Functional Connectivity Alterations in Neuromyelitis Optica Spectrum Disorder : Correlation with Disease Duration and Cognitive Impairment

Changes in brain functional connectivity and clinical correlations in neuromyelitis optica spectrum disorder: a longitudinal resting-state fMRI study

OBJECTIVES

Neuromyelitis Optica Spectrum Disorder (NMOSD) affects the optic nerves and spinal cord, but its longitudinal effects on brain function remain unclear. This study aims to examine changes in brain functional connectivity over time in NMOSD patients and assess their correlation with clinical outcomes, and explore whether shifts in connectivity, especially within the default-mode hub Brodmann area 23 (BA23), are indicative of changes in clinical status.

METHODS

Clinical assessments and resting-state fMRI data were analysed from 31 non-relapsing NMOSD patients at baseline and during one-year follow-up, and from 20 age- and gender-matched healthy controls (HCs) at baseline. We identified resting-state networks (RSNs) using independent component analysis (ICA). Functional connectivity (FC) was analyzed both within RSNs and between region-of-interest seeds and whole-brain voxels. Comparisons between groups (HCs vs. Baseline, HCs vs. Follow-up) and within the patient group (Baseline vs. Follow-up), as well as correlations with clinical evaluations, were conducted.

RESULTS

Significant FC changes were observed in NMOSD patients. At baseline, NMOSD patients exhibited significantly reduced FC in the lateral visual, sensorimotor, executive control, and left dorsal visual networks; however, these abnormalities showed partial recovery over time. Meanwhile, further decreases were noted in the medial visual and right dorsal visual networks at follow-up. Conversely, a significant increase in FC within the default mode network, particularly in the BA23 region, correlated with improvements in EDSS scores (r = 0.53, p < 0.01). Declines in connectivity between the BA23 region and both the lingual and fusiform gyri were associated with worsening Expanded Disability Status Scale (EDSS) scores (r =  - 0.38, p < 0.05) and reduced visual acuity (r =  - 0.45, p < 0.05).

CONCLUSION

NMOSD patients exhibit both compensatory and progressive changes in brain functional connectivity over time. Alterations in the BA23 region are closely associated with clinical outcomes, highlighting its potential as a functional biomarker. Highlights 1. Dynamic alterations in brain functional connectivity were observed in NMOSD patients during follow-up, reflecting both recovery and deterioration. 2. Increased connectivity within the default mode network, especially in the BA23 region, suggests compensatory neural adaptations. 3. Reduced connectivity between BA23 and visual processing regions (fusiform and lingual gyri) was linked to declines in visual acuity and neurological function.

Cognitive assessment in Neuromyelitis Optica spectrum disorders: A systematic review and meta-analysis

INTRODUCTION

Neuromyelitis optica spectrum disorders (NMOSD) is an autoimmune disorder primarily affecting the central nervous system, with cognitive impairments often overlooked in clinical studies. This systematic review and meta-analysis aimed to evaluate cognitive function in individuals with NMOSD, addressing gaps in the literature and informing clinical practice.

METHODS

A comprehensive literature search identified 28 eligible studies involving 1365 patients. Cognitive performance was assessed using validated neuropsychological tools, including the Controlled Oral Word Association Test (COWAT), California Verbal Learning Test (CVLT), Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Paced Auditory Serial Addition Test (PASAT), and Symbol Digit Modalities Test (SDMT).

RESULTS

The analysis revealed significant cognitive deficits across multiple domains. Verbal fluency (COWAT: mean score 24.68, 95 % CI: 23.70-25.70) and memory recall (CVLT: mean score 43.01, 95 % CI: 42.26-43.78) were notably impaired. Global cognitive function was mildly affected, with mean scores of 27.34 (95 % CI: 26.97-27.72) on the MMSE and 26.54 (95 % CI: 26.51-26.57) on the MoCA. High variability (I² > 80 %) in cognitive performance was attributed to differences in study methodologies and patient characteristics.

