyelitis optica spectrum disorders: An optical coherence tomography angiography study

PURPOSE

To assess the retinal structural and microvascular change in aquaporin-4 antibody (AQP4) positive neuromyelitis optica spectrum disorder (NMOSD) patients and the correlation with clinical features.

METHODS

A cross-sectional study was performed with optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) to measure retinal structure and microvascular parameters in AQP4 positive NMOSD patients.

RESULTS

Sixty-two NMOSD patients (44 eyes with ON, NMOSD+ON; 77 eyes without ON, NMOSD-ON) and 62 healthy controls (HC, 124 eyes) were included. BCVA was worse in NMOSD patients compared to HC (p<0.001). Peripapillary retinal nerve fiber layer (pRNFL, p<0.001) and ganglion cell complex (GCC, p<0.001) was thinner in NMOSD+ON eyes compared to NMOSD-ON eyes and HC. Compared to HC, pRNFL (p = 0.002) and GCC (p = 0.001) was thinner in NMOSD-ON eyes. The vessel density (VD) in superficial capillary plexus (SCP, NMOSD+ON vs HC p<0.001, NMOSD-ON vs HC p = 0.002) and radial peripapillary capillary (RPC, NMOSD+ON vs HC p<0.001, NMOSD-ON vs HC p = 0.001) were also lower in NMOSD patients than HC independent of the history of ON. ON frequency and BCVA were correlated with the thickness of pRNFL and GCC, and VD in SCP and RPC (all p<0.001). EDSS was correlated with thickness of GCC (p = 0.008), and VD in SCP (p = 0.013), DCP (p<0.001) and RPC (p = 0.009).

CONCLUSIONS

Subclinical degradation of retinal structure and microvasculature was found in NMOSD patients before the occurrence of ON, and was correlated with clinical disability. Retinal parameter might be a tool to estimate the disease progression and investigate the pathogenesis of NMOSD.

Tissue Hypoxia and Associated Innate Immune Factors in Experimental Autoimmune Optic Neuritis

Visual loss in acute optic neuritis is typically attributed to axonal conduction block due to inflammatory demyelination, but the mechanisms remain unclear. Recent research has highlighted tissue hypoxia as an important cause of neurological deficits and tissue damage in both multiple sclerosis (MS) and experimental autoimmune encephalomyelitis (EAE) and, here, we examine whether the optic nerves are hypoxic in experimental optic neuritis induced in Dark Agouti rats. At both the first and second peaks of disease expression, inflamed optic nerves labelled significantly for tissue hypoxia (namely, positive for hypoxia inducible factor-1α (HIF1α) and intravenously administered pimonidazole). Acutely inflamed nerves were also labelled significantly for innate markers of oxidative and nitrative stress and damage, including superoxide, nitric oxide and 3-nitrotyrosine. The density and diameter of capillaries were also increased. We conclude that in acute optic neuritis, the optic nerves are hypoxic and come under oxidative and nitrative stress and damage. Tissue hypoxia can cause mitochondrial failure and thus explains visual loss due to axonal conduction block. Tissue hypoxia can also induce a damaging oxidative and nitrative environment. The findings indicate that treatment to prevent tissue hypoxia in acute optic neuritis may help to restore vision and protect from damaging reactive oxygen and nitrogen species.

Optic Nerve MRI T2-Hyperintensity: A Nonspecific Marker of Optic Nerve Damage

BACKGROUND

MRI abnormalities are common in optic neuropathies, especially on dedicated orbital imaging. In acute optic neuritis, optic nerve T2-hyperintensity associated with optic nerve contrast enhancement is the typical imaging finding. In chronic optic neuropathies, optic nerve T2-hyperintensity and atrophy are regularly seen. Isolated optic nerve T2-hyperintensity is often erroneously presumed to reflect optic neuritis, frequently prompting unnecessary investigations and neuro-ophthalmology consultations. Our goal was to determine the significance of optic nerve/chiasm T2-hyperintensity and/or atrophy on MRI.

METHODS

Retrospective study of consecutive patients who underwent brain/orbital MRI with/without contrast at our institution between July 1, 2019, and June 6, 2022. Patients with optic nerve/chiasm T2-hyperintensity and/or atrophy were included. Medical records were reviewed to determine the etiology of the T2-hyperintensity and/or atrophy.

RESULTS

Four hundred seventy-seven patients (698 eyes) were included [mean age 52 years (SD ±18 years); 57% women]. Of the 364 of 698 eyes with optic nerve/chiasm T2-hyperintensity without atrophy, the causes were compressive (104), inflammatory (103), multifactorial (49), glaucoma (21), normal (19), and other (68); of the 219 of 698 eyes with optic nerve/chiasm T2-hyperintensity and atrophy, the causes were compressive (57), multifactorial (40), inflammatory (38), glaucoma (33), normal (7), and other (44); of the 115 of 698 eyes with optic nerve/chiasm atrophy without T2-hyperintensity, the causes were glaucoma (34), multifactorial (21), inflammatory (13), compressive (11), normal (10), and other (26). Thirty-six eyes with optic nerve/chiasm T2-hyperintensity or atrophy did not have evidence of optic neuropathy or retinopathy on ophthalmologic examination, and 17 eyes had clinical evidence of severe retinopathy without primary optic neuropathy.

CONCLUSIONS

Optic nerve T2-hyperintensity or atrophy can be found with any cause of optic neuropathy and with severe chronic retinopathy. These MRI findings should not automatically prompt optic neuritis diagnosis, workup, and treatment, and caution is advised regarding their use in the diagnostic criteria for multiple sclerosis. Cases of incidentally found MRI optic nerve T2-hyperintensity and/or atrophy without a known underlying optic neuropathy or severe retinopathy are rare. Such patients should receive an ophthalmologic examination before further investigations.

