Medulla oblongata volume: a biomarker of spinal cord damage and disability in multiple sclerosis

Neuroimaging assessment of facility-bound severely-affected MS reveals the critical role of cortical gray matter pathology: results from the CASA-MS case-controlled study

BACKGROUND

A subgroup of people with multiple sclerosis (pwMS) will develop severe disability. The pathophysiology underlying severe MS is unknown. The comprehensive assessment of severely affected MS (CASA-MS) was a case-controlled study that compared severely disabled in skilled nursing (SD/SN) (EDSS ≥ 7.0) to less-disabled (EDSS 3.0-6.5) community dwelling (CD) progressive pwMS, matched on age-, sex- and disease-duration (DDM).

OBJECTIVES

To identify neuroimaging and molecular biomarker characteristics that distinguish SD/SN from DDM-CD progressive pwMS.

METHODS

This study was carried at SN facility and at a tertiary MS center. The study collected clinical, molecular (serum neurofilament light chain, sNfL and glial acidic fibrillary protein, sGFAP) and MRI quantitative lesion-, brain volume-, and tissue integrity-derived measures. Statistical analyses were controlled for multiple comparisons.

RESULTS

42 SD/SN and 42 DDM-CD were enrolled. SD/SN pwMS showed significantly lower cortical volume (CV) (p < 0.001, d = 1.375) and thalamic volume (p < 0.001, d = 0.972) compared to DDM-CD pwMS. In a logistic stepwise regression model, the SD/SN pwMS were best differentiated from the DDM-CD pwMS by lower CV (p < 0.001) as the only significant predictor, with the accuracy of 82.3%. No significant differences between the two groups were observed for medulla oblongata volume, a proxy for spinal cord atrophy and white matter lesion burden, while there was a statistical trend for numerically higher sGFAP in SD/SN pwMS.

CONCLUSIONS

The CASA-MS study showed significantly more gray matter atrophy in severe compared to less-severe progressive MS.

Predictors of long-term disability in multiple sclerosis patients using routine magnetic resonance imaging data: A 15-year retrospective study

INTRODUCTION

Early identification of patients at high risk of progression could help with a personalised treatment strategy. Magnetic resonance imaging (MRI) measures have been proposed to predict long-term disability in multiple sclerosis (MS), but a reliable predictor that can be easily implemented clinically is still needed.

AIM

Assess MRI measures during the first 5 years of the MS disease course for the ability to predict progression at 10+ years.

METHODS

Eighty-two MS patients (53 females), with ≥10 years of clinical follow-up and having two MRI scans, were included. Clinical data were obtained at baseline, follow-up and at ≥10 years. White matter lesion (WML) counts and volumes, and four linear brain sizes were measured on T2/FLAIR 'Fluid-Attenuated-Inversion-Recovery' and T1-weighted images.

RESULTS

Baseline and follow-up inter-caudate diameter (ICD) and third ventricular width (TVW) measures correlated positively with Expanded Disability Status Scale, ≥10 or more of WMLs showed a high sensitivity in predicting progression, at ≥10 years. A steeper rate of lesion volume increase was observed in subjects converting to secondary progressive MS. The sensitivity and specificity of both ICD and TVW, to predict disability at ≥10 years were 60% and 64%, respectively.

CONCLUSION

Despite advances in brain imaging and computerised volumetric analysis, ICD and TVW remain relevant as they are simple, fast and have the potential in predicting long-term disability. However, in this study, despite the statistical significance of these measures, the clinical utility is still not reliable.

Design and Validation of an Expanded Disability Status Scale Model in Multiple Sclerosis

INTRODUCTION

We aimed to develop and validate an Expanded Disability Status Scale (EDSS) model through clinical, optical coherence tomography (OCT), and magnetic resonance imaging (MRI) measures.

METHODS

Sixty-four multiple sclerosis (MS) patients underwent peripapillary retinal nerve fiber layer and segmented macular layers evaluation through OCT (Spectralis, Heidelberg Engineering). Brain parenchymal fraction was quantified through Freesurfer, while cervical spinal cord (SC) volume was assessed manually guided by Spinal Cord Toolbox software analysis. EDSS, neuroradiological, and OCT assessment were carried out within 3 months. OCT parameters were calculated as the average of both nonoptic neuritis (ON) eyes, and in case the patient had previous ON, the value of the fellow non-ON eye was taken. Brain lesion volume, sex, age, disease duration, and history of disease-modifying treatment (1st or 2nd line disease-modifying treatments) were tested as covariables of the EDSS score.

RESULTS

EDSS values correlated with patient's age (r = 0.543, p = 0.001), SC volume (r = -0.301, p = 0.034), and ganglion cell layer (GCL, r = -0.354, p = 0.012). Using these correlations, an ordinal regression model to express probability of diverse EDSS scores were designed, the highest of which was the most probable (Nagelkerke R2 = 43.3%). Using EDSS cutoff point of 4.0 in a dichotomous model, compared to a cutoff of 2.0, permits the inclusion of GCL as a disability predictor, in addition to age and SC.