CONCLUSION

These findings underscore the prevalence of cognitive impairments in NMOSD and highlight the need for targeted neuropsychological assessments in this population. Incorporating cognitive evaluations into routine clinical practice could enhance patient management and improve quality of life.

Differentiation between multiple sclerosis and neuromyelitis optic spectrum disorders with multilevel fMRI features: A machine learning analysis

The conventional statistical approach for analyzing resting state functional MRI (rs-fMRI) data struggles to accurately distinguish between patients with multiple sclerosis (MS) and those with neuromyelitis optic spectrum disorders (NMOSD), highlighting the need for improved diagnostic efficacy. In this study, multilevel functional metrics including resting state functional connectivity, amplitude of low frequency fluctuation (ALFF), and regional homogeneity (ReHo) were calculated and extracted from 116 regions of interest in the anatomical automatic labeling atlas. Subsequently, classifiers were developed using different combinations of these selected features to distinguish between MS and NMOSD. Compared to models based on individual MRI features, support vector machine (SVM) and logistic regression (LR) models that integrated multilevel functional features such as RSFC, ALFF, and ReHo demonstrated the highest levels of performance on the testing cohorts (SVM, AUC = 0.857; LR, AUC = 0.929). Adding structural features of gray matter volume (GMV) data did not notably improve the classification performance of the machine learning models using multilevel rs-fMRI features. Notably, similar trends were observed across different brain templates, with models based on RSFC, ALFF, and ReHo yielding optimal performance. These findings suggest that utilizing multilevel fMRI features can effectively differentiate between MS and NMOSD patients.

Specific static and dynamic functional network connectivity changes in thyroid-associated ophthalmopathy and it predictive values using machine learning

Background

Thyroid-associated ophthalmopathy (TAO) is a prevalent autoimmune disease characterized by ocular symptoms like eyelid retraction and exophthalmos. Prior neuroimaging studies have revealed structural and functional brain abnormalities in TAO patients, along with central nervous system symptoms such as cognitive deficits. Nonetheless, the changes in the static and dynamic functional network connectivity of the brain in TAO patients are currently unknown. This study delved into the modifications in static functional network connectivity (sFNC) and dynamic functional network connectivity (dFNC) among thyroid-associated ophthalmopathy patients using independent component analysis (ICA).

Methods

Thirty-two patients diagnosed with thyroid-associated ophthalmopathy and 30 healthy controls (HCs) underwent resting-state functional magnetic resonance imaging (rs-fMRI) scanning. ICA method was utilized to extract the sFNC and dFNC changes of both groups.

Results

In comparison to the HC group, the TAO group exhibited significantly increased intra-network functional connectivity (FC) in the right inferior temporal gyrus of the executive control network (ECN) and the visual network (VN), along with significantly decreased intra-network FC in the dorsal attentional network (DAN), the default mode network (DMN), and the left middle cingulum of the ECN. On the other hand, FNC analysis revealed substantially reduced connectivity intra- VN and inter- cerebellum network (CN) and high-level cognitive networks (DAN, DMN, and ECN) in the TAO group compared to the HC group. Regarding dFNC, TAO patients displayed abnormal connectivity across all five states, characterized by notably reduced intra-VN connectivity and CN connectivity with high-level cognitive networks (DAN, DMN, and ECN), alongside compensatory increased connectivity between DMN and low-level perceptual networks (VN and basal ganglia network). No significant differences were observed between the two groups for the three dynamic temporal metrics. Furthermore, excluding the classification outcomes of FC within VN (with an accuracy of 51.61% and area under the curve of 0.35208), the FC-based support vector machine (SVM) model demonstrated improved performance in distinguishing between TAO and HC, achieving accuracies ranging from 69.35 to 77.42% and areas under the curve from 0.68229 to 0.81667. The FNC-based SVM classification yielded an accuracy of 61.29% and an area under the curve of 0.57292.

Conclusion

In summary, our study revealed that significant alterations in the visual network and high-level cognitive networks. These discoveries contribute to our understanding of the neural mechanisms in individuals with TAO, offering a valuable target for exploring future central nervous system changes in thyroid-associated eye diseases.

