Cognitive impairment and whole brain diffusion in patients with neuromyelitis optica after acute relapse

Abnormal functional connectivity of white-matter networks and gray-white matter functional networks in patients with NMOSD

Cognitive impairment (CI) has been reported in 29-70% of patients with neuromyelitis optica spectrum disorder (NMOSD). Abnormal white matter (WM) functional networks that correlate with cognitive functions have not been studied well in patients with NMOSD. The aim of the current study was to investigate functional connectivity (FC), spontaneous activity, and functional covariance connectivity (FCC) abnormalities of WM functional networks in patients with NMOSD and their correlation with cognitive performance. Twenty-four patients with NMOSD and 24 healthy controls (HCs) were included in the study. Participants underwent brain resting-state functional magnetic resonance imaging (fMRI) and the Montreal Cognitive Assessment (MoCA). Eight WM networks and nine gray matter (GM) networks were created. In patients, WM networks, including WM1-4, WM1-8, WM2-6, WM2-7, WM2-8, WM4-8, WM5-8 showed reduced FC (P < 0.05). All WM networks except WM1 showed decreased spontaneous activity (P < 0.05). The major GM networks demonstrated increased/decreased FC (P < 0.05), whereas GM7-WM7, GM8-WM4, GM8-WM6 and GM8-WM8 displayed decreased FC (P < 0.05). The MoCA results showed that two-thirds (16/24) of the patients had CI. FC and FCC in WM networks were correlated negatively with the MoCA scores (P < 0.05). WM functional networks are multi-layered. Abnormal FC of WM functional networks and GM functional networks may be responsible for CI.

Cognitive and psychopathological features of neuromyelitis optica spectrum disorder and myelin oligodendrocyte glycoprotein antibody-associated disease: A narrative review

Clinicians are becoming increasingly aware of the cognitive and psychopathological consequences of neurological diseases, which were once thought to manifest with motor and sensory impairments only. The cognitive profile of multiple sclerosis, in particular, is now well-characterised. Similar efforts are being made to better characterise the cognitive profile of other central nervous system inflammatory demyelinating autoimmune disorders. This review discusses the current understanding of the cognitive and psychological features of neuromyelitis optica spectrum disorder (NMOSD) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD). Detailed analysis of the cognitive sequelae of the above conditions can not only assist with understanding disease pathogenesis but also can guide appropriate management of the symptoms and consequently, improve the quality of life and long-term outcomes for these patients. This narrative review will also identify research gaps and provide recommendations for future directions in the field.

Exploring resting-state EEG oscillations in patients with Neuromyelitis Optica Spectrum Disorder

BACKGROUND AND OBJECTIVE

Quantitative resting-state electroencephalography (rs-EEG) is a convenient method for characterizing the functional impairments and adaptations of the brain that has been shown to be valuable for assessing many neurological and psychiatric disorders, especially in monitoring disease status and assisting neuromodulation treatment. However, it has not yet been explored in patients with neuromyelitis optica spectrum disorder (NMOSD). This study aimed to investigate the rs-EEG features of NMOSD patients and explore the rs-EEG features related to disease characteristics and complications (such as anxiety, depression, and fatigue).

METHODS

A total of 32 NMOSD patients and 20 healthy controls (HCs) were recruited; their demographic and disease information were collected, and their anxiety, depression, and fatigue symptoms were evaluated. The rs-EEG power spectra of all the participants were obtained. After excluding the participants with low-quality rs-EEG data during processing, statistical analysis was conducted based on the clinical information and rs-EEG data of 29 patients and 19 HCs. The rs-EEG power (the mean spectral energy (MSE) of absolute power and relative power in all frequency bands, as well as the specific power for all electrode sites) of NMOSD patients and HCs was compared. Furthermore, correlation analyses were performed between rs-EEG power and other variables for NMOSD patients (including the disease characteristics and complications).

RESULTS

The distribution of the rs-EEG power spectra in NMOSD patients was similar to that in HCs. The dominant alpha-peaks shifted significantly towards a lower frequency for patients when compared to HCs. The delta and theta power was significantly increased in the NMOSD group compared to that in the HC group. The alpha oscillation power was found to be significantly negatively associated with the degree of anxiety (reflected by the anxiety subscore of hospital anxiety and depression scale (HADS)) and the degree of depression (reflected by the depression subscore of HADS). The gamma oscillation power was revealed to be significantly positively correlated with the fatigue severity scale (FSS) score, while further analysis indicated that the electrode sites of almost the whole brain region showing correlations with fatigue. Regarding the disease variables, no statistically significant rs-EEG features were related to the main disease features in NMOSD patients.