CONCLUSIONS

MS disability measured through EDSS is an age-dependent magnitude that is partly conditioned by SC and GCL. Further studies assessing paraclinical disability predictors are needed.

Intersection of Redox Chemistry and Ubiquitylation: Post-Translational Modifications Required for Maintaining Cellular Homeostasis and Neuroprotection

Neurodegeneration has been predominantly recognized as neuronal breakdown induced by the accumulation of aggregated and/or misfolded proteins and remains a preliminary factor in age-dependent disease. Recently, critical regulating molecular mechanisms and cellular pathways have been shown to induce neurodegeneration long before aggregate accumulation could occur. Although this opens the possibility of identifying biomarkers for early onset diagnosis, many of these pathways vary in their modes of dysfunction while presenting similar clinical phenotypes. With selectivity remaining difficult, it is promising that these neuroprotective pathways are regulated through the ubiquitin-proteasome system (UPS). This essential post-translational modification (PTM) involves the specific attachment of ubiquitin onto a substrate, specifically marking the ubiquitin-tagged protein for its intracellular fate based upon the site of attachment, the ubiquitin chain type built, and isopeptide linkages between different ubiquitin moieties. This review highlights both the direct and indirect impact ubiquitylation has in oxidative stress response and neuroprotection, and how irregularities in these intricate processes lead towards the onset of neurodegenerative disease (NDD).

Evolution of tongue somatosensory evoked potentials in people with multiple sclerosis

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A significant deterioration of the trigeminal sensory pathway function occurs in pwMS.

•

Cervical spinal cord lesions were negative predictor of tSSEP improvement.

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There is a moderate to high correlation between ordinal and quantitative tSSEP scores calculations.

Introduction

The aim of the present study was to investigate the long-term evolution of tongue somatosensory evoked potentials (tSSEP) in people with multiple sclerosis (pwMS).

Methods

Out of initial 121 participants, after two-year follow-up, the data were available for 74 and after four-year follow-up for 58 pwMS. In all pwMS complete neurological examination, brain MRI, cervical spinal cord MRI (if available) and tSSEP were performed at baseline visit (M0). Complete neurological examination and tSSEP were performed 2 and 4 years later (M24 and M48). tSSEP results were interpreted in the form of ordinal tSSEP score and quantitative tSSEP zscore calculated from the sum of z-transformed tSSEP latencies.

Results

Differences in tSSEP scores and tSSEP zscores in three different timepoints showed significant worsening of both scores over time. For the tSSEP score the difference was significant for M0-M24 and M0-M48 visits, but not for M24-M48 visits. For the tSSEP zscore the difference was significant for M0-M48 and M24-M48 visits, but not for M0-M24 visits. The only significant negative predictor found for the tSSEP score improvement was presence of cervical spinal cord lesions on the MRI. A moderate to high correlation was observed between both forms of tSSEP score at all three timepoints.

Conclusion

This study demonstrates a significant deterioration of trigeminal sensory pathway in MS over time, giving further insight into trigeminal system damage in pwMS.

African Americans experience disproportionate neurodegenerative changes in the medulla and upper cervical spinal cord in early multiple sclerosis

OBJECTIVE

To compare the temporal changes in the 3-dimensional (3D) structure of the medulla-upper cervical spinal cord region in African American (AA) and white multiple sclerosis (MS) patients to identify early patterns of anatomical change prior to progressive symptom development.

METHODS

Standardized 3-Tesla 3D brain MRI studies were performed at two time points on AA and white MS patients along with controls. Longitudinal changes in volume, surface area, tissue compliance, and surface texture measured in total and within ventral and dorsal compartments were studied. Independent regression models were constructed to evaluate differences between groups.

RESULTS

Thirty-five individuals were studied, 10 AA with MS (female (F): 8; median age [IQR]=33.8 years (y) [10.9], median disease duration: 11.8y [11.3]), 20 white MS patients (F: 10; 35.6y [17.4], 7.23y [8.83], and 5 controls (F: 2, 51.8y [10.2]). Expanded Disability Status Scale scores were 0.0 at baseline and at the second MRI time point. Within the medulla-upper cervical spinal cord, AA versus white MS patients exhibited greater rates of atrophy in total (p<0.0001) and within the ventral (p<0.0001) and dorsal (p<0.0001) compartments, reduced surface area (p<0.0001), and reduced tissue compliance in the ventral (p=0.002) and dorsal (p=0.0005) compartments. The rate of change at the dorsal surface, but not the ventral surface, between MRI time points was also greater in AA relative to white MS patients (p<0.0001).

CONCLUSION

Structural changes in distinct anatomical regions of the medulla-upper cervical spinal cord may be reflective of early and disproportionate neurodegeneration in AA MS as compared to whites.

