Deepa P. Ramasamy

Memory impairment in multiple sclerosis: correlation with deep grey matter and mesial temporal atrophy

Background: MRI research in multiple sclerosis (MS) samples reveals pathology in both the cerebral cortex and deep grey matter (DGM). The classical subcortical dementia hypothesis has been ascribed to MS and is supported by studies highlighting the role of thalamic atrophy in neuropsychological outcomes. However, the importance of mesial temporal lobe (MTL) atrophy in MS is largely untested and poorly understood. New structural imaging techniques permit volumetric measures of multiple regions within the MTL lobe and DGM. Objective: To determine the relative importance of MTL and DGM structures in predicting MS performance on memory tests presented in the auditory/verbal and visual/spatial spheres. Methods: Cross sectional analysis of 50 patients with MS undergoing structural brain MRI and neuropsychological testing. Using Freesurfer software, the volumes of the MTL (hippocampus, amygdala) and DGM (thalamus, caudate) structures were calculated and compared with control values. Neuropsychological testing contributed measures of new learning, delayed recall and recognition memory, in the auditory/verbal and visual/spatial memory modalities. Results: Significant correlations between lower regional volume and poorer test performance were observed across all memory tests. For measures of free recall or new learning, DGM volumes were most strongly predictive of outcomes. In contrast, measures of recognition memory were predicted only by MTL volumetric measures. Conclusion: For the first time, the predictive validity of MTL and DGM atrophy were simultaneously compared with MS using reliable and validated neuropsychological measures. This study found that both compartments play significant but different roles in the amnesia of MS.

Extent of cerebellum, subcortical and cortical atrophy in patients with MS: A case-control study

Cortical and subcortical atrophy occurs in multiple sclerosis (MS) and relates to clinical outcomes. FreeSurfer, a voxel-based automated software for brain reconstruction was used to investigate the extent of subcortical and cortical atrophy in 71 MS and 17 clinically isolated syndrome (CIS) patients, and 38 normal controls (NC), and to relate group differences to disease type and severity. Segmentation was performed on 3D SPGR T1-weighted MRI 1.5T images. Region-specific subcortical tissue volumes were calculated in mm(3) and cortical thickness in mm. Logistic regression and general linear model analyses, adjusted for age and intracranial volume, examined differences between NC, MS and CIS patients and disease subtypes. The MS group was characterized by significantly lower volumes of thalamus (left and right p<0.0001), left inferior lateral ventricle, third ventricle (p<0.0001), ventral diencephalon, pallidum and putamen bilaterally, as well as of right accumbens and brainstem with corresponding bilateral increase in volumes of lateral ventricles (p<0.01). Focal cortical atrophy areas in the thalamus, inferior parietal lobule of left hemisphere and in right precuneus were also significant in the MS sample. Versus CIS patients, RR or progressive MS patients showed significantly lower volumes of subcortical regions and cortical thinning. Hippocampal atrophy appeared only in advanced disease stages. Cerebellum WM volumes were significantly lower in MS and CIS patients vs. NC. Subcortical and cortical atrophy correlated with higher disability as measured by EDSS. This study confirmed selective deep gray matter atrophy (mostly thalamic), revealed cerebellum WM atrophy from the earliest clinical stages, and showed that cortical thinning advances with disease progression.

Magnetic resonance imaging characteristics of children and adults with paediatric-onset multiple sclerosis