CONCLUSION

The results of this study suggest that the rs-EEG power spectra of NMOSD patients show increased slow oscillations and are potential biomarkers of widespread white matter microstructural damage in NMOSD. Moreover, this study revealed the rs-EEG features associated with anxiety, depression, and fatigue in NMOSD patients, which might help in the evaluation of these complications and the development of neuromodulation treatment. Quantitative rs-EEG analysis may play an important role in the management of NMOSD patients, and future studies are warranted to more comprehensively understand its application value.

Paths to hippocampal damage in neuromyelitis optica spectrum disorders

AIMS

Many patients with neuromyelitis optica spectrum disorders (NMOSD) suffer from cognitive impairment affecting memory, processing speed and attention and suffer from depressive symptoms. Because some of these manifestations could trace back to the hippocampus, several magnetic resonance imaging (MRI) studies have been performed in the past, with a number of groups describing volume loss of the hippocampus in NMOSD patients, whereas others did not observe such changes. Here, we addressed these discrepancies.

METHODS

We performed pathological and MRI studies on the hippocampi of NMOSD patients, combined with detailed immunohistochemical analysis of hippocampi from experimental models of NMOSD.

RESULTS

We identified different pathological scenarios for hippocampal damage in NMOSD and its experimental models. In the first case, the hippocampus was compromised by the initiation of astrocyte injury in this brain region and subsequent local effects of microglial activation and neuronal damage. In the second case, loss of hippocampal volume was seen by MRI in patients with large tissue-destructive lesions in the optic nerves or the spinal cord, and the pathological work-up of tissue derived from a patient with such lesions revealed subsequent retrograde neuronal degeneration affecting different axonal tracts and neuronal networks. It remains to be seen whether remote lesions and associated retrograde neuronal degeneration on their own are sufficient to cause extensive volume loss of the hippocampus, or whether they act in concert with small astrocyte-destructive, microglia-activating lesions in the hippocampus that escape detection by MRI, either due to their small size or due to the chosen time window for examination.

CONCLUSIONS

Different pathological scenarios can culminate in hippocampal volume loss in NMOSD patients.

Identifying different cognitive phenotypes and their relationship with disability in neuromyelitis optica spectrum disorder

Background

The existence, frequency, and features of cognitive impairment (CI) in patients with neuromyelitis optica spectrum disorder (NMOSD) are still debated. A precise classification and characterization of cognitive phenotypes in patients with NMOSD are lacking.

Methods

A total of 66 patients with NMOSD and 22 healthy controls (HCs) underwent a neuropsychological assessment. Latent profile analysis (LPA) on cognitive test z scores was used to identify cognitive phenotypes, and ANOVA was used to define the clinical features of each phenotype. Univariate and multivariate analyses were used to explore the predictors of severe CI, and a corresponding nomogram was created to visualize the predictive model.

Results

LPA results suggested four distinct meaningful cognitive phenotypes in NMOSD: preserved cognition (n = 20, 30.3%), mild-attention (n = 21, 31.8%), mild-multidomain (n = 18, 27.3%), and severe-multidomain (n = 7, 10.6%). Patients with the last three phenotypes were perceived to have CI, which accounts for 67.6% of patients with NMOSD. Patients with NMOSD and worse cognitive function were older (p < 0.001) and had lower educational levels (p < 0.001), later clinical onset (p = 0.01), worse Expanded Disability Status Scale scores (p = 0.001), and poorer lower-limb motor function (Timed 25-Foot Walk, p = 0.029; 12-item Multiple Sclerosis Walking Scale [MSWS-12], p < 0.001). Deterioration of Nine-Hole Peg Test (odds ratio, OR: 1.115 [1, 1.243], p = 0.05) and MSWS-12 (OR: 1.069 [1.003, 1.139], p = 0.04) were the independent risk factors for severe cognitive dysfunction. Finally, a nomogram was built based on the entire cohort and the above factors to serve as a useful tool for clinicians to evaluate the risk of severe cognitive dysfunction.

Conclusions

We introduced a classification scheme for CI and highlighted that the deterioration of upper- and lower-limb motor disability potentially predicts cognitive phenotypes in NMOSD.

Chronic Cognitive Impairment in AQP4+ NMOSD With Improvement in Cognition on Eculizumab: A Report of Two Cases