MRI biomarkers of disease progression and conversion to secondary-progressive multiple sclerosis

INTRODUCTION

Conventional imaging measures remain a key clinical tool for the diagnosis multiple sclerosis (MS) and monitoring of patients. However, most measures used in the clinic show unsatisfactory performance in predicting disease progression and conversion to secondary progressive MS.

AREAS COVERED

Sophisticated imaging techniques have facilitated the identification of imaging biomarkers associated with disease progression, such as global and regional brain volume measures, and with conversion to secondary progressive MS, such as leptomeningeal contrast enhancement and chronic inflammation. The relevance of emerging imaging approaches partially overcoming intrinsic limitations of traditional techniques is also discussed.

EXPERT OPINION

Imaging biomarkers capable of detecting tissue damage early on in the disease, with the potential to be applied in multicenter trials and at an individual level in clinical settings, are strongly needed. Several measures have been proposed, which exploit advanced imaging acquisitions and/or incorporate sophisticated post-processing, can quantify irreversible tissue damage. The progressively wider use of high-strength field MRI and the development of more advanced imaging techniques will help capture the missing pieces of the MS puzzle. The ability to more reliably identify those at risk for disability progression will allow for earlier intervention with the aim to favorably alter the disease course.

Accurate, rapid and reliable, fully automated MRI brainstem segmentation for application in multiple sclerosis and neurodegenerative diseases

Neurodegenerative disorders, such as Alzheimer's disease (AD) and progressive forms of multiple sclerosis (MS), can affect the brainstem and are associated with atrophy that can be visualized by MRI. Anatomically accurate, large-scale assessments of brainstem atrophy are challenging due to lack of automated, accurate segmentation methods. We present a novel method for brainstem volumetry using a fully-automated segmentation approach based on multi-dimensional gated recurrent units (MD-GRU), a deep learning based semantic segmentation approach employing a convolutional adaptation of gated recurrent units. The neural network was trained on 67 3D-high resolution T1-weighted MRI scans from MS patients and healthy controls (HC) and refined using segmentations of 20 independent MS patients' scans. Reproducibility was assessed in MR test-retest experiments in 33 HC. Accuracy and robustness were examined by Dice scores comparing MD-GRU to FreeSurfer and manual brainstem segmentations in independent MS and AD datasets. The mean %-change/SD between test-retest brainstem volumes were 0.45%/0.005 (MD-GRU), 0.95%/0.009 (FreeSurfer), 0.86%/0.007 (manually edited segmentations). Comparing MD-GRU to manually edited segmentations the mean Dice scores/SD were: 0.97/0.005 (brainstem), 0.95/0.013 (mesencephalon), 0.98/0.006 (pons), 0.95/0.015 (medulla oblongata). Compared to the manual gold standard, MD-GRU brainstem segmentations were more accurate than FreeSurfer segmentations (p < .001). In the multi-centric acquired AD data, the mean Dice score/SD for the MD-GRU-manual segmentation comparison was 0.97/0.006. The fully automated brainstem segmentation method MD-GRU provides accurate, highly reproducible, and robust segmentations in HC and patients with MS and AD in 200 s/scan on an Nvidia GeForce GTX 1080 GPU and shows potential for application in large and longitudinal datasets.

Applying causal models to explore the mechanism of action of simvastatin in progressive multiple sclerosis

Understanding the mode of action of drugs is a challenge with conventional methods in clinical trials. Here, we aimed to explore whether simvastatin effects on brain atrophy and disability in secondary progressive multiple sclerosis (SPMS) are mediated by reducing cholesterol or are independent of cholesterol. We applied structural equation models to the MS-STAT trial in which 140 patients with SPMS were randomized to receive placebo or simvastatin. At baseline, after 1 and 2 years, patients underwent brain magnetic resonance imaging; their cognitive and physical disability were assessed on the block design test and Expanded Disability Status Scale (EDSS), and serum total cholesterol levels were measured. We calculated the percentage brain volume change (brain atrophy). We compared two models to select the most likely one: a cholesterol-dependent model with a cholesterol-independent model. The cholesterol-independent model was the most likely option. When we deconstructed the total treatment effect into indirect effects, which were mediated by brain atrophy, and direct effects, simvastatin had a direct effect (independent of serum cholesterol) on both the EDSS, which explained 69% of the overall treatment effect on EDSS, and brain atrophy, which, in turn, was responsible for 31% of the total treatment effect on EDSS [β = -0.037; 95% credible interval (CI) = -0.075, -0.010]. This suggests that simvastatin's beneficial effects in MS are independent of its effect on lowering peripheral cholesterol levels, implicating a role for upstream intermediate metabolites of the cholesterol synthesis pathway. Importantly, it demonstrates that computational models can elucidate the causal architecture underlying treatment effects in clinical trials of progressive MS.

