Frequency of Asymptomatic Optic Nerve Enhancement in a Large Retrospective Cohort of Patients With Aquaporin-4+ NMOSD

The atypical faces of optic neuritis: neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein antibody-associated disease

PURPOSE OF REVIEW

The purpose of this article is to provide a review of neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD), with a focus on what renders optic neuritis "atypical" in these two conditions. Clinical features, diagnostic criteria, and epidemiology are outlined. Acute treatments for optic neuritis, as well as immunotherapy for NMOSD and MOGAD are discussed.

RECENT FINDINGS

Updates in NMOSD and MOGAD are highlighted, with an emphasis on novel work including the new 2023 MOGAD diagnostic criteria, our evolving understanding on the epidemiology of these conditions, and recently FDA-approved NMOSD treatments. Pipeline therapies are also discussed.

SUMMARY

A thorough history and examination, supported by ancillary testing, continues to be the mainstay of optic neuritis diagnosis. Stratifying typical versus atypical optic neuritis is paramount. Within the atypical category, NMOSD and MOGAD are important considerations. Clues can point towards these diagnoses and guide steps for treatment, which is increasingly becoming targeted to individual diseases, as the pathophysiology is different for these disorders.

Brain tissue integrity in neuromyelitis optica spectrum disorder through T1-w/T2-w ratio, MTR and DTI

BACKGROUND

The presence of diffuse brain damage in normal-appearing white matter (NAWM) and gray matter (NAGM) in neuromyelitis optica spectrum disorder (NMOSD) remains controversial. We aimed to address this controversy by applying a multiparametric MRI approach. Additionally, the association between MRI metrics and clinical variables was explored.

METHODS

In this cross-sectional study, we prospectively evaluated aquaporin-4-IgG positive NMOSD patients and healthy controls (HC) matched for age and sex. The clinical variables of interest were collected for each participant. The mean values of T1-w/T2-w ratio, magnetization transfer ratio (MTR), fractional anisotropy (FA), axial diffusivity (AD), mean diffusivity (MD), and radial diffusivity (RD) were obtained in NAWM, NAGM, as well as in global and hypointense lesion masks. Global lesions refer to those typically associated with aquaporin-4-IgG positive NMOSD. Hypointense lesions were defined as areas of hypointense signal in both T1-w and fluid-attenuated inversion recovery (FLAIR) images.

RESULTS

In total, we included 105 participants (59 NMOSD patients and 46 HC). T1-w/T2-w ratio was lower in NAWM of NMOSD patients versus HC (1.83 ± 0.14 vs 1.89 ± 0.14; p = 0.029), while no significant differences were found in NAWM or NAGM across the other metrics: (p range: 0.079 to 0.973). Hypointense lesions showed lower T1-w/T2-w ratio, MTR, and FA, and higher diffusivity metrics as compared to global lesion masks (p < 0.001). T1-w/T2-w ratio in NAWM was inversely correlated with time to start immunosuppressive therapy (r =  - 0.278; p = 0.036) and with MD (r =  - 0.325; p = 0.014).

CONCLUSION

Microstructural integrity loss seems to be confined to focal tissue damage in NMOSD. Decreased T1-w/T2-w ratio in NAWM may reflect subclinical water accumulation due to astrocyte and blood-brain barrier dysfunction. Hypointense lesions have shown a severe degree of microstructural damage.

Eculizumab Use in Neuromyelitis Optica Spectrum Disorders: Routine Clinical Care Data From a European Cohort

BACKGROUND AND OBJECTIVES

Attack prevention is crucial in managing neuromyelitis optica spectrum disorders (NMOSDs). Eculizumab (ECU), an inhibitor of the terminal complement cascade, was highly effective in preventing attacks in a phase III trial of aquaporin-4 (AQP4)-IgG seropositive(+) NMOSDs. In this article, we evaluated effectiveness and safety of ECU in routine clinical care.

