Sex ratio and age of onset in AQP4 antibody-associated NMOSD: a review and meta-analysis

BACKGROUND

Aquaporin-4 (AQP4) antibody-associated neuromyelitis optica spectrum disorder (NMOSD) is an antibody-mediated inflammatory disease of the central nervous system. We have undertaken a systematic review and meta-analysis to ascertain the sex ratio and mean age of onset for AQP4 antibody associated NMOSD. We have also explored factors that impact on these demographic data.

METHODS

A systematic search of databases was conducted according to the PRISMA guidelines. Articles reporting sex distribution and age of onset for AQP4 antibody-associated NMSOD were reviewed. An initially inclusive approach involving exploration with regression meta-analysis was followed by an analysis of just AQP4 antibody positive cases.

RESULTS

A total of 528 articles were screened to yield 89 articles covering 19,415 individuals from 88 population samples. The female:male sex ratio was significantly influenced by the proportion of AQP4 antibody positive cases in the samples studied (p < 0.001). For AQP4 antibody-positive cases the overall estimate of the sex ratio was 8.89 (95% CI 7.78-10.15). For paediatric populations the estimate was 5.68 (95% CI 4.01-8.03) and for late-onset cases, it was 5.48 (95% CI 4.10-7.33). The mean age of onset was significantly associated with the mean life expectancy of the population sampled (p < 0.001). The mean age of onset for AQP4 antibody-positive cases in long-lived populations was 41.7 years versus 33.3 years in the remainder.

CONCLUSIONS

The female:male sex ratio and the mean age of onset of AQP4 antibody-associated NMOSD are significantly higher than MS. The sex ratio increases with the proportion of cases that are positive for AQP4 antibodies and the mean age of onset increases with population life expectancy.

Chronic Relapsing Inflammatory Optic Neuropathy (CRION)

Purpose of review

This review highlights the epidemiology, clinical and radiologic characteristics of chronic relapsing inflammatory optic neuropathy (CRION) and treatment modalities.

Recent findings

Summary

CRION is an inflammatory optic neuropathy that is characterized by a chronic and relapsing course, that is characterized by pain associated with subacute vision loss. It is favorably responsive but highly dependent on corticosteroids with frequent relapses in the setting of steroid tapering. Additional diagnostic biomarkers and further studies are required to better diagnose and treat this rare but potentially debilitating condition.

A window into the future? MRI for evaluation of neuromyelitis optica spectrum disorder throughout the disease course

Neuromyelitis optica spectrum disorder (NMOSD) is a relapsing, inflammatory disease of the central nervous system marked by relapses often associated with poor recovery and long-term disability. Magnetic resonance imaging (MRI) is recognized as an important tool for timely diagnosis of NMOSD as, in combination with serologic testing, it aids in distinguishing NMOSD from possible mimics. Although the role of MRI for disease monitoring after diagnosis is not as well established, MRI may provide important prognostic information and help differentiate between relapses and pseudorelapses. Increasing evidence of subclinical disease activity and the emergence of newly approved, highly effective immunotherapies for NMOSD adjure us to re-evaluate MRI as a tool to guide optimal treatment selection and escalation throughout the disease course. In this article we review the role of MRI in NMOSD diagnosis, prognostication, disease monitoring, and treatment selection.

Recurrent Optic Neuritis as the Initial Symptom in Demyelinating Diseases

Background and Purpose

Optic neuritis (ON) is an inflammation of the optic nerve that can be recurrent, with unilateral or bilateral presentation. Diagnosing recurrent cases may be challenging. We aimed to compare patients with recurrent ON as their initial symptom according to their following final diagnoses: multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD), or chronic relapsing inflammatory optic neuropathy (CRION).

Methods

The medical records of patients with initial recurrent ON who were followed at the Neuroimmunology Clinic of the Federal University of São Paulo between 2004 and 2016 were analyzed retrospectively. Patients were classified according to their final diagnosis into MS, NMOSD, or CRION, and the characteristics of these groups were compared to identify predictive factors.

Results

Thirty-three patients with recurrent ON were included, and 6, 14, and 13 had final diagnoses of MS, NMOSD, and CRION, respectively. Most of the patients were female with unilateral and severe ON in their first episode, and the initial Visual Functional System Score (VFSS) was ≥5 in 63.6%, 85.7%, and 16.7% of the patients with CRION, NMOSD, and MS, respectively. Anti-aquaporin-4 antibodies were detected in 9 of 21 (42.8%) tested patients. Seven of nine (77.8%) seropositive NMOSD patients experienced transverse myelitis episodes during the follow-up period. A multivariate regression analysis showed that the VFSS at the last medical appointment predicted the final diagnosis.