A Comparative Review of Typical and Atypical Optic Neuritis: Advancements in Treatments, Diagnostics, and Prognosis

Optic neuritis (ON) is a debilitating condition that through various mechanisms, including inflammation or demyelination of the optic nerve, can result in partial or total permanent vision loss if left untreated. Accurate diagnosis and promptly initiated treatment are imperative related to the potential of permanent loss of vision if left untreated, which can lead to a significant reduction in the quality of life in affected patients. ON is subtyped as "typical" or "atypical" based on underlying causative etiology. The etiology of ON can be differentiated when appropriate diagnostic testing is performed. Using history taking, neuroimaging, and visual testing to localize the underlying pathology of ON in a time-sensitive manner is critical in mitigating these unsatisfactory outcomes. Herein, we examine the differences in presentation, pathophysiology, and treatments of typical ON causes, like multiple sclerosis (MS), and atypical causes such as neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein (MOG)-immunoglobulin G (IgG) ON. The present investigation places focus on both neuroimaging and visual imaging in the differentiation of ON. Additionally, this review presents physicians with a better understanding of different presentations, treatments, and prognoses of ON.

Prognostic factors of first-onset optic neuritis based on diagnostic criteria and antibody status: a multicentre analysis of 427 eyes

BACKGROUND

Optic neuritis (ON) prognosis is influenced by various factors including attack severity, underlying aetiologies, treatments and consequences of previous episodes. This study, conducted on a large cohort of first ON episodes, aimed to identify unique prognostic factors for each ON subtype, while excluding any potential influence from pre-existing sequelae.

METHODS

Patients experiencing their first ON episodes, with complete aquaporin-4 (AQP4) and myelin oligodendrocyte glycoprotein (MOG) antibody testing, and clinical data for applying multiple sclerosis (MS) diagnostic criteria, were enrolled. 427 eyes from 355 patients from 10 hospitals were categorised into four subgroups: neuromyelitis optica with AQP4 IgG (NMOSD-ON), MOG antibody-associated disease (MOGAD-ON), ON in MS (MS-ON) or idiopathic ON (ION). Prognostic factors linked to complete recovery (regaining 20/20 visual acuity (VA)) or moderate recovery (regaining 20/40 VA) were assessed through multivariable Cox regression analysis.

RESULTS

VA at nadir emerged as a robust prognostic factor for both complete and moderate recovery, spanning all ON subtypes. Early intravenous methylprednisolone (IVMP) was associated with enhanced complete recovery in NMOSD-ON and MOGAD-ON, but not in MS-ON or ION. Interestingly, in NMOSD-ON, even a slight IVMP delay in IVMP by >3 days had a significant negative impact, whereas a moderate delay up to 7-9 days was permissible in MOGAD-ON. Female sex predicted poor recovery in MOGAD-ON, while older age hindered moderate recovery in NMOSD-ON and ION.

CONCLUSION

This comprehensive multicentre analysis on first-onset ON unveils subtype-specific prognostic factors. These insights will assist tailored treatment strategies and patient counselling for ON.

Optic nerve topography in multiple sclerosis diagnostic criteria: Existing knowledge and future directions

Current diagnostic criteria for multiple sclerosis (MS) do not consider the optic nerve as a typical topography for establishing the diagnosis. Recent studies have proved the utility of optic nerve magnetic resonance imaging, optical coherence tomography and visual evoked potentials in detecting optic nerve lesions during the early stages of MS. In addition, emerging evidence supports the inclusion of optic nerve topography as a fifth region to fulfil the dissemination in space criteria. Anticipating a modification in the McDonald criteria, it is crucial for neurologists to familiarize with the diagnostic properties of each test in detecting optic nerve lesions and understand how to incorporate them into the MS diagnostic process. Therefore, the objective of this article is to review the existing evidence supporting the use of these tests in the diagnostic process of MS and provide a practical algorithm that can serve as a valuable guide for clinical practice.

Timing of MOG-IgG Testing Is Key to 2023 MOGAD Diagnostic Criteria

BACKGROUND AND OBJECTIVES

Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD) is a recently identified autoimmune demyelinating disorder of the CNS affecting both adults and children. Diagnostic criteria for MOGAD have recently been published. We aimed to validate the 2023 MOGAD diagnostic criteria in a real-world cohort of patients with atypical CNS inflammation.

METHODS

All patients referred to the National neuromyelitis optica spectrum disorder (NMOSD) specialized service at The Walton Center NHS Foundation Trust between 2012 and 2023 with an atypical demyelinating syndrome were evaluated. We systematically applied the 2023 MOGAD diagnostic criteria and previous 2018 International Diagnostic Recommendations for MOG encephalomyelitis to our retrospective cohort.

RESULTS

474 patients were screened and 66 were excluded for lack of clinical information. Preexisting diagnoses within our cohort included the following: MOGAD, n = 127; AQP4-IgG NMOSD, n = 125; seronegative NMOSD, n = 33; multiple sclerosis (MS), n = 10; and other diagnoses, n = 113. Of patients with preexisting MOGAD, 97% (123/127) fulfilled the 2023 MOGAD diagnostic criteria. Three patients with a low-positive MOG-IgG did not meet supportive features though 2/3 had insufficient investigations. Alternative diagnoses could not be excluded in 1 patient with MS-MOGAD overlap. No patients with a non-MOGAD diagnosis were found to fulfill the 2023 diagnostic criteria. The sensitivity and specificity of the 2023 MOGAD diagnostic criteria were 97% and 100% with no false positives, improving on 2018 International Diagnostic Recommendations for MOG encephalomyelitis. Low-positive MOG-IgG results were more often associated with a longer time from disease onset to sampling (p < 0.001). In addition, in patients with a MOG-IgG1 test within 6 months of clinical onset, approximately 25% can become low positive by 6 months. Of patients with preexisting MOGAD, 9% (12/127) had insufficient investigations and examinations to fully evaluate additional supportive features. However, in those who were completely evaluated, supportive features were fulfilled in 97% (111/115).