METHODS

We retrospectively evaluated patients with AQP4-IgG+ NMOSD treated with ECU between December 2014 and April 2022 at 20 German and 1 Austrian university center(s) of the Neuromyelitis Optica Study Group (NEMOS) by chart review. Primary outcomes were effectiveness (assessed using annualized attack rate [AAR], MRI activity, and disability changes [Expanded Disability Status Scale {EDSS}]) and safety (including adverse events, mortality, and attacks after meningococcal vaccinations), analyzed by descriptive statistics.

RESULTS

Fifty-two patients (87% female, age 55.0 ± 16.3 years) received ECU for 16.2 (interquartile range [IQR] 9.6 - 21.7) months. Forty-five patients (87%) received meningococcal vaccination before starting ECU, 9 with concomitant oral prednisone and 36 without. Seven of the latter (19%) experienced attacks shortly after vaccination (median: 9 days, IQR 6-10 days). No postvaccinal attack occurred in the 9 patients vaccinated while on oral prednisone before starting ECU and in 25 (re-)vaccinated while on ECU. During ECU therapy, 88% of patients were attack-free. The median AAR decreased from 1.0 (range 0-4) in the 2 years preceding ECU to 0 (range 0-0.8; p < 0.001). The EDSS score from start to the last follow-up was stable (median 6.0), and the proportion of patients with new T2-enhancing or gadolinium-enhancing MRI lesions in the brain and spinal cord decreased. Seven patients (13%) experienced serious infections. Five patients (10%; median age 53.7 years) died on ECU treatment (1 from myocardial infarction, 1 from ileus with secondary sepsis, and 3 from systemic infection, including 1 meningococcal sepsis), 4 were older than 60 years and severely disabled at ECU treatment start (EDSS score ≥ 7). The overall discontinuation rate was 19%.

DISCUSSION

Eculizumab proved to be effective in preventing NMOSD attacks. An increased risk of attacks after meningococcal vaccination before ECU start and potentially fatal systemic infections during ECU-particularly in patients with comorbidities-must be considered. Further research is necessary to explore optimal timing for meningococcal vaccinations.

CLASSIFICATION OF EVIDENCE

This study provides Class IV evidence that eculizumab reduces annualized attack rates and new MRI lesions in AQP4-IgG+ patients with NMOSD.

Frequency of Asymptomatic Optic Nerve Enhancement in 203 Patients With MOG Antibody-Associated Disease

BACKGROUND AND OBJECTIVES

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is a distinct CNS demyelinating disease. The rate of asymptomatic optic nerve enhancement on MRI has not been explored in patients with MOGAD. An improved understanding of this would guide clinical practice and assessment of treatment efficacy. We aimed to determine the frequency of asymptomatic optic nerve enhancement in MOGAD.

METHODS

This was a retrospective review of patients evaluated at Mayo Clinic with MOGAD between January 1, 2000, and August 1, 2021 (median follow-up 1.6 [range 1-19] years). MRI studies were reviewed by masked neuroradiologists. Scans performed within 30 days of ON attack were classified as attack scans. Images obtained for routine surveillance, before ON attack, or at the time of non-ON attack were classified as interattack scans.

RESULTS

Five hundred sixty-six MRIs (203 unique patients, 53% female) were included. Interattack MRIs represented 341 (60%) of the scans (median 36 days post-ON [range -1,032 to 6,001]). Of the interattack scans, 43 of 341 (13%), 30 unique patients, showed optic nerve enhancement. The enhancement was located at prior sites of ON in 35 of 43 (81%). Among the 8 patients with enhancement in new optic nerve areas, 6 had acute disseminated encephalomyelitis without an eye examination at the time of the MRI and 2 had preceding ON without imaging. Long-term visual outcomes showed no significant difference between those with and without asymptomatic enhancement, with improved visual acuity in most patients.

DISCUSSION

Asymptomatic optic nerve enhancement occurred in 13% of interattack MRIs, the majority in patients with prior ON and occurring at prior sites of optic nerve enhancement. New asymptomatic optic nerve enhancement in areas without prior ON was rare. These findings are important for understanding the natural history of MOGAD, the interpretation of symptoms or response to treatment, and the adjudication of attacks in clinical trials.

