Central nervous system inflammatory demyelinating disorders among Hong Kong Chinese

Recent progress in epidemiology, clinical features, and therapy of multiple sclerosis in China

Multiple sclerosis (MS) is a demyelinating disease of the central nervous system characterized by inflammation, demyelination, and neurodegeneration. It mainly affects young adults, imposing a heavy burden on families and society. The epidemiology, clinical features, and management of MS are distinct among different countries. Although MS is a rare disease in China, there are 1.4 billion people in China, so the total number of MS patients is not small. Because of the lack of specific diagnostic biomarkers for MS, there is a high misdiagnosis rate in China, as in other regions. Due to different genetic backgrounds, the clinical manifestations of MS in Chinese are different from those in the West. Herein, this review aims to summarize the disease comprehensively, including clinical profile and the status of disease-modifying therapies in China based on published population-based observation and cohort studies, and also to compare with data from other countries and regions, thus providing help to develop diagnostic guideline and the novel therapeutic drugs. Meanwhile, we also discuss the problems and challenges we face, specifically for the diagnosis and treatment of MS in the middle- and low-income countries.

Efficacy of Plasma Exchange Treatment for Demyelinating Optic Neuritis Associated with Various Serum Antibodies: A Prospective Cohort Study

INTRODUCTION

To evaluate the value of plasma exchange (PE) for patients with three subtypes of demyelinating optic neuritis (ON): aquaporin-4 (AQP4) antibody-positive ON (AQP4-ON), myelin oligodendrocyte glycoprotein (MOG) antibody-positive ON (MOG-ON), and AQP4 and MOG double-antibody-seronegative ON (D-ON).

METHODS

A single-center prospective study compared the logarithm of the minimum angle of resolution (logMAR) best-corrected visual acuity (BCVA) at most severe onset, 1 day before intravenous high-dose methylprednisolone (IVMP) treatment, 1 day before PE treatment, after five-cycles of PE therapy, and at 1-, 3-, and 6-month follow-up visits. The proportions of eyes in each visual outcome category were also compared. Logistic regression and a receiver operating characteristic curve were used to analyze predicted factors for VA improvement.

RESULTS

A total of 124 ON attacks of 122 patients were included. No significant differences were found in BCVA (P = 0.659) before and after PE therapy for 22 D-ON attacks, but VA improved in two of six MOG-ON patients. In 95 AQP4-ON patients suffering 96 attacks, the mean logMAR BCVA markedly improved and was steadily maintained after five-cycles of PE treatments (adjusted P < 0.001), with VA exhibiting a significantly increasing trend (adjusted P = 0.001) after PE treatment. The combination of the number of previous ON episodes and the time window to PE treatment showed accuracy of 74.7% for predicting an improvement in BCVA score ≥ 2 levels. In addition, a combination of logMAR VA before PE and the time window to PE treatment resulted in 83.4% accuracy in predicting whether VA would regain 1.0 logMAR.

CONCLUSION

PE therapy effectively improves visual outcomes for AQP4-ON patients, but offers limited value for D-ON patients. Early initiation greatly increases likelihood of achieving VA improvement.

MRI Patterns Distinguish AQP4 Antibody Positive Neuromyelitis Optica Spectrum Disorder From Multiple Sclerosis

Neuromyelitis optica spectrum disorder (NMOSD) and multiple sclerosis (MS) are inflammatory diseases of the CNS. Overlap in the clinical and MRI features of NMOSD and MS means that distinguishing these conditions can be difficult. With the aim of evaluating the diagnostic utility of MRI features in distinguishing NMOSD from MS, we have conducted a cross-sectional analysis of imaging data and developed predictive models to distinguish the two conditions. NMOSD and MS MRI lesions were identified and defined through a literature search. Aquaporin-4 (AQP4) antibody positive NMOSD cases and age- and sex-matched MS cases were collected. MRI of orbits, brain and spine were reported by at least two blinded reviewers. MRI brain or spine was available for 166/168 (99%) of cases. Longitudinally extensive (OR = 203), "bright spotty" (OR = 93.8), whole (axial; OR = 57.8) or gadolinium (Gd) enhancing (OR = 28.6) spinal cord lesions, bilateral (OR = 31.3) or Gd-enhancing (OR = 15.4) optic nerve lesions, and nucleus tractus solitarius (OR = 19.2), periaqueductal (OR = 16.8) or hypothalamic (OR = 7.2) brain lesions were associated with NMOSD. Ovoid (OR = 0.029), Dawson's fingers (OR = 0.031), pyramidal corpus callosum (OR = 0.058), periventricular (OR = 0.136), temporal lobe (OR = 0.137) and T1 black holes (OR = 0.154) brain lesions were associated with MS. A score-based algorithm and a decision tree determined by machine learning accurately predicted more than 85% of both diagnoses using first available imaging alone. We have confirmed NMOSD and MS specific MRI features and combined these in predictive models that can accurately identify more than 85% of cases as either AQP4 seropositive NMOSD or MS.