Cognitive impairment may be associated with aquaporin-4 antibody positive (AQP4+) NMOSD, particularly where there is prominent cerebral, corpus callosum, or thalamic involvement. It is unclear to what extent this phenomenon may be treatable after months to years. We describe two cases of AQP4+ NMOSD with cognitive impairment persisting over more than 6 months, where cognition improved after eculizumab was initiated. In the first case, a 51-year-old woman presented with a 2-month history of cognitive decline and ataxia, and diffuse involvement of the corpus callosum on MRI. AQP4 antibody testing returned positive. Cognitive impairment persisted on therapy with mycophenolate, then rituximab. She was switched to eculizumab from rituximab 18 months after disease onset because of breakthrough optic neuritis; memory and cognitive function improved on eculizumab. In the second case, a 26-year-old woman initially presented with visual, auditory and tactile hallucinations, and impairment in activities of daily living, and was given a diagnosis of schizophrenia. Nine months later she was hospitalized for increasing confusion. MRI showed leukoencephalopathy and diffuse involvement of the corpus callosum with multiple enhancing callosal lesions. AQP4 antibody testing was positive and CSF testing for other antibodies of autoimmune encephalitis was negative. She had some improvement in cognition with high dose corticosteroids but remained significantly impaired. On follow-up, her repeat MRI showed a small new right inferomedial frontal enhancing lesion although she did not complain of any new cognitive issues, her MOCA score was 21/30, and she was started on eculizumab. Two months after eculizumab initiation she and her family reported cognitive improvement and MOCA score was 25/30. Common features of these two cases included extensive callosal involvement and an element of ongoing gadolinium enhancement on MRI. Our experience suggests the possibility that cognitive impairment may be amenable to immunotherapy in certain cases of NMOSD.

The prevalence of cognitive impairment in patients with neuromyelitis optica spectrum disorders (NMOSD): A systematic review and meta-analysis

OBJECTIVE

To estimate pooled prevalence of cognitive impairment in neuromyelitis opticaspectrum disorders (NMOSD) cases.

METHODS

We searched PubMed, Scopus, EMBASE, Web of Science, and google scholar. We also searched the gray literature including references of the included studies, and conference abstracts which were published up to 20th October 2020. The search strategy included the MeSH and text words as (((Cognitive Dysfunctions) OR Cognitive Impairment) OR Cognitive Declines) OR Mild Cognitive Impairment) OR Mental Deterioration) AND (Neuromyelitis Optica spectrum disorder OR NMOSD OR Devic syndrome OR Neuromyelitis Optica spectrum disorders).

RESULTS

The literature search revealed 1830 articles, after deleting duplicates 1434 remained. For the meta-analysis, 25 studies were included. Totally, 761 NMOSD patients were evaluated and 329 patients had cognitive impairment. Mean age ranged from 34-53 years. The prevalence of cognitive impairment ranged from 3% to 75%.The pooled prevalence of cognitive impairment was 44%, 95%CI(35%-54%), (I²=89.1%, P<0.001) which shows a high statistical heterogeneity . By excluding the abstract of Jung et al which was published in 2009, we found that the pooled prevalence was 34% (95% CI:31-37%) (I²=0) CONCLUSION: Cognitive impairment should be considered in NMOSD patients as its pooled prevalence is estimated as 44%.

Cognitive impairment in NMOSD-More questions than answers

INTRODUCTION

Neuromyelitis optica spectrum disorder (NMOSD) is a type of central nervous system antibody-mediated disease which affects mainly optic nerves and spinal cord, but may also present with acute brainstem syndrome, acute diencephalic syndrome, and cerebral syndrome with typical brain lesions. One of the most disabling symptoms, diagnosed in 29%-67% of cases, is cognitive dysfunction, with such processes as memory, processing speed, executive function, attention, and verbal fluency being predominantly affected. However, description of cognition in NMOSD patients is still a relatively new area of research.

METHODS

A systematic MEDLINE search was performed to retrieve all studies that investigated cognitive impairment and its clinical correlates in patients with NMOSD.

RESULTS

We summarize the current knowledge on cognitive impairment profile, neuropsychological tests used to examine NMOSD patients, clinical and demographical variables affecting cognition, and magnetic resonance imaging correlates. We provide a comparison of cognitive profile of patients with multiple sclerosis and NMOSD.

CONCLUSION

Patients with NMOSD are at significant risk of cognitive deficits. However, the knowledge of cognitive symptoms in NMOSD and potential modifying interventions is still scarce. Further accumulation of clinical data may facilitate effective therapeutic interventions.

White Matter Network Disruption and Cognitive Dysfunction in Neuromyelitis Optica Spectrum Disorder

Background: In neuromyelitis optica spectrum disorder (NMOSD), brain involvement is common and cognitive dysfunction is frequently found. The study investigated alterations of white matter (WM) connectivity using graph theory and correlations with cognitive dysfunction in patients with NMOSD.

Methods: We prospectively enrolled patients with NMOSD (N = 14) and age- and sex-matched healthy controls (N = 21). Structural connections between any pair of the 90 cortical and subcortical regions were established using diffusion tensor imaging and graph theory. Network-based statistics was employed to assess differences in WM connectivity between the NMOSD and healthy control groups. We further investigated the relationship between the topological network characteristics and cognitive test performances.

