Evidence of axonal damage in the early stages of multiple sclerosis and its relevance to disability

Escalating immunotherapy of multiple sclerosis--new aspects and practical application

Recent clinical studies in multiple sclerosis (MS) provide new data on the treatment of clinically isolated syndromes, on secondary progression, on direct comparison of immunomodulatory treatments and on dosing issues. All these studies have important implications for the optimized care of MS patients. The multiple sclerosis therapy consensus group (MSTCG) critically evaluated the available data and provides recommendations for the application of immunoprophylactic therapies. Initiation of treatment after the first relapse may be indicated if there is clear evidence on MRI for subclinical dissemination of disease. Recent trials show that the efficacy of interferon beta treatment is more likely if patients in the secondary progressive phase of the disease still have superimposed bouts or other indicators of inflammatory disease activity than without having them. There are now data available, which suggest a possible dose-effect relation for recombinant beta-interferons. These studies have to be interpreted with caution, as some potentially important issues in the design of these studies (e. g. maintenance of blinding in the clinical part of the study) were not adequately addressed. A meta-analysis of selected interferon trials has been published challenging the value of recombinant IFN beta in MS. The pitfalls of that report are discussed in the present review as are other issues relevant to treatment including the new definition of MS, the problem of treatment failure and the impact of cost-effectiveness analyses. The MSTCG panel recommends that the new diagnostic criteria proposed by McDonald et al. should be applied if immunoprophylactic treatment is being considered. The use of standardized clinical documentation is now generally proposed to facilitate the systematic evaluation of individual patients over time and to allow retrospective evaluations in different patient cohorts. This in turn may help in formulating recommendations for the application of innovative products to patients and to health care providers. Moreover, in long-term treated patients, secondary treatment failure should be identified by pre-planned follow-up examinations, and other treatment options should then be considered.

Biological markers in CSF and blood for axonal degeneration in multiple sclerosis

Biomarkers in body fluids could help to predict and monitor neurological decline in people with multiple sclerosis (MS). We discuss markers for axonal damage in body fluids in people with MS. The most promising axonal marker for discriminating patients with MS from those with other neurological diseases is the neurofilament light chain in CSF. Antibodies against the heavy-chain isoform are associated with disease progression. Other studies have shown altered CSF concentrations of tau proteins, actin, tubulin, and 14-3-3 protein. Interestingly, the concentration of 24S-hydroxycholesterol was decreased in serum of patients with MS. No clear changes have been shown for the markers apolipoprotein E and neurospecific enolase. We describe three types of markers for axonal damage: markers that reflect processes in the CNS, those that reflect extraneural processes, and those that reflect whole-body changes. These concepts may be helpful for biomarker research in various neurodegenerative diseases.

The unique impact of changes in normal appearing brain tissue on cognitive dysfunction in secondary progressive multiple sclerosis patients

OBJECTIVE

The purpose of this study was to examine the relationships between cognitive functioning, whole brain magnetic transfer ratio (MTR) imaging, supratentorial 1H-magnetic resonance spectroscopy imaging (1HMRSI), and conventional T1 and T2 imaging in a homogenous sample of SPMS patients.

METHODS

Nineteen patients underwent a single 90-min imaging session that obtained T1-and T2-weighted images and MTR. 1HMRSI was obtained on 14 of these patients. Patients underwent a neuropsychological battery, which was used to create an integrated measure of cognitive impairment. Cognitive impairment was the dependent variable in two hierarchical multiple regression analyses in which T2 lesion load, T1 lesion load, and MTR or NAA/Cr were entered sequentially.

RESULTS

MTR was significantly related to cognitive functioning (deltaR2 = 0.22, P = 0.02) after accounting for T2 lesion load (deltaR2 = 0.33, P = 0.01) and T1 lesion load (deltaR2 = 0.00, P = 0.98). NAA/Cr was not significantly related to cognitive functioning.

CONCLUSIONS

Cognitive dysfunction may act as a clinical marker of normal appearing brain tissue pathology in multiple sclerosis.

The pros and cons of early treatment of relapsing forms of multiple sclerosis

Cerebral axonal damage and brain atrophy begin at the earliest stages of multiple sclerosis (MS). Progressive neuronal degeneration contributes to irreversible neurological deficit, and ultimately disability. Axonal loss, which seems to be related to the inflammatory process, occurs much more rapidly in the early than later phases of disease, providing additional impetus for early intervention. The CHAMPS (Controlled High risk Avonex MultiPle Sclerosis) and ETOMS (Early Treatment Of MS) studies show that fewer patients with a first demyelinating event and abnormal magnetic resonance imaging (MRI) had a second clinical attack within 2 years if once-weekly treatment with interferon beta-1a was started at the time of the first episode. However, these studies provide no information on long-term outcomes. The BENEFIT study (BEtaferon/betaseron in Newly Emerging multiple sclerosis For Initial Treatment) will evaluate the efficacy and tolerability of 250 micro g (8 MIU) interferon beta-1b administered every other day to patients with a first demyelinating event suggestive of MS. This study should add some information about some of the outstanding questions relating to the long-term effects of early treatment on disease course, although it is likely that further investigation will be needed before a definite picture can be obtained.