DISCUSSION

The 2023 MOGAD diagnostic criteria were highly sensitive and specific and closely align with historically established cases of MOGAD. However, because additional supportive features are stipulated for patients with a low-positive MOG-IgG result, missed diagnoses may occur due to delayed testing or insufficient investigations.

Acquired Demyelinating Syndromes

Acquired demyelinating syndromes (ADS) are a heterogenous group of inflammatory demyelinating conditions that include presentations of optic neuritis, transverse myelitis, and acute demyelinating encephalomyelitis. They can be monophasic or can develop into relapsing episodes of the initial demyelinating event or evolve to include other types of demyelination. Significant progress has been made in differentiating subtypes of ADS that differ in their tendency to relapse and in which anti-inflammatory therapies are effective. Differentiating between these subtypes is important for the optimal management of these patients. Clinical features, labs (especially autoantibodies), and MRI findings can help to differentiate between the different ADS.

Unveiling the Multifaceted Problems Associated with Dysrhythmia

Dysrhythmia is a term referring to the occurrence of spontaneous and repetitive changes in potentials with parameters deviating from those considered normal. The term refers to heart anomalies but has a broader meaning. Dysrhythmias may concern the heart, neurological system, digestive system, and sensory organs. Ion currents conducted through ion channels are a universal phenomenon. The occurrence of channel abnormalities will therefore result in disorders with clinical manifestations depending on the affected tissue, but phenomena from other tissues and organs may also manifest themselves. A similar problem concerns the implementation of pharmacotherapy, the mechanism of which is related to the impact on various ion currents. Treatment in this case may cause unfavorable effects on other tissues and organs. Drugs acting through the modulation of ion currents are characterized by relatively low tissue specificity. To assess a therapy's efficacy and safety, the risk of occurrences in other tissues with similar mechanisms of action must be considered. In the present review, the focus is shifted prominently onto a comparison of abnormal electrical activity within different tissues and organs. This review includes an overview of the types of dysrhythmias and the basic techniques of clinical examination of electrophysiological disorders. It also presents a concise overview of the available pharmacotherapy in particular diseases. In addition, the authors review the relevant ion channels and their research technique based on patch clumping.

Integrative analysis of purine metabolites and gut microbiota in patients with neuromyelitis optica spectrum disorders after mycophenolate mofetil treatment

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is a recurring inflammatory demyelinating disease that is commonly observed in Asian countries like China. Prior investigations have shown that mycophenolate mofetil (MMF) with better biocompatibility compared to azathioprine (AZA), and can prevent relapses of NMOSD, but the efficacy was controversially reported in different NMOSD cases. We aimed to explore the factors that weaken efficacy of MMF in NMOSD.

METHODS

A total of 34 NMOSD patients treated with MMF were prospectively enrolled and grouped according to the therapeutic efficacy as effective group (EG, n = 23) versus less-effective group (LEG, n = 11). The purine metabolites were profiled in serum samples and gut microbiota was analyzed using 16S rRNA sequencing with stool samples from the same patients.

RESULTS

Purine salvage pathway (PSP) metabolites (inosine, hypoxanthine, xanthine, guanine and uric acid) in the serum of NMOSD patients were elevated in the LEG compared to EG (p < 0.05). Additionally, the richness and microbial diversity of gut microbiota was found to be similar between EG and LEG patients. However, LEG patients had increased presence of Clostridium and Synergistes but decreased abundance of the Coprococcus genus.

CONCLUSIONS

The PSP metabolites and composition of the gut microbiota were changed between patients with or without optimal clinical response after MMF treatment. This may help us to understand the pharmacodynamics of MMF in NMOSD.

Uncovering the Genetics and Physiology behind Optic Neuritis

Optic neuritis (ON) is an inflammatory condition affecting the optic nerve, leading to vision impairment and potential vision loss. This manuscript aims to provide a comprehensive review of the current understanding of ON, including its definition, epidemiology, physiology, genetics, molecular pathways, therapy, ongoing clinical studies, and future perspectives. ON is characterized by inflammation of the optic nerve, often resulting from an autoimmune response. Epidemiological studies have shown a higher incidence in females and an association with certain genetic factors. The physiology of ON involves an immune-mediated attack on the myelin sheath surrounding the optic nerve, leading to demyelination and subsequent impairment of nerve signal transmission. This inflammatory process involves various molecular pathways, including the activation of immune cells and the release of pro-inflammatory cytokines. Genetic factors play a significant role in the susceptibility to ON. Several genes involved in immune regulation and myelin maintenance have been implicated in the disease pathogenesis. Understanding the genetic basis can provide insights into disease mechanisms and potential therapeutic targets. Therapy for ON focuses on reducing inflammation and promoting nerve regeneration. Future perspectives involve personalized medicine approaches based on genetic profiling, regenerative therapies to repair damaged myelin, and the development of neuroprotective strategies. Advancements in understanding molecular pathways, genetics, and diagnostic tools offer new opportunities for targeted therapies and improved patient outcomes in the future.

