NMO-IgG predicts the outcome of recurrent optic neuritis

Neuromyelitis optica and multiple sclerosis: Seeing differences through optical coherence tomography

Neuromyelitis optica (NMO) is an inflammatory autoimmune disease of the central nervous system that preferentially targets the optic nerves and spinal cord. The clinical presentation may suggest multiple sclerosis (MS), but a highly specific serum autoantibody against the astrocytic water channel aquaporin-4 present in up to 80% of NMO patients enables distinction from MS. Optic neuritis may occur in either condition resulting in neuro-anatomical retinal changes. Optical coherence tomography (OCT) has become a useful tool for analyzing retinal damage both in MS and NMO. Numerous studies showed that optic neuritis in NMO typically results in more severe retinal nerve fiber layer (RNFL) and ganglion cell layer thinning and more frequent development of microcystic macular edema than in MS. Furthermore, while patients’ RNFL thinning also occurs in the absence of optic neuritis in MS, subclinical damage seems to be rare in NMO. Thus, OCT might be useful in differentiating NMO from MS and serve as an outcome parameter in clinical studies.

Systemic inflammation and the brain: novel roles of genetic, molecular, and environmental cues as drivers of neurodegeneration

The nervous and immune systems have evolved in parallel from the early bilaterians, in which innate immunity and a central nervous system (CNS) coexisted for the first time, to jawed vertebrates and the appearance of adaptive immunity. The CNS feeds from, and integrates efferent signals in response to, somatic and autonomic sensory information. The CNS receives input also from the periphery about inflammation and infection. Cytokines, chemokines, and damage-associated soluble mediators of systemic inflammation can also gain access to the CNS via blood flow. In response to systemic inflammation, those soluble mediators can access directly through the circumventricular organs, as well as open the blood–brain barrier. The resulting translocation of inflammatory mediators can interfere with neuronal and glial well-being, leading to a break of balance in brain homeostasis. This in turn results in cognitive and behavioral manifestations commonly present during acute infections – including anorexia, malaise, depression, and decreased physical activity – collectively known as the sickness behavior (SB). While SB manifestations are transient and self-limited, under states of persistent systemic inflammatory response the cognitive and behavioral changes can become permanent. For example, cognitive decline is almost universal in sepsis survivors, and a common finding in patients with systemic lupus erythematosus. Here, we review recent genetic evidence suggesting an association between neurodegenerative disorders and persistent immune activation; clinical and experimental evidence indicating previously unidentified immune-mediated pathways of neurodegeneration; and novel immunomodulatory targets and their potential relevance for neurodegenerative disorders.

Longitudinally extensive optic neuritis in pediatric patients

Extensive optic nerve demyelinating lesions on magnetic resonance imaging (MRI) in adults could indicate a diagnosis other than multiple sclerosis with worse prognosis such as neuromyelitis optica. We report the frequency of longitudinally extensive lesions in children with first events of optic neuritis. Subjects had brain or orbit MRI within 3 months of onset and were evaluated at the University of California, San Francisco, Pediatric Multiple Sclerosis Center. Lesion length, determined by T2 hyperintensity or contrast enhancement, was blindly graded as absent, focal or longitudinally extensive (at least 2 contiguous segments of optic nerve). Of 25 subjects, 9 (36%) had longitudinally extensive optic neuritis. Extensive lesions were not associated with non-multiple sclerosis versus multiple sclerosis diagnosis (P = 1.00). No association between age and lesion extent was observed (P = .26). Prospective studies are needed to determine if longitudinally extensive optic neuritis can predict visual outcome.

Overlapping CNS inflammatory diseases: differentiating features of NMO and MS

Neuromyelitis optica (NMO) has long been considered as a variant of multiple sclerosis (MS) rather than a distinct disease. This concept changed with the discovery of serum antibodies (Ab) against aquaporin-4 (AQP4), which unequivocally differentiate NMO from MS. Patients who test positive for AQP4-Abs and present with optic neuritis (ON) and transverse myelitis (TM) are diagnosed with NMO and those who show an incomplete phenotype with isolated ON or longitudinally extensive TM (LETM) or less commonly brain/brainstem disease are referred to as NMO spectrum disorders (NMOSD). However, many patients, who have overlapping features of both NMO and MS, test negative for AQP4-Abs and may be difficult to definitively diagnose. This raises important practical issues, since NMO and MS respond differently to immunomodulatory treatment and have different prognoses. Here we review distinct features of AQP4-positive NMO and MS, which might then be useful in the diagnosis of antibody-negative overlap syndromes. We identify discriminators, which are related to demographic data (non-white origin, very late onset), clinical features (limited recovery from ON, bilateral ON, intractable nausea, progressive course of disability), laboratory results (cerebrospinal fluid (CSF) pleocytosis with eosinophils and/or neutrophils, oligoclonal bands, glial fibrillary acidic protein in the CSF) and imaging (LETM, LETM with T1 hypointensity, periependymal brainstem lesions, perivenous white matter lesions, Dawson's fingers, curved or S-shaped U-fibre juxtacortical lesions). We review the value of these discriminators and discuss the compelling need for new diagnostic markers in these two autoimmune demyelinating diseases of the central nervous system.

Neurological outcome and predictive factors of idiopathic optic neuritis in China

BACKGROUND

The neurological outcome and predictive factors of idiopathic optic neuritis (ION) in China are largely unknown.

OBJECTIVE

The aim of this paper is to study the neurological outcome of Chinese ION and to investigate the early predictors for multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD).

METHOD

Retrospective medical record review and supplementary follow-up of 107 ION patients was performed. Statistical analysis of the baseline characteristics as risk factors for ION patients converting into MS or NMOSD was performed.

RESULTS

With an average disease course of 9.5years, 19 of the 107 (17.7%) ION patients developed either MS (9, 8.4%) or NMOSD (10, 9.3%). The estimated 5-year and 10-year combined accumulative risk rates were 14.1% and 26.0%, respectively. Significantly higher estimated accumulative conversion risk was found in female versus male (P=0.047), adult versus children (P=0.032), patients with brain MRI lesions versus patients without leasions (P=0.026), patients with CSF positive oligoclonal bands and/or elevated IgG index versus without (P=0.003) and patients with poor visual recovery versus patients with good recovery (P=0.007). Furthermore, brain white matter lesions and good visual recovery were statistically more common typically in MS converters compared with the NMOSD converters (P=0.01 and P=0.006, respectively).

CONCLUSION

The combined conversion rate for ION to MS/NMO in Chinese population was lower than the reported rate for Western countries. In addition to some previously reported high risk factors, white matter lesions on the brain MRI at baseline and good visual recovery were found to be good predictors for Chinese ION converting into MS whereas poor visual recovery with a normal brain MRI suggested a higher likelihood of the ION converting into NMOSD.