Conclusions

A lower VFSS at the last medical appointment was predictive of MS. Patients with NMOSD and CRION have similar clinical characteristics, whereas NMOSD patients tend to have worse visual acuity.

Evaluation of the 2015 diagnostic criteria for neuromyelitis optica spectrum disorder

OBJECTIVE

To evaluate the application of the 2015 International Panel for NMO Diagnosis (IPND) criteria to consecutive cases of neuromyelitis optica spectrum disorder (NMOSD) in a large cohort of individuals with CNS inflammatory diseases.

METHODS

In total, 594 patients with CNS inflammatory diseases were included. Rigorous confirmation of the patients' aquaporin-4 immunoglobulin G antibodies (AQP4-IgG) status throughout the disease duration (mean 9.2 ± 5.7 years) using repeated assays, including ELISA and cell-based assay, was performed.

RESULTS

A total of 252 patients fulfilled the IPND criteria (AQP4-IgG positive: 226 [90%], AQP4-IgG negative: 26 [10%]). Of these, 136 (54%) patients met the 2006 neuromyelitis optica criteria. When we assumed an unknown AQP4-IgG status in the confirmed NMOSD group with AQP4-IgG, 162 of 226 (72%) patients with AQP4-IgG were classified as having NMOSD by the IPND criteria. The majority of patients were diagnosed with NMOSD within 2 years of onset (73%) or after a second attack (72%). Acute myelitis (83%) and optic neuritis (65%) were the most common clinical features throughout the disease duration. Optic neuritis (42%) was the most common initial manifestation, followed by acute myelitis (38%) and area postrema syndrome (14%).

CONCLUSIONS

The IPND criteria well-reflected the broader clinical spectrum of NMOSD and markedly improved the diagnostic yield compared to the previous criteria, even in patients with an unknown AQP4-IgG status.

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.

Utility of aquaporin-4 antibody assay in patients with neuromyelitis optica spectrum disorders

OBJECTIVE

Our aim was to evaluate the utility of aquaporin-4 antibodies (AQP4-Ab) in patients with neuromyelitis optica spectrum disorders (NMOSD).

METHODS

The clinical and radiological characteristics of 78 patients with NMOSD and 22 with multiple sclerosis (MS), who were tested for AQP4-Ab by a cell-based assay, were assessed.

RESULTS

The mean time interval between symptom onset and development of optic neuritis and myelitis was 39.9 months in neuromyelitis optica (NMO). About 40% of patients with limited NMO would have fulfilled the diagnostic criteria for MS in the absence of the antibody assay results. In patients with longitudinally extensive transverse myelitis, positive AQP4-Ab assay results were associated with the poor response to acute steroid treatment and asymptomatic visual evoked potential abnormality. Presence of either painful tonic spasm associated with myelitis or severe disability at onset had high specificity and relatively high sensitivity in differentiating NMOSD with AQP4-Ab from MS.

CONCLUSIONS

The AQP4-Ab assay can facilitate the early diagnosis of NMO and prevent limited NMO from being misdiagnosed as MS. It can predict the poor response to first-line acute-phase treatment and probably detect the subclinical optic nerve involvement in subgroups of NMOSD. Lastly, it will contribute to the upcoming revision of the current diagnostic criteria for NMO.

Neuromyelitis optica

Neuromyelitis optica (NMO) is a disabling inflammatory condition that targets astrocytes in the optic nerves and spinal cord. Neuro-ophthalmologists must be particularly aware of this disorder because about half of patients present as isolated unilateral optic neuritis months or years before a disease-defining and often crippling bout of myelitis. NMO is easily confused with multiple sclerosis because it is characterized by relapses that lead to stepwise accrual of deficits. The best predictor of conversion from optic neuritis to clinical definite NMO is the presence of a serum antibody to aquaporin-4 called NMO-IgG. However, this test is currently only about 75% sensitive. Suspicion of NMO should be high in patients who present with vision of light perception or worse or who are left with acuity of 20/50 or worse after optic neuritis and in those with simultaneous bilateral optic neuritis or recurrent attacks. Acute NMO relapses are generally treated with high-dose intravenous steroids, with plasma exchange often used as a rescue therapy for those who do not respond. Preventative strategies against relapses currently use broad-spectrum or selective B-lymphocyte immune suppression, but their use is based on small, generally uncontrolled studies. Hopefully, the future will bring more sensitive tools for defining risk and predicting outcome, as well as more targeted and effective forms of therapy.