Longitudinal in vivo evaluation of retinal ganglion cell complex layer and dendrites in mice with experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE), induced by the immunization of myelin oligodendrocyte glycoprotein (MOG), is related to human MOG antibody-associated disease (MOGAD). Neuroinflammation and demyelination of the optic nerve can lead to retinal ganglion cell (RGC) death and axonal damage in MOGAD. Here, we aimed to evaluate the structural changes in RGCs longitudinally by in vivo imaging in mice with RGCs expressing yellow fluorescent protein along the course of EAE. Successful induction of EAE was confirmed by the neurological function scores and histology analyses. The changes in the thickness of ganglion cell complex (GCC) layer and RGC survival and dendrites were monitored longitudinally along the course of EAE. Before the onset of EAE, there were no significant changes in the number and morphology of RGCs and the thickness of the GCC layer as compared to the mice without EAE induction. After the onset of EAE, the thickness of the GCC layer and the RGC number and dendritic network all gradually decreased along the course of EAE. Notably, dendritic shrinkage could be detected earlier than the thinning of the GCC layer. In summary, this study delineated the longitudinal profile of RGC structural changes in EAE mice, providing an assessment platform for monitoring outcomes of RGC treatments.

[Differential diagnostics of chronic eye pain from a neurological perspective-What can also lie behind it]

Periorbital pain and pain in the eye may arise from nociceptive processes such as chronic ocular surface destruction and inflammation, from neuropathic processes or often from a combination of different mechanisms. An important differential diagnosis are primary headache disorders and other neurological diseases, for example of inflammatory origin, which trigger secondary pain. Chronic eye pain therefore requires interdisciplinary collaboration in the diagnostics and treatment.

Assessing the Correlation Between Visual Acuity and Critical Fusion Frequency in Acute Optic Neuritis Before and After Steroid Therapy

Background Optic nerve diseases include inflammatory optic nerve diseases such as vasculitis, metabolic optic neuropathy, ischemic optic neuropathy, and optic neuritis. In this study, patients with acute optic neuritis are classified with better and poor visual acuity based on visual acuity after one month of steroid pulse therapy. To determine prognosis, initial visual acuity and critical fusion frequency (CFF) values will be compared with those recorded one month after treatment and at the last visit. Methods Visual acuity and CFF were evaluated one month after the start of treatment in patients diagnosed with acute optic neuritis, and follow-up was available for at least three months at Hiroshima University Hospital. Results All patients received steroid pulse therapy as initial treatment. After one month of treatment, visual acuity and CFF at the last visit were significantly improved in the group with improved visual acuity compared to the group with impaired visual acuity. Conclusions Visual acuity at the initial visit did not affect treatment outcome, and final visual acuity and CFF after one month of treatment for acute optic neuritis were better in patients with better visual acuity. Therefore, visual acuity values one month after treatment initiation may affect treatment outcomes.

Prevalence of serum MOG antibody and AQP4 antibody in optic neuritis after SARS-CoV-2 infection

Purpose

To evaluate the prevalence of serum myelin oligodendrocyte glycoprotein antibody (MOG-Ab) and aquaporin-4 antibody (AQP4-Ab) in optic neuritis (ON) patients after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection by cell-based indirect immunofluorescence assay (CBA).

Methods

In this prospective case series study, 35 patients clinically diagnosed as ON and laboratory-confirmed SARS-CoV-2 infection from 8 December 2022 to 8 February 2023 were included. All patients' clinical and laboratory data were collected and analyzed.

Results

The mean age of the 35 patients (46 eyes) was 38.2 years (ranging from 6 to 69 years), and 17 cases were female patients. Thirty-three and two cases showed positive SARS-CoV-2 RNA test results before or shortly after ON onset, respectively. ON occurred unilaterally in 24 cases and bilaterally in 11 cases. Ophthalmic examination revealed swollen optic disc in 37 eyes, normal optic disc in 6 eyes, and temporally or wholly paled optic disc in 3 eyes. CBA revealed seropositive MOG-Ab in 10 cases and AQP4-Ab in 2 cases, respectively, of which 2 AQP4-Ab-seropositive cases and 1 MOG-Ab-seropositive case had a past medical history of ON. Most ON patients showed a rapid and dramatic response to pulse steroid therapy. The median of BCVA at the onset and at the last follow-up was 20/500 (ranging from light perception to 20/20) and 20/67 (ranging from counting fingers to 20/20), respectively.

Conclusion

Serum MOG-Ab and AQP4-Ab were detected in 28.6% (10/35) and 5.7% (2/35) ON cases after SARS-CoV-2 infection. SARS-CoV-2 infection may trigger an onset or a relapse of ON, as well as the production of MOG-Ab.

Beyond Myelin Oligodendrocyte Glycoprotein and Aquaporin-4 Antibodies: Alternative Causes of Optic Neuritis

Optic neuritis (ON) is the most common cause of vision loss in young adults. It manifests as acute or subacute vision loss, often accompanied by retrobulbar discomfort or pain during eye movements. Typical ON is associated with Multiple Sclerosis (MS) and is generally mild and steroid-responsive. Atypical forms are characterized by unusual features, such as prominent optic disc edema, poor treatment response, and bilateral involvement, and they are often associated with autoantibodies against aquaporin-4 (AQP4) or Myelin Oligodendrocyte Glycoprotein (MOG). However, in some cases, AQP4 and MOG antibodies will return as negative, plunging the clinician into a diagnostic conundrum. AQP4- and MOG-seronegative ON warrants a broad differential diagnosis, including autoantibody-associated, granulomatous, and systemic disorders. These rare forms need to be identified promptly, as their management and prognosis are greatly different. The aim of this review is to describe the possible rarer etiologies of non-MS-related and AQP4- and MOG-IgG-seronegative inflammatory ON and discuss their diagnoses and treatments.

Neuro-ophthalmic manifestations of autoimmune disorders: diagnostic pearls & pitfalls

PURPOSE OF REVIEW

The purpose of this review is to highlight a clinical-anatomical approach to localizing neuro-ophthalmic manifestations of associated autoimmune disorders.

RECENT FINDINGS

Our understanding of autoimmune conditions has changed considerably over recent years, particularly with the emergence of novel autoantibodies. Cardinal neuro-ophthalmic signs and symptoms of antibody-mediated autoimmune disorders have been well characterized; knowledge thereof may be the first step towards an accurate diagnosis.