Results: WM network analysis showed decreased total strength of brain networks and two disrupted sub-networks in patients with NMOSD. The first featured six hub nodes in the rectus, hippocampus, calcarine, cuneus, and precuneus with the left-sided predominance. The second had six hub nodes in the orbitomiddle frontal, post-central, superior parietal, superior, and middle temporal, and caudate with the right-sided predominance. Compared to healthy controls, NMOSD patients showed poor performance on tests for attention/working memory and processing speed, visuospatial processing, and executive function, which were associated with significant decreases in nodal clustering coefficient, local efficiency, and regional efficiency in the disrupted sub-networks (all p < 0.05).

Conclusions: The data show the overall WM disruption and the relationship between poor cognitive function and sub-network alterations identified by the network analysis in NMOSD patients. We suggest that cognitive dysfunction is related to dysconnectivity of WM network including default mode network in NMOSD.

Comprehensive review of neuromyelitis optica and clinical characteristics of neuromyelitis optica patients in Puerto Rico

Neuromyelitis optica (NMO) is an immune-mediated inflammatory disorder of the central nervous system. It is characterized by concurrent inflammation and demyelination of the optic nerve (optic neuritis [ON]) and the spinal cord (myelitis). Multiple studies show variations in prevalence, clinical, and demographic features of NMO among different populations. In addition, ethnicity and race are known as important factors on disease phenotype and clinical outcomes. There are little data on information about NMO patients in underserved groups, including Puerto Rico (PR). In this research, we will provide a comprehensive overview of all aspects of NMO, including epidemiology, environmental risk factors, genetic factors, molecular mechanism, symptoms, comorbidities and clinical differentiation, diagnosis, treatment, its management, and prognosis. We will also evaluate the demographic features and clinical phenotype of NMO patients in PR. This will provide a better understanding of NMO and establish a basis of knowledge that can be used to improve care. Furthermore, this type of population-based study can distinguish the clinical features variation among NMO patients and will provide insight into the potential mechanisms that cause these variations.

Cerebral Blood Flow Changes in Multiple Sclerosis and Neuromyelitis Optica and Their Correlations With Clinical Disability

Distinguishing relapsing-remitting multiple sclerosis (RRMS) and neuromyelitis optica (NMO) is clinically important because they differ in prognosis and treatment. This study aimed to identify perfusion abnormalities in RRMS and NMO and their correlations with gray matter volume (GMV) atrophy and clinical parameters. Structural and arterial spin labeling MRI scans were performed in 39 RRMS patients, 62 NMO patients, and 73 healthy controls. The gray matter cerebral blood flow (CBF) values were voxel-wisely compared among the three groups with and without GMV correction. The regional CBF changes were correlated with the Expanded Disability Status Scale scores in the corresponding patient groups. Although multiple brain regions showed CBF differences among the three groups without GMV correction, only three of these regions remained significant after GMV correction. Specifically, both the RRMS and NMO groups showed reduced CBF in the occipital cortex and increased CBF in the right putamen compared to the control group. The RRMS group had increased CBF only in the medial prefrontal cortex compared to the other two groups. The occipital CBF was negatively correlated with clinical disability in the NMO group; however, the CBF in the right putamen was positively correlated with clinical disability in both patient groups. These findings suggest that there are perfusion alterations independent of GMV atrophy in RRMS and NMO patients. The regional CBF in the occipital cortex and putamen could be used as imaging features to objectively assess clinical disability in these patients.

Multimodal magnetic resonance imaging in relation to cognitive impairment in neuromyelitis optica spectrum disorder

Cognitive impairment (CI) is reported in 29–57% of patients with neuromyelitis optica spectrum disorder (NMOSD). However, the pathophysiology underlying CI in NMOSD is poorly understood. The present study aims to investigate the predictive values of various conventional and quantitative MRI parameters for cognitive performance in patients with NMOSD. Neurological assessment and conventional, diffusion tensor, and volumetric MRI sequences were collected form 73 patients with NMOSD and 44 healthy controls (HCs). Patients with ≥3 failed tests were considered to have CI. Brain lesion load, gray matter (GM) and white matter (WM) atrophy, deep GM (DGM) atrophy, cortical thickness, and diffuse microstructural WM damage were assessed. Twenty-three (32%) patients with NMOSD had CI. Compared to cognitively preserved (CP) individuals, patients with CI had atrophy in the WM, thalamus, and caudate, decreased fractional anisotropy (FA) and increased mean diffusivity in their WM. A multivariate model indicated that mean FA values in the WM and volume in the nucleus accumbens (NAc) were associated with overall cognition (p = 0.002 and p = 0.008, respectively). Diffuse microstructural damage in the WM and DGM atrophy in the NAc are the strongest predictors of cognitive impairment in patients with NMOSD.