Multi-slice echo-planar spectroscopic MR imaging provides both global and local metabolite measures in multiple sclerosis

MR spectroscopy (MRS) provides information about neuronal loss or dysfunction by measuring decreases in N-acetyl aspartate (NAA), a metabolite widely believed to be a marker of neuronal viability. In multiple sclerosis (MS), whole-brain NAA (WBNAA) has been suggested as a marker of disease progression and treatment efficacy in treatment trials, and the ability to measure NAA loss in specific brain regions early in the evolution of this disease may have prognostic value. Most spectroscopic studies to date have been limited to single voxels or nonlocalized measurements of WBNAA only, and longitudinal studies have often been hampered by standardization and reproducibility problems. Multi-slice echo-planar spectroscopic imaging (EPSI) is presented as a promising alternative to single-voxel or nonlocalized spectroscopy for obtaining global metabolite estimates in MS. In the same session, measurements of metabolites in specific brain areas chosen after image acquisition (e.g., normal-appearing white matter (NAWM), gray matter (GM), and lesions) can be obtained. The identification and exclusion of regions that are inadequate for spectroscopic evaluation in global assessments can significantly improve quality and reproducibility, as demonstrated by a low within-subject variance in healthy controls. The reproducibility of the technique makes it a promising tool for future longitudinal spectroscopic studies of MS.

Multicentre proton magnetic resonance spectroscopy imaging of primary progressive multiple sclerosis

Multicentre baseline proton magnetic resonance spectroscopic data on primary progressive multiple sclerosis (PPMS) patients are acquired and analysed, using automatic analysis software. The metabolite ratios did not differ from centre to centre. The average N-acetylaspartate/creatine (NAA/Cr) ratio in PPMS was significantly lower compared to normal controls. No significant differences were observed in this ratio between lesion-containing regions (LCR) and normal-appearing tissues (NAT). Strong lipid resonances, even in the absence of lesions, are observed in the both grey and white matter in these patients. These observations suggest extensive diffuse and/or microscopic pathology in PPMS. No significant correlation between any of the metabolite ratios and the Extended Disability Scale Score (EDSS) or with other MR measures such as lesion burden and enhancement volumes is observed.

The pathogenesis of multiple sclerosis: is it really a primary inflammatory process?

The pathogenesis of multiple sclerosis (MS) remains unknown. Although inflammation, demyelination and axonal injury are all involved, the primary pathogenic process is not clear. In this paper we challenge the hypothesis that MS is a primary inflammatory condition, and suggest that axonal damage may occur independently.

Spinal motoneurone distress during experimental allergic encephalomyelitis

The main pathophysiological feature characterizing multiple sclerosis (MS) is demyelination. However, the possibility of neural damage has recently been proposed as a mechanism in chronic disease. Experimental allergic encephalomyelitis (EAE) is the most widely used experimental model for MS. We investigated occurrences of microglial activation and astrocytosis in the spinal cord, choline acetyl‐transferase (ChAT) and calcitonin gene‐related peptide (CGRP) mRNA regulation in spinal motoneurones during EAE. EAE was induced in female Lewis rats by injecting guinea pig spinal cord tissue in complete Freund's adjuvant (CFA) to which heat‐inactivated Mycobacterium had been added. Rats injected with CFA and uninjected rats were used as controls. ChAT and CGRP mRNAs were studied by in situ hybridization in the lumbar spinal cord and a computerized grain counting procedure was used for quantification. No differences in ChAT mRNA level were found between control and CFA‐injected rats. ChAT mRNA level was strongly reduced in EAE 14 days after immunization and then recovered (29 days after immunization). CGRP mRNA increased 14 days after immunization, and then recovered to control level. Extensive long‐lasting gliosis developed in the spinal cord and around motoneurones and a transient expression of p75^LNGFR in motoneurones was also found. These data suggest that during EAE, gliosis induces distress in spinal cord neurones involving the synthesis enzyme for the main transmitter.

The Expression of Microfilament-Associated Cell-Cell Contacts in Brain Endothelial Cells Is Modified by IFN-β1a (Rebif®)

In multiple sclerosis (MS), a crucial step in the induction phase of the inflammatory process in the central nervous system (CNS) is the disruption of the endothelial blood-brain barrier (BBB). Its permeability depends on the expression of intercellular adhesion molecules, such as vinculin and N-cadherin in endothelial cells. Interferon-gamma (IFN-gamma), as a proinflammatory cytokine, decreases the expression of both adhesion molecules in epithelial and astrocytic cells, whereas IFN-beta1a, an established treatment for MS, increases the expression of N-cadherin and vinculin in astrocytic cells and is postulated to preserve endothelial cell barrier function and to inhibit transendothelial migration of activated leukocytes. We analyzed the expression of N-cadherin and vinculin in a murine brain endothelial cell line by immunofluorescence staining and Western blot to study the presumed reversal effects of IFN-beta1a (Rebif, Serono Pharma, Unterschleissheim, Germany) and IFN-gamma on the formation of intercellular contacts. Vinculin and N-cadherin expression in brain endothelial cells was decreased after treatment with IFN-gamma, whereas stimulation with IFN-beta1a caused increased expression of both adhesion molecules. Combined treatment with both IFNs did not affect vinculin and N-cadherin expression. These data suggest that IFN-gamma contributes to BBB disruption by decreasing and IFN-beta1a restores the BBB by an upregulation of vinculin and N-cadherin expression in brain endothelial cells. This action of IFN-beta1a may contribute to its beneficial effects in MS therapy.