Diagnostic Criteria for Multiple Sclerosis, Neuromyelitis Optica Spectrum Disorders, and Myelin Oligodendrocyte Glycoprotein-immunoglobulin G-associated Disease

The diagnostic workup of multiple sclerosis (MS) has evolved considerably. The 2017 revision of the McDonald criteria shows high sensitivity and accuracy in predicting clinically definite MS in patients with a typical clinically isolated syndrome and allows an earlier MS diagnosis. Neuromyelitis optica spectrum disorders (NMOSD) and myelin oligodendrocyte glycoprotein-immunoglobulin G-associated disease (MOGAD) are recognized as separate conditions from MS, with specific diagnostic criteria. New MR imaging markers may improve diagnostic specificity for these conditions, thus reducing the risk of misdiagnosis. This study summarizes the most recent updates regarding the application of MR imaging for the diagnosis of MS, NMOSD, and MOGAD.

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.

Neuromyelitis Optica Spectrum Disorders and Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease

For over two centuries, clinicians have been aware of various conditions affecting white matter which had come to be grouped under the umbrella term multiple sclerosis. Within the last 20 years, specific scientific advances have occurred leading to more accurate diagnosis and differentiation of several of these conditions including, neuromyelitis optica spectrum disorders and myelin oligodendrocyte glycoprotein antibody disease. This new understanding has been coupled with advances in disease-modifying therapies which must be accurately applied for maximum safety and efficacy.

Asymptomatic spinal lesions in patients with AQP4-IgG-positive NMOSD: A real-world cohort study

OBJECTIVE

This study aims to explore the frequency and influencing factors of asymptomatic spinal lesions (ASLs) and their impact on subsequent relapses in patients with AQP4-IgG-positive NMOSD (AQP4-NMOSD) in a real-world setting.

METHODS

We retrospectively reviewed clinical information and spinal MRI data from AQP4-NMOSD patients who had at least one spinal cord MRI during their follow-ups. Kaplan-Meier curves and Cox proportional hazards models were employed to ascertain potential predictors of remission ASLs and to investigate factors associated with subsequent relapses.

RESULTS

In this study, we included 129 patients with AQP4-NMOSD and reviewed 173 spinal MRIs during attacks and 89 spinal MRIs during remission. Among these, 6 ASLs (3.5%) were identified during acute attacks, while 8 ASLs (9%) were found during remission. Remission ASLs were linked to the use of immunosuppressive agents, particularly conventional ones, whereas no patients using rituximab developed ASLs (p = 0.005). Kaplan-Meier curve analysis indicated that patients with ASLs had a significantly higher relapse risk (HR = 4.658, 95% CI: 1.519-14.285, p = 0.007) compared to those without. Additionally, the use of mycophenolate mofetil (HR = 0.027, 95% CI: 0.003-0.260, p = 0.002) and rituximab (HR = 0.035, 95% CI: 0.006-0.203, p < 0.001) significantly reduced the relapse risk. However, after accounting for other factors, the presence of ASLs did not exhibit a significant impact on subsequent relapses (HR = 2.297, 95% CI: 0.652-8.085, p = 0.195).

INTERPRETATION

ASLs may be observed in patients with AQP4-NMOSD. The presence of ASLs may signify an underlying inflammatory activity due to insufficient immunotherapy. The administration of immunosuppressive agents plays a key role in the presence of remission ASLs and the likelihood of subsequent relapses.