Treatment of Neuromyelitis Optica Spectrum Disorders

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune central nervous system (CNS) inflammatory disorder that can lead to serious disability and mortality. Females are predominantly affected, including those within the reproductive age. Most patients develop relapsing attacks of optic neuritis; longitudinally extensive transverse myelitis; and encephalitis, especially brainstem encephalitis. The majority of NMOSD patients are seropositive for IgG autoantibodies against the water channel protein aquaporin-4 (AQP4-IgG), reflecting underlying aquaporin-4 autoimmunity. Histological findings of the affected CNS tissues of patients from in-vitro and in-vivo studies support that AQP4-IgG is directly pathogenic in NMOSD. It is believed that the binding of AQP4-IgG to CNS aquaporin-4 (abundantly expressed at the endfoot processes of astrocytes) triggers astrocytopathy and neuroinflammation, resulting in acute attacks. These attacks of neuroinflammation can lead to pathologies, including aquaporin-4 loss, astrocytic activation, injury and loss, glutamate excitotoxicity, microglial activation, neuroinflammation, demyelination, and neuronal injury, via both complement-dependent and complement-independent pathophysiological mechanisms. With the increased understanding of these mechanisms underlying this serious autoimmune astrocytopathy, effective treatments for both active attacks and long-term immunosuppression to prevent relapses in NMOSD are increasingly available based on the evidence from retrospective observational data and prospective clinical trials. Knowledge on the indications and potential side effects of these medications are essential for a clear evaluation of the potential benefits and risks to NMOSD patients in a personalized manner. Special issues such as pregnancy and the coexistence of other autoimmune diseases require additional concern and meticulous care. Future directions include the identification of clinically useful biomarkers for the prediction of relapse and monitoring of the therapeutic response, as well as the development of effective medications with minimal side effects, especially opportunistic infections complicated by long-term immunosuppression.

Magnetic resonance imaging in neuromyelitis optica spectrum disorder

Neuromyelitis optica spectrum disorder (NMOSD) is an inflammatory disease of the central nervous system (CNS) associated with antibodies to aquaporin-4 (AQP4), which has distinct clinical, radiological and pathological features, but also has some overlap with multiple sclerosis and myelin oligodendrocyte glycoprotein (MOG) antibody associated disease. Early recognition of NMOSD is important because of differing responses to both acute and preventive therapy. Magnetic resonance (MR) imaging has proved essential in this process. Key MR imaging clues to the diagnosis of NMOSD are longitudinally extensive lesions of the optic nerve (more than half the length) and spinal cord (three or more vertebral segments), bilateral optic nerve lesions and lesions of the optic chiasm, area postrema, floor of the IV ventricle, periaqueductal grey matter, hypothalamus and walls of the III ventricle. Other NMOSD-specific lesions are denoted by their unique morphology: heterogeneous lesions of the corpus callosum, 'cloud-like' gadolinium (Gd)-enhancing white matter lesions and 'bright spotty' lesions of the spinal cord. Other lesions described in NMOSD, including linear periventricular peri-ependymal lesions and patch subcortical white matter lesions, may be less specific. The use of advanced MR imaging techniques is yielding further useful information regarding focal degeneration of the thalamus and optic radiation in NMOSD and suggests that paramagnetic rim patterns and changes in normal appearing white matter are specific to MS. MR imaging is crucial in the early recognition of NMOSD and in directing testing for AQP4 antibodies and guiding immediate acute treatment decisions. Increasingly, MR imaging is playing a role in diagnosing seronegative cases of NMOSD.

Update on Acute Disseminated Encephalomyelitis in Children and Adolescents

Acute disseminated encephalomyelitis (ADEM) is an immune-mediated, inflammatory demyelinating disease of the central nervous system (CNS) that usually affects children and young adults after an infection or vaccination. The presence of several conditions mimicking ADEM, added to the lack of specific biomarkers, makes diagnosis potentially hard. Prompt diagnosis is necessary to start adequate treatment to improve the clinical course and long-term outcome. Because of its heterogeneity in both clinical presentation and course, challenges remain in establishing the most appropriate therapeutic approach in each patient. The aim of this review is to provide an update on management of this disease with a focus on acute treatment and to give suggestions for future research. We showed that there are currently no guidelines that help clinicians manage ADEM and therapeutic decisions are often made on a case-by-case basis. Further studies are necessary to identify clinical, laboratory, and instrumental criteria that could be correlated with outcomes and guide clinicians in choosing when and what treatment should be given in each case.