Axonal damage in multiple sclerosis patients with high versus low expanded disability status scale score

BACKGROUND

The pathophysiological basis for differences in disability in patients with multiple sclerosis is unclear.

METHODS

We used magnetic resonance imaging to examine whether differences in disability in cohorts of multiple sclerosis patients with similar T2-weighted lesion volume and disease duration were associated with a more destructive disease process in the more disabled patients.

RESULTS

The benign and severely disabled groups had similar brain atrophy metrics and similar decreases of the neuronal marker, N-acetylaspartate, in the normal appearing white matter of the cerebrum on magnetic resonance spectroscopy examination in vivo. The severely disabled cohort had more spinal cord atrophy.

CONCLUSION

The dissociation of spinal cord atrophy and cerebral atrophy between these two groups suggests that the difference between the more benign and more disabled groups cannot be explained by a more aggressive pathological process that is affecting the entire neuroaxis in a homogeneous fashion.

Early glial responses in murine models of multiple sclerosis

Investigations of functional interactions among axons and glia over the last decade have revealed the extent and complexity of glial-neuronal and glial-glial communication during development, adult function and recovery from injury. These data have profound implications for the understanding of central nervous system (CNS) disorders, which until recently, have been classified as either neuronal or glial diseases. Re-evaluation of the pathological processes in a number of conditions has clearly shown involvement of both neurons and glia in early pathology. In multiple sclerosis (MS), the myelin sheath has traditionally been regarded as the primary target. However, recent evidence has clearly demonstrated axonal damage in new lesions. We have addressed the question of the role of axonal pathology in early MS by using well-characterized murine models for the relapsing-remitting (RR) or the primary progressive (PP) forms of the disease. We performed a histopathological survey of the CNS, following induction of the disease, to determine the timing of appearance, as well as the development of lesions. Then we analysed the relationship between inflammation, demyelination and axonal damage together with responses from astrocytes and microglia in each model from the earliest evidence of inflammation. We found that axonal damage begins well ahead of the appearance of motor symptoms. Pathology appears to be more closely related to the degree of inflammation than to demyelination. We also show that early astrocyte responses and the degree of axonal loss are markedly different in the two models and relate to the severity of pathology. These data support the now widely accepted hypothesis that axonal damage begins early in the disease process, but also suggest modulation of axonal loss and disease progression by the astrocytic response.

Magnetic resonance spectroscopy of normal appearing white matter in early relapsing-remitting multiple sclerosis: correlations between disability and spectroscopy

Background

What currently appears to be irreversible axonal loss in normal appearing white matter, measured by proton magnetic resonance spectroscopy is of great interest in the study of Multiple Sclerosis. Our aim is to determine the axonal damage in normal appearing white matter measured by magnetic resonance spectroscopy and to correlate this with the functional disability measured by Multiple Sclerosis Functional Composite scale, Neurological Rating Scale, Ambulation Index scale, and Expanded Disability Scale Score.

Methods

Thirty one patients (9 male and 22 female) with relapsing remitting Multiple Sclerosis and a Kurtzke Expanded Disability Scale Score of 0–5.5 were recruited from four hospitals in Andalusia, Spain and included in the study. Magnetic resonance spectroscopy scans and neurological disability assessments were performed the same day.

Results

A statistically significant correlation was found (r = -0.38 p < 0.05) between disability (measured by Expanded Disability Scale Score) and N-Acetyl Aspartate (NAA/Cr ratio) levels in normal appearing white matter in these patients. No correlation was found between the NAA/Cr ratio and disability measured by any of the other disability assessment scales.

Conclusions

There is correlation between disability (measured by Expanded Disability Scale Score) and the NAA/Cr ratio in normal appearing white matter. The lack of correlation between the NAA/Cr ratio and the Multiple Sclerosis Functional Composite score indicates that the Multiple Sclerosis Functional Composite is not able to measure irreversible disability and would be more useful as a marker in stages where axonal damage is not a predominant factor.

Neural stem/progenitor cells express costimulatory molecules that are differentially regulated by inflammatory and apoptotic stimuli

Increased expression of the costimulatory molecule CD80 (B7-1) was noted in the subventricular zone of the brain during the course of experimental autoimmune encephalomyelitis (EAE). This area of the brain is a neural stem cell (NSC) niche in the adult. We show that isolated NSCs from adult brain express CD80 and CD86 (B7-2) and this expression is increased after exposure to IFN-gamma or TNF-alpha, the prototypical Th1 cytokines expressed during EAE. CD80 and CD86 expressed by NSCs are functional and can costimulate allogeneic cells in a mixed lymphocyte reaction. Furthermore, cross-linking of CD80 on the surface of NSCs results in apoptosis of NSCs. In vitro, we show that T cells can interact with NSCs and form conjugates with redistribution of CD3 on the surface of T cells to the area of contact. These data raise the possibility that during CNS inflammatory diseases such as EAE, NSCs may express immune molecules and interact with the inflammatory environment potentially resulting in injury to the NSCs, which may have implications for repair mechanisms in the central nervous system.