Comparison of spontaneous brain activity revealed by regional homogeneity in AQP4-IgG neuromyelitis optica-optic neuritis versus MOG-IgG optic neuritis patients: a resting-state functional MRI study

OBJECTIVE

Many previous studies have demonstrated that neuromyelitis optica (NMO) patients have abnormalities of brain anatomy and function. However, differences in spontaneous brain activity between myelin oligodendrocyte glycoprotein (MOG)-IgG ON and aquaporin 4(AQP4)-neuromyelitis optica-optic neuritis (ON) remain unknown. In the current study, we investigated the brain neural homogeneity in MOG-IgG ON versus AQP4-IgG NMO-ON subjects by regional homogeneity (ReHo) method using magnetic resonance imaging (MRI).

PATIENTS AND METHODS

A total of 32 NMO-ON and ON subjects (21 with AQP4-IgG+NMO-ON and 11 with MOG-IgG+ON) and 34 healthy controls (HCs) closely matched for age were recruited, and scans were performed for all subjects. A one-way analysis of variance (ANOVA) was performed to determine the regions in which the ReHo was different across the three groups. NMO-ON and ON subjects were distinguished from HCs by a receiver operating characteristic (ROC) curve. The relationship between the mean ReHo in many brain regions and clinical features in NMO subjects was calculated by Pearson correlation analysis.

RESULTS

Compared with HCs, MOG-IgG+ON subjects had significantly decreased ReHo values in the posterior lobe of the left cerebellum and increased ReHo values in the left inferior frontal gyrus, right prefrontal gyrus, and left precentral/postcentral gyrus. AQP4-IgG+NMO-ON subjects showed higher ReHo values in the left inferior frontal gyrus and right middle temporal/occipital gyrus. Compared with MOG-IgG+ON subjects, AQP4-IgG+NMO-ON subjects had lower ReHo values in the posterior lobe of the right cerebellum. AQP4-Ig+NMO-ON subjects showed higher ReHo values in the left precentral/postcentral gyrus and right superior temporal gyrus.

CONCLUSION

AQP4-IgG+NMO-ON and MOG-IgG+ON subjects showed abnormal synchronized neuronal activity in many brain regions, which is consistent with deficits in visual, motor, and cognitive function. Furthermore, different patterns of synchronized neuronal activity occurred in the AQP4-IgG+NMO-ON and MOG-IgG+ON.

Cognitive dysfunction in adult patients with neuromyelitis optica: a systematic review and meta-analysis

The objective of this study was to investigate cognitive dysfunction in 24-60-year-old neuromyelitis optica (NMO) patients, demographically matched healthy subjects, and MS patients. We conducted a comprehensive literature review of the PubMed, Medline, EMBASE, CNKI, Wan Fang Date, Web of Science, and Cochrane Library databases from inception to May 2016 for case-control studies that reported cognitive test scores in NMO patients, healthy subjects, and MS patients. Outcome measures were cognitive function evaluations, including performance on attention, language, memory, information processing speed, and executive function tests. The meta-analysis included eight studies. NMO patients performed significantly worse on attention (P < 0.00001), language (P = 0.00008), memory (P = 0.00004), information processing speed (P < 0.00001), and executive function tests (P = 0.00009) than healthy subjects. There were no significant differences in performance between NMO patients and MS patients on these tests. This meta-analysis indicates that NMO patients aged 24-60 years have significantly worse cognitive performance than demographically matched healthy subjects. However, this was comparable to the performance of demographically matched MS patients. There is a need for further rigorous randomized controlled trials with focus on elucidating the underlying mechanism of cognitive dysfunction in NMO patients.

Cognitive and psychiatric comorbidities in neuromyelitis optica

OBJECTIVE

Our primary objective was to examine the neuropsychological and psychopathological profile of patients with neuromyelitis optica (NMO) and compare these to multiple sclerosis (MS) and healthy control (HC) groups. We also examined for relationships between cognitive and psychiatric variables and clinical factors including accumulated neurological disability and disease duration.

METHODS

A neuropsychological test battery was administered along with a structured psychiatric interview and quantitative measures of mood symptoms.

RESULTS

42 NMO, 42 MS and 42 HC participants were assessed. Cognitive impairments were observed in 67% of NMO patients. The prevalence and profile of cognitive impairments and lifetime prevalence of depression was similar between NMO and MS groups. However, significantly higher rates of recurrent depression and suicidality were observed in NMO patients. Correlational analyses revealed higher levels of anxiety symptoms were associated with shorter disease duration in NMO, while higher depression symptom levels were associated with higher neurological disability and poorer cognition.

CONCLUSIONS

Our results demonstrate substantial cognitive and psychiatric comorbidities in NMO patients. Similar rates of lifetime and current depression between NMO and MS appear to mask greater underlying psychiatric burden in NMO and further understandings of the course of neurobehavioural comorbidities is required to better comprehend the additional morbidity in NMO. Our data support a role for cognitive and psychiatric assessments in the comprehensive care of NMO patients.