Evaluation of aquaporin-4 antibody assays

Aquaporin-4 (AQP4) is a water channel protein that is most highly, but not exclusively, expressed in the central nervous system. In 2005 AQP4 was shown to be the antigenic target of neuromyelitis optica-immunoglobulin G (NMO-IgG, or AQP4-IgG), an antibody found specifically in patients with NMO and in formes frustes of NMO, such as longitudinally extensive transverse myelitis (LETM) or optic neuritis (ON). This discovery facilitated the clinical, pathological, and radiological distinction of NMO and the spectrum of NMO-related disorders from classical multiple sclerosis. In addition to its use as a diagnostic tool, AQP4-IgG predicts a high risk of relapse in patients with a clinically isolated syndrome of either LETM or ON. As disability in NMO is attack-related, early diagnosis and treatment are predicted to have a major effect on long-term disability. Thus, the importance of sensitive and specific assays to detect AQP4-IgG cannot be overstated. Both academic institutions and commercial companies have developed assays to identify AQP4-IgG in patients' sera or cerebrospinal fluid. Both AQP4 isoforms from different species have been used as the antigenic target in the form of frozen tissue sections in indirect immunofluorescence assays, partially purified protein for fluorescence immunoprecipitation assay, radioimmunoprecipita-tion assay or enzyme-linked immunosorbent assay, or transfected into cells for cell based assays or flow cytometry. We carried out a systematic review of the literature reporting different methodologies used to identify AQP4-IgG, examine whether longitudinal AQP4-IgG titers predict relapses in seropositive patients, and attempt to establish a reasonable timeframe for retesting negative serum samples.

Risk factors for idiopathic optic neuritis recurrence

BACKGROUND

Approximately 30-50% of idiopathic optic neuritis (ION) patients experience one or multiple episodes of recurrence. The aim of this study was to search for risk factors for ION recurrence.

METHODS

Clinical data on hospitalized patients diagnosed with ION between January 2003 and January 2011 at the First Affiliated Hospital of Guangxi Medical University were retrospectively collected. Univariate and multivariate analyses were performed on factors that might cause ION recurrence. In total, 115 ION cases (32 recurrent and 83 non-recurrent cases) with complete data were analyzed. The length of the follow-up period ranged from 12 to 108 months (median: 42 months).

RESULTS

The univariate analysis showed that the recurrence rate for unilateral ION was higher than that for bilateral ION (40% vs. 12%, p=0.001). Underlying diseases had a significant impact on recurrence (p<0.001): the recurrence rates due to neuromyelitis optica (NMO), multiple sclerosis (MS), demyelinating lesions alone of the central nervous system, and unknown causes were 89%, 70%, 41%, and 8.7%, respectively. The multivariate analysis showed that the factors causing relatively high recurrence rates included NMO (odds ratio [OR], 73.5; 95% confidence interval [CI], 7.3 to 740.9), MS (OR, 33.9; 95% CI, 5.2 to 222.2), and demyelinating lesions alone (OR, 8.9; 95% CI, 2.3 to 34.4), unilateral involvement (OR, 5.7; 95% CI, 1.5 to 21.3), relatively low initial glucocorticoid dosage (equivalent to ≤ 100 mg prednisone/day) (OR, 4.3; 95% CI, 1.0 to 17.9).

CONCLUSION

Underlying diseases, laterality (unilateral or bilateral), and initial glucocorticoid dosage are important risk factors of ION recurrence. Clinical physicians are advised to treat ION patients with a sufficient dose of glucocorticoid in the initial treatment stage to reduce the recurrence risk.

Paraneoplastic neuromyelitis optica associated with ANNA-1 antibodies in invasive thymoma

Background

Thymoma is associated with various paraneoplastic autoimmune disorders. Herein, we report paraneoplastic neuromyelitis optica (NMO) associated with both anti-aquaporin-4 (AQP4) immunoglobulin G (IgG) and type 1 antineuronal nuclear antibody (ANNA-1) in an invasive thymoma patient.

Case presentation

A woman presented with a sudden onset of bilateral progressive visual loss associated with recurrence of invasive thymoma, 6 years after thymectomy and immunosuppressive treatment. AQP4-IgG and ANNA-1 were present in the patient’s serum. Visual outcome was poor despite immunosuppressive treatment. Longitudinally extensive transverse myelitis developed 27 months after the onset of visual symptoms.

Conclusions

We have reported a case of paraneoplastic NMO associated with both AQP4-IgG and ANNA-1 autoantibodies in an invasive thymoma patient.

Dock3 protects myelin in the cuprizone model for demyelination

Dedicator of cytokinesis 3 (Dock3) belongs to an atypical family of the guanine nucleotide exchange factors. It is predominantly expressed in the neural tissues and causes cellular morphological changes by activating the small GTPase Rac1. We previously reported that Dock3 overexpression protects retinal ganglion cells from excitotoxic cell death. Oligodendrocytes are the myelinating cells of axons in the central nervous system and these cells are damaged in demyelinating disorders including multiple sclerosis (MS) and optic neuritis. In this study, we examined if Dock3 is expressed in oligodendrocytes and if increasing Dock3 signals can suppress demyelination in a cuprizone-induced demyelination model, an animal model of MS. We demonstrate that Dock3 is expressed in oligodendrocytes and Dock3 overexpression protects myelin in the corpus callosum following cuprizone treatment. Furthermore, we show that cuprizone demyelinates optic nerves and the extent of demyelination is ameliorated in mice overexpressing Dock3. Cuprizone treatment impairs visual function, which was demonstrated by multifocal electroretinograms, an established non-invasive method, and Dock3 overexpression prevented this effect. In mice overexpressing Dock3, Erk activation is increased, suggesting this may at least partly explain the observed protective effects. Our findings suggest that Dock3 may be a therapeutic target for demyelinating disorders including optic neuritis.

Neuromyelitis optica spectrum disorders without and with autoimmune diseases

Background

Neuromyelitis optica spectrum disorder (NMOSD) can coexist with non-organ-specific or organ-specific autoimmune diseases. The aim of this study was to investigate and compare the features between NMOSD without and with autoimmune diseases, and NMOSD with non-organ-specific and organ-specific autoimmune diseases.

Methods

One hundred and fifty five NMOSD patients without autoimmune diseases (n = 115) and with autoimmune diseases (n = 40) were enrolled. NMOSD with autoimmune diseases were divided by organ-specific autoimmune diseases. The clinical, laboratory and magnetic resonance imaging features between two groups were assessed.

Results

Motor deficit was less frequent in NMOSD patients with non-organ-specific autoimmune diseases (p = 0.024). Cerebrospinal fluid white blood cell and protein, serum C-reactive protein and immunoglobulin G were lower in NMOSD patients without autoimmune diseases, while several autoantibodies seropositivity and thyroid indexes were significantly higher in NMOSD patients with autoimmune diseases (p < 0.05). No difference was found in other clinical and laboratory characteristics between different NMOSD subtypes (p > 0.05). NMOSD patients with autoimmune diseases had higher brain abnormalities than NMOSD without autoimmune diseases (p < 0.001).

