Neuromyelitis optica spectrum disorders: Comparison according to the phenotype and serostatus

Immunopathogenesis in Myasthenia Gravis and Neuromyelitis Optica

Myasthenia gravis (MG) and neuromyelitis optica (NMO) are autoimmune channelopathies of the peripheral neuromuscular junction (NMJ) and central nervous system (CNS) that are mainly mediated by humoral immunity against the acetylcholine receptor (AChR) and aquaporin-4 (AQP4), respectively. The diseases share some common features, including genetic predispositions, environmental factors, the breakdown of tolerance, the collaboration of T cells and B cells, imbalances in T helper 1 (Th1)/Th2/Th17/regulatory T cells, aberrant cytokine and antibody secretion, and complement system activation. However, some aspects of the immune mechanisms are unique. Both targets (AChR and AQP4) are expressed in the periphery and CNS, but MG mainly affects the NMJ in the periphery outside of CNS, whereas NMO preferentially involves the CNS. Inflammatory cells, including B cells and macrophages, often infiltrate the thymus but not the target—muscle in MG, whereas the infiltration of inflammatory cells, mainly polymorphonuclear leukocytes and macrophages, in NMO, is always observed in the target organ—the spinal cord. A review of the common and discrepant characteristics of these two autoimmune channelopathies may expand our understanding of the pathogenic mechanism of both disorders and assist in the development of proper treatments in the future.

Pattern Recognition of the Multiple Sclerosis Syndrome

During recent decades, the autoimmune disease neuromyelitis optica spectrum disorder (NMOSD), once broadly classified under the umbrella of multiple sclerosis (MS), has been extended to include autoimmune inflammatory conditions of the central nervous system (CNS), which are now diagnosable with serum serological tests. These antibody-mediated inflammatory diseases of the CNS share a clinical presentation to MS. A number of practical learning points emerge in this review, which is geared toward the pattern recognition of optic neuritis, transverse myelitis, brainstem/cerebellar and hemispheric tumefactive demyelinating lesion (TDL)-associated MS, aquaporin-4-antibody and myelin oligodendrocyte glycoprotein (MOG)-antibody NMOSD, overlap syndrome, and some yet-to-be-defined/classified demyelinating disease, all unspecifically labeled under MS syndrome. The goal of this review is to increase clinicians’ awareness of the clinical nuances of the autoimmune conditions for MS and NMSOD, and to highlight highly suggestive patterns of clinical, paraclinical or imaging presentations in order to improve differentiation. With overlay in clinical manifestations between MS and NMOSD, magnetic resonance imaging (MRI) of the brain, orbits and spinal cord, serology, and most importantly, high index of suspicion based on pattern recognition, will help lead to the final diagnosis.

Epidemiology of NMOSD in Catalonia: Influence of the new 2015 criteria in incidence and prevalence estimates

BACKGROUND

Population-based studies on neuromyelitis optica spectrum disorders (NMOSD) are limited, and it is unclear whether the rates have changed with the implementation of the new 2015 criteria.

OBJECTIVES

To estimate the incidence and prevalence of NMOSD in Catalonia (Spain), using both the 2006 and the 2015 criteria.

METHODS

In this clinic-based retrospective study, patients diagnosed with NMOSD between 2006 and 2015 were identified using multiple sources, including direct contact to all Catalan hospitals, identification of cases through the Catalan Health Surveillance System, and registry of antibodies to aquaporin-4 (AQP4-IgG) and myelin oligodendrocyte glycoprotein (MOG-IgG) in a reference laboratory. The incidence rate was calculated for the period 1 January 2006-1 January 2016 and prevalence for the date 1 January 2016.

RESULTS

We identified 74 patients (by the 2015 criteria). Most patients were Caucasian (81%), and female (76%) with a median age at disease onset of 42 years (range, 10-76 years). In total, 54 (73%) patients were positive for AQP4-IgG, 11 (15%) double-seronegative, and 9 (12%) MOG-IgG-positive. Rates of incidence and prevalence (0.63/1,000,000 person-years and 0.89/100,000, respectively) were 1.5-fold higher than those reported by the 2006 criteria. Lowest rates were seen in children and elder people and highest in women and middle-aged people (40-59 years). The female predominance was lost in incident AQP4-IgG-seronegative children and AQP4-IgG-positive elder people. MOG-IgG and double-seronegativity contributed similarly but did not influence the long-term outcome.