Structural MRI substrates of cognitive impairment in neuromyelitis optica

OBJECTIVE

To identify the clinical and structural MRI markers for predicting cognitive impairment (CI) in patients with neuromyelitis optica (NMO).

METHODS

Fifty-four patients with NMO and 27 healthy controls underwent extensive neuropsychological testing and multimodal 3.0T MRI. The patient group was classified as CI or cognitively preserved (CP), using a criterion of ≤1.5 SD on at least 2 cognitive domains. MRI measurements included white matter (WM) lesion volume, gray matter (GM), WM, and deep GM (DGM) volume, cortical thickness, and the severity and extent of WM tract diffusion metric alterations based on fractional anisotropy and mean, axial, and radial diffusivity. Groups were compared using a multivariate general linear model, and clinical and MRI measurements were related to average cognition z scores by partial correlations and a stepwise linear regression model.

RESULTS

Twenty-six patients with NMO (48.2%) were classified as CI and showed WM tract diffusion abnormalities, particularly increased radial diffusivity, and GM especially DGM atrophy compared with healthy controls. Patients classified as CP also showed alterations of WM tract diffusion but without significant GM atrophy. Compared with the CP group, patients with CI demonstrated a lower level of education and decreased hippocampal volume. In the whole patient group, average cognition z scores were best predicted by the level of education and hippocampal volume (R(2) = 0.46, p < 0.001).

CONCLUSION

In patients with NMO, WM tract integrity disruption was identified in both CP and CI groups. GM atrophy, particularly in the DGM, was only found in the CI group. Hippocampal volume is the main MRI predictor of cognition in NMO.

Gray Matter Volume Reduction Is Associated with Cognitive Impairment in Neuromyelitis Optica

BACKGROUND AND PURPOSE

Whether gray matter impairment occurs in neuromyelitis optica is a matter of ongoing debate, and the association of gray matter impairment with cognitive deficits remains largely unknown. The purpose of this study was to investigate gray matter volume reductions and their association with cognitive decline in patients with neuromyelitis optica.

MATERIALS AND METHODS

This study included 50 patients with neuromyelitis optica and 50 sex-, age-, handedness-, and education-matched healthy subjects who underwent high-resolution structural MR imaging examinations and a battery of cognitive assessments. Gray matter volume and cognitive differences were compared between the 2 groups. The correlations of the regional gray matter volume with cognitive scores and clinical variables were explored in the patients with neuromyelitis optica.

RESULTS

Compared with healthy controls (635.9 ± 51.18 mL), patients with neuromyelitis optica (602.8 ± 51.03 mL) had a 5.21% decrease in the mean gray matter volume of the whole brain (P < .001). The significant gray matter volume reduction in neuromyelitis optica affected the frontal and temporal cortices and the right thalamus (false discovery rate correction, P < .05). The regional gray matter volumes in the frontal and temporal cortices were negatively correlated with disease severity in patients with neuromyelitis optica (Alphasim correction, P < .05). Patients with neuromyelitis optica had impairments in memory, information processing speed, and verbal fluency (P < .05), which were correlated with gray matter volume reductions in the medial prefrontal cortex and thalamus (Alphasim correction, P < .05).

CONCLUSIONS

Gray matter volume reduction is present in patients with neuromyelitis optica and is associated with cognitive impairment and disease severity in this group.

Assessment of Optic Nerve Impairment in Patients with Neuromyelitis Optica by MR Diffusion Tensor Imaging

BACKGROUND

Diffusion tensor imaging (DTI) has been used for the evaluation of the white matter integrity. In this study, we evaluated optic nerve impairment in patients with neuromyelitis optica (NMO) using DTI.

METHODOLOGY/PRINCIPAL FINDINGS

Optic nerve DTI were performed on 28 NMO patients and 38 normal controls. Fractional anisotropy (FA) values were measured in the anterior, middle, and posterior parts of the intraorbital optic nerve segment. For the posterior intraorbital optic nerve, FA values of BI (0.20±0.07), MI (0.24±0.16), and NA (0.25±0.14) decreased significantly compared with that of NC (0.43±0.07) (P<0.05), and ROC analysis demonstrated that the area under the curve (AUC) measurements for BI vs. NC, MI vs. NC, NA vs. NC, and NMO (including BI, MI, and NA) vs. NC were 0.99, 0.93, 0.88, and 0.96, respectively. The corresponding diagnostic sensitivities of ROC analysis were 100%, 80%, 80%, and 91%; and the specificities were 93%, 97%, 91%, and 93%.

CONCLUSIONS/SIGNIFICANCE

Decreased FA value in the intraorbital optic nerve, especially in the posterior part of the nerve, was demonstrated as a characteristic MR feature for NMO-related optic nerve impairment.

Cognitive impairment in Chinese neuromyelitis optica

BACKGROUND

Cognitive dysfunction is frequently seen in neuromyelitis optica (NMO). However, the features and influencing factors of cognitive impairment of Chinese NMO patients are unclear.