Analysis of prognostic factors associated with longitudinally extensive transverse myelitis

OBJECTIVE

The aim of this study is to report the clinical profile and outcome of longitudinally extensive transverse myelitis (LETM).

METHODS

We prospectively studied adult patients who presented with LETM from January 2008 to December 2011. Information on demographic, clinical course, magnetic resonance imaging (MRI) and outcome was collected. HLA-DRB1 genotype was compared with those of 225 normal controls and patients with MS (228) and neuromyelitis optica (NMO) (22).

RESULTS

In total, 23 patients (16 female) with a median age of 44.5 years (range: 20-77 years) were included. Most (74%) had moderate-severe disability at nadir (48% non-ambulatory), normal/non-multiple sclerosis (MS) brain MRI (96%) and a median MRI cord lesion of 5 vertebral segments (range: 3-19). Laboratory analysis showed cerebrospinal fluid pleocytosis (45%), NMO-IgG (9%), antinuclear antibodies (70%), and genotype HLA-DRB1*13 (57%). The frequency of DRB1*13 genotype was higher compared with controls (p=0.002), MS (p=0.001) and NMO (p=0.003) patients. After a median follow-up of 32 months, one patient converted to MS, two had relapsing LETM with NMO-IgG, and 20 remained as idiopathic with recurrences in four (20%). Twelve (52%) patients recovered with minimal disability (Expanded Disability Status Scale (EDSS) ≤2.5) and three (13%) remained wheelchair dependent. Disability at nadir was associated with the final outcome and extension of the spinal cord lesion with risk of recurrence. Recurrence was not associated with worse outcome.

CONCLUSIONS

Inflammatory LETM is mostly idiopathic with a good outcome. It includes a relatively homogenous group of patients with an overrepresentation of the HLA-DRB1*13 genotype. EDSS at nadir is a predictor of the final outcome and extension of the myelitis of the recurrence risk.

The expanded spectrum of neuromyelitis optica: evidences for a new definition

Neuromyelitis optica (NMO) has been traditionally described as the association of recurrent or bilateral optic neuritis and longitudinally extensive transverse myelitis (LETM). Identification of aquaporin-4 antibody (AQP4-IgG) has deeply changed the concept of NMO. A spectrum of NMO disorders (NMOSD) has been formulated comprising conditions which include both AQP4-IgG seropositivity and one of the index events of the disease (recurrent or bilateral optic neuritis and LETM). Most NMO patients harbor asymptomatic brain MRI lesions, some of them considered as typical of NMO. Some patients with aquaporin-4 autoimmunity present brainstem, hypothalamic or encephalopathy symptoms either preceding an index event or occurring isolatedly with no evidence of optic nerve or spinal involvement. On the opposite way, other patients have optic neuritis or LETM in association with typical lesions of NMO on brain MRI and yet are AQP4-IgG seronegative. An expanded spectrum of NMO disorders is proposed to include these cases.

Quantitative assays for anti-aquaporin-4 antibody with subclass analysis in neuromyelitis optica

BACKGROUND

To clarify the clinical relevance of anti-aquaporin-4 (anti-AQP4) antibody titers and immunoglobulin (IgG) subclass.

METHODS

Using a bridging enzyme-linked immunosorbent assay (ELISA), a flow cytometric assay (FCMA) and an immunofluorescence assay (IFA) for anti-AQP4 antibodies, sera from 142 patients with multiple sclerosis (MS) as defined by the McDonald criteria (2005), 29 with neuromyelitis optica (NMO) who fulfilled the 1999 criteria, 19 with recurrent and/or longitudinally extensive myelitis (RM/LM), 86 with other non-inflammatory neurological diseases (OND) and 28 healthy controls (HC) were studied.

RESULTS

Anti-AQP4 antibody positivity rates by IFA, FCMA, and ELISA were 41.4%, 51.7% and 48.3%, respectively, in NMO (1999) patients, and 0% in the OND and HC groups. Twenty-six MS patients (18.3%) were positive for the antibody; 17 met the 2006 NMO criteria, including positivity for anti-AQP4 antibody, and five had longitudinally extensive myelitis (LM). Among the cases with anti-AQP4 antibody detected by FCMA, IgG1, 2, 3, and 4 anti-AQP4 antibodies were found in 97.8%, 37.0%, 6.5% and 6.5% respectively. There was no association of either antibody positivity or level of anti-AQP4 antibody IgG subclasses with clinical parameters after adjustment of p values for multiple comparisons.

CONCLUSIONS

FCMA and bridging ELISA are useful for detecting and quantifying anti-AQP4 antibodies.