Astrocytic beta2-adrenergic receptors and multiple sclerosis

Despite intensive research, the cause and a cure of multiple sclerosis (MS) have remained elusive and many aspects of the pathogenesis are not understood. Immunohistochemical experiments have shown that astrocytic beta(2)-adrenergic receptors are lost in MS. Because norepinephrine mediates important supportive and protective actions of astrocytes via activation of these beta(2)-adrenergic receptors, we postulate that this abnormality may play a prominent role in the pathogenesis of MS. First, it may allow astrocytes to act as facultative antigen-presenting cells, thereby initiating T-cell mediated inflammatory responses that lead to the characteristic demyelinated lesions. Second, it may contribute to inflammatory injury by stimulating the production of nitric oxide and proinflammatory cytokines, and reducing glutamate uptake. Third, it may lead to apoptosis of oligodendrocytes by reducing the astrocytic production of trophic factors, including neuregulin, nerve growth factor and brain-derived neurotrophic factor. Fourth, it may impair astrocytic glycogenolysis, which supplies energy to axons, and this may represent a mechanism underlying axonal degeneration that is hold responsible for the progressive chronic disability.

Beta 2-adrenoceptor involvement in inflammatory demyelination and axonal degeneration in multiple sclerosis

Relapses of multiple sclerosis (MS) are considered to be the clinical expression of acute T-cell-mediated inflammatory demyelinating lesions disseminated in the CNS, whereas disease progression seems to result from widespread axonal degeneration. The pathophysiology of both disease components is incompletely understood. Astrocytes in MS lack beta(2)-adrenoceptors, which via cAMP-mediated processes inhibit the expression of major histocompatibility (MHC) class II molecules and stimulate glycogenolysis in normal conditions. In a pro-inflammatory CNS environment this beta(2)-adrenoceptor defect might allow astrocytes to transform into facultative antigen-presenting cells that can initiate the inflammatory cascade. The same receptor defect might impair astrocytic glycogenolysis, which normally generates lactate that is transported to axons as an energy source. Failure of axonal energy metabolism might result in axonal degeneration through mechanisms that involve intra-axonal accumulation of Ca(2+) ions and mitochondrial dysfunction. If this hypothesis is correct, therapies designed to elevate cAMP levels in astrocytes should reduce or prevent both relapses and progression of MS.

Metabolite ratios to assumed stable creatine level may confound the quantification of proton brain MR spectroscopy

In localized brain proton MR spectroscopy ((1)H-MRS), metabolites' levels are often expressed as ratios, rather than as absolute concentrations. Frequently, their denominator is the creatine [Cr], which level is explicitly assumed to be stable in normal as well as in many pathologic states. The rationale is that ratios self-correct for imager and localization method differences, gain instabilities, regional susceptibility variations and partial volume effects. The implicit assumption is that these benefits are worth their cost(w)-(w) propagation of the individual variation of each of the ratio's components. To test this hypothesis, absolute levels of N-acetylaspartate [NAA], choline [Cho] and [Cr] were quantified in various regions of the brains of 8 volunteers, using 3-dimensional (3D) (1)H-MRS at 1.5 T. The results show that in over 50% of approximately 2000 voxels examined, [NAA]/[Cr] and [Cho]/[Cr] exhibited higher coefficients of variations (CV) than [NAA] and [Cho] individually. Furthermore, in approximately 33% of these voxels, the ratios' CVs exceeded even the combined constituents' CVs. Consequently, basing metabolite quantification on ratios and assuming stable [Cr] introduces more variability into (1)H-MRS than it prevents. Therefore, its cost exceeds the benefit.

Simple and complex movement-associated functional MRI changes in patients at presentation with clinically isolated syndromes suggestive of multiple sclerosis

Using functional magnetic resonance imaging (fMRI), we investigated whether movement-associated functional changes of the brain are present in patients who are, most likely, at the earliest stage of multiple sclerosis (MS). Functional MRI exams were obtained from 16 patients at presentation with clinically isolated syndromes (CIS) suggestive of MS and 15 sex- and age-matched healthy volunteers during the performance of three simple and one more complex motor tasks with fully normal functioning extremities. fMRI analysis was performed using statistical parametric mapping (SPM99). Compared to healthy volunteers, CIS patients had increased activations of the contralateral primary sensorimotor cortex (SMC), secondary somatosensory cortex (SII), and inferior frontal gyrus (IFG), when performing a simple motor task with the dominant hand. The increased recruitment of the contralateral primary SMC was also found during the performance of the same motor task with the non-dominant hand and with the dominant foot. In this latter case, an anterior shift of the center of activation of this region was detected. During the performance of a complex motor task with the dominant upper and lower limbs, CIS patients had an increased recruitment of a widespread network (including the frontal lobe, the insula, the thalamus), usually considered to function in motor, sensory, and multimodal integration processing. The comparison of brain activations during the performance of simple vs. complex motor tasks showed that the movement-associated somatotopic organization of the cerebral and cerebellar cortices was retained in patients with CIS. Cortical reorganization occurs in patients at presentation with CIS highly suggestive of MS. Local synaptic reorganization, recruitment of parallel existing pathways, and reorganization of distant sites are all likely to contribute to the observed functional changes. Hum. Brain Mapping 21:106-115, 2004.