Conclusions

The characteristics between NMOSD without and with autoimmune diseases were similar. NMOSD with autoimmune diseases have high frequency of brain abnormalities.

Conventional and advanced imaging in neuromyelitis optica

Myelitis and optic neuritis are prototypic clinical presentations of both multiple sclerosis and neuromyelitis optica. Once considered a subtype of multiple sclerosis, neuromyelitis optica, is now known to have a discrete pathogenesis in which antibodies to the water channel, aquaporin 4, play a critical role. Timely differentiation of neuromyelitis optica from MS is imperative, determining both prognosis and treatment strategy. Early, aggressive immunosuppression is required to prevent the accrual of severe disability in neuromyelitis optica; conversely, MS-specific therapies may exacerbate the disease. The diagnosis of neuromyelitis optica requires the integration of clinical, MR imaging, and laboratory data, but current criteria are insensitive and exclude patients with limited clinical syndromes. Failure to recognize the expanding spectrum of cerebral MR imaging patterns associated with aquaporin 4 antibody seropositivity adds to diagnostic uncertainty in some patients. We present the state of the art in conventional and nonconventional MR imaging in neuromyelitis optica and review the place of neuroimaging in the diagnosis, management, and research of the condition.

Autologous hematopoietic stem cell transplantation in neuromyelitis optica: A registry study of the EBMT Autoimmune Diseases Working Party

Background:

Neuromyelitis optica (NMO) is an inflammatory autoimmune disorder of the central nervous system, hallmarked by pathogenic anti-aquaporin 4 antibodies. NMO prognosis is worse compared with multiple sclerosis.

Objective:

The European Group for Blood and Marrow Transplantation (EBMT) Autoimmune Diseases Working Party (ADWP) conducted a retrospective survey to analyze disease outcome following autologous stem cell transplantation (ASCT).

Methods:

This retrospective multicenter study assessed the efficacy and safety of ASCT in 16 patients suffering from refractory NMO reported to the EBMT registry between 2001 and 2011.

Results:

Fifteen patients were successfully mobilized with cyclophosphamide (Cy) and G-CSF, one with G-CSF alone. All patients received an unmanipulated autologous peripheral blood stem cell graft, after conditioning with BEAM plus anti-thymocyte globulin (ATG, n = 9 patients), thiotepa-Cy ( n = 3) or Cy (200 mg/kg) plus ATG ( n = 4). After a median follow-up of 47 months, three of 16 cases were progression and treatment free, while in the remaining 13 patients further treatments were administered for disability progression or relapse after ASCT. Altogether, relapse-free survival at three and five years was 31% and 10%, respectively, while progression-free survival remained 48% at three and five years.

Conclusions:

In these NMO patients, highly resistant to conventional treatment, ASCT allows for temporary control of the disease, despite a tendency to progress or relapse in the long term.

Aquaporin-4 antibody testing: direct comparison of M1-AQP4-DNA-transfected cells with leaky scanning versus M23-AQP4-DNA-transfected cells as antigenic substrate

BACKGROUND

Neuromyelitis optica (NMO, Devic syndrome) is associated with antibodies to aquaporin-4 (NMO-IgG/AQP4-Ab) in the majority of cases. NMO-IgG/AQP4-Ab seropositivity in patients with NMO and its spectrum disorders has important differential diagnostic, prognostic and therapeutic implications. So-called cell-based assays (CBA) are thought to provide the best AQP4-Ab detection rates.

OBJECTIVE

To compare directly the AQP4-IgG detection rates of the currently most widely used commercial CBA, which employs cells transfected with a full-length (M1)-human AQP4 DNA in a fashion that allows leaky scanning (LS) and thus expression of M23-AQP4 in addition to M1-AQP, to that of a newly developed CBA from the same manufacturer employing cells transfected with human M23-AQP4-DNA.

METHODS

Results from 368 serum samples that had been referred for routine AQP4-IgG determination and had been tested in parallel in the two assays were compared.

RESULTS

Seventy-seven out of 368 samples (20.9%) were positive for NMO-IgG/AQP4-Ab in at least one assay. Of these, 73 (94.8%) were positive in both assays. A single sample (1.3%) was exclusively positive in the novel assay; three samples (3.9%) were unequivocally positive only in the 'classic' assay due to high background intensity in the novel assay. Both median fluorescence intensity and background intensity were higher in the new assay.

CONCLUSIONS

This large study did not reveal significant differences in AQP4-IgG detection rates between the 'classic' CBA and a new M23-DNA-based CBA. Importantly, our results largely re-affirm the validity of previous studies that had used the 'classic' AQP4-CBA to establish NMO-IgG/AQP4-Ab seropositivity rates in NMO and in a variety of NMO spectrum disorders.

Frequency of autoantibodies and connective tissue diseases in Chinese patients with optic neuritis

Background

Optic neuritis (ON) is often associated with other clinical or serological markers of connective tissue diseases (CTDs). To date, the effects of autoantibodies on ON are not clear.

Purpose

To assess the prevalence, clinical patterns, and short outcomes of autoantibodies and Sjögren’s syndrome (SS) involvement in Chinese ON patients and evaluate the relationship between ON, including their subtypes, and autoantibodies.

Methods

A total of 190 ON patients were divided into recurrent ON (RON), bilateral ON (BON), and isolated monocular ON (ION). Demographic, clinical, and serum autoantibodies data were compared between them with and without SS involvement. Serum was drawn for antinuclear antibody (ANA), extractable nuclear antigen antibodies (SSA/SSB), rheumatoid factor (RF), anticardiolipin antibodies (ACA), and anti-double-stranded DNA antibody (A-ds DNA), anticardiolipin antibody (ACLs), anti-β2-glycoprotein I (β2-GPI) and Aquaporin-4 antibodies (AQP4-Ab). Spectral-domain optical coherence tomography (SD-OCT) was used to evaluate the atrophy of the optic nerve.

Results

68 patients (35.79%) had abnormal autoantibodies, 26(13.68%) patients met diagnostic criteria for CTDs, including 15(7.89%) patients meeting the criteria for SS. Antibodies including SSA/SSB 23 (30.26%) (p1 and p 2<0.001) and AQP4–Ab10 (13.16%) (p1 = 0.044, p2 = 0.01) were significantly different in patients in the RON group when compared with those in the BON (P1 = RON VS ION) and ION (p2 = RON VS ION) groups. SS was more common in RON patients (p1 = 0.04, p2 = 0.028). There was no significant difference between SSA/SSB positive and negative patients in disease characteristics or severity. Similar results were obtained when SS was diagnosed in SSA/SSB positive patients.

Conclusion

RON and BON were more likely associated with abnormal autoantibodies; furthermore, AQP4 antibody, SSA/SSB and SS were more common in the RON patients. AQP4 antibodydetermination is crucial in RON patients who will develop NMO. However, when compared with other autoantibodies, SSA/SSB detected in patients was not significantly associated with disease characteristics or severity.