The purpose of this study was to compare the clinical and quantitative magnetic resonance imaging metrics of paediatric-onset multiple sclerosis to adult-onset multiple sclerosis. It was a prospective comparison of clinical and magnetic resonance imaging characteristics of two paediatric onset multiple sclerosis and two adult onset multiple sclerosis groups that were matched for disease duration. The paediatric-onset-C group consisted of children with paediatric-onset multiple sclerosis with mean disease duration of 2.7 years, whereas the paediatric onset-A group consisted of adults with mean disease duration of 20 years. The adult onset multiple sclerosis-1 and adult onset multiple sclerosis-2 groups were matched to the paediatric onset-C and paediatric onset-A groups. The brain magnetic resonance imaging measures included: T(1)-, T(2)- and gadolinium contrast-enhancing volumes and the T(2)-lesion volume relative magnetization transfer ratio, global and tissue specific white and grey matter brain atrophy and normal appearing grey and white matter magnetization transfer ratio. Regression analyses were employed for magnetic resonance imaging measures. The paediatric onset multiple sclerosis-C (n = 17) and adult onset multiple sclerosis-1 (n = 81) groups had mean disease duration values of 2.7 +/- standard deviation 2.0 and 2.6 +/- 1.1 years, respectively. The paediatric onset multiple sclerosis-A group (n = 33) and adult onset multiple sclerosis-2 group (n = 300) had mean disease durations of 20 +/- standard deviation 10.9 and 20 +/- 9.3 years, respectively. In regression analysis, the T(2)- lesion volume of the paediatric onset multiple sclerosis-C and adult onset multiple sclerosis-1 groups were similar but there was a trend toward higher T(1)- lesion volume (P = 0.028) in the paediatric onset group. The brain parenchymal fraction and grey matter fraction in the paediatric-onset multiple sclerosis-C group were higher than those for the adult onset multiple sclerosis-1 group (both P < 0.001). The frequency of progressive multiple sclerosis in the paediatric onset multiple sclerosis-A group (27.3%) trended lower (odds ratio = 0.43, P = 0.042) than that in the adult onset multiple sclerosis-2 group (46.3%). The Expanded Disability Status Scale (median; inter-quartile range) in the paediatric onset multiple sclerosis-A group (2.25; 2.5) trended lower (P = 0.058) compared with the adult onset multiple sclerosis-2 group (3.5; 4.0). There was a trend toward lower magnetization transfer ratio values in T(2)-lesions, normal appearing grey matter and normal appearing white matter and higher grey matter fraction in the paediatric onset multiple sclerosis-A group compared with the adult onset multiple sclerosis-2 group. There was no evidence for differences on T(2)-lesion volume, T(1)-lesion volume, brain parenchymal fraction or white matter fraction. Paediatric-onset multiple sclerosis is characterized by a significant disease burden both early and later in the disease course. Despite this, disability is slower to accrue in paediatric onset multiple sclerosis than adult onset multiple sclerosis.

Brain atrophy and disability progression in multiple sclerosis patients: a 10-year follow-up study.

Objectives To identify MRI biomarkers associated with long-term disability progression in patients with multiple sclerosis (MS), and to define the rate of evolution of global, tissue-specific and regional atrophy in patients with MS over long-term. Methods MRI of the brain and clinical neurological assessment was performed in 81 patients at time of first visit and after 5 and 10 years of follow-up. MRI was acquired on 1.5 T scanners. T1-lesion and T2-lesion volumes (LVs) were calculated. Global and tissue-specific atrophy changes were longitudinally assessed, using a direct measurement approach, by calculating percentage volume changes between different time points. Regional tissue volumes for the subcortical deep grey matter (SDGM) structures were also obtained. Disability progression was defined as an increase in Expanded Disability Status Scale of ≥1.0 compared to baseline at 5-year and 10-year follow-up. Results Over 5 years, patients with disability progression showed significantly increased loss of whole brain (−3.8% vs −2.0%, p<0.001), cortical (−3.4% vs −1.8%, p=0.009) and putamen volume changes (−10.6% vs −3.8%, p=0.003) compared to patients with no disability progression. No significant change in white matter (WM) volume was observed when comparing progressing and non-progressing patients. Over 10 years, there was a trend for greater decrease in whole brain volume (−5.5% vs −3.7%, p=0.015) in the progressing patients. No significant changes in LV measures were detected between the patients with and without disability progression. Conclusion This long-term study shows that whole brain, cortical and putamen atrophy occurs throughout the 10-year follow-up of this MS cohort and is more pronounced in the group that showed disability progression at 5, but not at 10 years of follow-up. Overall, GM atrophy showed better association with disease progression than WM atrophy over 5-year and 10-year follow-up.

