Central Nervous System Atrophy Research Articles

Measurement of Brain and Spinal Cord Atrophy by Magnetic Resonance Imaging as a Tool to Monitor Multiple Sclerosis

Evaluation of brain and spinal cord atrophy by magnetic resonance imaging (MRI) has become an increasingly important component of understanding the multiple sclerosis (MS) disease process. These destructive aspects of the disease develop early in the disease course. A growing body of data links brain and spinal cord atrophy to clinical impairment more closely than can be linked with conventional measures of overt lesions. Thus, irreversible tissue damage may be a key factor leading to disease progression. In this review, the authors present the proposed mechanisms leading to central nervous system (CNS) atrophy. They describe the available MRI-based techniques to measure regional and global atrophy of the brain and spinal cord. They compare the rate of atrophy among MS phenotypes and summarize the emerging data linking atrophy to neurological and neuropsychological impairment. Finally, they discuss the effect of disease-modifying immunotherapies on the rate of CNS atrophy in patients with MS. Future research to clarify the etiology and pathophysiology of brain and spinal cord atrophy should provide new targets for therapeutic development.

Central nervous system atrophy and clinical status in multiple sclerosis.

In this review, the authors focus on clinical aspects of central nervous system (CNS) atrophy in multiple sclerosis (MS), including the relationship between atrophy and disability, disease course, disease duration, quality of life, and fatigue. Cross-sectional studies have demonstrated a moderate but significant correlation between brain or spinal cord atrophy and physical disability in patients with MS. Longitudinal studies (>/= 5 years) have shown that CNS atrophy is a significant predictor of subsequent long-term neurologic deterioration. The clinical relevance of CNS atrophy is reinforced by studies showing that atrophy accounts for more variance than conventional lesion measures in predicting disability. Impaired quality of life and both urodynamic and sexual dysfunction, but not fatigue, are associated with brain atrophy. It is likely that once the level of CNS atrophy reaches a critical threshold, patients begin to suffer clinical impairment and disease progression. Longitudinal studies suggest that CNS atrophy may occur in patients with clinically isolated demyelinating syndromes who are at high risk for developing clinically definite MS. Longitudinal natural history studies in relapsing-remitting, secondary progressive, and primary progressive MS have suggested that patients develop CNS atrophy at a faster rate in the first few years of disease than later in the disease course. Similarly, long-term follow-up studies have shown a poor relationship between disease duration and the rate of brain atrophy. The authors conclude that measurement of atrophy of the CNS is emerging as a clinically relevant biomarker of the MS disease process.

Central Nervous System Atrophy and Clinical Status in Multiple Sclerosis

ABSTRACTIn this review, the authors focus on clinical aspects of central nervous system (CNS) atrophy in multiple sclerosis (MS), including the relationship between atrophy and disability, disease course, disease duration, quality of life, and fatigue. Crosssectional studies have demonstrated a moderate but significant correlation between brain or spinal cord atrophy and physical disability in patients with MS. Longitudinal studies ([.greaterequal] 5 years) have shown that CNS atrophy is a significant predictor of subsequent long‐term neurologic deterioration. The clinical relevance of CNS atrophy is reinforced by studies showing that atrophy accounts for more variance than conventional lesion measures in predicting disability. Impaired quality of life and both urodynamic and sexual dysfunction, but not fatigue, are associated with brain atrophy. It is likely that once the level of CNS atrophy reaches a critical threshold, patients begin to suffer clinical impairment and disease progression. Longitudinal studies suggest that CNS atrophy may occur in patients with clinically isolated demyelinating syndromes who are at high risk for developing clinically definite MS. Longitudinal natural history studies in relapsing‐remitting, secondary progressive, and primary progressive MS have suggested that patients develop CNS atrophy at a faster rate in the first few years of disease than later in the disease course. Similarly, long‐term follow‐up studies have shown a poor relationship between disease duration and the rate of brain atrophy. The authors conclude that measurement of atrophy of the CNS is emerging as a clinically relevant biomarker of the MS disease process.