MS and Disability Progression in Latin America, Africa, Asia and the Middle East: A Systematic Review

BACKGROUND

There is evidence of an increased prevalence and disease burden of Multiple Sclerosis (MS) in parts of the world where the risk was once considered low, such as Latin America (LA), Sub-Saharan Africa, Asia and the Middle East-North Africa (MENA). Despite the growing number of clinical reports, the phenotype and course of MS in these regions remains understudied compared with Europe and North America. We aimed to investigate MS phenotypes and long-term clinical outcomes across these regions.

METHOD

A Boolean search of the medical literature was conducted between January 1980 and April 30, 2020. PubMed, SCOPUS, Global Health, and the Cochrane databases, were used to identify all relevant citations. Articles were collated and managed on Covidence® software. We independently appraised the articles for meeting study criteria and for quality using the Critical Appraisal Skills Program (CASP) and the Specialist Unit for Review Evidence (SURE) system.

RESULTS

A total of 1,639 studies were imported for screening. After removing 545 duplicates, two authors assessed 1,094 abstracts and selected 515 for full-text screening. 72 articles met study criteria, including 19 studies from LA, 4 from sub-Saharan Africa, 24 from Asia and 25 from MENA. The overall sex ratio was 2.5:1 (female: male). Disability was assessed using the Expanded Disability Status Scale (EDSS). Longitudinal disability progression and time to standard endpoints was compared by region and with relevant Western reports. Patients with MS living in the MENA region appear to reach disability milestones faster than those in the Western world, although this finding is not uniform. South Asia shows distinct disability features compared with East Asia, more closely resembling those of the West. Disease morbidity in East Asia appears more benign than in the West after careful exclusion of neuromyelitis optica spectrum disorder cases. Populations in LA tend to have similar MS features to the Western world, but some exceptions exist, including African descendants that reach disability milestones earlier. Using all studies with appropriate survival analysis, the mean time to EDSS 6.0 was 16.97 years with a heterogeneity index of 24.59.

CONCLUSION

The clinical phenotypes and disability progression of MS in LA, Africa, Asia and the MENA region have similarities to Western MS. In some regions and subpopulations there is evidence of a more aggressive course, possibly due to a combination of genetic and environmental factors. More population-based longitudinal data are needed, particularly in Sub-Saharan Africa.

Central nervous system neuroinflammatory disorders in Asian/Pacific regions

PURPOSE OF REVIEW

The discovery of aquaporin-4 (AQP4) antibodies with high specificity for neuromyelitis optica spectrum disorder (NMOSD) has induced tremendous changes in the approach and management of central nervous system (CNS) neuroinflammatory disorders. Owing to the increasing availability of the AQP4 antibody assay and evolution of diagnostic criteria for multiple sclerosis and NMOSD, recent studies have reevaluated CNS neuroinflammatory disorders. This review describes recent advances in the understanding of CNS neuroinflammatory disorders in Asian/Pacific regions.

RECENT FINDINGS

Although multiple sclerosis prevalence is lower in Asian countries than in Western countries, the overall clinical features of multiple sclerosis are comparable between these countries. Hospital-based studies have reported that the frequency of NMOSD is higher in Asian populations (22-42%) than in white populations (2-26%). Despite improvements in the AQP4 antibody assay, AQP4 antibodies are not detected in certain patients with NMOSD. Recently, myelin oligodendrocyte glycoprotein (MOG) antibodies have been identified in AQP4 antibody-negative patients with the NMOSD phenotype, and the clinical features differ slightly between MOG antibody-positive patients and AQP4 antibody-positive patients.

SUMMARY

The understanding of CNS neuroinflammatory disorders in Asian/Pacific regions continues to evolve owing to the discovery of new biological markers and recognition of broader clinical phenotypes.

Differential brainstem atrophy patterns in multiple sclerosis and neuromyelitis optica spectrum disorders

BACKGROUND

Multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD) are central nervous system (CNS) inflammatory demyelinating disorders. It is clinically important to distinguish MS from NMOSD, as treatment and prognosis differ. Brainstem involvement is common in both disorders.

PURPOSE

To investigate whether the patterns of brainstem atrophy on volumetric analysis in MS and NMOSD were different and correlated with clinical disability.

STUDY TYPE

Case-control cross-sectional study.

SUBJECTS

In all, 17 MS, 13 NMOSD, and 18 healthy control (HC) subjects were studied.