Neuroplasticity of the sensorimotor neural network associated with walking aid training in people with multiple sclerosis

The objective of this pilot study was to identify neural descriptors and correlates of participation in a multicomponent walking aid program, the Assistive Device Selection, Training and Education Program (ADSTEP), in people with multiple sclerosis, as reflected by resting state functional MRI. Fourteen people with multiple sclerosis who used a walking aid at baseline and reported falling at least once in the prior year were recruited from the multiple sclerosis clinic in a Veterans Affairs and the surrounding community to participate in a trial of ADSTEP, a multicomponent program of walking aid selection, fitting and six weekly progressive task-oriented walking aid training sessions and undergo resting state functional brain MRI. The functional MRI was performed at baseline and at program completion to assess for changes in neural connectivity of the sensorimotor neural network. Compared to baseline, following ADSTEP participation, functional connectivity between the supplementary motor areas and both the primary somatosensory cortices and the putamen was increased; whereas functional connectivity between the supplementary motor areas and the cerebellum was decreased. This study provides preliminary support for supraspinal sensorimotor neuroplasticity in response to rehabilitation interventions such as task-oriented walking aid training, suggests specific neural targets for future mobility interventions, and supports the need for full-scale randomized controlled trials in this area.

Differential brainstem atrophy patterns in multiple sclerosis and neuromyelitis optica spectrum disorders

BACKGROUND

Multiple sclerosis (MS) and neuromyelitis optica spectrum disorders (NMOSD) are central nervous system (CNS) inflammatory demyelinating disorders. It is clinically important to distinguish MS from NMOSD, as treatment and prognosis differ. Brainstem involvement is common in both disorders.

PURPOSE

To investigate whether the patterns of brainstem atrophy on volumetric analysis in MS and NMOSD were different and correlated with clinical disability.

STUDY TYPE

Case-control cross-sectional study.

SUBJECTS

In all, 17 MS, 13 NMOSD, and 18 healthy control (HC) subjects were studied.

FIELD STRENGTH/SEQUENCE

T₁ -weighted and T₂ w spin-echo images were acquired with a 3T scanner.

ASSESSMENT

Semiautomated segmentation and volumetric measurement of brainstem regions were performed. Anatomical information was obtained from whole brain T₁ w images using a 3D magnetization-prepared rapid gradient-echo (MPRAGE) imaging sequence (TR/TE/T: 7.0/3.2/800 msec, voxel size: 1 × 1 × 1 mm³ , scan time: 10 min 41 sec).

STATISTICAL TESTS

Independent samples t-test, Mann-Whitney U-test, partial correlation, and multiple regression analysis.

RESULTS

Baseline characteristics were similar across the three groups, without significant difference in disease duration (P = 0.354) and EDSS score (P = 0.159) between MS and NMOSD subjects. Compared to HC, MS subjects had significantly smaller normalized whole brainstem (-5.2%, P = 0.027), midbrain (-8.3%, P = 0.0001), and pons volumes (-5.9%, P = 0.048), while only the normalized medulla volume was significantly smaller in NMOSD subjects compared to HC (-8.5% vs. HC, P = 0.024). Normalized midbrain volume was significantly smaller in MS compared to NMOSD subjects (-5.0%, P = 0.014), whereas normalized medulla volume was significantly smaller in NMOSD compared to MS subjects (-8.1%, P = 0.032). Partial correlations and multiple regression analysis revealed that smaller normalized whole brainstem, pons, and medulla oblongata volumes were associated with greater disability on the Expanded Disability Status Scale (EDSS), Functional System Score (FSS)-brainstem and FSS-cerebellar in NMOSD subjects.

DATA CONCLUSION

Differential patterns of brainstem atrophy were observed, with the midbrain being most severely affected followed by pons in MS, whereas only the medulla oblongata was affected in NMOSD.

LEVEL OF EVIDENCE

2 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1601-1609.

Assessing Repair in Multiple Sclerosis: Outcomes for Phase II Clinical Trials

Multiple Sclerosis (MS) pathology is complex and includes inflammatory processes, neurodegeneration, and demyelination. While multiple drugs have been developed to tackle MS-related inflammation, to date there is scant evidence regarding which therapeutic approach, if any, could be used to reverse demyelination, foster tissue repair, and thus positively impact on chronic disability. Here, we reviewed the current structural and functional markers (magnetic resonance imaging, positron emission tomography, optical coherence tomography, and visual evoked potentials) which could be used in phase II clinical trials of new compounds aimed to foster tissue repair in MS. Magnetic transfer ratio recovery in newly formed lesions currently represents the most widely used biomarker of tissue repair in MS, even if other markers, such as optical coherence tomography and positron emission tomography hold great promise to complement magnetic transfer ratio in tissue repair clinical trials. Future studies are needed to better characterize the different possible biomarkers to study tissue repair in MS, especially regarding their pathological specificity, sensitivity to change, and their relationship with disease activity.