Atrophy of the Brain and Spinal Cord in Multiple Sclerosis

ABSTRACTThe destructive nature of the multiple sclerosis disease process is of growing clinical and neuroscientific interest. Axonal transection, neuronal loss, Wallerian degeneration, and chronic demyelination likely contribute to macroscopic atrophy of the brain and spinal cord in patients with the disease. This neurodegenerative process belies the traditional view of multiple sclerosis as an inflammatory demyelinating disease. Magnetic resonance imaging is a key tool in the diagnosis and longitudinal monitoring of central nervous system atrophy. This supplement to theJournal of Neuroimaging is devoted to brain and spinal cord atrophy in MS, with a focus on the role of magnetic resonance imaging. The authors and topics of the articles have been chosen by the Guest Editor to provide a state‐of‐the‐art review of this important field. An emphasis is placed on several key issues pertaining to central nervous system atrophy in multiple sclerosis: pathogenesis, magnetic resonance imaging techniques for quantification, clinical relevance, and effects of disease‐modifying therapies.

Pathogenesis of Brain and Spinal Cord Atrophy in Multiple Sclerosis

ABSTRACTFor more than a century, multiple sclerosis was viewed as a disease process characterized by oligodendrocyte and myelin loss, and research into the pathogenesis of multiple sclerosis was mainly focused on the mechanisms of inflammation. However, with development of more sophisticated neuroimaging and molecular biology techniques, attention has shifted to new aspects of pathogenesis of multiple sclerosis: axonal loss and neurodegeneration. Evidence is increasing that tissue destruction, primarily axonal loss and neurodegeneration, is a key element in the pathogenesis of multiple sclerosis. In addition, it is now known that brain and spinal cord atrophy begins early in the disease process of multiple sclerosis and advances relentlessly throughout the course of the disease. Cumulative data suggest that axonal loss is the major determinant of progressive neuro logic disability in patients with multiple sclerosis. Magnetic resonance imaging and magnetic resonance spectroscopy in patients with multiple sclerosis for < 5 years indicate brain atrophy and loss of axonal integrity. Neurodegeneration and axonal loss in patients with multiple sclerosis are initially accompanied by a local response from oligodendrocyte progenitor cells and some remyelination. However, these repair mechanisms eventually fail, and patients typically develop generalized brain atrophy, cognitive decline, and permanent disability. Although the exact mechanisms underlying central nervous system atrophy in patients with multiple sclerosis are largely unknown, evidence exists that atrophy may represent an epiphenomenon related to the effects of dynamic inflammation within the central nervous system, including demyelination, axonal injury, neuronal loss, Wallerian degeneration, and possibly iron deposition. This article summarizes the potential mechanisms involved in central nervous system atrophy in patients with multiple sclerosis.

Pathogenesis of brain and spinal cord atrophy in multiple sclerosis.

For more than a century, multiple sclerosis was viewed as a disease process characterized by oligodendrocyte and myelin loss, and research into the pathogenesis of multiple sclerosis was mainly focused on the mechanisms of inflammation. However, with development of more sophisticated neuroimaging and molecular biology techniques, attention has shifted to new aspects of pathogenesis of multiple sclerosis: axonal loss and neurodegeneration. Evidence is increasing that tissue destruction, primarily axonal loss and neurodegeneration, is a key element in the pathogenesis of multiple sclerosis. In addition, it is now known that brain and spinal cord atrophy begins early in the disease process of multiple sclerosis and advances relentlessly throughout the course of the disease. Cumulative data suggest that axonal loss is the major determinant of progressive neurologic disability in patients with multiple sclerosis. Magnetic resonance imaging and magnetic resonance spectroscopy in patients with multiple sclerosis for < 5 years indicate brain atrophy and loss of axonal integrity. Neurodegeneration and axonal loss in patients with multiple sclerosis are initially accompanied by a local response from oligodendrocyte progenitor cells and some remyelination. However, these repair mechanisms eventually fail, and patients typically develop generalized brain atrophy, cognitive decline, and permanent disability. Although the exact mechanisms underlying central nervous system atrophy in patients with multiple sclerosis are largely unknown, evidence exists that atrophy may represent an epiphenomenon related to the effects of dynamic inflammation within the central nervous system, including demyelination, axonal injury, neuronal loss, Wallerian degeneration, and possibly iron deposition. This article summarizes the potential mechanisms involved in central nervous system atrophy in patients with multiple sclerosis.