OBJECTIVE

To investigate the patterns of cognitive impairment in Chinese NMO patients, and correlate the neuropsychiatric scores with clinical and MRI parameters.

METHODS

Thirty-six Chinese NMO patients, and 30 sex and age-matched healthy controls were recruited with extensive neuropsychological assessments, using the modified Minimal Assessment of Cognitive Function in MS (MACFIMS). The demographic and clinical characteristics as well as MRI parameters were compared between cognitively impaired (CI) and cognitively preserved (CP) patients.

RESULTS

NMO patients were significantly impaired in the Paced Auditory Serial Addition Task (P<0.05), the Symbol Digit Modalities Test (P<0.001), the California Verbal Learning Test-Second Edition (P<0.05), the Brief Visuospatial Memory Test-Revised (P<0.05) and semantic fluency (P<0.001). Only lower education level was associated with cognitive dysfunction in NMO (odds ratio: 0.57, P<0.05). There were no significant differences of MRI parameters regarding white matter (WM) lesions, grey matter and WM brain volume between CI and CP patients.

CONCLUSIONS

Chinese NMO patients particularly demonstrated cognitive impairment in information processing speed, executive function and memory. Lower education level was the main factor contributing to cognitive impairment in NMO.

The impact of neuromyelitis optica on the recognition of emotional facial expressions: a preliminary report

Although neuromyelitis optica (NMO) is classically recognized as an affectation of optic nerves and spinal cord, recent reports have shown brain atrophy and cognitive dysfunction in this condition. Importantly, emotion-related brain regions appear to be impaired in NMO. However, no studies of NMO' emotional processing have been published. The goal of the current study was to investigate facial emotion recognition in 10 patients with NMO and 10 healthy controls by controlling for relevant cognitive factors. Consistent with previous reports, NMO patients performed poorly across cognitive domains (divided attention, working memory, and information-processing speed). Our findings further evidence the relative inability of NMO patients to recognize negative emotions (disgust, anger, and fear), in comparison to controls, with these deficits not explained by other cognitive impairments. Results provide the first evidence that NMO may impair the ability to recognize negative emotions. These impairments appear to be related to possible damage in brain regions underling emotional networks, including the anterior cingulate cortex, amygdala, and medial prefrontal cortex. Findings increased both our understanding of NMO's cognitive impairment, and the neural networks underlying negative emotions.

How embodied is action language? Neurological evidence from motor diseases

Although motor-language coupling is now being extensively studied, its underlying mechanisms are not fully understood. In this sense, a crucial opposition has emerged between the non-representational and the representational views of embodiment. The former posits that action language is grounded on the non-brain motor system directly engaged by musculoskeletal activity - i.e., peripheral involvement of ongoing actions. Conversely, the latter proposes that such grounding is afforded by the brain's motor system - i.e., activation of neural areas representing motor action. We addressed this controversy through the action-sentence compatibility effect (ACE) paradigm, which induces a contextual coupling of motor actions and verbal processing. ACEs were measured in three patient groups - early Parkinson's disease (EPD), neuromyelitis optica (NMO), and acute transverse myelitis (ATM) patients - as well as their respective healthy controls. NMO and ATM constitute models of injury to non-brain motor areas and the peripheral motor system, whereas EPD provides a model of brain motor system impairment. In our study, EPD patients exhibited impaired ACE and verbal processing relative to healthy participants, NMO, and ATM patients. These results indicate that the processing of action-related words is mainly subserved by a cortico-subcortical motor network system, thus supporting a brain-based embodied view on action language. More generally, our findings are consistent with contemporary perspectives for which action/verb processing depends on distributed brain networks supporting context-sensitive motor-language coupling.

Cognitive performance of neuromyelitis optica patients: comparison with multiple sclerosis

The aim of the present research was to investigate cognitive pattern of patients with neuromyelitis optica (NMO) and to compare it with multiple sclerosis (MS) patients' performance.

METHODS

Fourteen NMO, 14 relapsing remitting multiple sclerosis (RRMS), and 14 healthy control patients participated in the investigation. Neuropsychological functions were evaluated with the Brief Repeatable Neuropsychological Battery for MS; Symbol Digit Modalities Test; Digit Span; and Semantic Fluency.

RESULTS

Fifty-seven percent of NMO patients and 42.85% of the MS ones had abnormal performance in at least two cognitive tests. The NMO Group showed abnormal performance in verbal fluency, verbal and visual memories, with greater attention deficits. NMO patients outperformed healthy control in the paced auditory serial addition test (PASAT). However, no difference was found between NMO and RRMS patients.