The Role of Advanced Magnetic Resonance Imaging Techniques in Multiple Sclerosis Clinical Trials

Magnetic resonance imaging has been crucial in the development of anti-inflammatory disease-modifying treatments. The current landscape of multiple sclerosis clinical trials is currently expanding to include testing not only of anti-inflammatory agents, but also neuroprotective, remyelinating, neuromodulating, and restorative therapies. This is especially true of therapies targeting progressive forms of the disease where neurodegeneration is a prominent feature. Imaging techniques of the brain and spinal cord have rapidly evolved in the last decade to permit in vivo characterization of tissue microstructural changes, connectivity, metabolic changes, neuronal loss, glial activity, and demyelination. Advanced magnetic resonance imaging techniques hold significant promise for accelerating the development of different treatment modalities targeting a variety of pathways in MS.

How changes in brain activity and connectivity are associated with motor performance in people with MS

People with multiple sclerosis (MS) exhibit pronounced changes in brain structure, activity, and connectivity. While considerable work has begun to elucidate how these neural changes contribute to behavior, the heterogeneity of symptoms and diagnoses makes interpretation of findings and application to clinical practice challenging. In particular, whether MS related changes in brain activity or brain connectivity protect against or contribute to worsening motor symptoms is unclear. With the recent emergence of neuromodulatory techniques that can alter neural activity in specific brain regions, it is critical to establish whether localized brain activation patterns are contributing to (i.e. maladaptive) or protecting against (i.e. adaptive) progression of motor symptoms. In this manuscript, we consolidate recent findings regarding changes in supraspinal structure and activity in people with MS and how these changes may contribute to motor performance. Furthermore, we discuss a hypothesis suggesting that increased neural activity during movement may be either adaptive or maladaptive depending on where in the brain this increase is observed. Specifically, we outline preliminary evidence suggesting sensorimotor cortex activity in the ipsilateral cortices may be maladaptive in people with MS. We also discuss future work that could supply data to support or refute this hypothesis, thus improving our understanding of this important topic.

The Role of T1-Weighted Derived Measures of Neurodegeneration for Assessing Disability Progression in Multiple Sclerosis

Introduction

Multiple sclerosis (MS) is characterised by the accumulation of permanent neurological disability secondary to irreversible tissue loss (neurodegeneration) in the brain and spinal cord. MRI measures derived from T1-weighted image analysis (i.e., black holes and atrophy) are correlated with pathological measures of irreversible tissue loss. Quantifying the degree of neurodegeneration in vivo using MRI may offer a surrogate marker with which to predict disability progression and the effect of treatment. This review evaluates the literature examining the association between MRI measures of neurodegeneration derived from T1-weighted images and disability in MS patients.

Methods

A systematic PubMed search was conducted in January 2017 to identify MRI studies in MS patients investigating the relationship between “black holes” and/or atrophy in the brain and spinal cord, and disability. Results were limited to human studies published in English in the previous 10 years.

Results

A large number of studies have evaluated the association between the previous MRI measures and disability. These vary considerably in terms of study design, duration of follow-up, size, and phenotype of the patient population. Most, although not all, have shown that there is a significant correlation between disability and black holes in the brain, as well as atrophy of the whole brain and grey matter. The results for brain white matter atrophy are less consistently positive, whereas studies evaluating spinal cord atrophy consistently showed a significant correlation with disability. Newer ways of measuring atrophy, thanks to the development of segmentation and voxel-wise methods, have allowed us to assess the involvement of strategic regions of the CNS (e.g., thalamus) and to map the regional distribution of damage. This has resulted in better correlations between MRI measures and disability and in the identification of the critical role played by some CNS structures for MS clinical manifestations.

Conclusion

The evaluation of MRI measures of atrophy as predictive markers of disability in MS is a highly active area of research. At present, measurement of atrophy remains within the realm of clinical studies, but its utility in clinical practice has been recognized and barriers to its implementation are starting to be addressed.

Brain Parenchymal Fraction in Healthy Adults-A Systematic Review of the Literature

Brain atrophy is an important feature of many neurodegenerative disorders. It can be described in terms of change in the brain parenchymal fraction (BPF). In order to interpret the BPF in disease, knowledge on the BPF in healthy individuals is required. The aim of this study was to establish a normal range of values for the BPF of healthy individuals via a systematic review of the literature. The databases PubMed and Scopus were searched and 95 articles, including a total of 9269 individuals, were identified including the required data. We present values of BPF from healthy individuals stratified by age and post-processing method. The mean BPF correlated with mean age and there were significant differences in age-adjusted mean BPF between methods. This study contributes to increased knowledge about BPF in healthy individuals, which may assist in the interpretation of BPF in the setting of disease. We highlight the differences between post-processing methods and the need for a consensus gold standard.

