Structural and functional imaging features of cognitive phenotypes in pediatric multiple sclerosis

OBJECTIVE

The present study aimed to identify the clinical and MRI features of the distinct cognitive phenotypes in pediatric multiple sclerosis (pedMS).

METHODS

PedMS patients (n = 73) and healthy controls (n = 30) underwent clinical examination and 3.0T MRI. All patients completed neuropsychological testing, and cognitive phenotypes were identified by performing K-means clustering on cognitive scores. MRI metrics included brain T2-hyperintese lesion volume and normalized brain volumes. Within seven cognitively relevant cortical networks, structural disconnectivity (i.e., the mean percentage of streamlines connecting each pair of cortical regions passing through a lesion) and resting-state (RS) functional connectivity (FC) were estimated.

RESULTS

Three cognitive phenotypes emerged: Preserved cognition (PC; n = 27, 37%), mild verbal learning and memory/semantic fluency involvement (MVS; n = 28, 38%), and multidomain involvement (MI; n = 18, 25%). Age, sex, and disease duration did not differ among groups. Compared with healthy subjects, PC patients had decreased RS FC within the default mode network (p = 0.045); MVS patients exhibited lower cortical volume and reduced RS FC within the frontoparietal network (all p = 0.045); and MI patients showed decreased volumes in all brain compartments except the hippocampus, and reduced RS FC within the frontoparietal network (all p ≤ 0.045). Compared to PC, MI patients had more severe disability and higher structural disconnectivity within four cortical networks (all p ≤ 0.045). Compared to PC and MVS, MI patients had lower intelligence quotient (all p ≤ 0.005).

INTERPRETATION

We identified three cognitive phenotypes in pedMS that demonstrate the existence of a spectrum of impairment. Such phenotypes showed distinct clinical and MRI characteristics that contributed to explain their cognitive profiles.

An Update on the Measurement of Motor Cerebellar Dysfunction in Multiple Sclerosis

Multiple sclerosis (MS) is a progressive disease that often affects the cerebellum. It is characterised by demyelination, inflammation, and neurodegeneration within the central nervous system. Damage to the cerebellum in MS is associated with increased disability and decreased quality of life. Symptoms include gait and balance problems, motor speech disorder, upper limb dysfunction, and oculomotor difficulties. Monitoring symptoms is crucial for effective management of MS. A combination of clinical, neuroimaging, and task-based measures is generally used to diagnose and monitor MS. This paper reviews the present and new tools used by clinicians and researchers to assess cerebellar impairment in people with MS (pwMS). It also describes recent advances in digital and home-based monitoring for people with MS.

Relation of sensorimotor and cognitive cerebellum functional connectivity with brain structural damage in patients with multiple sclerosis and no disability

Background and purpose

To investigate the relationship between the functional connectivity (FC) of the sensorimotor and cognitive cerebellum and measures of structural damage in patients with multiple sclerosis (MS) and no physical disability.

Methods

We selected 144 relapsing–remitting MS patients with an Expanded Disability Status Scale score of ≤1.5 and 98 healthy controls from the Italian Neuroimaging Network Initiative database. From multimodal 3T magnetic resonance imaging (MRI), including functional MRI at rest, we calculated lesion load, cortical thickness, and white matter, cortical gray matter, and caudate, putamen, thalamic, and cerebellar volumes. Voxel‐wise FC of the sensorimotor and cognitive cerebellum was assessed with seed‐based analysis, and multiple regression analysis was used to evaluate the relationship between FC and structural damage.

Results

Whole brain, white matter, caudate, putamen, and thalamic volumes were reduced in patients compared to controls, whereas cortical gray matter was not significantly different in patients versus controls. Both the sensorimotor and cognitive cerebellum showed a widespread pattern of increased and decreased FC that were negatively associated with structural measures, indicating that the lower the FC, the greater the tissue loss. Lastly, among multiple structural measures, cortical gray matter and white matter volumes were the best predictors of cerebellar FC alterations.

Conclusions

Increased and decreased cerebellar FC with several brain areas coexist in MS patients with no disability. Our data suggest that white matter loss hampers FC, whereas, in the absence of atrophy, cortical volume represents the framework for FC to increase.

The role of cerebellar damage in explaining disability and cognition in multiple sclerosis phenotypes: a multiparametric MRI study

BACKGROUND

Cerebellar involvement is not comprehensively studied from an MRI point of view in multiple sclerosis (MS). We aimed to quantify cerebellar damage and identify predictors of physical disability and cognitive dysfunction in MS patients, and to characterize patients with cerebellar disability.