Magnetic resonance spectroscopy in cognitive research

The neurophysiological basis of cognition is relatively unexplained, with most studies reporting weak relationships between cognition and measures of brain function, such as event-related potentials, brain size and cerebral blood flow. Magnetic resonance spectroscopy (MRS) is an in vivo method used to detect neurochemicals within the brain that are relevant to certain brain processes. The most widely used methods are 1H-MRS and 31P-MRS, which detect compounds that contain hydrogen and phosphorus, respectively. Recent studies have shown that the absolute concentrations or ratios of these neurochemicals, in particular N-acetyl aspartate (NAA), which is associated with neuronal viability, correlate with performance on neuropsychological tests or other measures of cognitive function in normal subjects. Many studies in adults and children have shown a relationship between neurometabolite values and cognitive status or extent of cognitive dysfunction in various neurological and neuropsychiatric disorders. We review these studies and conclude that MRS has potential applications for the study of cognitive processes in health and disease and may be used clinically for differential diagnosis, the early detection of pathology and the examination of longitudinal change.

Diffusion tensor imaging detects and differentiates axon and myelin degeneration in mouse optic nerve after retinal ischemia

Both axon and myelin degeneration have significant impact on the long-term disability of patients with white matter disorder. However, the clinical manifestations of the neurological dysfunction caused by white matter disorders are not sufficient to determine the origin of neurological deficits. A noninvasive biological marker capable of detecting and differentiating axon and myelin degeneration would be a significant addition to currently available tools. Directional diffusivities derived from diffusion tensor imaging (DTI) have been previously proposed by this group as potential biological markers to detect and differentiate axon and myelin degeneration. To further test the hypothesis that axial (lambdaparallel) and radial (lambdaperpendicular) diffusivities reflect axon and myelin pathologies, respectively, the optic nerve was examined serially using DTI in a mouse model of retinal ischemia. A significant decrease of lambdaparallel, the putative DTI axonal marker, was observed 3 days after ischemia without concurrently detectable changes in lambdaperpendicular, the putative myelin marker. This result is consistent with histological findings of significant axonal degeneration with no detectable demyelination at 3 days after ischemia. The elevation of lambdaperpendicular observed 5 days after ischemia is consistent with histological findings of myelin degeneration at this time. These results support the hypothesis that lambdaparallel and lambdaperpendicular hold promise as specific markers of axonal and myelin injury, respectively, and, further, that the coexistence of axonal and myelin degeneration does not confound this utility.

Cytokine producing CD8+ T cells are correlated to MRI features of tissue destruction in MS

Specific T-cell subsets and their ability to produce cytokines have been involved in concepts of multiple sclerosis (MS) pathogenesis. Evidence to link cytokine producing T-cell subsets to magnetic resonance imaging (MRI) features of tissue destruction, however, is limited. Cytokine flow cytometry was performed in 124 patients with different subtypes of MS. In a subgroup of 69 patients, from whom longitudinal MRI was available, the ability of circulating types 1 and 2 helper T cells to produce cytokines was correlated to changes in T1 hypointense and T2 hyperintense lesion load (LL) on brain MRI during 3 years of follow-up. Significant negative correlations were found between baseline CD8(+) T-cell subsets producing IL-2, IL-4 or IL-13 and the change in T1 LL. Subgroup analyses demonstrated that in RRMS, CD8(+) T cells producing IL-2, IL-4 or IL-13, and in PPMS, CD8(+) IL-10(+) T cells correlated negatively with T1 LL. To our knowledge, this study provides the first direct immunophenotypic evidence of cytokine producing CD8(+) T cells being directly related to long-term development of MRI features of demyelination and axonal loss.

Compensatory cortical activation observed by fMRI during a cognitive task at the earliest stage of MS

Recent functional magnetic resonance imaging (fMRI) studies have suggested that functional cortical changes seen in patients with early relapsing-remitting multiple sclerosis (MS) can have an adaptive role to limit the clinical impact of tissue injury. To determine whether cortical reorganization occurs during high cognitive processes at the earliest stage of multiple sclerosis (MS), we performed an fMRI experiment using the conventional Paced Auditory Serial Addition Test (PASAT) as paradigm in a population of ten patients with clinically isolated syndrome suggestive of multiple sclerosis (CISSMS). At the time of the fMRI exploration, mean disease duration was 6.8 +/- 3.3 months. We compared these results to those obtained in a group of ten education-, age-, and sex-matched healthy controls. Subjects were explored on a 1.5 T MRI system using single-shot gradient-echo EPI sequence. Performances of the two groups during PASAT recorded inside the MR scanner were not different. Statistical assessment of brain activation was based on the random effect analysis (between-group analysis two-sample t-test P < 0.005 confirmed by individual analyses performed in the surviving regions P < 0.05 Mann Whitney U-test). Compared to controls, patients showed significantly greater activation in the right frontopolar cortex, the bilateral lateral prefrontal cortices, and the right cerebellum. Healthy controls did not show greater activation compared to CISSMS patients. The present study argues in favor of the existence of compensatory cortical activations at the earliest stage of MS mainly located in regions involved in executive processing in patients performing PASAT. It also suggests that fMRI can evidence the active processes of neuroplasticity contributing to mask the clinical cognitive expression of brain pathology at the earliest stage of MS.