Updates in NMOSD and MOGAD Diagnosis and Treatment: A Tale of Two Central Nervous System Autoimmune Inflammatory Disorders

Aquaporin-4-IgG positive neuromyelitis optica spectrum disorder (AQP4+NMOSD) and myelin-oligodendrocyte glycoprotein antibody-associated disease (MOGAD) are antibody-associated diseases targeting astrocytes and oligodendrocytes, respectively. Their recognition as distinct entities has led to each having its own diagnostic criteria that require a combination of clinical, serologic, and MRI features. The therapeutic approach to acute attacks in AQP4+NMOSD and MOGAD is similar. There is now class 1 evidence to support attack-prevention medications for AQP4+NMOSD. MOGAD lacks proven treatments although clinical trials are now underway. In this review, we will outline similarities and differences between AQP4+NMOSD and MOGAD in terms of diagnosis and treatment.

Peripheral Retinal Haemorrhages in a Patient with MOG-Associated Optic Neuritis

A 15-year-old female presented with headaches and bilateral vision loss. Fundoscopic examination revealed bilateral optic nerve oedema as well as peripheral retinal haemorrhages. Magnetic resonance imaging of the brain showed findings consistent with bilateral optic neuritis. The patient was started on high dose intravenous corticosteroids but her vision failed to improve. The presence of retinal haemorrhages raised concern that a vasculitis was underlying her symptoms, prompting an extensive work-up, which was unrevealing. Plasmapheresis was initiated and the patient's vision eventually improved to 20/20 in both eyes. Ultimately, she was found to be positive for myelin oligodendrocyte glycoprotein (MOG) antibodies, consistent with a diagnosis of MOG-associated optic neuritis. The patient's course was typical for MOG-associated optic neuritis but her peripheral retinal haemorrhages were atypical, which created diagnostic uncertainty. It is important to be aware of the possibility of retinal findings in this disease. We also review potential causes for retinal haemorrhages in optic neuritis.

Understanding the Pathophysiology and Magnetic Resonance Imaging of Multiple Sclerosis and Neuromyelitis Optica Spectrum Disorders

Magnetic resonance imaging (MRI) has been extensively applied in the study of multiple sclerosis (MS), substantially contributing to diagnosis, differential diagnosis, and disease monitoring. MRI studies have significantly contributed to the understanding of MS through the characterization of typical radiological features and their clinical or prognostic implications using conventional MRI pulse sequences and further with the application of advanced imaging techniques sensitive to microstructural damage. Interpretation of results has often been validated by MRI-pathology studies. However, the application of MRI techniques in the study of neuromyelitis optica spectrum disorders (NMOSD) remains an emerging field, and MRI studies have focused on radiological correlates of NMOSD and its pathophysiology to aid in diagnosis, improve monitoring, and identify relevant prognostic factors. In this review, we discuss the main contributions of MRI to the understanding of MS and NMOSD, focusing on the most novel discoveries to clarify differences in the pathophysiology of focal inflammation initiation and perpetuation, involvement of normal-appearing tissue, potential entry routes of pathogenic elements into the CNS, and existence of primary or secondary mechanisms of neurodegeneration.

MRI to differentiate multiple sclerosis, neuromyelitis optica, and myelin oligodendrocyte glycoprotein antibody disease

Differentiating multiple sclerosis (MS) from other relapsing inflammatory autoimmune diseases of the central nervous system such as neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is crucial in clinical practice. The differential diagnosis may be challenging but making the correct ultimate diagnosis is critical, since prognosis and treatments differ, and inappropriate therapy may promote disability. In the last two decades, significant advances have been made in MS, NMOSD, and MOGAD including new diagnostic criteria with better characterization of typical clinical symptoms and suggestive imaging (magnetic resonance imaging [MRI]) lesions. MRI is invaluable in making the ultimate diagnosis. An increasing amount of new evidence with respect to the specificity of observed lesions as well as the associated dynamic changes in the acute and follow-up phase in each condition has been reported in distinct studies recently published. Additionally, differences in brain (including the optic nerve) and spinal cord lesion patterns between MS, aquaporin4-antibody-positive NMOSD, and MOGAD have been described. We therefore present a narrative review on the most relevant findings in brain, spinal cord, and optic nerve lesions on conventional MRI for distinguishing adult patients with MS from NMOSD and MOGAD in clinical practice. In this context, cortical and central vein sign lesions, brain and spinal cord lesions characteristic of MS, NMOSD, and MOGAD, optic nerve involvement, role of MRI at follow-up, and new proposed diagnostic criteria to differentiate MS from NMOSD and MOGAD were discussed.

