Serial MRI in multiple sclerosis: a prospective pilot study of lesion load, whole brain volume and thalamic atrophy

Measuring brain atrophy in multiple sclerosis

The last decade has seen the development of methods that use conventional magnetic resonance imaging (MRI) to provide sensitive and reproducible assessments of brain volumes. This has increased the interest in brain atrophy measurement as a reliable indicator of disease progression in many neurological disorders, including multiple sclerosis (MS). After a brief introduction in which we discuss the most commonly used methods for assessing brain atrophy, we will review the most relevant MS studies that have used MRI-based quantitative measures of brain atrophy, the clinical importance of these results, and the potential for future application of these measures to understand MS pathology and progression. Despite the number of issues that still need to be solved, the measurement of brain atrophy by MRI is sufficiently precise and accurate. It represents one of most promising in vivo measures of neuroaxonal degeneration in MS, and it should be used extensively in the future to assess and monitor pathological evolution and treatment efficacy in this disease.

Magnetic resonance imaging measures of brain atrophy in multiple sclerosis

Magnetic resonance imaging (MRI) has been widely used to diagnose and monitor multiple sclerosis (MS). Although MRI-visible lesions are a key feature of MS, they are thought to correlate poorly with clinical progression. Neurodegeneration is increasingly being recognized as an important factor in the pathogenesis of MS, and MRI measures of brain atrophy have been suggested as surrogate markers of neuroaxonal loss and disease progression. This pathology may be more relevant to the progression of disability than focal inflammation. A number of MRI-based methods have been developed for the measurement of global and regional brain atrophy. Natural-history studies of MS and clinically isolated syndromes suggestive of MS have observed atrophy in these subjects above that seen in controls, over periods ranging from three months to years. Brain atrophy has also been incorporated as an outcome measure in therapeutic trials of disease-modifying treatments. This paper considers neuroaxonal loss and the pathological basis of brain atrophy, methods developed to quantify brain atrophy, the findings of natural-history and therapeutic studies, the relationship of brain atrophy to disability and cognition, and the future research directions and clinical applications of brain atrophy measurements.

The measurement and clinical relevance of brain atrophy in multiple sclerosis

Brain atrophy has emerged as a clinically relevant component of disease progression in multiple sclerosis. Progressive loss of brain tissue bulk can be detected in vivo in a sensitive and reproducible manner by MRI. Clinical studies have shown that brain atrophy begins early in the disease course. The increasing amount of data linking brain atrophy to clinical impairments suggest that irreversible tissue destruction is an important determinant of disease progression to a greater extent than can be explained by conventional lesion assessments. In this review, we will summarise the proposed mechanisms contributing to brain atrophy in patients with multiple sclerosis. We will critically discuss the wide range of MRI-based methods used to quantify regional and whole-brain-volume loss. Based on a review of current information, we will summarise the rate of atrophy among phenotypes for multiple sclerosis, the clinical relevance of brain atrophy, and the effect of disease-modifying treatments on its progression.

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.

Demyelinated neocortical lesions in marmoset autoimmune encephalomyelitis mimic those in multiple sclerosis

The use of immunohistochemical methods has led to a new understanding of the prevalence and significance of cortical lesions in multiple sclerosis but these lesions have not yet been formally described in an animal model. In this study we have set out to use immunohistochemical techniques to identify and describe cortical lesions in marmosets with experimental autoimmune encephalomyelitis (EAE). Using antibodies to proteolipid protein (PLP), we found a total of 70 cortical lesions in 11 tissue blocks from 6 animals. These lesions were subdivided into leucocortical (40), intracortical (12) and subpial lesions (18). We quantified the density of inflammatory cells within lesions using a double labelling protocol which employed anti-PLP in addition to antibodies against markers of B-lymphocytes (CD20), T-lymphocytes (CD3), macrophages (MAC387) and MHC-II expressing cells (CR3/43). This analysis revealed that the large subpial lesions accounted for the majority of demyelinated cortex (88%) despite possessing the lowest density of inflammatory cells. This study has shown that lesions in this model share many of the major features of cortical lesions in multiple sclerosis both in terms of morphology and inflammatory cell content. We believe that this tool can be exploited in future studies to investigate the aetiology, development and clinical significance of cortical lesions in demyelinating disease.