Abnormal brain spontaneous neural activity in neuromyelitis optica spectrum disorder with neuropathic pain

Background

Neuropathic pain is one of the most common symptoms in neuromyelitis optica spectrum disorder (NMOSD). Notwithstanding, its underlying mechanism remains obscure.

Methods

The amplitude of low-frequency fluctuations (ALFF) metric was employed to investigate spontaneous neural activity alterations via resting-state functional magnetic resonance imaging (rs-MRI) data from a 3.0 T MRI scanner, in a sample of 26 patients diagnosed with NMOSD with neuropathic pain (NMOSD-WNP), 20 patients with NMOSD but without neuropathic pain (NMOSD-WoNP), and 38 healthy control (HC) subjects matched for age and sex without the comorbidity of depressive or anxious symptoms.

Results

It was observed that patients with NMOSD-WNP displayed a significant ALFF decrease in the left amygdala and right anterior insula, relative to both patients with NMOSD-WoNP and HC subjects. Furthermore, ALFF values in the left amygdala were negatively correlated with the scores of the Douleur Neuropathique en 4 Questions and McGill Pain Questionnaire (both sensory and affective descriptors) in patients with NMOSD-WNP. Additionally, there were negative correlations between the ALFF values in the right anterior insula and the duration of pain and the number of relapses in patients with NMOSD-WNP.

Conclusion

The present study characterizes spontaneous neural activity changes in brain regions associated with sensory and affective processing of pain and its modulation, which underscore the central aspects in patients with NMOSD-WNP. These findings might contribute to a better understanding of the pathophysiologic basis of neuropathic pain in NMOSD.

Spinal cord and brain atrophy patterns in neuromyelitis optica spectrum disorder and multiple sclerosis

BACKGROUND

Spinal cord and brain atrophy are common in neuromyelitis optica spectrum disorder (NMOSD) and relapsing-remitting multiple sclerosis (RRMS) but harbor distinct patterns accounting for disability and cognitive impairment.

METHODS

This study included 209 NMOSD and 304 RRMS patients and 436 healthy controls. Non-negative matrix factorization was used to parse differences in spinal cord and brain atrophy at subject level into distinct patterns based on structural MRI. The weights of patterns were obtained using a linear regression model and associated with Expanded Disability Status Scale (EDSS) and cognitive scores. Additionally, patients were divided into cognitive impairment (CI) and cognitive preservation (CP) groups.

RESULTS

Three patterns were observed in NMOSD: (1) Spinal Cord-Deep Grey Matter (SC-DGM) pattern was associated with high EDSS scores and decline of visuospatial memory function; (2) Frontal-Temporal pattern was associated with decline of language learning function; and (3) Cerebellum-Brainstem pattern had no observed association. Patients with CI had higher weights of SC-DGM pattern than CP group. Three patterns were observed in RRMS: (1) DGM pattern was associated with high EDSS scores, decreased information processing speed, and decreased language learning and visuospatial memory functions; (2) Frontal-Temporal pattern was associated with overall cognitive decline; and (3) Occipital pattern had no observed association. Patients with CI trended to have higher weights of DGM and Frontal-Temporal patterns than CP group.

CONCLUSION

This study estimated the heterogeneity of spinal cord and brain atrophy patterns in NMOSD and RRMS patients at individual level, and evaluated the clinical relevance of these patterns, which may contribute to stratifying participants for targeted therapy.

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.

Macrophage Migration Inhibitory Factor as a Potential Plasma Biomarker of Cognitive Impairment in Cerebral Small Vessel Disease