SUMMARY

A thorough history, further refined by a comprehensive examination are cornerstones to disease localization in clinical medicine. Taken together, these essential steps both guide investigations and facilitate early recognition of autoimmune disorders. From a neuro-ophthalmic perspective, it is important to understand heralding signs and symptoms of autoimmune syndromes, avoid cognitive errors, and remain mindful of common diagnostic pitfalls to optimize care.

VIDEO ABSTRACT

http://links.lww.com/COOP/A61.

An update on optic neuritis

Optic neuritis (ON) is the most common cause of subacute optic neuropathy in young adults. Although most cases of optic neuritis (ON) are classified as typical, meaning idiopathic or associated with multiple sclerosis, there is a growing understanding of atypical forms of optic neuritis such as antibody mediated aquaporin-4 (AQP4)-IgG neuromyelitis optica spectrum disorder (NMOSD) and the recently described entity, myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease (MOGAD). Differentiating typical ON from atypical ON is important because they have different prognoses and treatments. Findings of atypical ON, including severe vision loss with poor recovery with steroids or steroid dependence, prominent optic disc edema, bilateral vision loss, and childhood or late adult onset, should prompt serologic testing for AQP4-IgG and MOG-IgG. Although the traditional division of typical and atypical ON can be helpful, it should be noted that there can be severe presentations of otherwise typical ON and mild presentations of atypical ON that blur these traditional lines. Rare causes of autoimmune optic neuropathies, such as glial fibrillary acidic protein (GFAP) and collapsin response-mediator protein 5 (CRMP5) autoimmunity also should be considered in patients with bilateral painless optic neuropathy associated with optic disc edema, especially if there are other accompanying suggestive neurologic symptoms/signs. Typical ON usually recovers well without treatment, though recovery may be expedited by steroids. Atypical ON is usually treated with intravenous steroids, and some forms, such as NMOSD, often require plasma exchange for acute attacks and long-term immunosuppressive therapy to prevent relapses. Since treatment is tailored to the cause of the ON, elucidating the etiology of the ON is of the utmost importance.

Basic CSF parameters and MRZ reaction help in differentiating MOG antibody-associated autoimmune disease versus multiple sclerosis

Background

Myelin oligodendrocyte glycoprotein antibody-associated autoimmune disease (MOGAD) is a rare monophasic or relapsing inflammatory demyelinating disease of the central nervous system (CNS) and can mimic multiple sclerosis (MS). The variable availability of live cell-based MOG-antibody assays and difficulties in interpreting low-positive antibody titers can complicate diagnosis. Literature on cerebrospinal fluid (CSF) profiles in MOGAD versus MS, one of the most common differential diagnoses, is scarce. We here analyzed the value of basic CSF parameters to i) distinguish different clinical MOGAD manifestations and ii) differentiate MOGAD from MS.

Methods

This is retrospective, single-center analysis of clinical and laboratory data of 30 adult MOGAD patients and 189 adult patients with relapsing-remitting multiple sclerosis. Basic CSF parameters included CSF white cell count (WCC) and differentiation, CSF/serum albumin ratio (QAlb), intrathecal production of immunoglobulins, CSF-restricted oligoclonal bands (OCB) and MRZ reaction, defined as intrathecal production of IgG reactive against at least 2 of the 3 viruses measles (M), rubella (R) and varicella zoster virus (Z).

Results

MOGAD patients with myelitis were more likely to have a pleocytosis, a QAlb elevation and a higher WCC than those with optic neuritis, and, after review and combined analysis of our and published cases, they also showed a higher frequency of intrathecal IgM synthesis. Compared to MS, MOGAD patients had significantly more frequently neutrophils in CSF and WCC>30/µl, QAlb>10×10-3, as well as higher mean QAlb values, but significantly less frequently CSF plasma cells and CSF-restricted OCB. A positive MRZ reaction was present in 35.4% of MS patients but absent in all MOGAD patients. Despite these associations, the only CSF parameters with relevant positive likelihood ratios (PLR) indicating MOGAD were QAlb>10×10-3 (PLR 12.60) and absence of CSF-restricted OCB (PLR 14.32), whereas the only relevant negative likelihood ratio (NLR) was absence of positive MRZ reaction (NLR 0.00).

Conclusion

Basic CSF parameters vary considerably in different clinical phenotypes of MOGAD, but QAlb>10×10-3 and absence of CSF-restricted OCB are highly useful to differentiate MOGAD from MS. A positive MRZ reaction is confirmed as the strongest CSF rule-out parameter in MOGAD and could be useful to complement the recently proposed diagnostic criteria.

Visual System Involvement in Glial Fibrillary Acidic Protein Astrocytopathy: Two Case Reports and a Systematic Literature Review

BACKGROUND AND OBJECTIVES

Glial fibrillary acidic protein (GFAP) antibodies can associate with an astrocytopathy often presenting as a meningoencephalitis. Visual involvement has been reported but scarcely defined. We describe 2 cases of GFAP astrocytopathy with predominant visual symptoms and present a systematic review of the literature.

METHODS

We describe 2 patients with GFAP astrocytopathy from our neurology department. We performed a systematic review of the literature according to PRISMA guidelines, including all patients with this disease and available clinical data, focusing on visual involvement.