Frequency of new asymptomatic MRI lesions during attacks and follow-up of patients with NMOSD in a real-world setting

BACKGROUND

We aimed to assess the frequency of new asymptomatic lesions on brain and spinal imaging (magnetic resonance imaging (MRI)) and their association with subsequent relapses in a large cohort of neuromyelitis optica spectrum disorder (NMOSD) patients in Argentina.

METHODS

We retrospectively reviewed 675 MRI (225 performed during an attack and 450 during the relapse-free period (performed at least 3 months from the last attack)) of NMOSD patients who had at least 2 years of clinical and MRI follow-up since disease onset. Kaplan-Meier (KM) curves were used for depicting time from remission MRI to subsequent relapse.

RESULTS

We included 135 NMOSD patients (64.4% were aquaporin-4-immunoglobulin G (AQP4-IgG)-positive). We found that 26 (19.26%) and 66 (48.88%) of patients experienced at least one new asymptomatic MRI lesion during both the relapse-free period and attacks, respectively. The most frequent asymptomatic MRI lesions were optic nerves followed by short-segment myelitis during the relapse-free period and attacks. KM curves did not show differences in the time taken to develop a new relapse.

CONCLUSION

Our findings showed that new asymptomatic lesions are relatively frequent. However, the presence of new asymptomatic MRI lesions during the relapse-free period and at relapses was not associated with a shorter time to developing subsequent relapses.

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

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

Literature Commentary

In this issue of Journal of Neuro-Ophthalmology, Drs. Marc J. Dinkin, Deborah I. Friedman, and Mark L. Moster discuss the following 6 articles: Mollan SP, Mitchell JL, Yiangou A, Ottridge RS, Alimajstorovic Z, Cartwright DM, Hickman SJ, Markey KA, Singhal R, Tahrani AA, Frew E, Brock K, Sinclair AJ. Association of amount of weight lost after bariatric surgery with intracranial pressure in women with idiopathic intracranial hypertension. Neurology. 2022;99. doi:10.1212/WNL.0000000000200839.Nia AM, Srinivasan VM, Lall R, Kan P. Dural venous sinus stenting in idiopathic intracranial hypertension: a national database study of 541 patients. World Neurosurg. 2022:S1878-8750(22)01135-4. doi: 10.1016/j.wneu.2022.08.035.Eide PK, Hansson HA. A new perspective on the pathophysiology of idiopathic intracranial hypertension: role of the glia-neuro-vascular interface. Front Mol Neurosci. 2022;15:900057.Shah S, Morris P, Buciuc M, Tajfirouz D, Wingerchuk DM, Weinshenker BG, Eggenberger ER, Di Nome M, Pittock SJ, Flanagan EP, Bhatti MT, Chen JJ. Frequency of asymptomatic optic nerve enhancement in a large retrospective cohort of patients with aquaporin-4+ NMOSD. Neurology. 2022;99:e851-e857.Bsteh G, Krajnc N, Riedl K, Altmann P, Kornek B, Leutmezer F, Macher S, Mitsch C, Pruckner P, Rommer PS, Zulehner G, Pemp B, Berger T; Vienna Multiple Sclerosis Database Study Group. Retinal layer thinning after optic neuritis is associated with future relapse remission in relapsing multiple sclerosis. Neurology. 2022. doi: 10.1212/WNL.0000000000200970.Tsai RK, Lin KL, Huang CT, Wen YT. Transcriptomic analysis reveals that granulocyte colony-stimulating factor trigger a novel signaling pathway (TAF9-P53-TRIAP1-CASP3) to protect retinal ganglion cells after ischemic optic neuropathy. Int J Mol Sci. 2022;23:8359. doi: 10.3390/ijms23158359.