As the pathogenesis of cerebral small vessel disease with cognitive impairment (CSVD-CI) remains unclear, identifying effective biomarkers can contribute to the clinical management of CSVD-CI. This study recruited 54 healthy controls (HCs), 60 CSVD-CI patients, and 57 CSVD cognitively normal (CSVD-CN) patients. All participants underwent neuropsychological assessments and multimodal magnetic resonance imaging. Macrophage migration inhibitory factors (MIFs) were assessed in plasma. The least absolute shrinkage and selection operator model was used to determine a composite marker. Compared with HCs or CSVD-CN patients, CSVD-CI patients had significantly increased plasma MIF levels. In CSVD-CI patients, plasma MIF levels were significantly correlated with multiple cognitive assessment scores, plasma levels of blood-brain barrier (BBB)-related indices, white matter hyperintensity Fazekas scores, and the mean amplitude of low-frequency fluctuation in the right superior temporal gyrus. Higher plasma MIF levels were significantly associated with worse global cognition and information processing speed in CSVD-CI patients. The composite marker (including plasma MIF) distinguished CSVD-CI patients from CSVD-CN and HCs with >80% accuracy. Meta-analysis indicated that blood MIF levels were significantly increased in CSVD-CI patients. In conclusion, plasma MIF is a potential biomarker for early identification of CSVD-CI. Plasma MIF may play a role in cognitive decline in CSVD through BBB dysfunction and changes in white matter hyperintensity and brain activity.

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.

Temporal and topological properties of dynamic networks reflect disability in patients with neuromyelitis optica spectrum disorders

Approximately 36% of patients with neuromyelitis optica spectrum disorders (NMOSD) suffer from severe visual and motor disability (blindness or light perception or unable to walk) with abnormalities of whole-brain functional networks. However, it remains unclear how whole-brain functional networks and their dynamic properties are related to clinical disability in patients with NMOSD. Our study recruited 30 NMOSD patients (37.70 ± 11.99 years) and 45 healthy controls (HC, 41.84 ± 11.23 years). The independent component analysis, sliding-window approach and graph theory analysis were used to explore the static strength, time-varying and topological properties of large-scale functional networks and their associations with disability in NMOSD. Compared to HC, NMOSD patients showed significant alterations in dynamic networks rather than static networks. Specifically, NMOSD patients showed increased occurrence (fractional occupancy; P < 0.001) and more dwell times of the low-connectivity state (P < 0.001) with fewer transitions (P = 0.028) between states than HC, and higher fractional occupancy, increased dwell times of the low-connectivity state and lower transitions were related to more severe disability. Moreover, NMOSD patients exhibited altered small-worldness, decreased degree centrality and reduced clustering coefficients of hub nodes in dynamic networks, related to clinical disability. NMOSD patients exhibited higher occurrence and more dwell time in low-connectivity states, along with fewer transitions between states and decreased topological organizations, revealing the disrupted communication and coordination among brain networks over time. Our findings could provide new perspective to help us better understand the neuropathological mechanism of the clinical disability in NMOSD.

In patients with mild disability NMOSD: is the alteration in the cortical morphological or functional network topological properties more significant

Objective

To assess the alteration of individual brain morphological and functional network topological properties and their clinical significance in patients with neuromyelitis optica spectrum disorder (NMOSD).

Materials and methods

Eighteen patients with NMOSD and twenty-two healthy controls (HCs) were included. The clinical assessment of NMOSD patients involved evaluations of disability status, cognitive function, and fatigue impact. For each participant, brain images, including high-resolution T1-weighted images for individual morphological brain networks (MBNs) and resting-state functional MR images for functional brain networks (FBNs) were obtained. Topological properties were calculated and compared for both MBNs and FBNs. Then, partial correlation analysis was performed to investigate the relationships between the altered network properties and clinical variables. Finally, the altered network topological properties were used to classify NMOSD patients from HCs and to analyses time- to-progression of the patients.

Results

The average Expanded Disability Status Scale score of NMOSD patients was 1.05 (range from 0 to 2), indicating mild disability. Compared to HCs, NMOSD patients exhibited a higher normalized characteristic path length (λ) in their MBNs (P = 0.0118, FDR corrected) but showed no significant differences in the global properties of FBNs (p: 0.405-0.488). Network-based statistical analysis revealed that MBNs had more significantly altered connections (P< 0.01, NBS corrected) than FBNs. Altered nodal properties of MBNs were correlated with disease duration or fatigue scores (P< 0.05/6 with Bonferroni correction). Using the altered nodal properties of MBNs, the accuracy of classification of NMOSD patients versus HCs was 96.4%, with a sensitivity of 93.3% and a specificity of 100%. This accuracy was better than that achieved using the altered nodal properties of FBNs. Nodal properties of MBN significantly predicted Expanded Disability Status Scale worsening in patients with NMOSD.