RESULTS

Patient 1 presented with bilateral optic disc edema and severe sudden bilateral loss of vision poorly responsive to therapy. Patient 2 showed bilateral optic disc edema, headache, and mild visual loss with complete recovery after steroids. We screened 275 records and included 84 articles (62 case reports and 22 case series) for a total of 592 patients. Visual involvement was reported in 149/592 (25%), with either clinical symptoms or paraclinical test-restricted abnormalities. Bilateral optic disc edema was found in 80/159 (50%) of patients investigated with fundoscopy, among which 49/80 (61%) were asymptomatic. One hundred (100/592, 17%) reported visual symptoms, often described as blurred vision or transient visual obscurations. Optic neuritis was rare and diagnosed in only 6% of all patients with GFAP astrocytopathy, often without consistent clinical and paraclinical evidence to support the diagnosis. Four patients (including patient 1) manifested a severe, bilateral optic neuritis with poor treatment response. In patients with follow-up information, a relapsing disease course was more frequently observed in those with vs without visual involvement (35% vs 11%, p = 0.0035, OR 3.6 [CI 1.44-8.88]).

DISCUSSION

Visual system involvement in GFAP astrocytopathy is common and heterogeneous, ranging from asymptomatic bilateral optic disc edema to severe bilateral loss of vision, but optic neuritis is rare. GFAP CSF antibody testing should be considered in patients with encephalitis/meningoencephalitis or myelitis and bilateral optic disc edema, even without visual symptoms, and in patients with severe bilateral optic neuritis, especially when AQP4 antibodies are negative. Visual symptoms might associate with a higher relapse risk and help to identify patients who may require chronic immunosuppression.

Real-world application of the 2022 diagnostic criteria for first-ever episode of optic neuritis

Optic neuritis (ON) admits diverse differential diagnoses. Petzold proposed diagnostic criteria for ON in 2022, although real-world application of these criteria is missing. We conducted a retrospective review of patients with ON. We classified patients into definite or possible ON, and into groups A (typical neuritis), B (painless), or C (binocular) and estimated the frequency of etiologies for each group. We included 77 patients, with 62% definite and 38% possible ON. CRION and NMOSD-AQP4 negative-ON were less commonly seen in definite ON. Application of the 2022 criteria revealed a lower-than-expected frequency of definite ON, particularly for seronegative non-MS causes.

Differential diagnosis of suspected multiple sclerosis: an updated consensus approach

Accurate diagnosis of multiple sclerosis requires careful attention to its differential diagnosis-many disorders can mimic the clinical manifestations and paraclinical findings of this disease. A collaborative effort, organised by The International Advisory Committee on Clinical Trials in Multiple Sclerosis in 2008, provided diagnostic approaches to multiple sclerosis and identified clinical and paraclinical findings (so-called red flags) suggestive of alternative diagnoses. Since then, knowledge of disorders in the differential diagnosis of multiple sclerosis has expanded substantially. For example, CNS inflammatory disorders that present with syndromes overlapping with multiple sclerosis can increasingly be distinguished from multiple sclerosis with the aid of specific clinical, MRI, and laboratory findings; studies of people misdiagnosed with multiple sclerosis have also provided insights into clinical presentations for which extra caution is warranted. Considering these data, an update to the recommended diagnostic approaches to common clinical presentations and key clinical and paraclinical red flags is warranted to inform the contemporary clinical evaluation of patients with suspected multiple sclerosis.

Acute optic neuritis: What are the clues to the aetiological diagnosis in real life?

BACKGROUND

Previous cross-sectional studies have reported distinct clinical and radiological features among the different acute optic neuritis (ON) aetiologies. Nevertheless, these reports often included the same number of patients in each group, not taking into account the disparity in frequencies of ON aetiologies in a real-life setting and thus, it remains unclear what are the truly useful features for distinguishing the different ON causes. To determine whether clinical evaluation, ophthalmological assessment including the optical coherence tomography (OCT), CSF analysis, and MRI imaging may help to discriminate the different causes of acute ON in a real-life cohort.

METHODS

In this prospective monocentric study, adult patients with recent acute ON (<1 month) underwent evaluation at baseline and 1 and 12 months, including, high- and low-contrast visual acuity, visual field assessment and OCT measurements, baseline CSF analysis and MRI.

RESULTS

Among 108 patients, 71 (65.7%) had multiple sclerosis (MS), 19 (17.6%) had idiopathic ON, 13 (12.0%) and 5 (4.6%) had myelin oligodendrocyte glycoprotein and aquaporin-4 antibodies, at last follow up respectively.At baseline, the distribution of bilateral ON, CSF-restricted oligoclonal bands, optic perineuritis, optic nerve length lesions and positive dissemination in space and dissemination in time criteria on MRI were significantly different between the four groups (p <0.001). No significant difference in visual acuity nor inner retinal layer thickness was found between the different ON aetiologies.

CONCLUSIONS

In this large prospective study, bilateral visual involvement, CSF and MRI results are the most useful clues in distinguishing the different aetiologies of acute ON, whereas ophthalmological assessments including OCT measurements revealed no significant difference between the aetiologies.

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD): current understanding and challenges

New diagnostic criteria for myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) have recently been proposed, distinguishing this syndrome from other inflammatory diseases of the central nervous system. Seropositivity status for MOG-IgG autoantibodies is important for diagnosing MOGAD, but only in the context of robust clinical characterization and cautious interpretation of neuroimaging. Over the last several years, access to cell-based assay (CBA) techniques has improved diagnostic accuracy, yet the positive predictive value of serum MOG-IgG values varies with the prevalence of MOGAD in any given patient population. For this reason, possible alternative diagnoses need to be considered, and low MOG-IgG titers need to be carefully weighted. In this review, cardinal clinical features of MOGAD are discussed. Key challenges to the current understanding of MOGAD are also highlighted, including uncertainty regarding the specificity and pathogenicity of MOG autoantibodies, the need to identify immunopathologic targets for future therapies, the quest to validate biomarkers that facilitate diagnosis and detect disease activity, and the importance of deciphering which patients with MOGAD require long-term immunotherapy.