Magnetic Resonance Imaging Surrogates of Multiple Sclerosis Pathology and Their Relationship to Central Nervous System Atrophy

This article focuses on the various magnetic resonance imaging metrics currently used in multiple sclerosis and discusses how they relate to central nervous system atrophy. The authors discuss the significance of T2 lesion burden, gray matter damage, T1 hypointense lesions (black holes), contrast-enhanced lesions, magnetization transfer imaging, diffusion imaging, and magnetic resonance spectroscopy. These magnetic resonance imaging surrogates exhibit different sensitivities for each of the underlying pathogenic processes of multiple sclerosis. By exploiting the complementary nature and varying sensitivities of these magnetic resonance imaging surrogates, it is possible to create a more comprehensive picture of the degenerative process of multiple sclerosis.

Magnetic Resonance Imaging Surrogates of Multiple Sclerosis Pathology and Their Relationship to Central Nervous System Atrophy

ABSTRACTThis article focuses on the various magnetic resonance imaging metrics currently used in multiple sclerosis and discusses how they relate to central nervous system atrophy. The authors discuss the significance of T2 lesion burden, gray matter damage, T1 hypointense lesions (black holes), contrast‐enhanced lesions, magnetization transfer imaging, diffusion imaging, and magnetic resonance spectroscopy. These magnetic resonance imaging surrogates exhibit different sensitivities for each of the underlying pathogenic processes of multiple sclerosis. By exploiting the complementary nature and varying sensitivities of these magnetic resonance imaging surrogates, it is possible to create a more comprehensive picture of the degenerative process of multiple sclerosis.

Role of MRI in multiple sclerosis II: brain and spinal cord atrophy.

A growing body of evidence indicates that irreversible tissue destruction including axonal and neuronal degeneration is a key component of the multiple sclerosis (MS) disease process. Magnetic resonance imaging (MRI) is a powerful technique that can be combined with semiautomated or automated computer assisted analysis approaches to detect progressive atrophy of the brain and spinal cord with high sensitivity and reproducibility. The pathophysiology of central nervous system (CNS) atrophy in MS is unknown but likely represents an epiphenomenon related to the effects of inflammation including chronic demyelination, axonal injury, neuronal loss and Wallerian degeneration. Other factors that may contribute to tissue atrophy include injury to the normal appearing gray and white matter by mechanisms such as loss of growth factors, altered electrical conduction and pathologic iron deposition. Prospective studies have suggested that atrophy in MS is predicted by previous inflammatory activity as measured by overt MRI lesions. Gadolinium (Gd)-enhancing lesions have shown a particularly strong predictive value in some but not all longitudinal studies of brain atrophy. Brain atrophy has also been related in cross-sectional and longitudinal studies to T2-hypointense lesions in deep grey matter, suggesting a link between tissue iron deposition and atrophy. The measurement of brain atrophy seems to be of growing clinical relevance as a biomarker of the MS disease process. Atrophy should now be included as a secondary endpoint in trials of therapies aimed at limiting disease progression. Currently available anti-inflammatory immunomodulatory agents and immunosuppressive treatments, while effective at preventing clinical deterioration, have shown at best partial effects in preventing CNS atrophy. Thus, there is a need to further validate atrophy as an outcome measure and ultimately develop treatment strategies that will protect against the destructive aspects of the disease process. This should in turn lead to better long term neurologic functioning and a better quality of life for patients with MS.

The role of nonconventional magnetic resonance imaging techniques in demyelinating disorders.

The use of nonconventional magnetic resonance imaging techniques (eg, magnetization transfer, magnetic resonance spectroscopy, and diffusion weighted imaging) allows for an accurate characterization of lesions as compared with conventional or standard approaches in demyelinating diseases. Magnetization transfer, magnetic resonance spectroscopy, and diffusion weighted imaging have revolutionized our understanding of demyelinating diseases because these techniques have been used to identify pathologic changes of normal-appearing brain tissue and characterize the differences in lesions. Metrics derived from these methods correlate with clinical disability and provide more accurate tools for monitoring disease activity and treatment effect over time. Quantitative T1 and T2 relaxation time maps provide additional information on demyelinating diseases, allowing for the evaluation of myelin water and distribution of water within tissues. Finally, the measurement of central nervous system atrophy has become a valuable element in determining the course of multiple sclerosis.

Congenital muscular dystrophy and severe central nervous system atrophy in two siblings

Congenital muscular dystrophy and severe central nervous system atrophy in two siblings