Conclusion

The results indicated that patients with mild disability NMOSD exhibited compensatory increases in local network properties to maintain overall stability. Furthermore, the alterations in the morphological network nodal properties of NMOSD patients not only had better relevance for clinical assessments compared with functional network nodal properties, but also exhibited predictive values of EDSS worsening.

Cerebellar connectome alterations and associated genetic signatures in multiple sclerosis and neuromyelitis optica spectrum disorder

BACKGROUND

The cerebellum plays key roles in the pathology of multiple sclerosis (MS) and neuromyelitis optica spectrum disorder (NMOSD), but the way in which these conditions affect how the cerebellum communicates with the rest of the brain (its connectome) and associated genetic correlates remains largely unknown.

METHODS

Combining multimodal MRI data from 208 MS patients, 200 NMOSD patients and 228 healthy controls and brain-wide transcriptional data, this study characterized convergent and divergent alterations in within-cerebellar and cerebello-cerebral morphological and functional connectivity in MS and NMOSD, and further explored the association between the connectivity alterations and gene expression profiles.

RESULTS

Despite numerous common alterations in the two conditions, diagnosis-specific increases in cerebellar morphological connectivity were found in MS within the cerebellar secondary motor module, and in NMOSD between cerebellar primary motor module and cerebral motor- and sensory-related areas. Both diseases also exhibited decreased functional connectivity between cerebellar motor modules and cerebral association cortices with MS-specific decreases within cerebellar secondary motor module and NMOSD-specific decreases between cerebellar motor modules and cerebral limbic and default-mode regions. Transcriptional data explained > 37.5% variance of the cerebellar functional alterations in MS with the most correlated genes enriched in signaling and ion transport-related processes and preferentially located in excitatory and inhibitory neurons. For NMOSD, similar results were found but with the most correlated genes also preferentially located in astrocytes and microglia. Finally, we showed that cerebellar connectivity can help distinguish the three groups from each other with morphological connectivity as predominant features for differentiating the patients from controls while functional connectivity for discriminating the two diseases.

CONCLUSIONS

We demonstrate convergent and divergent cerebellar connectome alterations and associated transcriptomic signatures between MS and NMOSD, providing insight into shared and unique neurobiological mechanisms underlying these two diseases.

The Characteristics of Cognitive Proficiency in Patients with Acute Neuromyelitis Optica Spectrum Disease and its Correlation with Serum Aquaporin-4 Antibody Titer

Objective: To explore the characteristics and dynamic evolution of cognitive impairment in patients with neuromyelitis optica spectrum disorder (NMOSD). Methods: Twenty-five patients with acute NMOSD and 30 age-matched healthy individuals were consecutively recruited in this study. The Montreal Cognitive Assessment (MoCA), Chinese Version of Rey Auditory Vocabulary Learning Test (CRAVLT), Verbal Fluency Test (VFT), Digital Span Test (DST), Paced Auditory Serial Addition Task 3/2s version (PASAT-3/2), Rey−Osterrieth Complex Figure Test (ROCF) and Stroop Color and Word Test (CWT) were used to evaluate cognitive function. The correlations between cognitive function and serum aquaporin-4 (AQP-4) antibody titer were analyzed. Results: Sixty-four percent of patients with acute NMOSD had cognitive dysfunction. MoCA (p < 0.001), CRAVLT-N7 (p = 0.004), CRAVLT-N8 (p = 0.011), ROCF-C (p = 0.005), ROCF-R (p < 0.001), PASAT-3 (p = 0.013), PASAT-2 (p = 0.001) and CWT-A (p = 0.017) were significantly worse in patients with acute NMOSD than those in control group. During follow-up visits, significant differences of serum AQP-4 antibody titers were still noted in NMOSD patients (p < 0.001), while no significant differences were found by MoCA. Conclusion: A high number of patients with acute NMOSD suffer from cognitive dysfunction. Serum AQP-4 antibody titers can decrease during disease remission, while obvious cognitive decline in these patients still exists.