Cannabinoids inhibit neurodegeneration in models of multiple sclerosis

Multiple sclerosis is increasingly being recognized as a neurodegenerative disease that is triggered by inflammatory attack of the CNS. As yet there is no satisfactory treatment. Using experimental allergic encephalo myelitis (EAE), an animal model of multiple sclerosis, we demonstrate that the cannabinoid system is neuroprotective during EAE. Mice deficient in the cannabinoid receptor CB1 tolerate inflammatory and excitotoxic insults poorly and develop substantial neurodegeneration following immune attack in EAE. In addition, exogenous CB1 agonists can provide significant neuroprotection from the consequences of inflammatory CNS disease in an experimental allergic uveitis model. Therefore, in addition to symptom management, cannabis may also slow the neurodegenerative processes that ultimately lead to chronic disability in multiple sclerosis and probably other diseases.

Interferon-β in the treatment of relapsing–remitting multiple sclerosis

The role of interferon-beta as a disease-modifying drug (DMD) for the treatment of relapsing-remitting multiple sclerosis (RRMS) is now well established, and its efficacy has been demonstrated unequivocally in large-scale clinical trials. However, current evidence suggests that in order to increase the benefit of therapy, use of an effective drug and dosing regimen should be commenced early in the course of the disease, a finding that places new emphasis on the need for early diagnosis. Indeed, it is now known that MS lesions often develop at a subclinical level and that axonal damage occurs even in the very early stages of the disease. Moreover, such damage may be irreversible, and there is strong evidence to suggest that efficacy lost as a consequence of delay in the onset of treatment or the use of a suboptimal drug regimen cannot be regained. At present, the choice of interferon-beta is complicated by the availability of 3 different products, each with a different dosing regimen. Although the optimal interferon-beta dosing regimen for RRMS has been the focus of much discussion, the issues of dose, and particularly dosing frequency, have not been satisfactorily addressed in clinical trials until recently. Over the last 2 years, however, 3 comparative studies of interferon-beta products have been conducted. The results obtained from these recent trials underline the importance of both dose and dosing frequency and indicate that for improved efficacy in RRMS, interferon-beta therapy should be administered frequently at the highest tolerable, and thus most effective, dose.

Genetic programs and responses of neural stem/progenitor cells during demyelination: potential insights into repair mechanisms in multiple sclerosis

In recent years, it has become evident that the adult mammalian CNS contains a population of neural stem cells (NSCs) described as immature, undifferentiated, multipotent cells, that may be called upon for repair in neurodegenerative and demyelinating diseases. NSCs may give rise to oligodendrocyte progenitor cells (OPCs) and other myelinating cells. This article reviews recent progress in elucidating the genetic programs and dynamics of NSC and OPC proliferation, differentiation, and apoptosis, including the response to demyelination. Emerging knowledge of the molecules that may be involved in such responses may help in the design of future stem cell-based treatment of demyelinating diseases such as multiple sclerosis.

The use of quantitative magnetic-resonance-based techniques to monitor the evolution of multiple sclerosis

Conventional MRI can improve accuracy in the diagnosis of multiple sclerosis (MS) and monitor the efficacy of experimental treatments. However, conventional MRI provides only gross estimates of the extent and nature of tissue damage associated with this disease. Other quantitative magnetic-resonance-based techniques have the potential to overcome the limitations of conventional MRI and, as a consequence, to improve our understanding of the natural history of MS. Magnetisation-transfer, diffusion-weighted, and functional MRI--as well as proton magnetic-resonance spectroscopy--are helping us to elucidate the mechanisms that underlie injury, repair, and functional adaptation in patients with MS. These techniques are substantially changing our understanding of how MS causes irreversible disability and should be used more extensively in clinical trials and in studies of disease progression.

Axonal injury in multiple sclerosis

The pivotal role of axons in the pathophysiology and pathogenesis of multiple sclerosis (MS) is increasingly becoming the focus of our attention. Axonal injury, considered at one time to be a late phenomenon, is now recognized as an early occurrence in the inflammatory lesions of MS. There is converging evidence from histopathologic, as well as magnetic resonance imaging and magnetic resonance spectroscopy studies, that axons play a crucial and dynamic role during the evolution of MS pathology and the development of clinical disability. It has been repeatedly demonstrated that neurologic functional impairment correlates best with axonal, rather than myelin, injury. The pathophysiology of axonal injury remains speculative. Although generally considered to be sequelae of demyelination, it is possible that axonal injury in MS is indeed a primary event. The discovery that axonal injury can be reversible has provided an impetus to institute early therapy. The finding that irreversible axonal transection occurs in early lesions has underscored now, more than ever before, the need to curtail inflammation and the need to institute early treatment with disease-modifying agents. The axon will undoubtedly remain the focus of our attention regarding research on MS now and in the future.