The place of conventional MRI and newly emerging MRI techniques in monitoring different aspects of treatment outcome

Magnetic resonance imaging (MRI) is the most important paraclinical measure for assessing and monitoring the pathologic changes implicated in the onset and progression of multiple sclerosis (MS). Conventional MRI sequences, such as T1-weighted gadolinium (Gd) enhanced and spin-echo T2-weighted imaging, only provide an incomplete picture of the degree of inflammation and underlying neurodegenerative changes in this disease. Two- and three-dimensional fluid-attenuated inversion recovery and double inversion recovery sequences allow better identification of cortical, periventricular and infratentorial lesions. Ultra-high field strength MRI has the potential to detect subpial cortical and deep gray matter lesions. Unenhanced T1-weighted imaging can reveal hypointense black holes, a measure of chronic neurodegeneration. Magnetization transfer imaging (MTI) is increasingly used to characterize the evolution of MS lesions and normal-appearing brain tissue. Evidence suggests that the dynamics of magnetization transfer changes correlate with the extent of demyelination and remyelination. Magnetic resonance spectroscopy, which provides details on tissue biochemistry, metabolism, and function, also has the capacity to reveal neuroprotective mechanisms. By measuring the motion of water, diffusion imaging can provide information about the orientation, size, and geometry of tissue damage in white and gray matter. These advanced non-conventional MRI techniques relate better to clinical impairment, disease progression, accumulation of disability, and have the potential to detect neuroprotective effects of treatment. Although detecting the status of neuronal integrity using MRI techniques continues to improve, a “gold standard” model remains to be established.

Cardiovascular risk factors are associated with increased lesion burden and brain atrophy in multiple sclerosis

Background Cardiovascular (CV) risk factors have been associated with changes in clinical outcomes in patients with multiple sclerosis (MS). Objectives To investigate the frequency of CV risks in patients with MS and their association with MRI outcomes. Methods In a prospective study, 326 patients with relapsing–remitting MS and 163 patients with progressive MS, 61 patients with clinically isolated syndrome (CIS) and 175 healthy controls (HCs) were screened for CV risks and scanned on a 3T MRI scanner. Examined CV risks included hypertension, heart disease, smoking, overweight/obesity and type 1 diabetes. MRI measures assessed lesion volumes (LVs) and brain atrophy. Association between individual or multiple CV risks and MRI outcomes was examined adjusting for age, sex, race, disease duration and treatment status. Results Patients with MS showed increased frequency of smoking (51.7% vs 36.5%, p=0.001) and hypertension (33.9% vs 24.7%, p=0.035) compared with HCs. In total, 49.9% of patients with MS and 36% of HCs showed ≥2 CV risks (p=0.003), while the frequency of ≥3 CV risks was 18.8% in the MS group and 8.6% in the HCs group (p=0.002). In patients with MS, hypertension and heart disease were associated with decreased grey matter (GM) and cortical volumes (p<0.05), while overweight/obesity was associated with increased T1-LV (p<0.39) and smoking with decreased whole brain volume (p=0.049). Increased lateral ventricle volume was associated with heart disease (p=0.029) in CIS. Conclusions Patients with MS with one or more CV risks showed increased lesion burden and more advanced brain atrophy.

Ventricular enlargement and mild cognitive impairment in early Parkinson's disease†

Mild cognitive impairment (MCI) may predict future development of dementia in Parkinsons disease (PD). We aimed to examine the extent of subcortical brain atrophy in patients with early PD with and without MCI compared to normal controls (NC). Participating in a population‐based study were 43 early, drug‐naïve PD patients and 41 NC. Eleven patients were classified with MCI (MCI PD) and 32 patients without (non‐MCI PD). Volumetric segmentation of 3D‐T1 weighted brain MRI was performed using FreeSurfer. Groups were compared applying MANCOVA corrected for total intracranial volume, age, and sex. Results showed that left inferior lateral ventricle and third ventricle volumes were significantly larger in MCI PD than in non‐MCI PD and NC. Fourth ventricular size in MCI PD was significantly different from NC and highly correlated with memory performance in MCI PD patients. This suggests that cognitive dysfunction in early PD may be associated with ventricular enlargement.