Altered functional connectivity associated with cognitive impairment in neuromyelitis optica spectrum disorder

BACKGROUND

Cognitive impairment is one of the common symptoms in patients with neuromyelitis optica spectrum disorder (NMOSD). However, the underlying mechanism remains unclear. Resting-state functional magnetic resonance imaging (rs-fMRI) offers the opportunity to reveal the patterns of brain activity in patients with different cognitive states. Accordingly, this study investigated functional connectivity (FC) abnormalities within and between the main cognitive networks in cognitively impaired (CI) patients with NMOSD and their correlations with cognitive performance.

METHODS

Thirty-four patients with NMOSD and 39 healthy controls (HC) were included. Neuropsychological evaluations and rs-fMRI scanning were performed. Patients were classified as CI (n = 16) or cognitively preserved (CP; n = 18) according to neuropsychological evaluations. Seven components representing six main cognitive networks were selected by group independent component analysis. The differences in inter- and intranetwork FC among CI, CP, and HC groups were assessed. The correlation between FC values and neuropsychological data in NMOSD was calculated.

RESULTS

The CI group showed decreased intranetwork connectivity in the posterior default mode network (pDMN) compared with the HC group (P < 0.05, GRF corrected), and decreased internetwork connectivity between the salience network (SN) and pDMN, and between the SN and right frontoparietal network (rFPN) compared with CP and HC groups. The altered FC values were significantly correlated with cognitive performance in the whole NMOSD group.

CONCLUSION

The disconnection within the pDMN and between the SN and pDMN or rFPN might suggest the neural substrates underlying cognitive impairment in NMOSD.

The role of basal ganglia network in neural plasticity in neuromyelitis optica spectrum disorder with myelitis

OBJECTIVES

To explore the alternation of the brain baseline activity in neuromyelitis optica spectrum disorder (NMOSD) patients after myelitis, and characterize the representation of the neural plasticity process.

METHODS

Clinical evaluation and resting-state fMRI were obtained from 20 NMOSD patients with myelitis and 20 healthy controls, matched in gender and age. Resting-state networks (RSNs) were identified through independent component analysis (ICA), and functional connectivity (FC) intra-RSNs and between region-of-interest (ROI) seed to whole-brain voxels were analyzed. Between-group comparisons and correlations with motor performance were also assessed.

RESULTS

A total of 14 main functional RSNs were identified. Group comparison of intra-network FCs revealed that FC strengths increased in basal ganglia network (BGN) and left frontoparietal network, decreased in sensorimotor network and default mode network in NMOSD. Better motor performance was found closely correlated with higher FC of BGN. Additionally, remarkably increased FC between caudate in BGN with cerebellum, frontal lobe and parietal lobe was discovered in further ROI-based whole-brain voxels FC analysis.

CONCLUSIONS

NMOSD patients presented wide brain resting-state functional connectivity alterations after myelitis, and BGN might be highly active in the process of neural plasticity in chronic stage of NMOSD. Besides, understanding neural plasticity representation, especially that in NMOSD patients after myelitis, might have important applications in monitoring and designing rehabilitative approaches.

Time-varying connectivity of the precuneus and its association with cognition and depressive symptoms in neuromyelitis optica: A pilot MRI study

Background:

The precuneus is involved in cognition and depression; static functional connectivity (SFC) abnormalities of this region have been observed in neuromyelitis optica spectrum disorders (NMOSD). Time-varying functional connectivity (TVC) underpins dynamic variations of brain connectivity.

Objective:

The aim of this study was to explore precuneus SFC and TVC in NMOSD patients and their associations with neuropsychological features.

Methods:

This retrospective study includes 27 NMOSD patients and 30 matched healthy controls undergoing resting state functional magnetic resonance imaging (MRI) and a neuropsychological evaluation of cognitive performance and depressive symptoms. A sliding-window correlation analysis using bilateral precuneus as seed region assessed TVC, which was quantified by the standard deviation of connectivity across windows. Mean connectivity indicated SFC.