Therapeutic vaccine for acute and chronic motor neuron diseases: implications for amyotrophic lateral sclerosis

Therapeutic vaccination with Copaxone (glatiramer acetate, Cop-1) protects motor neurons against acute and chronic degenerative conditions. In acute degeneration after facial nerve axotomy, the number of surviving motor neurons was almost two times higher in Cop-1-vaccinated mice than in nonvaccinated mice, or in mice injected with PBS emulsified in complete Freund's adjuvant (P < 0.05). In mice that express the mutant human gene Cu/Zn superoxide dismutase G93A (SOD1), and therefore simulate the chronic human motor neuron disease amyotrophic lateral sclerosis, Cop-1 vaccination prolonged life span compared to untreated matched controls, from 211 +/- 7 days (n = 15) to 263 +/- 8 days (n = 14; P < 0.0001). Our studies show that vaccination significantly improved motor activity. In line with the experimentally based concept of protective autoimmunity, these findings suggest that Cop-1 vaccination boosts the local immune response needed to combat destructive self-compounds associated with motor neuron death. Its differential action in CNS autoimmune diseases and neurodegenerative disorders, depending on the regimen used, allows its use as a therapy for either condition. Daily administration of Cop-1 is an approved treatment for multiple sclerosis. The protocol for non-autoimmune neurodegenerative diseases such as amyotrophic lateral sclerosis, remains to be established by future studies.

Cognitive impairment in probable multiple sclerosis

OBJECTIVES

To evaluate and characterise cognitive impairment in the very early stage of multiple sclerosis (MS), in which patients are still diagnosed as suffering from probable MS.

METHODS

The Brief Repeatable Battery-Neuropsychological (BRB-N) that has been validated for MS patients was used. Abnormal performance was defined as one standard deviation below the mean reported for healthy age matched subjects. Neurological disability and brain magnetic resonance imaging (MRI) were performed for all patients. Correlation coefficients were calculated between disease burden variables and performance on the BRB-N.

RESULTS

Sixty seven patients with probable MS were evaluated within a mean of one month of the onset of new neurological symptoms. Evidence for the presence of cognitive impairment was shown in 53.7% of patients. Verbal abilities and attention span were most frequently affected. Impairment was not correlated with neurological disability or MRI disease burden.

CONCLUSION

Prevalent cognitive impairment already exists at onset of MS.

Evidence for axonal pathology and adaptive cortical reorganization in patients at presentation with clinically isolated syndromes suggestive of multiple sclerosis

Previous work has suggested that functional reorganization of cortical areas might have a role in limiting the clinical impact of axonal pathology in patients with established multiple sclerosis (MS). Since there is evidence for irreversible tissue damage even in patients with early MS, we assessed, using functional MRI (fMRI) and a general search method, the brain pattern of movement-associated cortical activations in patients at presentation with clinically isolated syndromes (CIS) suggestive of MS. To elucidate the role of cortical reorganization in these patients, we also investigated the extent to which the fMRI changes correlated with the extent of overall axonal injury of the brain. From 16 right-handed patients at presentation with CIS and 15 right-handed, age- and sex-matched healthy volunteers, we obtained: (1). fMRI (repetitive flexion-extension of the last four fingers of the right hand), (2). conventional MRI scans, and (3). a new, unlocalized proton MR spectroscopy ((1)HMRS) sequence to measure the concentration of N-acetylaspartate of the whole brain (WBNAA). Compared to controls, patients with CIS had more significant activations of the contralateral primary somatomotor cortex (SMC), secondary somatosensory cortex, and inferior frontal gyrus. They also had significant decreased WBNAA concentration. Relative activation of the contralateral primary SMC was strongly correlated with WBNAA levels (r = -0.78, P < 0.001). This study shows that axonal pathology and functional cortical changes over a rather distributed sensorimotor network occur in patients at presentation with CIS suggestive of MS and that these two aspects of the disease are strictly correlated. This suggests that the increased functional recruitment of the cortex in these patients might have an adaptive role in limiting the clinical impact of irreversible tissue damage.

IFN-beta1a (Rebif) modifies the expression of microfilament-associated cell-cell contacts in C6 glioma cells

Multiple sclerosis (MS) is a chronic inflammatory disease characterized by multifocal demyelination and axonal damage in the central nervous system (CNS). The disruption of the endothelial blood-brain barrier (BBB) with consecutive transmigration of inflammatory cells into the brain parenchyma is of critical importance in the pathogenesis of MS. The integrity of the BBB and the adjacent network of glial cells partially depends on the assembly of intercellular contacts between astrocytes. We demonstrate that recombinant interferon-gamma (rIFN-gamma), a proinflammatory cytokine critically involved in the disruption of the BBB, downregulates the expression of the cell adhesion molecules N-cadherin and vinculin in astrocytic C6 cells using Western blot and immunofluorescence microscopy. By contrast, IFN-beta1a, an established treatment for relapsing-remitting MS, increases the expression of N-cadherin and vinculin and partly inhibits the downregulation of these adhesion molecules by phytohemagglutinin (PHA)-stimulated IFN-gamma-secreting human T lymphocytes in coculture experiments. In summary, we demonstrate that IFN-beta1a modifies the assembly of N-cadherin- and vinculin-mediated intercellular contacts between astrocytic C6 cells in vitro. This effect may also contribute to the therapeutic action of IFN-beta1a in MS.