Neuromyelitis optica: clinical features, immunopathogenesis and treatment

The term 'neuromyelitis optica' ('Devic's syndrome', NMO) refers to a syndrome characterized by optic neuritis and myelitis. In recent years, the condition has raised enormous interest among scientists and clinical neurologists, fuelled by the detection of a specific serum immunoglobulin (Ig)G reactivity (NMO-IgG) in up to 80% of patients with NMO. These autoantibodies were later shown to target aquaporin-4 (AQP4), the most abundant water channel in the central nervous system (CNS). Here we give an up-to-date overview of the clinical and paraclinical features, immunopathogenesis and treatment of NMO. We discuss the widening clinical spectrum of AQP4-related autoimmunity, the role of magnetic resonance imaging (MRI) and new diagnostic means such as optical coherence tomography in the diagnosis of NMO, the role of NMO-IgG, T cells and granulocytes in the pathophysiology of NMO, and outline prospects for new and emerging therapies for this rare, but often devastating condition.

The retinal nerve fiber layer of patients with neuromyelitis optica and chronic relapsing optic neuritis is more severely damaged than patients with multiple sclerosis

BACKGROUND

To compare the retinal nerve fiber layer (RNFL) in eyes of patients with relapsing remitting multiple sclerosis (RRMS), neuromyelitis optica (NMO) and chronic relapsing inflammatory optic neuritis (CRION).

METHODS

Evaluation of 62 patients with RRMS, NMO, and CRION in a cross-sectional study with spectral domain optical coherence tomography.

RESULTS

A total of 124 eyes were evaluated (96 RRMS, 18 NMO, and 10 CRION). Frequency of optic neuritis for each disease was: 34% for RRMS, 84% for NMO, and 100% for CRION. Visual acuity and RNFL thickness were significantly worse in NMO and CRION eyes than in RRMS, but there were no differences between NMO and CRION eyes. A RNFL of 41 μm was 100% specific for optic neuritis associated with NMO and CRION when compared to RRMS.

CONCLUSION

This study established RNFL values to differentiate optic neuritis of RRMS from NMO and CRION. Although similarities observed between NMO and CRION eyes might suggest that they are within the same disease spectrum, it is still recommended that these 2 conditions be differentiated on clinical grounds. Optical coherence tomography serves as an additional diagnostic tool and can be used to monitor disease progression.

Aquaporin-4 antibodies (NMO-IgG) as a serological marker of neuromyelitis optica: a critical review of the literature

Antibodies to aquaporin-4 (called NMO-IgG or AQP4-Ab) constitute a sensitive and highly specific serum marker of neuromyelitis optica (NMO) that can facilitate the differential diagnosis of NMO and classic multiple sclerosis. NMO-IgG/AQP4-Ab seropositive status has also important prognostic and therapeutic implications in patients with isolated longitudinally extensive myelitis (LETM) or optic neuritis (ON). In this article, we comprehensively review and critically appraise the existing literature on NMO-IgG/AQP4-Ab testing. All available immunoassays-including tissue-based (IHC), cell-based (ICC, FACS) and protein-based (RIPA, FIPA, ELISA, Western blotting) assays-and their differential advantages and disadvantages are discussed. Estimates for sensitivity, specificity, and positive and negative likelihood ratios are calculated for all published studies and accuracies of the various immunoassay techniques compared. Subgroup analyses are provided for NMO, LETM and ON, for relapsing vs. monophasic disease, and for various control groups (eg, MS vs. other controls). Numerous aspects of NMO-IgG/AQP4-Ab testing relevant for clinicians (eg, impact of antibody titers and longitudinal testing, indications for repeat testing, relevance of CSF testing and subclass analysis, NMO-IgG/AQP4-Ab in patients with rheumatic diseases) as well as technical aspects (eg, AQP4-M1 vs. AQP4-M23-based assays, intact AQP4 vs. peptide substrates, effect of storage conditions and freeze/thaw cycles) and pitfalls are discussed. Finally, recommendations for the clinical application of NMO-IgG/AQP4-Ab serology are given.

Neuromyelitis optica and aquaporin-4 (AQP4) autoantibodies in consecutive optic neuritis patients in Southern Finland

PURPOSE

  To analyse the frequency of neuromyelitis optica (NMO) among consecutive optic neuritis (ON) patients in Southern Finland and the feasibility of Aquaporin-4 (AQP4) autoantibody assay in the diagnosis of NMO.

METHODS

  Consecutive patients with symptoms suggestive of acute ON and managed in the Helsinki University Central Hospital were evaluated critically screened for AQP4 autoantibody during a 47.5-month period. The antibodies were determined using radioimmunoprecipitation method. AQP4 index >15 was considered positive, 10-15 borderline and <10 normal. Brain magnetic resonance imaging (MRI) was performed for all patients.

RESULTS

  Of the 300 patients with suspected ON, 191 were eventually diagnosed as ON, and 66 (35%) of them had a previous diagnosis or were diagnosed with multiple sclerosis (MS). Of the 125 patients without MS diagnosis, 62 (50%) had demyelinative lesions in MRI, which is a risk factor for developing MS. Two patients (1.1%; 95% CI 0.3-4.5) fulfilled the criteria of NMO. Positive AQP4 antibodies were found in three patients (1.6% 95% CI 0.3-4.5), one of them had NMO, one had MS and one became diagnosed with MS a month later. Borderline autoantibody levels were found in 10 patients, 7 of whom had MS.

CONCLUSIONS

  NMO is rare among ON patients in the population of Southern Finland. In this small cohort, the sensitivity and positive predictive values of the AQP4 autoantibody index for NMO were low, 1/2 and 1/3 respectively, and do not support initiating routine screening.

Evaluation of aquaporin-4 antibody assays

Aquaporin-4 (AQP4) is a water channel protein that is most highly, but not exclusively, expressed in the central nervous system. In 2005 AQP4 was shown to be the antigenic target of neuromyelitis optica-immunoglobulin G (NMO-IgG, or AQP4-IgG), an antibody found specifically in patients with NMO and in formes frustes of NMO, such as longitudinally extensive transverse myelitis (LETM) or optic neuritis (ON). This discovery facilitated the clinical, pathological, and radiological distinction of NMO and the spectrum of NMO-related disorders from classical multiple sclerosis. In addition to its use as a diagnostic tool, AQP4-IgG predicts a high risk of relapse in patients with a clinically isolated syndrome of either LETM or ON. As disability in NMO is attack-related, early diagnosis and treatment are predicted to have a major effect on long-term disability. Thus, the importance of sensitive and specific assays to detect AQP4-IgG cannot be overstated. Both academic institutions and commercial companies have developed assays to identify AQP4-IgG in patients' sera or cerebrospinal fluid. Both AQP4 isoforms from different species have been used as the antigenic target in the form of frozen tissue sections in indirect immunofluorescence assays, partially purified protein for fluorescence immunoprecipitation assay, radioimmunoprecipita-tion assay or enzyme-linked immunosorbent assay, or transfected into cells for cell based assays or flow cytometry. We carried out a systematic review of the literature reporting different methodologies used to identify AQP4-IgG, examine whether longitudinal AQP4-IgG titers predict relapses in seropositive patients, and attempt to establish a reasonable timeframe for retesting negative serum samples.