Myelin Oligodendrocyte Glycoprotein Optic Neuritis Presenting With Orbital Apex Syndrome

A 36-year-old man presented with an acute onset of a right eye monocular altitudinal defect associated with pain on eye movement upon waking up from sleep. His right eye subsequently developed outward deviation and a total loss of vision. Clinical examination of the right eye revealed a visual acuity of no light perception (NLP) with the presence of relative afferent pupillary defect (RAPD) and involvement of cranial nerves II, III, IV, and VI. A marked optic disc swelling and peripapillary hemorrhages were seen in the right fundus. Contrast-enhanced computed tomography of the brain and orbit showed a unilateral enlargement and enhancement of the right intraorbital and intracanalicular segments of the optic nerve with surrounding fat stranding and orbital apex crowding. Magnetic resonance imaging showed T2/fluid-attenuated inversion recovery hyperintensity and enhancement of the optic nerve and the myelin sheath. Serum anti-myelin oligodendrocyte glycoprotein antibodies were detected. He was treated with corticosteroids, plasma exchange, and intravenous immunoglobulin. His vision improved slowly after treatment. This case report shows the diverse manifestations of myelin oligodendrocyte glycoprotein antibody disease, which includes the orbital apex syndrome.

Isolated optic neuritis with positive glial fibrillary acidic protein antibody

BACKGROUND AND OBJECTIVES

Autoimmune glial fibrillary acidic protein (GFAP) astrocytopathy (GFAP-A) has been reported as a spectrum of autoimmune, inflammatory central nervous system disorders. Linear perivascular radial gadolinium enhancement patterns on brain magnetic resonance imaging (MRI) are a hallmark of these disorders. GFAP-A is associated with cerebrospinal fluid (CSF) GFAP antibody (GFAP-Ab), while the association with serum GFAP-Ab is less clear. This study aimed to observe the clinical characteristic and MRI changes of GFAP-Ab-positive optic neuritis (ON).

METHODS

We performed a retrospective, observational case study at the department of neurology, Beijing Tongren Hospital, from December 2020 to December 2021. The serum of 43 patients and CSF samples of 38 patients with ON were tested for GFAP-Ab by cell-based indirect immune-fluorescence test.

RESULTS

Four patients (9.3%) were detected GFAP-Ab positive, and in three out of the four patients, GFAP-Abs were detected only in serum. All of them demonstrated unilateral optic neuritis. Three patients (1, 2, and 4) experienced severe visual loss (best corrected visual acuity ≤ 0.1). Two patients (2 and 4) had experienced more than one episode of ON at the time of sampling. MRI showed optic nerve hyperintensity on T2 FLAIR images in all GFAP-Ab positive patients, and orbital section involvement was the most common. During follow-up (mean 4.5 ± 1 months), only Patient 1 had a recurrent ON, and no patient developed new other neurological events or systemic symptoms.

CONCLUSION

GFAP-Ab is rare in patients with ON and may manifest as isolated, relapsing ON. This supports the notion that the GFAP-A spectrum should comprise isolated ON.

Overview of diet and autoimmune demyelinating optic neuritis: a narrative review

This review summarizes the cellular and molecular underpinnings of autoimmune demyelinating optic neuritis (ADON), a common sequela of multiple sclerosis and other demyelinating diseases. We further present nutritional interventions tested for people with multiple sclerosis focusing on strategies that have shown efficacy or associations with disease course and clinical outcomes. We then close by discuss the potential dietary guidance for preventing and/or ameliorating ADON.

Dissection of complement and Fc-receptor-mediated pathomechanisms of autoantibodies to myelin oligodendrocyte glycoprotein

Autoantibodies against myelin oligodendrocyte glycoprotein (MOG) have recently been established to define a new disease entity, MOG-antibody-associated disease (MOGAD), which is clinically overlapping with multiple sclerosis. MOG-specific antibodies (Abs) from patients are pathogenic, but the precise effector mechanisms are currently still unknown and no therapy is approved for MOGAD. Here, we determined the contributions of complement and Fc-receptor (FcR)-mediated effects in the pathogenicity of MOG-Abs. Starting from a recombinant anti-MOG (mAb) with human IgG1 Fc, we established MOG-specific mutant mAbs with differential FcR and C1q binding. We then applied selected mutants of this MOG-mAb in two animal models of experimental autoimmune encephalomyelitis. First, we found MOG-mAb-induced demyelination was mediated by both complement and FcRs about equally. Second, we found that MOG-Abs enhanced activation of cognate MOG-specific T cells in the central nervous system (CNS), which was dependent on FcR-, but not C1q-binding. The identification of complement-dependent and -independent pathomechanisms of MOG-Abs has implications for therapeutic strategies in MOGAD.

Extracellular vesicles as a new horizon in the diagnosis and treatment of inflammatory eye diseases: A narrative review of the literature

Extracellular vesicles include exosomes, microvesicles, and apoptotic bodies. Their cargos contain a diverse variety of lipids, proteins, and nucleic acids that are involved in both normal physiology and pathology of the ocular system. Thus, studying extracellular vesicles may lead to a more comprehensive understanding of the pathogenesis, diagnosis, and even potential treatments for various diseases. The roles of extracellular vesicles in inflammatory eye disorders have been widely investigated in recent years. The term “inflammatory eye diseases” refers to a variety of eye conditions such as inflammation-related diseases, degenerative conditions with remarkable inflammatory components, neuropathy, and tumors. This study presents an overview of extracellular vesicles’ and exosomes’ pathogenic, diagnostic, and therapeutic values in inflammatory eye diseases, as well as existing and potential challenges.