CONCLUSION

The new criteria increase the estimates, but NMOSD remains as a rare disease. The differences in age- and sex-specific estimates highlight the importance of the serologic classification.

Postinfectious Anti-Myelin Oligodendrocyte Glycoprotein Antibody Positive Optic Neuritis and Myelitis

We report the case of a 9-year-old girl admitted with fever, headache, and a cerebrospinal fluid lymphocytic pleocytosis. Polymerase chain reaction was positive for human herpes virus 6. She subsequently developed ataxia and bilateral loss of vision. Magnetic resonance imaging (MRI) showed bilateral optic nerve lesions with extension to optic chiasm and a short-segment myelitis. Serologic studies were positive for Borrelia burgdorferi IgM. Anti-aquaporin 4 antibody was negative and anti-myelin oligodendrocyte glycoprotein antibody (MOG) positive. After intravenous methylprednisolone, ceftriaxone, and intravenous immunoglobulin, her vision slowly recovered. The patient was discharged with only mild visual acuity loss, 1 month after admission. Brain MRI was repeated later and was normal and MOG assay became negative. In our view, this patient suffered from a postinfectious, anti-MOG-mediated, spinal cord and optic nerve demyelination.

Clinical profile of patients with paraneoplastic neuromyelitis optica spectrum disorder and aquaporin-4 antibodies

BACKGROUND

In a minority of patients with neuromyelitis optica spectrum disorder (NMOSD) and aquaporin-4 antibodies (AQP4-IgG), the disease has a paraneoplastic origin. It is unknown whether these patients have distinctive clinical features.

OBJECTIVE

To report the clinical features of a series of patients with paraneoplastic NMOSD and AQP4-IgG and to review previously reported cases.

METHODS

Retrospective analysis of clinical records of 156 patients with NMOSD and AQP4-IgG and review of previously reported patients with paraneoplastic NMOSD and AQP4-IgG. Paraneoplastic patients were defined as those with cancer identified within 2 years of the diagnosis of NMOSD.

RESULTS

Five (3.2%) of 156 patients had paraneoplastic NMOSD, and 12 previously reported patients were identified. The most common tumors were adenocarcinoma of the lung (five patients) and breast (five). Compared with the 151 non-paraneoplastic NMOSD patients, the 17 (5 current cases and 12 previously reported) were older at symptom onset (median age = 55 (range: 17-87) vs 40 (range: 10-77) years; p = 0.006), more frequently male (29.4% vs 6.6%; p = 0.009), and presented with severe nausea and vomiting (41.2% vs 6.6%; p < 0.001). The frequency of longitudinal extensive transverse myelitis (LETM) as heralding symptom was similar in both groups, but patients with paraneoplastic NMOSD were older than those with non-paraneoplastic NMOSD (median age: 63 (range: 48-73) vs 43 (range: 14-74) years; p = 0.001).

CONCLUSION

Patients, predominantly male, with NMOSD and AQP4-IgG should be investigated for an underlying cancer if they present with nausea and vomiting, or LETM after 45 years of age.

Immunotherapies in neuromyelitis optica spectrum disorder: efficacy and predictors of response

OBJECTIVE

To analyse predictors for relapses and number of attacks under different immunotherapies in patients with neuromyelitis optica spectrum disorder (NMOSD).

DESIGN

This is a retrospective cohort study conducted in neurology departments at 21 regional and university hospitals in Germany. Eligible participants were patients with aquaporin-4-antibody-positive or aquaporin-4-antibody-negative NMOSD. Main outcome measures were HRs from Cox proportional hazard regression models adjusted for centre effects, important prognostic factors and repeated treatment episodes.

RESULTS

265 treatment episodes with a mean duration of 442 days (total of 321 treatment years) in 144 patients (mean age at first attack: 40.9 years, 82.6% female, 86.1% aquaporin-4-antibody-positive) were analysed. 191 attacks occurred during any of the treatments (annual relapse rate=0.60). The most common treatments were rituximab (n=77, 111 patient-years), azathioprine (n=52, 68 patient-years), interferon-β (n=32, 61 patient-years), mitoxantrone (n=34, 32.1 patient-years) and glatiramer acetate (n=17, 10 patient-years). Azathioprine (HR=0.4, 95% CI 0.3 to 0.7, p=0.001) and rituximab (HR=0.6, 95% CI 0.4 to 1.0, p=0.034) reduced the attack risk compared with interferon-β, whereas mitoxantrone and glatiramer acetate did not. Patients who were aquaporin-4-antibody-positive had a higher risk of attacks (HR=2.5, 95% CI 1.3 to 5.1, p=0.009). Every decade of age was associated with a lower risk for attacks (HR=0.8, 95% CI 0.7 to 1.0, p=0.039). A previous attack under the same treatment tended to be predictive for further attacks (HR=1.5, 95% CI 1.0 to 2.4, p=0.065).