A serial 10-year follow-up study of brain atrophy and disability progression in RRMS patients

Background: We explored the evolution of brain atrophy in relation to development of confirmed disability progression (CDP) on serial 1.5T magnetic resonance imaging (MRI) scans over a 10-year period in 181 patients with early relapsing–remitting multiple sclerosis (RRMS). Methods: At 10-year follow-up, they were divided into those with (100) or without (76) CDP (confirmed after 48 weeks). Changes in whole brain (WB), cortical, gray matter (GM), white matter, and ventricular cerebrospinal fluid (vCSF) volumes were calculated on three-dimensional T1-weighted (3D-T1) scans between all available time points. Results: In multiple sclerosis (MS) patients with CDP compared to those without, the greatest effect size percentage volume change from baseline to follow-up was detected for WB (d = 0.55, −7.5% vs −5.2%, p < 0.001), followed by vCSF (d = 0.51, +41.1% vs +25.7%, p < 0.001), cortical (d = 0.49, −7.7% vs −6.2%, p = 0.001), and GM (d = 0.40, −7.1% vs −5.8%, p = 0.006) volumes. Mixed-effects model analysis, adjusted for age, sex, and treatment change, showed significant interactions between CDP status and percentage changes for WB and vCSF (p < 0.001), cortical (p = 0.02), and GM (p = 0.04) volumes. Conclusions: WB and cortical atrophy, and enlargement of vCSF spaces are associated with development of CDP on serial yearly MRI assessments over a period of 10 years.

Cognitive reserve moderates the impact of subcortical gray matter atrophy on neuropsychological status in multiple sclerosis.

Background: Cognitive decline is characterized in multiple sclerosis (MS), but the rate and severity vary. The reserve hypothesis proposes that baseline neurological differences impact cognitive outcome in neurodegenerative disease. Objective: To elucidate how brain reserve and cognitive reserve influence subcortical gray matter (SCGM) atrophy and cognitive decline in MS over 3 years. Methods: Seventy-one MS patients and 23 normal controls underwent magnetic resonance imaging and cognitive assessment at baseline and 3-year follow-up. The influence of reserve on cognitive processing speed (CPS) and memory was examined. Results: SCGM volume and cognitive scores were lower in MS than normal controls (P⩽0.001). Accounting for baseline, comparison of follow-up means yielded a difference between groups in SCGM volume (P<0.001) but not cognition (NS). Cognitive reserve (P=0.005), but not brain reserve, contributed to CPS, with only low cognitive reserve MS subjects showing decline in CPS (P=0.029). SCGM change predicted CPS outcome in MS with low cognitive reserve (P=0.002) but not high cognitive reserve. There were no effects in the domain of memory. Conclusions: SCGM atrophy occurs in normal controls, but significantly more so in MS. While CPS did not change in normal controls, low cognitive reserve was associated with CPS decline in MS. High cognitive reserve protect MS patients from cognitive decline related to SCGM atrophy.

Interdependence and contributions of sun exposure and vitamin D to MRI measures in multiple sclerosis

Purpose To assess the relationships of sun exposure history, supplementation and environmental factors to vitamin D levels in multiple sclerosis (MS) patients and to evaluate the associations between sun exposure and MRI measures. Methods This study included 264 MS patients (mean age 46.9±10 years, disease duration 14.6±10 years; 67.8% relapsing–remitting, 28% secondary progressive and 4.2% primary progressive MS) and 69 healthy controls. Subjects underwent neurological and 3 T MRI examinations, provided blood samples and answered questions to a structured questionnaire. Information on race, skin and eye colour, supplement use, body mass index (BMI) and sun exposure was obtained by questionnaire. The vitamin D metabolites (25-hydroxy vitamin D3, 1, 25-dihydroxy vitamin D3 and 24, 25-dihydroxy vitamin D3) were measured using mass spectrometry. Results Multivitamin supplementation (partial correlation rp=0.29, p<0.001), BMI (rp=−0.24, p=0.001), summer sun exposure (rp=0.22, p=0.002) and darker eye colour (rp=−0.18, p=0.015) had the strongest associations with vitamin D metabolite levels in the MS group. Increased summer sun exposure was associated with increased grey matter volume (GMV, rp=0.16, p=0.019) and whole brain volume (WBV, rp=0.20, p=0.004) after correcting for Extended Disability Status Scale in the MS group. Inclusion of 25-hydroxy vitamin D3 levels did not substantially affect the positive associations of sun exposure with WBV (rp=0.18, p=0.003) and GMV (rp=0.14, p=0.026) in the MS group. Conclusions Sun exposure may have direct effects on MRI measures of neurodegeneration in MS, independently of vitamin D.