Autoantibody biomarkers in childhood-acquired demyelinating syndromes: results from a national surveillance cohort

BACKGROUND

Autoantibodies to glial, myelin and neuronal antigens have been reported in a range of central demyelination syndromes and autoimmune encephalopathies in children, but there has not been a systematic evaluation across the range of central nervous system (CNS) autoantibodies in childhood-acquired demyelinating syndromes (ADS).

METHODS

Children under the age of 16 years with first-episode ADS were identified from a national prospective surveillance study; serum from 65 patients had been sent for a variety of diagnostic tests. Antibodies to astrocyte, myelin and neuronal antigens were tested or retested in all samples.

RESULTS

Fifteen patients (23%) were positive for at least one antibody (Ab): AQ4-Ab was detected in three; two presenting with neuromyelitis optica (NMO) and one with isolated optic neuritis (ON). Myelin oligodendrocyte glycoprotein (MOG)-Ab was detected in seven; two with acute disseminated encephalomyelitis (ADEM), two with ON, one with transverse myelitis (TM) and two with clinically isolated syndrome (CIS). N-Methyl-D-Aspartate receptor (NMDAR)-Ab was found in two; one presenting with ADEM and one with ON. Voltage-gated potassium channel (VGKC)-complex antibodies were positive in three; one presenting with ADEM, one with ON and one with CIS. GlyR-Ab was detected in one patient with TM. All patients were negative for the VGKC-complex-associated proteins LGI1, CASPR2 and contactin-2.

CONCLUSIONS

A range of CNS-directed autoantibodies were found in association with childhood ADS. Although these antibodies are clinically relevant when associated with the specific neurological syndromes that have been described, further studies are required to evaluate their roles and clinical relevance in demyelinating diseases.

Neuromyelitis optica MOG-IgG causes reversible lesions in mouse brain

Introduction

Antibodies against myelin oligodendrocyte glycoprotein (MOG-IgG) are present in some neuromyelitis optica patients who lack antibodies against aquaporin-4 (AQP4-IgG). The effects of neuromyelitis optica MOG-IgG in the central nervous system have not been investigated in vivo. We microinjected MOG-IgG, obtained from patients with neuromyelitis optica, into mouse brains and compared the results with AQP4-IgG.

Results

MOG-IgG caused myelin changes and altered the expression of axonal proteins that are essential for action potential firing, but did not produce inflammation, axonal loss, neuronal or astrocyte death. These changes were independent of complement and recovered within two weeks. By contrast, AQP4-IgG produced complement-mediated myelin loss, neuronal and astrocyte death with limited recovery at two weeks.

Conclusions

These differences mirror the better outcomes for MOG-IgG compared with AQP4-IgG patients and raise the possibility that MOG-IgG contributes to pathology in some neuromyelitis optica patients.

Long-term efficacy, tolerability and retention rate of azathioprine in 103 aquaporin-4 antibody-positive neuromyelitis optica spectrum disorder patients: a multicentre retrospective observational study from the UK

BACKGROUND

Azathioprine (AZA) is a common immunosuppressive drug used for relapse prevention in neuromyelitis optica (NMO).

OBJECTIVES

The objective of this paper is to assess efficacy, tolerability and retention of AZA in a large NMO cohort.

METHODS

We conducted a retrospective review of medical records of 103 aquaporin-4 antibody-positive NMO and NMO spectrum disorder (NMOSD) patients treated with AZA.

RESULTS

This is the largest reported cohort of AQP4-Ab positive patients treated with AZA. Eighty-nine per cent (n = 92) had reduction in median annualised relapse rates from 1.5 (IQR 0.6-4.0) to 0 (IQR 0-0.27, p < 0.00005) with treatment. Sixty-one per cent (n = 63) remained relapse free at a median follow-up of 18 months. Neurological function improved or stabilised in 78%. At last follow-up, treatment was discontinued in 46% (n = 47). Of these, 62% (n = 29) were because of side effects, 19% (n = 9) because of death, 15% (n = 7) because of ongoing disease activity, and 2% (n = 1) because of pregnancy. Using Kaplan-Meyer curves, we estimate that 73%, 58%, 47% and 33% of patients will remain on AZA for longer than one, three, five and 10 years, respectively, after initiation of treatment.

CONCLUSIONS

AZA is a modestly effective treatment for NMO. However, many patients discontinue AZA over time and this seems to reflect poor tolerability more than lack of efficacy.

Allogeneic hematopoietic stem cell transplantation for neuromyelitis optica

Neuromyelitis optica is a rare neurological autoimmune disorder characterized by a poor prognosis. Immunosuppression can halt disease progression, but some patients are refractory to multiple treatments, experiencing frequent relapses with accumulating disability. Here we report on durable clinical remissions after allogeneic hematopoietic stem cell transplantation in 2 patients suffering from severe forms of the disease. Immunological data evidenced disappearance of the pathogenic antibodies and regeneration of a naive immune system of donor origin. These findings correlated with evident clinical and radiological improvement in both patients, warranting extended clinical trials to investigate this promising therapeutic option.

Optic neuritis

Acute optic neuritis is the most common optic neuropathy affecting young adults. Exciting developments have occurred over the past decade in understanding of optic neuritis pathophysiology, and these developments have been translated into treatment trials. In its typical form, optic neuritis presents as an inflammatory demyelinating disorder of the optic nerve, which can be associated with multiple sclerosis. Atypical forms of optic neuritis can occur, either in association with other inflammatory disorders or in isolation. Differential diagnosis includes various optic nerve and retinal disorders. Diagnostic investigations include MRI, visual evoked potentials, and CSF examination. Optical coherence tomography can show retinal axonal loss, which correlates with measures of persistent visual dysfunction. Treatment of typical forms with high-dose corticosteroids shortens the period of acute visual dysfunction but does not affect the final visual outcome. Atypical forms can necessitate prolonged immunosuppressive regimens. Optical coherence tomography and visual evoked potential measures are suitable for detection of neuroaxonal loss and myelin repair after optic neuritis. Clinical trials are underway to identify potential neuroprotective or remyelinating treatments for acutely symptomatic inflammatory demyelinating CNS lesions.