New Magnetic Resonance Imaging Features Predictive for Post-Treatment Ambulatory Function: Imaging Analysis of Metastatic Spinal Cord Compression

STUDY DESIGN

This is a retrospective, single-institute, radiographical study.

OBJECTIVE

The study aimed to determine the correlation of magnetic resonance imaging (MRI) findings observed in metastatic spinal cord compression (MSCC) with post-treatment ambulatory status.

SUMMARY OF BACKGROUND DATA

Previous studies have reported various predictors of ambulatory outcome in patients with MSCC, but the relationship between the MRI features and post-treatment ambulatory function remains to be elucidated.

METHODS

Fifty-six hospitalized patients with MSCC and risk of MSCC were examined using MRI before therapeutic intervention. Circumferential ratio of cord compression (CRCC), clock position of compression, cross-sectional area (CSA), and change in signal intensity of the spinal cord were recorded. Each imaging feature was analyzed statistically regarding unassisted ambulatory status at the time of hospital discharge as the endpoint.

RESULTS

CRCC showed a prognostic value for post-treatment ambulatory function. More than half of CRCC predicted poor functional prognosis with statistical significance. However, the site of cord compression expressed by clock position on axial plane showed no relationship with functional prognosis. CSA of the spinal cord was enlarged in 23% of patients at the level of MSCC, which indicated that cord compression could also be formed by a relative relationship between cord swelling and surrounding mass effect. The said patients showed a better functional outcome. High intensity of the spinal cord on T2-weighted sagittal image was not useful because of lack of inter-rater reliability.

CONCLUSION

CRCC on axial T2 image can guide clinicians to identify cancer patients at risk of paraplegia because of MSCC. More than half of CRCC entails urgent treatment despite preserved ambulatory function. Furthermore, some cases of MSCC accompany increased cord CSA. The measurement is also a useful guide to balance the risk and benefit of systemic steroid therapy. MRI is the key imaging modality in the risk assessment of MSCC.

LEVEL OF EVIDENCE

4.

Spinal cord MRI in multiple sclerosis--diagnostic, prognostic and clinical value

Multiple sclerosis (MS) is an inflammatory disorder of the CNS that affects both the brain and the spinal cord. MRI studies in MS focus more often on the brain than on the spinal cord, owing to the technical challenges in imaging this smaller, mobile structure. However, spinal cord abnormalities at disease onset have important implications for diagnosis and prognosis. Furthermore, later in the disease course, in progressive MS, myelopathy becomes the primary characteristic of the clinical presentation, and extensive spinal cord pathology--including atrophy, diffuse abnormalities and numerous focal lesions--is common. Recent spinal cord imaging studies have employed increasingly sophisticated techniques to improve detection and quantification of spinal cord lesions, and to elucidate their relationship with physical disability. Quantitative MRI measures of cord size and tissue integrity could be more sensitive to the axonal loss and other pathological processes in the spinal cord than is conventional MRI, putting quantitative MRI in a key role to elucidate the association between disability and spinal cord abnormalities seen in people with MS. In this Review, we summarize the most recent MS spinal cord imaging studies and discuss the new insights they have provided into the mechanisms of neurological impairment. Finally, we suggest directions for further and future research.

Cervical cord area measurement using volumetric brain magnetic resonance imaging in multiple sclerosis

BACKGROUND

In multiple sclerosis (MS), recent work suggests that cervical cord atrophy is more consistently correlated with physical disability than brain white matter lesion load and atrophy. Although spinal cord imaging has not been routinely obtained in many clinical trial and research studies, brain volumetric imaging usually has and includes the upper cervical cord.

OBJECTIVES

Using volumetric T1-weighted brain images, we investigated cross-sectional area measures in the uppermost cervical cord and compared them with areas at the standard C2/3 level.

METHODS

Using T1-weighted brain scans from 13 controls and 37 people with MS, and an active surface technique, cross-sectional area was measured over 5mm and 1mm cord segments at C2/3, below the level of odontoid peg, and 2cm and 2.5cm below the pons. Brain volume was also measured.

RESULTS

Cord area measurements were most reliable in a 5mm segment 2.5cm below the pons (inter-rater coefficient of variation 1.5%, intraclass correlation coefficient 0.99). Cord area at this level correlated more with that at C2/3 area than with brain volume (r=0.811 with C2/3, r=0.502 with brain volume).

CONCLUSION

Whereas the standard C2/3 level is often not within the field of view on brain images, the level 2.5cm below the pons usually is, and measurement at this level may be a good way to investigate upper cervical cord atrophy when only brain images are available.

Brain size and white matter content of cerebrospinal tracts determine the upper cervical cord area: evidence from structural brain MRI

INTRODUCTION

Measurement of the upper cervical cord area (UCCA) from brain MRI may be an effective way to quantify spinal cord involvement in neurological disorders such as multiple sclerosis. However, knowledge on the determinants of UCCA in healthy controls (HCs) is limited.