FIELD STRENGTH/SEQUENCE

T₁ -weighted and T₂ w spin-echo images were acquired with a 3T scanner.

ASSESSMENT

Semiautomated segmentation and volumetric measurement of brainstem regions were performed. Anatomical information was obtained from whole brain T₁ w images using a 3D magnetization-prepared rapid gradient-echo (MPRAGE) imaging sequence (TR/TE/T: 7.0/3.2/800 msec, voxel size: 1 × 1 × 1 mm³ , scan time: 10 min 41 sec).

STATISTICAL TESTS

Independent samples t-test, Mann-Whitney U-test, partial correlation, and multiple regression analysis.

RESULTS

Baseline characteristics were similar across the three groups, without significant difference in disease duration (P = 0.354) and EDSS score (P = 0.159) between MS and NMOSD subjects. Compared to HC, MS subjects had significantly smaller normalized whole brainstem (-5.2%, P = 0.027), midbrain (-8.3%, P = 0.0001), and pons volumes (-5.9%, P = 0.048), while only the normalized medulla volume was significantly smaller in NMOSD subjects compared to HC (-8.5% vs. HC, P = 0.024). Normalized midbrain volume was significantly smaller in MS compared to NMOSD subjects (-5.0%, P = 0.014), whereas normalized medulla volume was significantly smaller in NMOSD compared to MS subjects (-8.1%, P = 0.032). Partial correlations and multiple regression analysis revealed that smaller normalized whole brainstem, pons, and medulla oblongata volumes were associated with greater disability on the Expanded Disability Status Scale (EDSS), Functional System Score (FSS)-brainstem and FSS-cerebellar in NMOSD subjects.

DATA CONCLUSION

Differential patterns of brainstem atrophy were observed, with the midbrain being most severely affected followed by pons in MS, whereas only the medulla oblongata was affected in NMOSD.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1601-1609.

Detection of Thyroid Abnormalities in Aquaporin-4 Antibody-Seropositive Optic Neuritis Patients

OBJECTIVE

This study retrospectively analyzed the frequency of anti-thyroid antibodies (ATAs) and thyroid disease in patients with optic neuritis (ON).

METHODS

Tests of serum thyroglobulin (TG) and thyroid peroxidase (TPO) antibodies and thyroid function were performed in 97 ON patients. Blood also was drawn to test for AQP4-Ab using cell-based and enzyme-linked immunosorbent assays. Comparisons of the frequencies of ATAs, thyroid diseases and thyroid function were performed based on AQP4-Ab status.

RESULTS

Seropositive AQP4-Ab was found in 47/97 (48.5%) patients. ATA was considered positive in 34/97 (35.1%) patients. The prevalence of ATA was two times higher (P = 0.019) in the AQP4-Ab+ group compared to the AQP4-Ab- group. AQP4-Ab+ ON patients exhibited lower FT3 (P = 0.006) and FT4 (P = 0.025) levels and a higher prevalence of definite Hashimoto thyroiditis (HT) (P = 0.005). Among AQP4-Ab+ patients, those with HT had a worse visual outcome than non-HT patients.

CONCLUSION

A high prevalence of ATAs and HT was found in AQP4-Ab+ ON patients, and AQP4-Ab+ patients with HT exhibited worse visual outcomes than non-HT patients.

Application of diffusional kurtosis imaging to detect occult brain damage in multiple sclerosis and neuromyelitis optica

Multiple sclerosis (MS) and neuromyelitis optica (NMO) are two common types of inflammatory demyelinating disease of the central nervous system. Early distinction of NMO from MS is crucial but quite challenging. In this study, 13 NMO spectrum disorder patients (Expanded Disability Status Scale (EDSS) of 3.0 ± 1.7, ranging from 2 to 6.5; disease duration of 5.3 ± 4.7 years), 17 relapsing-remitting MS patients (EDSS of 2.6 ± 1.4, ranging from 1 to 5.5; disease duration of 7.9 ± 7.8 years) and 18 healthy volunteers were recruited. Diffusional kurtosis imaging was employed to discriminate NMO and MS patients at the early or stable stage from each other, and from healthy volunteers. The presence of alterations in diffusion and diffusional kurtosis metrics in normal-appearing white matter (NAWM) and diffusely increased mean diffusivity (MD) in the cortical normal-appearing gray matter (NAGM) favors the diagnosis of MS rather than NMO. Meanwhile, normal diffusivities and kurtosis metrics in all NAWM as well as increases in MD in the frontal and temporal NAGM suggest NMO. Our results suggest that diffusion and diffusional kurtosis metrics may well aid in discriminating the two diseases.