Multiple sclerosis: diagnosis, differential diagnosis, and clinical presentation

The diagnosis of multiple sclerosis (MS) is based on demonstrating evidence of inflammatory-demyelinating injury within the central nervous system that is disseminated in both time and space. Diagnosis is made through a combination of the clinical history, neurologic examination, magnetic resonance imaging and the exclusion of other diagnostic possibilities. Other so-called "paraclinical" tests, including the examination of the cerebrospinal fluid, the recording of evoked potentials, urodynamic studies of bladder function, and ocular coherence tomography, may be helpful in establishing the diagnosis for individual patients, but are often unnecessary. Differential diagnosis in MS must be guided by clinical presentation and neurologic localization. While the list of conditions that can mimic MS clinically or radiologically is long, in clinical practice there are few conditions that truly mimic MS on both fronts. A positive test for a putative MS "mimic" does not unto itself exclude the diagnosis of MS. Typical symptoms of MS include discrete episodes ("attacks" or "relapses") of numbness, tingling, weakness, vision loss, gait impairment, incoordination, imbalance, and bladder dysfunction. In between attacks, patients tend to be stable, but may experience fatigue and heat sensitivity. Some MS patients go on to experience, or only experience, an insidious worsening of neurologic function and accumulation of disability ("progression") that is not associated with discrete relapse activity. Progression accounts for most of the long-term disability in MS. Diagnostic criteria for MS have evolved over the past several decades, with each revision impacting the apparent prevalence and prognosis of the disorder - the result has been to encourage earlier diagnosis without compromising accuracy.

Update on the diagnosis and treatment of neuromyelitis optica: recommendations of the Neuromyelitis Optica Study Group (NEMOS)

Neuromyelitis optica (NMO, Devic’s syndrome), long considered a clinical variant of multiple sclerosis, is now regarded as a distinct disease entity. Major progress has been made in the diagnosis and treatment of NMO since aquaporin-4 antibodies (AQP4-Ab; also termed NMO-IgG) were first described in 2004. In this review, the Neuromyelitis Optica Study Group (NEMOS) summarizes recently obtained knowledge on NMO and highlights new developments in its diagnosis and treatment, based on current guidelines, the published literature and expert discussion at regular NEMOS meetings. Testing of AQP4-Ab is essential and is the most important test in the diagnostic work-up of suspected NMO, and helps to distinguish NMO from other autoimmune diseases. Furthermore, AQP4-Ab testing has expanded our knowledge of the clinical presentation of NMO spectrum disorders (NMOSD). In addition, imaging techniques, particularly magnetic resonance imaging of the brain and spinal cord, are obligatory in the diagnostic workup. It is important to note that brain lesions in NMO and NMOSD are not uncommon, do not rule out the diagnosis, and show characteristic patterns. Other imaging modalities such as optical coherence tomography are proposed as useful tools in the assessment of retinal damage. Therapy of NMO should be initiated early. Azathioprine and rituximab are suggested as first-line treatments, the latter being increasingly regarded as an established therapy with long-term efficacy and an acceptable safety profile in NMO patients. Other immunosuppressive drugs, such as methotrexate, mycophenolate mofetil and mitoxantrone, are recommended as second-line treatments. Promising new therapies are emerging in the form of anti-IL6 receptor, anti-complement or anti-AQP4-Ab biologicals.

An optimized immunohistochemistry technique improves NMO-IgG detection: study comparison with cell-based assays

Cell-based assays (CBA) have increased the sensitivity of the neuromyelitis optica (NMO)-IgG/aquaporin-4-antibody detection compared to classical tissue-based indirect assays. We describe the sensitivity of an optimized immunohistochemistry (IHC-o) to detect NMO-IgG/aquaporin-4-antibody in comparison with that of two CBA: an in-house (CBA-ih) and a commercial (CBA-c) assay (Euroimmun, Germany). Coded serum from 103 patients with definite NMO and 122 inflammatory controls were studied by IHC-o, CBA-ih, and CBA-c. IHC-o used the same protocol described to detect antibodies against cell surface antigens. CBA-ih used live cells transfected with the aquaporin-4-M23-isoform. The sensitivity of the IHC-o was 74.8% (95% confidence interval [CI] 65-83) and was similar to that of the CBA-ih 75.7% (95% CI 66-84) and the CBA-c 73.8% (95% CI 64-82). The specificity of the three assays was 100% (95% CI 97-100). Interassay concordance was high, 100 of 103 samples were coincident in all techniques. The optimized immunohistochemistry proves to be as sensitive and specific as the cell-based assays. This assay extends the available tools for NMO-IgG/aquaporin-4-antibody detection.

Relapsing optic neuritis: a multicentre study of 62 patients

Background:

Optic neuritis (ON) may be the first symptom of a central nervous system demyelinating, systemic or infectious disease but few patients experience recurrent episodes and have a negative workup.

Objective:

This disorder, named relapsing optic neuritis (RON), is poorly described in the literature and still presents a particular challenge in diagnosis and management.

Methods:

We describe the clinical, laboratory, magnetic resonance imaging (MRI) and disability course of RON in a French cohort of 62 patients, based on a multicentre, retrospective, observational study.

Results:

In our cohort, we identified two distinct groups of RON patients. The first is characterised by relapsing inflammatory optic neuritis (RION, 68%), which is non-progressive, whereas the second presented as a chronic relapsing inflammatory optic neuritis (CRION, 32%), which is progressive. We have noted more cases with steroid dependence in the CRION group than the RION group (42% vs 10%). The long-term visual prognosis was more severe in CRION patients and neuromyelitis optica-immunoglobulin G (NMO-IgG)-positive patients.

Conclusion:

RON is likely a separate entity corresponding to an autoimmune disease that differs from multiple sclerosis (MS), NMO and vasculitis. We provide a new classification system based on a better understanding of RON which could allow an improved management by early treatment of poor prognosis forms.

Aquaporin-4 antibodies (NMO-IgG) as a serological marker of neuromyelitis optica: a critical review of the literature

Antibodies to aquaporin-4 (called NMO-IgG or AQP4-Ab) constitute a sensitive and highly specific serum marker of neuromyelitis optica (NMO) that can facilitate the differential diagnosis of NMO and classic multiple sclerosis. NMO-IgG/AQP4-Ab seropositive status has also important prognostic and therapeutic implications in patients with isolated longitudinally extensive myelitis (LETM) or optic neuritis (ON). In this article, we comprehensively review and critically appraise the existing literature on NMO-IgG/AQP4-Ab testing. All available immunoassays-including tissue-based (IHC), cell-based (ICC, FACS) and protein-based (RIPA, FIPA, ELISA, Western blotting) assays-and their differential advantages and disadvantages are discussed. Estimates for sensitivity, specificity, and positive and negative likelihood ratios are calculated for all published studies and accuracies of the various immunoassay techniques compared. Subgroup analyses are provided for NMO, LETM and ON, for relapsing vs. monophasic disease, and for various control groups (eg, MS vs. other controls). Numerous aspects of NMO-IgG/AQP4-Ab testing relevant for clinicians (eg, impact of antibody titers and longitudinal testing, indications for repeat testing, relevance of CSF testing and subclass analysis, NMO-IgG/AQP4-Ab in patients with rheumatic diseases) as well as technical aspects (eg, AQP4-M1 vs. AQP4-M23-based assays, intact AQP4 vs. peptide substrates, effect of storage conditions and freeze/thaw cycles) and pitfalls are discussed. Finally, recommendations for the clinical application of NMO-IgG/AQP4-Ab serology are given.