METHODS

In this prospective study, 164 (89 relapsing-remitting and 75 progressive) MS patients and 53 healthy controls were enrolled. Subjects underwent 3T MRI with sequences for assessing lesions and atrophy in cerebellum, supratentorial brain, brainstem and cervical cord. Cerebellar peduncle diffusion-tensor metrics were also derived. Random forest models identified MRI predictors of Expanded Disability Status Scale (EDSS) score and cognition z-score. Hierarchical clustering was applied on MRI metrics in patients with cerebellar disability.

RESULTS

In MS patients, predictors of higher EDSS score (out-of-bag-R² = 0.83) were: lower cord grey matter (GM) and global areas, brain volume, GM volume (GMV), cortical GMV, cerebellum lobules I-IV and vermis GMV; and higher cord GM and brainstem lesion volume (LV). Predictors of lower cognition z-score (out-of-bag-R² = 0.25) were: higher supratentorial and superior cerebellar peduncle LV; and lower brain, thalamus and basal ganglia volumes, GMV, cerebellum lobule VIIIb and Crus II GMV. In patients with cerebellar disability, we found three clusters with homogenous MRI metrics: patients with high brain lesion volumes (including cerebellar peduncles), those with marked cerebellum GM atrophy and patients with severe cord damage.

CONCLUSIONS

Damage to cerebellum GM and connecting structures has a relevant role in explaining cognitive dysfunction and physical disability in MS. Data-driven MRI clustering might improve our knowledge of MRI-clinical correlations.

Dentate-nucleus gadolinium deposition on magnetic resonance imaging: ultrasonographic and clinical correlates in multiple sclerosis patients

Objective

The objective of this study is to find out whether gadolinium accumulation in the dentate nucleus (DN) after repeated gadolinium-based contrast agent (GBCA) administration in multiple sclerosis (MS) patients is related to tissue alteration detectable on transcranial ultrasound.

Methods

In this case–control study, 34 patients (17 with, and 17 age-, sex-, MS severity-, and duration-matched participants without visually rated DN T1-hyperintensity) who had received 2–28 (mean, 11 ± 7) consecutive 1.5-Tesla MRI examinations with application of linear GBCA were included. Real-time MRI-ultrasound fusion imaging was applied, exactly superimposing the DN identified on MRI to calculate its corresponding echo-intensity on digitized ultrasound image analysis. In addition, cerebellar ataxia and cognitive performance were assessed. Correlation analyses were adjusted for age, MS duration, MS severity, and time between MRI scans.

Results

DN-to-pons T1-signal intensity-ratios (DPSIR) were larger in patients with visually rated DN T1-hyperintensity compared to those without (1.16 ± 0.10 vs 1.09 ± 0.06; p = 0.01). In the combined group, DPSIR correlated with the cumulative linear-GBCA dose (r = 0.49, p = 0.003), as did the DPSIR change on last versus first MRI (r = 0.59, p = 0.003). Neither DPSIR nor globus pallidus internus-to-thalamus T1-signal intensity-ratios were related to echo-intensity of corresponding ROI’s. DPSIR correlated with the dysarthria (r = 0.57, p = 0.001), but no other, subscore of the International Cooperative Ataxia Rating Scale, and no other clinical score.

Conclusions

DN gadolinium accumulation is not associated with trace metal accumulation, calcification, or other tissue alteration detectable on ultrasound. A possible mild effect of DN gadolinium accumulation on cerebellar speech function in MS patients, suggested by present data, needs to be validated in larger study samples.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10072-021-05702-4.

Cognitive Issues in Pediatric Multiple Sclerosis

Multiple sclerosis (MS) is one of the leading causes of disability in young adults. The onset of MS during developmental age makes pediatric patients particularly susceptible to cognitive impairment, resulting from both disease-related damage and failure of age-expected brain growth. Despite different test batteries and definitions, cognitive impairment has been consistently reported in approximately one-third of pediatric patients with MS. However, the lack of a uniform definition of cognitive impairment and the adoption of different test batteries have led to divergent results in terms of cognitive domains more frequently affected across the cohorts explored. This heterogeneity has hampered large international collaborative studies. Moreover, research aimed at the identification of risk factors (e.g., demographic, clinical, and radiological features) or protective factors (e.g., cognitive reserve, leisure activities) for cognitive decline is still scanty. Mood disorders, such as depression and anxiety, can be detected in these patients alongside cognitive decline or in isolation, and can negatively affect quality of life scores as well as academic performances. By using MRI, cognitive impairment was attributed to damage to specific brain compartments as well as to abnormal network activation patterns. However, multimodal MRI studies are still needed in order to assess the contribution of each MRI metric to cognitive impairment. Importantly, longitudinal studies have recently demonstrated failure of age-expected brain growth and of white matter (WM) and gray matter (GM) maturation plays a relevant role in determining cognitive dysfunction, in addition to MS-related direct damage. Whether these growth retardations might result in specific cognitive profiles according to the age at disease onset has not been studied, yet. A better characterization of cognitive profiles in pediatric MS patients, as well as the definition of neuroanatomical substrates of cognitive impairment and their longitudinal evolution are needed to develop efficient therapeutic strategies against cognitive impairment in this patient population.