METHODS

In two cohorts of 133 and 285 HCs, we studied the influence of different demographic, body-related, and brain-related parameters on UCCA by simple and partial correlation analyses as well as by voxel-based morphometry (VBM) across both cerebral gray matter (GM) and white matter (WM).

RESULTS

First, we confirmed the known but moderate effect of age on UCCA in the older cohort. Second, we studied the correlation of UCCA with sex, body height, and total intracranial volume (TIV). TIV was the only variable that correlated significantly with UCCA after correction for the other variables. Third, we studied the correlation of UCCA with brain-related parameters. Brain volume correlated stronger with UCCA than TIV. Both volumes of the brain tissue compartments GM and WM correlated with UCCA significantly. WM volume explained variance of UCCA after correction for GM volume, whilst the opposite was not observed. Correspondingly, VBM did not yield any brain region, whose GM content correlated significantly with UCCA, whilst cerebral WM content of cerebrospinal tracts strongly correlated with UCCA. This latter effect increased along a craniocaudal gradient.

CONCLUSION

UCCA is mainly determined by brain volume as well as by WM content of cerebrospinal tracts.

Revisiting brain atrophy and its relationship to disability in multiple sclerosis

Background

Brain atrophy is a well-accepted imaging biomarker of multiple sclerosis (MS) that partially correlates with both physical disability and cognitive impairment.

Methodology/Principal Findings

Based on MRI scans of 60 MS cases and 37 healthy volunteers, we measured the volumes of white matter (WM) lesions, cortical gray matter (GM), cerebral WM, caudate nucleus, putamen, thalamus, ventricles, and brainstem using a validated and completely automated segmentation method. We correlated these volumes with the Expanded Disability Status Scale (EDSS), MS Severity Scale (MSSS), MS Functional Composite (MSFC), and quantitative measures of ankle strength and toe sensation. Normalized volumes of both cortical and subcortical GM structures were abnormally low in the MS group, whereas no abnormality was found in the volume of the cerebral WM. High physical disability was associated with low cerebral WM, thalamus, and brainstem volumes (partial correlation coefficients ∼0.3–0.4) but not with low cortical GM volume. Thalamus volumes were inversely correlated with lesion load (r = −0.36, p<0.005).

Conclusion

The GM is atrophic in MS. Although lower WM volume is associated with greater disability, as might be expected, WM volume was on average in the normal range. This paradoxical result might be explained by the presence of coexisting pathological processes, such as tissue damage and repair, that cause both atrophy and hypertrophy and that underlie the observed disability.

The relationships among MRI-defined spinal cord involvement, brain involvement, and disability in multiple sclerosis

OBJECTIVE

To determine the interrelationships between MRI-defined lesion and atrophy measures of spinal cord involvement and brain involvement and their relationships to disability in a small cohort of patients with multiple sclerosis (MS).

BACKGROUND

Although it is known that cervical spinal cord atrophy correlates with disability in MS, it is unknown whether it is the most important determinant when compared to other regions of the central nervous system (CNS). Furthermore, it is not clear to what extent brain and cord lesions and atrophy are related.

DESIGN AND METHODS

3T MRI of the whole brain and whole spinal cord was obtained in 21 patients with MS, including 18 with relapsing-remitting, one with secondary progressive, one with primary progressive, and one with a clinically isolated syndrome. Brain global gray and white matter volumes were segmented with Statistical Parametric Mapping 8. Spinal cord contour volume was segmented in whole by a semi-automated method with bins assigned to either the cervical or thoracic regions. All CNS volumes were normalized by the intracranial volume. Brain and cord T2 hyperintense lesions were segmented using a semi-automated edge finding tool.

RESULTS

Among all MRI measures, only upper cervical spinal cord volume significantly correlated with Expanded Disability Status Scale score (r =-.515, P = .020). The brain cord relationships between whole or regional spinal cord volume or lesions and gray matter, white matter, or whole brain volume or whole brain lesions were generally weak and all nonsignificant.

CONCLUSIONS AND RELEVANCE

In this preliminary study of mildly disabled, treated MS patients, cervical spinal cord atrophy most strongly correlates with physical disability in MS when accounting for a wide range of other CNS measures of lesions and atrophy, including thoracic or whole spinal cord volume, and cerebral gray, white or whole brain volume. The weak relationship between spinal cord and brain lesions and atrophy may suggest that they progress rather independently in patients with MS.