CONCLUSIONS

Age, antibody status and possibly previous attacks predict further attacks in patients treated for NMOSD. Azathioprine and rituximab are superior to interferon-β.

Incidence and prevalence of NMOSD in Australia and New Zealand

OBJECTIVES

We have undertaken a clinic-based survey of neuromyelitis optica spectrum disorders (NMOSDs) in Australia and New Zealand to establish incidence and prevalence across the region and in populations of differing ancestry.

BACKGROUND

NMOSD is a recently defined demyelinating disease of the central nervous system (CNS). The incidence and prevalence of NMOSD in Australia and New Zealand has not been established.

METHODS

Centres managing patients with demyelinating disease of the CNS across Australia and New Zealand reported patients with clinical and laboratory features that were suspicious for NMOSD. Testing for aquaporin 4 antibodies was undertaken in all suspected cases. From this group, cases were identified who fulfilled the 2015 Wingerchuk diagnostic criteria for NMOSD. A capture-recapture methodology was used to estimate incidence and prevalence, based on additional laboratory identified cases.

RESULTS

NMOSD was confirmed in 81/170 (48%) cases referred. Capture-recapture analysis gave an adjusted incidence estimate of 0.37 (95% CI 0.35 to 0.39) per million per year and a prevalence estimate for NMOSD of 0.70 (95% CI 0.61 to 0.78) per 100 000. NMOSD was three times more common in the Asian population (1.57 (95% CI 1.15 to 1.98) per 100 000) compared with the remainder of the population (0.57 (95% CI 0.50 to 0.65) per 100 000). The latitudinal gradient evident in multiple sclerosis was not seen in NMOSD.

CONCLUSIONS

NMOSD incidence and prevalence in Australia and New Zealand are comparable with figures from other populations of largely European ancestry. We found NMOSD to be more common in the population with Asian ancestry.

Liver injury and glatiramer acetate, an uncommon association: case report and literature review

We report the case of a 65-year-old woman who presented with a 1-month history of progressive paraparesia associated with a thoracic lesion with irregular ring-like gadolinium enhancement. Biopsy of the lesion confirmed the demyelinating origin and brain magnetic resonance imaging showed additional lesions demonstrative of dissemination in space. Immunomodulatory therapy with glatiramer acetate (GA) was started after having a second relapse 2 months later. Shortly after initiation, the patient developed acute hepatitis. Liver function tests returned to normal values 5 months after discontinuation and the patient was diagnosed with drug-induced liver injury (DILI) associated with GA. A literature review identified 11 previous cases of GA-related liver injury associated with two specific mechanisms: DILI (seven cases) and autoimmune hepatitis (four cases). Despite the fact that GA hepatic toxicity is uncommon and laboratory monitoring is not required during GA therapy, it should be considered at least in some special conditions such as comorbidities and previous history of DILI associated with other drugs.

Diffusion tensor imaging for multilevel assessment of the visual pathway: possibilities for personalized outcome prediction in autoimmune disorders of the central nervous system

The afferent visual pathway represents the most frequently affected white matter pathway in multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD). Diffusion tensor imaging (DTI) can reveal microstructural or non-overt brain tissue damage and quantify pathological processes. DTI facilitates the reconstruction of major white matter fiber tracts allowing for the assessment of structure-function and damage-dysfunction relationships. In this review, we outline DTI studies investigating the afferent visual pathway in idiopathic optic neuritis (ON), NMOSD, and MS. Since MS damage patterns are believed to depend on multiple factors, i.e., ON (anterior visual pathway damage), inflammatory lesions (posterior visual pathway damage), and global diffuse inflammatory and neurodegenerative processes, comprehensive knowledge on different contributing factors using DTI in vivo may advance our understanding of MS disease pathology. Combination of DTI measures and visual outcome parameters yields the potential to improve routine clinical diagnostic procedures and may further the accuracy of individual prognosis with regard to visual function and personalized disease outcome. However, due to the inherent limitations of DTI acquisition and post-processing techniques and the so far heterogeneous and equivocal data of previous studies, evaluation of the true potential of DTI as a possible biomarker for afferent visual pathway dysfunction is still substantially limited. Further research efforts with larger longitudinal studies and standardized DTI acquisition and post-processing validation criteria are needed to overcome current DTI limitations. DTI evaluation at different levels of the visual pathway has the potential to provide markers for individual damage evaluation in the future. As an imaging biomarker, DTI may support individual outcome prediction during personalized treatment algorithms in MS and other neuroinflammatory diseases, hereby leveraging the concept of predictive, preventive, and personalized medicine in the field of clinical neuroimmunology.