Neuroimaging Correlates of Cognitive Dysfunction in Adults with Multiple Sclerosis

Cognitive impairment is a frequent and meaningful symptom in multiple sclerosis (MS), caused by the accrual of brain structural damage only partially counteracted by effective functional reorganization. As both these aspects can be successfully investigated through the application of advanced neuroimaging, here, we offer an up-to-date overview of the latest findings on structural, functional and metabolic correlates of cognitive impairment in adults with MS, focusing on the mechanisms sustaining damage accrual and on the identification of useful imaging markers of cognitive decline.

Identifying Early Neuropsychological Indicators of Cognitive Involvement in Multiple Sclerosis

Multiple sclerosis (MS) is a debilitating disease of the central nervous system that is most commonly seen in early to middle adulthood, although it can be diagnosed during childhood or later in life. While cognitive impairment can become more prevalent and severe as the disease progresses, signs of cognitive involvement can be apparent in the early stages of the disease. In this review, we discuss the prevalence and types of cognitive impairment seen in early MS, including the specific measures used to identify them, as well as the challenges in characterizing their frequency and progression. In addition to examining the progression of early cognitive involvement over time, we explore the clinical factors associated with early cognitive involvement, including demographics, level of physical disability, disease modifying therapy use, vocational status, and psychological and physical symptoms. Given the prevalence and functional impact these impairments can have for persons with MS, considerations for clinicians are provided, such as the role of early cognitive screenings and the importance of comprehensive neuropsychological assessments.

Resting-state functional connectivity of anterior and posterior cerebellar lobes is altered in multiple sclerosis

BACKGROUND

Damage to the cerebellar sensorimotor and cognitive domains may underlie physical and cognitive disability.

OBJECTIVE

To investigate resting-state functional connectivity (FC) of sensorimotor and cognitive cerebellum, and clinical correlates in multiple sclerosis (MS).

METHODS

A total of 119 patients with MS and 42 healthy subjects underwent multimodal 3T-magnetic resonance imaging (MRI). Patients were evaluated using the Expanded Disability Status Scale and Multiple Sclerosis Functional Composite Scale. After parcellation of sensorimotor (lobules I-V + VIII) and cognitive cerebellum (lobules VI, VII, IX, X), we calculated cerebellar resting-state FC using a seed-based approach.

RESULTS

In patients with MS, the sensorimotor cerebellum showed increased FC mainly with cerebellar, thalamic, and cortical (frontal, parietal, temporal) areas and decreased FC with insular areas; the cognitive cerebellum showed increased FC mainly with thalamic and cortical (temporal-occipital) areas, and decreased FC with frontal-insular areas. Both sensorimotor and cognitive cerebellar FC negatively correlated with disability, and positively with cognitive scores. Cerebellar structural damage only partially influenced results.

CONCLUSION

The two neocerebellar circuits showed altered FC with subcortical and cortical areas. The association between increased sensorimotor and cognitive cerebellar FC and low levels of physical and cognitive disability suggests that altered FC might modulate the effects of cerebellar structural damage on clinical condition.

Functional Connectivity in Multiple Sclerosis: Recent Findings and Future Directions

Multiple sclerosis is a debilitating disorder resulting from scattered lesions in the central nervous system. Because of the high variability of the lesion patterns between patients, it is difficult to relate existing biomarkers to symptoms and their progression. The scattered nature of lesions in multiple sclerosis offers itself to be studied through the lens of network analyses. Recent research into multiple sclerosis has taken such a network approach by making use of functional connectivity. In this review, we briefly introduce measures of functional connectivity and how to compute them. We then identify several common observations resulting from this approach: (a) high likelihood of altered connectivity in deep-gray matter regions, (b) decrease of brain modularity, (c) hemispheric asymmetries in connectivity alterations, and (d) correspondence of behavioral symptoms with task-related and task-unrelated networks. We propose incorporating such connectivity analyses into longitudinal studies in order to improve our understanding of the underlying mechanisms affected by multiple sclerosis, which can consequently offer a promising route to individualizing imaging-related biomarkers for multiple sclerosis.

Cerebellum and cognition in progressive MS patients: functional changes beyond atrophy?

BACKGROUND

The cerebellum is a predilection site of pathology in progressive multiple sclerosis (PMS) patients, contributing to cognitive deficits. Aim of this study was to investigate lobular cerebellar functional connectivity (FC) in PMS patients in relation to cognition.