Anti-aquaporin-1 autoantibodies in patients with neuromyelitis optica spectrum disorders

Autoantibodies against aquaporin-4 (AQP4), a water channel in CNS astrocytes, are detected in ∼50–80% of patients with neuromyelitis optica spectrum disorders (NMOsd), characterized by longitudinally extensive transverse myelitis (LETM) and/or optic neuritis. Although these autoantibodies present an invaluable biomarker for NMOsd and for the differential diagnosis of multiple sclerosis (MS), diagnosis of anti-AQP4-seronegative NMOsd remains challenging. We hypothesized that seronegative NMOsd patients might have autoantibodies against aquaporin-1 (AQP1), another water channel in CNS astrocytes. We initially developed a radioimmunoprecipitation assay to search for anti-AQP1 antibodies in sera from 632 individuals. Anti-AQP1 or anti-AQP4 autoantibodies were detected in 16.7% and 12%, respectively, of 348 patients with suspected NMOsd. Anti-AQP1 specificity was confirmed by competition, protein immunoblotting and ELISA assays, whereas epitope localization was studied by immunoadsorption on intact cells expressing AQP1 and peptide mapping experiments. Most anti-AQP1 autoantibodies were of the complement-activating IgG1 subclass and the majority bound to the extracellular domain of AQP1, suggesting a possible pathogenic role. Five out of 42 MS patients had anti-AQP1 antibodies, but 2 of them also had spinal cord lesions, while the anti-AQP1 antibodies in the other 3 bound to the cytoplasmic domain of AQP1. Anti-AQP1 antibodies were not detected in 100 healthy individuals or 142 patients with non-demyelinating neuroimmune diseases. Analysis of 17 anti-AQP1+/anti-AQP4- patients with suspected NMOsd showed that 5 had NMO and 11 had LETM. 12/17 of these sera bound predominantly to the extracellular AQP1 loop-Α. Overall, we found that anti-AQP1 autoantibodies are present in a subgroup of patients with chronic demyelination in the CNS and similarities with anti-AQP4-seronegative NMOsd, offering a novel potential biomarker for CNS demyelination disorders.

Aquaporin-4 antibody negative recurrent isolated optic neuritis: clinical evidence for disease heterogeneity

Recurrent optic neuritis is frequently observed in multiple sclerosis (MS) and is a typical finding in neuromyelitis optica (NMO). Patients that lack further evidence of demyelinating disease are diagnosed with RION (recurrent isolated optic neuritis) or CRION (chronic relapsing inflammatory neuropathy) if they require immunosuppressive therapy to prevent further relapses. The etiology and disease course of this rare condition are not well defined. We studied a series of 10 patients who presented with recurrent episodes of isolated optic neuritis (ON, n=57) and were followed over a median of 3.5 years. Visual acuity was severely reduced at the nadir of the disease (20/200 to 20/800). All patients had MRI non-diagnostic for MS/NMO and were aquaporin-4 antibody negative. Six patients fulfilled the CRION criteria. In two of these a single ON followed by a long disease-free interval preceded development of CRION for years, suggesting the conversion of an initially "benign" isolated ON into the chronic relapsing course. Cerebrospinal fluid (CSF) analysis revealed mild pleocytosis in 5 patients, identical oligoclonal bands in serum and CSF were observed in 2 patients, while the others remained negative. In conclusion, recurrent ON is a disease entity that requires aggressive glucocorticoid and eventually long-term immunosuppressive therapy to prevent substantial visual impairment.

Inflammatory Optic Neuritis: From Multiple Sclerosis to Neuromyelitis Optica

Inflammatory optic neuritis represents a frequent clinical situation in neurology and ophthalmology. In those parts of the world where multiple sclerosis is common, it is the condition most discussed as the cause of optic neuritis. However, the risk for conversion from optic neuritis to multiple sclerosis is evaluated at only around 50% after 15 years of follow-up. The risk is higher in cases in whom abnormalities typical of multiple sclerosis are found on magnetic resonance imaging of the brain and oligoclonal bands found on cerebrospinal fluid protein electrophoresis with no corresponding bands in serum. When these investigations are normal, optic neuritis is usually considered as "idiopathic" with a suspected viral aetiology, but in some cases, a systemic disease such as sarcoidosis, systemic lupus erythematosis, or Sjögren syndrome may be diagnosed. In rare cases, either recurrent optic neuritis or myelitis may occur without any evidence for multiple sclerosis. In the first case, it corresponds to a recently characterised disorder referred to as chronic relapsing inflammatory optic neuropathy and in the second case to a recently better identified entity, neuromyelitis optica. In the present paper, the differential diagnosis of inflammatory optic neuritis is presented from multiple sclerosis to infectious optic neuritis, systemic disease, and neuromyelitis optica.

Antibodies target microvessels in neuromyelitis optica and multiple sclerosis patients

OBJECTIVE

This study investigated the presence of serum antibodies targeting microvessels in Chinese patients with multiple sclerosis (MS) and neuromyelitis optica (NMO).

METHODS

Serum samples were collected from 50 patients with NMO, 10 with longitudinally extensive transverse myelitis (LETM), 4 with recurrent optic neuritis, 42 with MS and 27 controls. Serum antibodies binding to microvessels were measured by indirect immunofluorescence (IIF) assay of tissue sections from the brain, stomach and pancreas, and human umbilical vein endothelial cells (HUVEC). Aquaporin-4 (AQP4) antibodies were detected using a cell-based assay.

RESULTS

Indirect immunofluorescence assay of tissue sections from 42 samples (30.4%, 42/138) were positive for microvessel antibodies, where microvessel antibody positivity was 38% (19/50) in patients with NMO, 57.1% (8/14) in high-risk NMO (hrNMO), 26.2% (11/42) in MS, and 14.8% (4/27) in controls. Based on HUVEC analysis, 14 patients with NMO (28%, 14/50), 5 with hrNMO (35.7%, 5/14), 15 with MS (35.7%, 15/42), and 5 controls (18.5%, 5/27) had (AECA). Sixteen patients (32%, 16/50) with NMO, four with hrNMO (28.6%, 4/14), two with MS (4·8%, 2/42), and 0% of controls were positive for antinuclear antibodies (ANA). In MS patients, seropositive AECA MS patients had higher numbers of relapse events and increased spinal lesions than seronegative MS patients (P < 0.05).

CONCLUSIONS

Serum microvessel antibodies were present in patients with NMO and MS and the role of microvessel antibodies in diseases may be heterogeneous. This study suggests that AECA may have some significance in MS patients.