Understanding the molecular basis and pathogenesis of hereditary optic neuropathies: towards improved diagnosis and management

Hereditary optic neuropathies result from defects in the human genome, both nuclear and mitochondrial. The two main and most recognised phenotypes are dominant optic atrophy and Leber hereditary optic neuropathy. Advances in modern molecular diagnosis have expanded our knowledge of genotypes and phenotypes of inherited disorders that affect the optic nerve, either alone or in combination, with various forms of neurological and systemic degeneration. A unifying feature in the pathophysiology of these disorders appears to involve mitochondrial dysfunction, suggesting that the retinal ganglion cells and their axons are especially susceptible to perturbations in mitochondrial homoeostasis. As we better understand the pathogenesis behind these genetic diseases, aetiologically targeted therapies are emerging and entering into clinical trials, including treatments aimed at halting the cascade of neurodegeneration, replacing or editing the defective genes or their protein products, and potentially regenerating damaged optic nerves, as well as preventing generational disease transmission.

Synapse Dysfunctions in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic neuroinflammatory disease of the central nervous system (CNS) affecting nearly three million humans worldwide. In MS, cells of an auto-reactive immune system invade the brain and cause neuroinflammation. Neuroinflammation triggers a complex, multi-faceted harmful process not only in the white matter but also in the grey matter of the brain. In the grey matter, neuroinflammation causes synapse dysfunctions. Synapse dysfunctions in MS occur early and independent from white matter demyelination and are likely correlates of cognitive and mental symptoms in MS. Disturbed synapse/glia interactions and elevated neuroinflammatory signals play a central role. Glutamatergic excitotoxic synapse damage emerges as a major mechanism. We review synapse/glia communication under normal conditions and summarize how this communication becomes malfunctional during neuroinflammation in MS. We discuss mechanisms of how disturbed glia/synapse communication can lead to synapse dysfunctions, signaling dysbalance, and neurodegeneration in MS.

[Clinical features and modern diagnostic criteria of the disease associated with myelin oligodendrocyte glycoprotein antibody disease]

Demyelinating disease of the central nervous system associated with antibodies to myelin oligodendrocyte glycoprotein (MOGAD) has been proposed to be distinguished from neuromyelitis optica spectrum disorders (NMOSD) into a separate nosological form. The basis for the recognition of nosological independence was the presence of clinical features of this disease and the detection of a specific biomarker in the blood serum of patients - IgG class antibodies to MOG. The article summarizes the current data on the clinical and radiological phenotypes of MOGAD in children and adults and the features of the course of the disease. The requirements for the laboratory diagnosis of the disease and diagnostic criteria for MOGAD proposed by an international group of experts in 2023 are given.

[Typical and atypical optic neuritis]

Optic neuritis (ON) is one of the most common neuro-ophthalmic causes of vision loss worldwide. Demyelinating ON can be idiopathic or be one of the symptoms of autoimmune demyelinating diseases of the central nervous system (CNS) such as multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD), myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). Demographic, clinical and radiological signs of ON in these CNS diseases have differences. In this regard, typical and atypical ON are currently distinguished. Recognizing the clinical features that differentiate typical MS-associated ON from atypical ON in NMOSD and MOGAD is important for choosing the correct disease management and treatment strategy. This review summarizes the data from clinical, laboratory, instrumental methods of management used for the differential diagnosis of optic neuritis.

Treatment with MDL 72527 Ameliorated Clinical Symptoms, Retinal Ganglion Cell Loss, Optic Nerve Inflammation, and Improved Visual Acuity in an Experimental Model of Multiple Sclerosis

Multiple Sclerosis (MS) is a highly disabling neurological disease characterized by inflammation, neuronal damage, and demyelination. Vision impairment is one of the major clinical features of MS. Previous studies from our lab have shown that MDL 72527, a pharmacological inhibitor of spermine oxidase (SMOX), is protective against neurodegeneration and inflammation in the models of diabetic retinopathy and excitotoxicity. In the present study, utilizing the experimental autoimmune encephalomyelitis (EAE) model of MS, we determined the impact of SMOX blockade on retinal neurodegeneration and optic nerve inflammation. The increased expression of SMOX observed in EAE retinas was associated with a significant loss of retinal ganglion cells, degeneration of synaptic contacts, and reduced visual acuity. MDL 72527-treated mice exhibited markedly reduced motor deficits, improved neuronal survival, the preservation of synapses, and improved visual acuity compared to the vehicle-treated group. The EAE-induced increase in macrophage/microglia was markedly reduced by SMOX inhibition. Upregulated acrolein conjugates in the EAE retina were decreased through MDL 72527 treatment. Mechanistically, the EAE-induced ERK-STAT3 signaling was blunted by SMOX inhibition. In conclusion, our studies demonstrate the potential benefits of targeting SMOX to treat MS-mediated neuroinflammation and vision loss.

A Practical Approach to the Diagnosis and Management of Optic Neuritis

Optic neuritis (ON), as an umbrella term, refers to a spectrum of inflammatory optic neuropathies arising from a myriad of potential causes. In its most common form, "typical" ON presents as a unilateral, painful subacute vision loss event in young Caucasian women. The Optic Neuritis Treatment Trial (ONTT) has historically guided our treatment of ON, and taught us important lessons about the clinical presentation, visual prognosis, and future risk of multiple sclerosis (MS) diagnosis associated with this condition. However, in the decades since the ONTT, several immune-mediated conditions such as neuromyelitis optica spectrum disorder (NMOSD), and myelin-oligodendrocyte glycoprotein IgG associated disease (MOGAD) have been discovered, complicating the clinical approach to ON. Unlike MS, other central nervous system (CNS) inflammatory conditions are associated with ON subtypes that are potentially blinding, and prone to recurrence. Owing to differences in the clinical presentation, serological biomarkers, radiological findings, and prognostic implications associated with MS ON, NMOSD ON, and MOGAD ON subtypes, it is imperative that clinicians be aware of the diagnostic approach and management options for these conditions.

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.