Direct in vivo measurement of glycine and the neurochemical profile in the rat medulla oblongata

The medulla oblongata (MO) contains a high density of glycinergic synapses and a particularly high concentration of glycine. The aims of this study were to measure directly in vivo the neurochemical profile, including glycine, in MO using a spin-echo-based (1)H MRS sequence at TE = 2.8 ms and to compare it with three other brain regions (cortex, striatum and hippocampus) in the rat. Glycine was quantified in MO at TE = 2.8 ms with a Cramér-Rao lower bound (CRLB) of approximately 5%. As a result of the relatively low level of glycine in the other three regions, the measurement of glycine was performed at TE = 20 ms, which provides a favorable J-modulation of overlapping myo-inositol resonance. The other 14 metabolites composing the neurochemical profile were quantified in vivo in MO with CRLBs below 25%. Absolute concentrations of metabolites in MO, such as glutamate, glutamine, γ-aminobutyrate, taurine and glycine, were in the range of previous in vitro quantifications in tissue extracts. Compared with the other regions, MO had a three-fold higher glycine concentration, and was characterised by reduced (p < 0.001) concentrations of glutamate (-50 ± 4%), glutamine (-54 ± 3%) and taurine (-78 ± 3%). This study suggests that the functional specialisation of distinct brain regions is reflected in the neurochemical profile.

Regional white matter atrophy--based classification of multiple sclerosis in cross-sectional and longitudinal data

BACKGROUND AND PURPOSE

The different clinical subtypes of multiple sclerosis (MS) may reflect underlying differences in affected neuroanatomic regions. Our aim was to analyze the effectiveness of jointly using the inferior subolivary medulla oblongata volume (MOV) and the cross-sectional area of the corpus callosum in distinguishing patients with relapsing-remitting multiple sclerosis (RRMS), secondary-progressive multiple sclerosis (SPMS), and primary-progressive multiple sclerosis (PPMS).

MATERIALS AND METHODS

We analyzed a cross-sectional dataset of 64 patients (30 RRMS, 14 SPMS, 20 PPMS) and a separate longitudinal dataset of 25 patients (114 MR imaging examinations). Twelve patients in the longitudinal dataset had converted from RRMS to SPMS. For all images, the MOV and corpus callosum were delineated manually and the corpus callosum was parcellated into 5 segments. Patients from the cross-sectional dataset were classified as RRMS, SPMS, or PPMS by using a decision tree algorithm with the following input features: brain parenchymal fraction, age, disease duration, MOV, total corpus callosum area and areas of 5 segments of the corpus callosum. To test the robustness of the classification technique, we applied the results derived from the cross-sectional analysis to the longitudinal dataset.

RESULTS

MOV and central corpus callosum segment area were the 2 features retained by the decision tree. Patients with MOV >0.94 cm(3) were classified as having RRMS. Patients with progressive MS were further subclassified as having SPMS if the central corpus callosum segment area was <55.12 mm(2), and as having PPMS otherwise. In the cross-sectional dataset, 51/64 (80%) patients were correctly classified. For the longitudinal dataset, 88/114 (77%) patient time points were correctly classified as RRMS or SPMS.

CONCLUSIONS

Classification techniques revealed differences in affected neuroanatomic regions in subtypes of multiple sclerosis. The combination of central corpus callosum segment area and MOV provides good discrimination among patients with RRMS, SPMS, and PPMS.

The challenge of multiple sclerosis: how do we cure a chronic heterogeneous disease?

Multiple sclerosis is (MS) a T-cell autoimmune disease characterized by a relapsing-remitting followed by a progressive phase. Relapses are driven by the adaptive immune system and involve waves of T helper cell 1 (Th1), Th17, and CD8 cells that infiltrate the nervous system and provoke a attack. These cells are modulated by regulatory T and B cells. Infiltration of T cells into the nervous system initiates a complex immunological cascade consisting of epitope spreading, which triggers new attacks, and activation of the innate immune system (microglia, dendritic cells, astrocytes, B cells), which leads to chronic inflammation. The secondary progressive phase is due to neurodegeneration triggered by inflammation and is driven by the innate immune system. Why a shift to the progressive stage occurs and how to prevent it is a central question in MS. Effective treatment of MS must affect multiple disease pathways: suppression of proinflammatory T cells, induction of regulatory T cells, altering traffic of cells into the nervous system, protecting axons and myelin, and controlling innate immune responses. Without biomarkers, the clinical and pathological heterogeneity of MS makes treatment difficult. Treatment is further hampered by untoward adverse effects caused by immune suppression. Nonetheless, major progress has been made in the understanding and treatment of MS. There are three definitions of cure as it applies to MS: (1) halt progression of disease, (2) reverse neurological deficits, and (3) prevent MS. Although the pathways to each of these cures are linked, each requires a unique strategy.

No volume difference of medulla oblongata between young and old Korean people

The purpose of this study was to determine the effects of aging and gender on the volumes of total brain, brainstem, cerebellum and lateral ventricle of healthy Koreans by magnetic resonance imaging (MRI). Using three-dimensional MRI volumetry, we compared the volumes of various brain regions according to age and gender in 115 healthy Koreans. There were significant differences in the volumes of midbrain, cerebellum and lateral ventricle, whereas those of brainstem and medulla showed no differences between old-age group and young-age group. Men have larger volume of medulla than women. Age-related differences in the volumes of total brain and pons were significantly larger in men than women.