Results:

Compared to controls, patients had reduced SFC between precuneus, temporal lobe, putamen and cerebellum, and reduced TVC between precuneus and prefronto-parietal-temporo-occipital cortices and caudate. Patients also had increased intra-precuneal TVC and increased TVC between the precuneus and the temporal cortex. More severe depressive symptoms correlated with increased TVC between the precuneus and the temporal lobe; worse cognitive performance mainly correlated with higher TVC between the precuneus and the parietal lobe.

Conclusion:

TVC rather than SFC of the precuneus correlates with NMOSD neuropsychological features; different TVC abnormalities underlie depressive symptoms and cognitive impairment.

Effective connectivity within the corticothalamic circuit in the neuromyelitis optica patients: A comparative study using resting-state fMRI

Neuromyelitis Optica, which is known as NMO, is a demyelination syndrome and inflammatory condition of the central nervous system that affects the optic nerves. Since structural imaging approaches cannot adequately describe the brain disorders in patients with NMO, functional magnetic resonance imaging (fMRI) can be used. Resting-state fMRI was performed on 25 healthy subjects and 26 NMO patients. After preprocessing the data, the time series belonging to the regions of the middle frontal gyrus (MFG), inferior frontal gyrus (IFG), precuneus (PRE), thalamus (THA), and middle temporal gyrus (MTG) were extracted as components of the corticothalamic circuit. The obtained time series were statistically analyzed as the input of dynamic causal modeling (DCM) in order to evaluate the effective connectivity within the corticothalamic circuit. The statistical analyses showed that the mean of effective connectivity power was significantly higher in the healthy subjects than in the NMO patients. For the healthy subjects, there was no significant difference in effective connectivity power between the two groups of males and females at the significance level of 0.05. In the NMO patients, there was a significant difference between the effective connectivity levels of the male and female groups only for IFG → MFG, in which it was greater in males than in females. The results of our studies showed that resting-state fMRI could exhibit the difference between healthy and NMO subjects.

Reduced GABA levels in the medial prefrontal cortex are associated with cognitive impairment in patients with NMOSD

BACKGROUND

Cognitive impairment is a symptom present in part of patients with neuromyelitis optica spectrum disorder (NMOSD) and its pathophysiology is unknown. Dysfunction of the GABAergic/glutamatergic pathways involving inhibitory and excitatory neurotransmitters have been implicated in several neurological disorders. This study aimed to investigate the changes in inhibitory gamma-aminobutyric acid (GABA) and excitatory glutamate and glutamine (Glx) neurotransmitter levels and their correlations with cognitive functions in patients with NMOSD.

METHODS

A total of 29 patients with NMOSD and 28 sex-, age-, and education-matched healthy controls (HCs) were included in the study. All participants underwent clinical and cognitive assessments and proton magnetic resonance spectroscopy scanning. Meshcher-Garwood point-resolved spectroscopy was used to measure GABA and Glx levels in the medial prefrontal cortex (mPFC) and left thalamus. Total creatine (tCr) was applied as an internal reference. The GABA and Glx levels in the patient group were compared with those in HCs and correlated with cognitive scores and clinical variables.

RESULTS

Patients with NMOSD showed lower GABA+/tCr levels in the mPFC compared with HCs (P = 0.028). The GABA+/tCr levels in the mPFC were significantly associated with verbal memory performance (r = 0.462, P = 0.027) and overall cognition (r = 0.440, P = 0.035) in the NMOSD group. The GABA+/tCr levels in the left thalamus or Glx/tCr levels in both regions were not significantly different between groups, nor were they related to any cognitive domain in patients with NMOSD (all P values > 0.05).

CONCLUSION

The GABA+ levels in the mPFC decreased and correlated with cognitive dysfunction in patients with NMOSD, suggesting that the changes in regional GABA+ levels might be a potential metabolic feature of cognitive decline in patients with NMOSD.