METHODS

In this cross-sectional study, resting state fMRI analysis was carried out on 29 PMS patients (11 males, mean age 51.2 ± 11.9 years) and 22 age- and sex-matched healthy controls (HC) (11 males, mean age 49.6 ± 8.8 years). Data were analyzed with a seed-based approach, with four different seeds placed at the level of cerebellar Lobule VI, Crus I, Crus II and Lobule VIIb, accounting for cerebellar structural damage. Cognitive status was assessed with the BICAMS battery. Correlations between fMRI data and clinical variables were probed with the Spearman correlation coefficient.

RESULTS

When testing FC differences between PMS and HC without taking into account cerebellar structural damage, PMS patients showed a reduction of FC between Crus II/Lobule VIIb and the right frontal pole (p = 0.001 and p = 0.002, respectively), with an increased FC between Lobule VIIb and the right precentral gyrus (p < 0.001). After controlling for structural damage, PMS patients still showed a reduced FC between Crus II and right frontal pole (p = 0.005), as well as an increased FC between Lobule VIIb and right precentral gyrus (p = 0.003), with the latter showing an inverse correlation with BVMT scores (r = - 0.393; p = 0.03).

CONCLUSION

PMS patients show cerebellar FC rearrangements that are partially independent from cerebellar structural damage, and are likely expression of a maladaptive functional rewiring.

Dentate nucleus connectivity in adult patients with multiple sclerosis: functional changes at rest and correlation with clinical features

BACKGROUND AND OBJECTIVE

The dentate nucleus, which is the largest of the cerebellar nuclei, plays a critical role in movement and cognition. The aim of our study was to assess any changes in dentate functional connectivity (FC) in adult relapsing remitting multiple sclerosis (RR-MS) patients and to investigate possible clinical correlates.

MATERIALS AND METHODS

In all, 54 patients and 24 healthy subjects (HS) underwent multimodal magnetic resonance imaging (MRI), including diffusion tensor imaging (DTI), three-dimensional-T1-weighted and resting state (RS) functional images; they also underwent a cognitive evaluation, that is, attention and information processing speed, by means of the Paced Auditory Serial Addition Test (PASAT). Patients were also scored according to Expanded Disability Status Scale (EDSS). RS-MRI data were analysed using FMRIB Software Library (FSL) tools, with the seed-based method to identify dentate FC.

RESULTS

When compared with HS, patients exhibited brain atrophy and widespread DTI abnormalities, as well as greater FC between the dentate nucleus and cortical areas, particularly in the frontal and parietal lobes. Within these areas, FC in patients correlated inversely with clinical impairment. Finally, FC correlated inversely with lesion load and microstructural brain damage.

CONCLUSION

Our findings indicate that dentate FC at rest is altered in MS patients. Whether these functional changes are induced by the disease and play a compensatory role remains to be established.

Functional cortical changes in relapsing-remitting multiple sclerosis at amplitude configuration: a resting-state fMRI study

OBJECTIVE

The aim of this study was to explore the amplitude of spontaneous brain activity fluctuations in patients with relapsing-remitting multiple sclerosis (RRMS) using the amplitude of low-frequency fluctuation (ALFF) method.

METHODS

ALFF and SPM8 were utilized to assess alterations in regional spontaneous brain activities in patients with RRMS in comparison with healthy controls (HCs). The beta values of altered brain regions between patients with RRMS and HCs were extracted, and a receiver operating characteristic (ROC) curve was generated to calculate the sensitivities and specificities of these different brain areas for distinguishing patients with RRMS from HCs. Pearson correlation analyses were applied to assess the relationships between the beta values of altered brain regions and disease duration and Expanded Disability Status Scale (EDSS) score.

PATIENTS AND PARTICIPANTS

A total of 18 patients with RRMS (13 females; five males) and 18 sex-, age-, and education-matched HCs (14 females; four males) were recruited for this study.

MEASUREMENTS AND RESULTS

Compared with HCs, patients with RRMS showed higher ALFF responses in the right fusiform gyrus (Brodmann area [BA] 37) and lower ALFF responses in the bilateral anterior cingulate cortices (BA 24 and 32), bilateral heads of the caudate nuclei, and bilateral brainstem. The ROC analysis revealed that the beta values of these abnormal brain areas showed high degrees of sensitivity and specificity for distinguishing patients with RRMS from HCs. The EDSS score showed a significant negative Pearson correlation with the beta value of the caudate head (r=-0.474, P=0.047).

CONCLUSION

RRMS is associated with disturbances in spontaneous regional brain activity in specific areas, and these specific abnormalities may provide important information about the neural mechanisms underlying behavioral impairment in RRMS.