Distinctive clinical and neuroimaging characteristics of longitudinally extensive transverse myelitis associated with aquaporin-4 autoantibodies

Longitudinally extensive transverse myelitis (LETM) is a characteristic feature of Neuromyelitis Optica (NMO), but it can also occur in several other inflammatory diseases of the central nervous system (CNS). An IgG autoantibody that binds to aquaporin-4 (AQP4), the predominant water channel of the CNS, is a reliable biomarker of the NMO spectrum disorders, and if detected predicts the recurrence of the myelitis. In this study, we compared the clinical and neuroimaging characteristics of AQP4-IgG+ and AQP4-IgG- LETM patients. Thirty-seven first-ever LETM patients were retrospectively evaluated and divided into two groups according to the presence of AQP4 autoantibodies. AQP4-IgG was detected in the serum and in the cerebrospinal fluid of sixteen patients. The female to male ratio was higher in AQP4-IgG+ patients. Intractable nausea and vomiting and paroxysmal tonic spasms often accompanied the LETM in AQP4-IgG+ patients. T2-weighted spinal cord MRI revealed that inflammatory lesions extending into the brainstem and involving the central grey matter occurred more frequently in AQP4-IgG+ LETM patients. Hypointense lesions on T1-weighted spinal cord MRI were detected more frequently in the seropositive group, and their presence correlated with attack severity. In conclusion, this study provides clinical and spinal cord neuroimaging clues that can help distinguishing AQP4-IgG+ LETM patients.

Neuromyelitis optica mimicking intramedullary tumor

Neuromyelitis optica (NMO) is considered to be a rarer autoimmune disease than multiple sclerosis. It is very difficult to make a diagnosis of MNO for doctors who are not familiar with its clinical features and diagnostic criteria. We report a case of a young female patient who had been suffering motor weakness and radiating pain in both upper extremities. Cervical MRI showed tumorous lesion in spinal cord and performed surgery to remove lesion. We could not find a tumor mass in operation field and final diagnosis was NMO. NMO must be included in the differential diagnosis of lesions to rescue the patient from invasive surgical interventions. More specific diagnostic tools may be necessary for early diagnosis and proper treatment.

Chronic relapsing inflammatory optic neuropathy: a systematic review of 122 cases reported

Chronic relapsing inflammatory optic neuropathy (CRION) is an entity that was described in 2003. Early recognition of patients suffering from CRION is relevant because of the associated risk for blindness if treated inappropriately. It seems timely to have a clinical review on this recently defined entity. A systematic literature review, irrespective of language, retrieved 22 case series and single reports describing 122 patients with CRION between 2003 and 2013. We review the epidemiology, diagnostic workup, differential diagnosis, and treatment (acute, intermediate, and long term) in view of the collective data. These data suggest that CRION is a distinct nosological entity, which is seronegative for anti-aquaporin four auto-antibodies and recognized by and managed through its dependency on immuno-suppression. Revised diagnostic criteria are proposed in light of the data compromising a critical discussion of relevant limitations.

Pediatric multiple sclerosis

Recognition of multiple sclerosis (MS) and other acquired demyelinating disorders in children has increased significantly in the last decade. Consensus definitions that characterize the varied clinical presentations of acute demyelination, and proposed clinical and MRI criteria specific for MS in children have aided diagnostic consistency. Care of children with an acute demyelinating attack is influenced by clinical severity, with corticosteroids, immunoglobulin, and plasma exchange being the most commonly employed therapies. Children with confirmed MS are often managed with immunomodulatory therapies (interferon and glatiramer acetate) approved for the treatment of MS in adults. Routine assessment of hepatic and hematological cell indices are important to monitor for safety of interferon therapy. While clinical treatment trials of interferon and glatiramer acetate in pediatric MS have yet to be conducted, case series evidence supports clinical safety and relapse rate reduction in the pediatric MS population. Epidemiological studies have implicated place of residence during childhood as a key determinant of MS risk. As such, pediatric-onset MS provides an opportunity to explore these risk factors contemporaneous with the clinical onset of disease. Studies of vitamin D, microbial exposures, and parental smoking are areas under active investigation. Finally, research exploring primary immunological mechanisms and host responses in patients with pediatric-onset MS, who by virtue of their young age may harbor fewer extraneous immune abnormalities, may yield new insights into the fundamental pathobiology of MS.

Evaluation of clinical interest of anti-aquaporin-4 autoantibody followup in neuromyelitis optica

Neuromyelitis optica (NMO) is an autoimmune disease in which a specific biomarker named NMO-IgG and directed against aquaporin-4 (AQP4) has been found. A correlation between disease activity and anti-AQP4 antibody (Ab) serum concentration or complement-mediated cytotoxicity has been reported, but the usefulness of longitudinal evaluation of these parameters remains to be evaluated in actual clinical practice. Thirty serum samples from 10 NMO patients positive for NMO-IgG were collected from 2006 to 2011. Anti-AQP4 Ab serum concentration and complement-mediated cytotoxicity were measured by flow cytometry using two quantitative cell-based assays (CBA) and compared with clinical parameters. We found a strong correlation between serum anti-AQP4 Ab concentration and complement-mediated cytotoxicity (P < 0.0001). Nevertheless, neither relapse nor worsening of impairment level was closely associated with a significant increase in serum Ab concentration or cytotoxicity. These results suggest that complement-mediated serum cytotoxicity assessment does not provide extra insight compared to anti-AQP4 Ab serum concentration. Furthermore, none of these parameters appears closely related to disease activity and/or severity. Therefore, in clinical practice, serum anti-AQP4 reactivity seems not helpful as a predictive biomarker in the followup of NMO patients as a means of predicting the onset of a relapse and adapting the treatment accordingly.

Acute necrotizing encephalopathy (ANE1): rare autosomal-dominant disorder presenting as acute transverse myelitis

The term "acute transverse myelitis (ATM)" comprises various non-traumatic disorders that eventually can be associated with a focal myelopathy. Patients characteristically present with an acutely occurring paraparesis/plegia and require a comprehensive and timely diagnostic work up for the initiation of an appropriate treatment. We present a case of a 36-year-old female patient with a rare genetic disorder (ANE1: Acute Necrotizing Encephalopathy due to a RANBP2 mutation) who presented with an acute quadriplegia. Following an acute pulmonal infection, she rapidly (< 24 h) developed a severe quadriplegia (total motor score 38) with some facial sensory symptoms (perioral hypoesthesia). Magnetic resonance imaging (MRI) revealed a combination of longitudinal extensive transverse myelitis and symmetrical thalamic lesions. A work-up for infectious and systemic diseases was negative; specifically, no findings related to multiple sclerosis, neuromyelitis optica or vascular disorders. After empirical high dose steroid treatment and rehabilitation therapy, the patient gained almost normal gait and upper limb function. She was found to carry an autosomal-dominant missense mutation in the RANBP2 gene predisposing for ANE. Gene segregation was confirmed in other family members that had been affected by other episodes of acute steroid-responsive encephalopathies. We propose that a redefined diagnostic workup of ATM might include ANE1, as the frequency of this rare disorder might be underestimated.