Brain structural and functional alterations in MOG antibody disease

BACKGROUND

The impact of myelin oligodendrocyte glycoprotein antibody disease (MOGAD) on brain structure and function is unknown.

OBJECTIVES

The aim of this study was to study the multimodal brain MRI alterations in MOGAD and to investigate their clinical significance.

METHODS

A total of 17 MOGAD, 20 aquaporin-4 antibody seropositive neuromyelitis optica spectrum disorders (AQP4 + NMOSD), and 28 healthy controls (HC) were prospectively recruited. Voxel-wise gray matter (GM) volume, fractional anisotropy (FA), mean diffusivity (MD), and degree centrality (DC) were compared between groups. Clinical associations and differential diagnosis were determined using partial correlation and stepwise logistic regression.

RESULTS

In comparison with HC, MOGAD had GM atrophy in frontal and temporal lobe, insula, thalamus, and hippocampus, and WM fiber disruption in optic radiation and anterior/posterior corona radiata; DC decreased in cerebellum and increased in temporal lobe. Compared to AQP4 + NMOSD, MOGAD presented lower GM volume in postcentral gyrus and decreased DC in cerebellum. Hippocampus/parahippocampus atrophy associated with Expanded Disability Status Scale (R = -0.55, p = 0.04) and California Verbal Learning Test (R = 0.62, p = 0.031). The differentiation of MOGAD from AQP4 + NMOSD achieved an accuracy of 95% using FA in splenium of corpus callosum and DC in occipital gyrus.

CONCLUSION

Distinct structural and functional alterations were identified in MOGAD. Hippocampus/parahippocampus atrophy associated with clinical disability and cognitive impairment.

Altered resting-state functional connectivity density in patients with neuromyelitis optica-spectrum disorders

BACKGROUND

Neuromyelitis optica spectrum disorder (NMOSD) is an autoimmune, demyelinating disorder, accompanied by abnormal spontaneous activity of the brain and impairment of the retina and optic nerve. Functional connectivity density (FCD) map, a graph theory method, was applied to explore the functional connectivity alterations of brian in NMOSD patients and investigate the alterations of FCD to the structural and microvascular changes around the optic nerve head (ONH).

METHODS

Nineteen NMOSD patients and 22 healthy controls (HCs) were included in our study. All participants underwent resting-state functional magnetic resonance imaging (fMRI) scans of the brain, and ophthalmological examinations included optical coherence tomographic angiography (OCT-A) imaging, visual acuity (VA), and intraocular pressure (IOP). The long- and short-range FCD was calculated by the fMRI graph theory method and two-sample t-tests were performed to compare the discrepancy of FCD between NMOSD and HCs. OCT-A imaging was used to obtain the structure (peripapillary retinal nerve fiber layer, pRNFL) and microvessels (radial peripapillary capillary, RPC) details around the ONH. The association between the long- and short-range FCD values with the structural and microvascular variation around the ONH were evaluated using Spearman's correlation.

RESULTS

Significantly decreased (corrected p < 0.05) long-range FCD was seen in the right superior parietal gyrus (SPG) in patients with NMOSD when compared to HCs. Increased long-range FCD was seen in the right fusiform gyrus (FFG), left orbital part of superior frontal orbital gyrus (ORBsup) and left anterior cingulum and paracingulate gyri (ACG) in NMOSD patients (corrected p < 0.05). The regions with reduced short-range FCD in NMOSD were the left angular gyrus (ANG) and right SPG (corrected p < 0.05). Increased short-range FCD was shown (corrected p < 0.05) in the right FFG of NMOSD. The pRNFL thickness and RPC density in all participants were negatively correlated with the long-range FCD values in the right FFG, left ORBsup, and left ACG as well as short-range FCD values in the right FFG, besides, both were positively correlated with the long-range FCD values in the right SPG and short-range FCD values in the left ANG and right SPG (p < 0.05).

CONCLUSION

Our study demonstrates that patients with NMOSD have widespread brain dysfunction after optic neuritis attacks which shows as impairment of widespread spatial distribution in long- and short-range FCD. Structural and microvascular changes around the ONH are associated with neural changes in the brain.