CONCLUSIONS

The NMO Group showed more dysfunction in attention and verbal fluencies than in verbal and visual memories. When compared with the MS patients, a similar dysfunction pattern was found. O objetivo da presente pesquisa foi investigar o padrão cognitivo de pacientes com neuromielite óptica (NMO) e compará-lo com o desempenho de pacientes com esclerose múltipla (EM). Métodos: Quatorze pacientes com NMO, 14 com esclerose múltipla recorrente remitente (EMRR) e 14 participantes do Controle saudáveis participaram da presente investigação. As funções neuropsicológicas foram avaliadas com a Bateria Breve de Testes Neuropsicológicos de Rao, Teste Símbolo Digit e a Fluência Semântica. Resultados: Cinquenta e sete por cento dos pacientes com NMO e 42,85% daqueles com EM apresentaram desempenho anormal em pelo menos dois testes cognitivos. O Grupo NMO apresentarou desempenho anormal na fluência verbal e nas memórias visual e verbal, com maiores déficits de atenção. Pacientes com NMO superaram os controles saudáveis em PASAT. No entanto, não foi encontrada diferença entre os pacientes com NMO e aqueles com EMRR. Conclusões: O Grupo NMO mostrou mais disfunção nas fluências de atenção e verbais do que nas memórias verbal e visual. Quando comparados com os pacientes com EM, um padrão de disfunção semelhante foi encontrado.

Longitudinal change detection: inference on the diffusion tensor along white matter pathways

Diffusion weighted magnetic resonance imaging (DW-MRI) makes it possible to probe brain connections in vivo. This paper presents a change detection framework that relies on white matter pathways with application to neuromyelitis optica (NMO). The objective is to detect local or global fiber diffusion property modifications between two longitudinal DW-MRI acquisitions of a patient. To this end, we develop two frameworks based on statistical tests on tensor eigenvalues to detect local or global changes along the white matter pathways: a pointwise test that compares tensor populations extracted in bundles cross sections and a fiberwise test that compares paired tensors along all the fiber bundles. Experiments on both synthetic and real data highlight the benefit of considering fiber based statistical tests compared to standard voxelwise strategies.

White matter atrophy and cognitive dysfunctions in neuromyelitis optica

Neuromyelitis optica (NMO) is an inflammatory disease of central nervous system characterized by optic neuritis and longitudinally extensive acute transverse myelitis. NMO patients have cognitive dysfunctions but other clinical symptoms of brain origin are rare. In the present study, we aimed to investigate cognitive functions and brain volume in NMO. The study population consisted of 28 patients with NMO and 28 healthy control subjects matched for age, sex and educational level. We applied a French translation of the Brief Repeatable Battery (BRB-N) to the NMO patients. Using SIENAx for global brain volume (Grey Matter, GM; White Matter, WM; and whole brain) and VBM for focal brain volume (GM and WM), NMO patients and controls were compared. Voxel-level correlations between diminished brain concentration and cognitive performance for each tests were performed. Focal and global brain volume of NMO patients with and without cognitive impairment were also compared. Fifteen NMO patients (54%) had cognitive impairment with memory, executive function, attention and speed of information processing deficits. Global and focal brain atrophy of WM but not Grey Matter (GM) was found in the NMO patients group. The focal WM atrophy included the optic chiasm, pons, cerebellum, the corpus callosum and parts of the frontal, temporal and parietal lobes, including superior longitudinal fascicle. Visual memory, verbal memory, speed of information processing, short-term memory and executive functions were correlated to focal WM volumes. The comparison of patients with, to patients without cognitive impairment showed a clear decrease of global and focal WM, including brainstem, corticospinal tracts, corpus callosum but also superior and inferior longitudinal fascicles. Cognitive impairment in NMO patients is correlated to the decreased of global and focal WM volume of the brain. Further studies are needed to better understand the precise origin of cognitive impairment in NMO patients, particularly in the WM.

Longitudinal change detection in diffusion MRI using multivariate statistical testing on tensors

This paper presents a longitudinal change detection framework for detecting relevant modifications in diffusion MRI, with application to neuromyelitis optica (NMO) and multiple sclerosis (MS). The core problem is to identify image regions that are significantly different between two scans. The proposed method is based on multivariate statistical testing which was initially introduced for tensor population comparison. We use this method in the context of longitudinal change detection by considering several strategies to build sets of tensors characterizing the variability of each voxel. These strategies make use of the variability existing in the diffusion weighted images (thanks to a bootstrap procedure), or in the spatial neighborhood of the considered voxel, or a combination of both. Results on synthetic evolutions and on real data are presented. Interestingly, experiments on NMO patients highlight the ability of the proposed approach to detect changes in the normal-appearing white matter (according to conventional MRI) that are related with physical status outcome. Experiments on MS patients highlight the ability of the proposed approach to detect changes in evolving and non-evolving lesions (according to conventional MRI). These findings might open promising prospects for the follow-up of NMO and MS pathologies.