Diagnostic algorithm for relapsing acquired demyelinating syndromes in children

Objective:

To establish whether children with relapsing acquired demyelinating syndromes (RDS) and myelin oligodendrocyte glycoprotein antibodies (MOG-Ab) show distinctive clinical and radiologic features and to generate a diagnostic algorithm for the main RDS for clinical use.

Methods:

A panel reviewed the clinical characteristics, MOG-Ab and aquaporin-4 (AQP4) Ab, intrathecal oligoclonal bands, and Epstein-Barr virus serology results of 110 children with RDS. A neuroradiologist blinded to the diagnosis scored the MRI scans. Clinical, radiologic, and serologic tests results were compared.

Results:

The findings showed that 56.4% of children were diagnosed with multiple sclerosis (MS), 25.4% with neuromyelitis optica spectrum disorder (NMOSD), 12.7% with multiphasic disseminated encephalomyelitis (MDEM), and 5.5% with relapsing optic neuritis (RON). Blinded analysis defined baseline MRI as typical of MS in 93.5% of children with MS. Acute disseminated encephalomyelitis presentation was seen only in the non-MS group. Of NMOSD cases, 30.7% were AQP4-Ab positive. MOG-Ab were found in 83.3% of AQP4-Ab–negative NMOSD, 100% of MDEM, and 33.3% of RON. Children with MOG-Ab were younger, were less likely to present with area postrema syndrome, and had lower disability, longer time to relapse, and more cerebellar peduncle lesions than children with AQP4-Ab NMOSD. A diagnostic algorithm applicable to any episode of CNS demyelination leads to 4 main phenotypes: MS, AQP4-Ab NMOSD, MOG-Ab–associated disease, and antibody-negative RDS.

Conclusions:

Children with MS and AQP4-Ab NMOSD showed features typical of adult cases. Because MOG-Ab–positive children showed notable and distinctive clinical and MRI features, they were grouped into a unified phenotype (MOG-Ab–associated disease), included in a new diagnostic algorithm.

Myelin Oligodendrocyte Glycoprotein: Deciphering a Target in Inflammatory Demyelinating Diseases

Myelin oligodendrocyte glycoprotein (MOG), a member of the immunoglobulin (Ig) superfamily, is a myelin protein solely expressed at the outermost surface of myelin sheaths and oligodendrocyte membranes. This makes MOG a potential target of cellular and humoral immune responses in inflammatory demyelinating diseases. Due to its late postnatal developmental expression, MOG is an important marker for oligodendrocyte maturation. Discovered about 30 years ago, it is one of the best-studied autoantigens for experimental autoimmune models for multiple sclerosis (MS). Human studies, however, have yielded controversial results on the role of MOG, especially MOG antibodies (Abs), as a biomarker in MS. But with improved detection methods using different expression systems to detect Abs in patients' samples, this is meanwhile no longer the case. Using cell-based assays with recombinant full-length, conformationally intact MOG, several recent studies have revealed that MOG Abs can be found in a subset of predominantly pediatric patients with acute disseminated encephalomyelitis (ADEM), aquaporin-4 (AQP4) seronegative neuromyelitis optica spectrum disorders (NMOSD), monophasic or recurrent isolated optic neuritis (ON), or transverse myelitis, in atypical MS and in N-methyl-d-aspartate receptor-encephalitis with overlapping demyelinating syndromes. Whereas MOG Abs are only transiently observed in monophasic diseases such as ADEM and their decline is associated with a favorable outcome, they are persistent in multiphasic ADEM, NMOSD, recurrent ON, or myelitis. Due to distinct clinical features within these diseases it is controversially disputed to classify MOG Ab-positive cases as a new disease entity. Neuropathologically, the presence of MOG Abs is characterized by MS-typical demyelination and oligodendrocyte pathology associated with Abs and complement. However, it remains unclear whether MOG Abs are a mere inflammatory bystander effect or truly pathogenetic. This article provides deeper insight into recent developments, the clinical relevance of MOG Abs and their role in the immunpathogenesis of inflammatory demyelinating disorders.

Combined brain and anterior visual pathways' MRIs assist in early identification of neuromyelitis optica spectrum disorder at onset of optic neuritis

Acute optic neuritis (ON) is the initial presentation in half of neuromyelitis optica spectrum disorder (NMO-SD) cases. Our objective was to evaluate accuracy of combined MRIs of the anterior visual pathways and of the brain to correctly identify NMO-SD among patients with acute ON. We performed a retrospective study on patients with acute ON in NMO-SD (16 episodes) and first-event non-NMO-SD (32 episodes). All MRIs included exams of the brain and anterior visual pathways using T2-weighted and post-gadolinium T1-weighted coronal thin slices. Images were reviewed by a neuroradiologist who was blinded to the final diagnosis. There were no multiple sclerosis (MS)-like lesions with dissemination in space (DIS) with NMO-SD (0 vs. 53%, p < 0.01). Non-NMO-SD ON usually spared the chiasma (3 vs. 44%, p < 0.01) and the optic tracts (0 vs. 19%, p < 0.01). Optic nerve lesions were longer [median (range) 26 mm (14-64) vs. 13 mm [8-36], p < 0.01] and the number of segments involved higher (3 [1-8] vs. 1 [1-4], p < 0.01) in NMO-SD. Bilateral optic nerve involvement, or involvement of ≥3 segments, or involvement of the chiasma, or optic tracts in the absence of MS-like lesions with DIS were suggestive of NMO-SD with a sensitivity of 69% (CI 95% 41-89) and a specificity of 97% (CI 95% 84-99) (p < 0.01). Combining brain and anterior visual pathways' MRIs seems efficient for detecting acute ON patients who are at high risk for NMO-SD.

Short segment myelitis as a first manifestation of neuromyelitis optica spectrum disorders

BACKGROUND

Some patients with neuromyelitis optica spectrum disorders (NMOSD) present with spinal cord lesions extending fewer than three vertebral segments (short transverse myelitis, STM), hindering an early diagnosis.

OBJECTIVE

We investigated the frequency and imaging characteristics of STM lesions in patients presenting with myelitis as an initial manifestation of NMOSD.

METHODS

Patients seen at three referral hospitals in Korea between June 2005 and March 2015 who met the following inclusion criteria were recruited for review: seropositivity for aquaporin-4 antibody, initial presentation with myelitis and spinal cord magnetic resonance imaging (MRI) performed within 1 month of initial myelitis onset.

RESULTS

Of the 76 enrolled patients, 65 (85.5%) collectively had 69 longitudinally extensive transverse myelitis lesions, while the remaining 11 (14.5%) had a total of 15 STM lesions. Of the 15 STM lesions, 5 spanned 2.5 vertebral segments, 6 were continuous over two segments, 3 showed a length of 1.5 segments and 1 was confined to a single segment. On axial imaging, all of the STM lesions involved the central grey matter.

CONCLUSION

These MRI findings suggested that STM does not preclude the possibility of an NMOSD diagnosis.

The clinical characteristics of AQP4 antibody positive NMO/SD in a large cohort of Chinese Han patients

We aim to summarize the clinical features of AQP4-ab-positive NMO/SD in a large Chinese Han cohort. The clinical data of 145 AQP4-ab-seropositive patients was retrospectively reviewed. 55.9% (81/145) of the patients were defined as NMO while 39.3% (57/145) were defined as NMOSD according to the criteria established in 2006 and 2007. The mean onset age was 34.4years and the female to male ratio was 8.7:1. The median disease duration was 57months. The median of "time to second attack" and "time to develop NMO" was 7 and 13months respectively. Ratio of monophasic to relapsing was 1:7.1. Myelitis and optic neuritis (ON) were the most common manifestations at onset, followed by postrema syndrome. The median age of patients presenting with ON at disease onset was significantly younger than patients presenting with myelitis. Only 17.2% of the patients younger than 30years presented with longitudinally extensive transverse myelitis (LETM) at onset, while 55.6% of the patients over 30years presented with LETM at onset. The patients presenting with ON at disease onset all exhibited a relapsing course, had a higher probability of subsequent involvement of other CNS regions and developing into definite NMO over time compared with those with LETM as the first attack. AQP4-ab levels were higher in patients with circulating auto-antibodies such as ANA, SSA, anti-Ro-52, anti-dsDNA, anti-histone antibody, pANCA and SSB, and positively correlated with CSF protein concentrations.