Magnetic resonance-based techniques for the study and management of multiple sclerosis

Conventional magnetic resonance imaging (cMRI) is widely used for diagnosing multiple sclerosis (MS) and for monitoring its activity and evolution. However, the correlation between cMRI and clinical findings of MS is limited, possibly due to the low pathological specificity of the abnormalities seen on cMRI scans and to the inability of cMRI to quantify the extent of the damage of the normal-appearing tissues. Magnetization transfer and diffusion-weighted MRI can quantify the extent and pathological severity of structural changes occurring within and outside cMRI-visible MS lesions. Proton MR spectroscopy can add information on the biochemical nature of such changes. Finally, functional MRI can provide new insights into the role of cortical adaptive changes in limiting the clinical consequences of MS structural damage. The application of quantitative MR-based techniques is changing dramatically our understanding of how MS causes irreversible disability and there is increasing perception that these methodologies should be more extensively employed in clinical trials to derive innovative information.

Dysmyelination revealed through MRI as increased radial (but unchanged axial) diffusion of water

Myelin loss and axonal damage are both observed in white matter injuries. Each may have significant impact on the long-term disability of patients. Currently, there does not exist a noninvasive biological marker that enables differentiation between myelin and axonal injury. We describe herein the use of magnetic resonance diffusion tensor imaging (DTI) to quantify the effect of dysmyelination on water directional diffusivities in brains of shiverer mice in vivo. The principal diffusion eigenvalues of eight axonal fiber tracts that can be identified with certainty on DTI maps were measured. The water diffusivity perpendicular to axonal fiber tracts, lambda(perpendicular), was significantly higher in shiverer mice compared with age-matched controls, reflecting the lack of myelin and the increased freedom of cross-fiber diffusion in white matter. The water diffusivity parallel to axonal fiber tracts, lambda(parallel), was not different, which is consistent with the presence of intact axons. It is clear that dysmyelination alone does not impact lambda(parallel). The presence of intact axons in the setting of incomplete myelination was confirmed by electron microscopy. Although further validation is still needed, our finding suggests that changes in lambda(perpendicular) and lambda(parallel) may potentially be used to differentiate myelin loss versus axonal injury.

Microglia as liaisons between the immune and central nervous systems: functional implications for multiple sclerosis

Multiple sclerosis is a chronic demyelinating inflammatory disease of the central nervous system (CNS). As the tissue macrophage of the CNS, microglia have the potential to regulate and be regulated by cells of the CNS and by CNS-infiltrating immune cells. The exquisite sensitivity of microglia to these signals, coupled with their ability to develop a broad range of effector functions, allows the CNS to tailor microglial function for specific physiological needs. However, the great plasticity of microglial responses can also predispose these cells to amplify disproportionately the irrelevant or dysfunctional signals provided by either the CNS or immune systems. The consequences of such an event could be the conversion of self-limiting inflammatory responses into chronic neurodegeneration and may explain in part the heterogeneous nature of multiple sclerosis.

Prevention of autoimmune attack and disease progression in multiple sclerosis: current therapies and future prospects

Multiple sclerosis (MS) is an important cause of progressive neurological disability, typically commencing in early adulthood. There is a need for safe and effective therapy to prevent the progressive central nervous system (CNS) damage and resultant disability that characterize the disease course. Increasing evidence supports a chronic autoimmune basis for CNS damage in MS. In the present study, we review current concepts of autoimmune pathogenesis in MS, assess current therapies aimed at countering autoimmune attack and discuss potential therapeutic strategies. Among currently available therapies, beta-interferon and glatiramer acetate have a modest effect on reducing relapses and slowing the accumulation of disability in relapsing-remitting MS. Beta-interferon is of doubtful efficacy in secondary progressive MS and appears to aggravate primary progressive MS, possibly by increasing antibody-mediated CNS damage through inhibition of B-cell apoptosis. Mitoxantrone may reduce relapses and slow disability progression in relapsing-remitting and secondary progressive MS, but its use is limited by the risk of cardiomyopathy. There are currently no effective treatments for primary progressive MS. Many therapies that are effective in the animal model, experimental autoimmune encephalomyelitis (EAE), are either ineffective in MS or--in the case of gamma-interferon, lenercept and altered peptide ligands--actually make MS worse. This discrepancy may be explained by the occurrence in MS of defects in immunoregulatory mechanisms, the integrity of which is essential for the efficacy of these treatments in EAE. It is likely that the development of safe, effective therapy for MS will depend on a better understanding of immunoregulatory defects in MS.

Relapsing-remitting multiple sclerosis and whole-brain N-acetylaspartate measurement: evidence for different clinical cohorts initial observations

PURPOSE

To quantify the rate of concentration decline of neuronal marker N-acetylaspartate (NAA) in the entire brain of patients with relapsing-remitting multiple sclerosis (MS) in relation to healthy age-matched control subjects.

MATERIALS AND METHODS

Whole-brain NAA (WBNAA) concentration was quantified in 49 patients with relapsing-remitting MS by using magnetic resonance (MR) imaging and proton MR spectroscopy. It was statistically analyzed by using Spearman rank correlation coefficients to test the intragroup relationship between WBNAA and Expanded Disability Status Scale (EDSS) score and Mann-Whitney analyses to test for differences between subgroups' EDSS scores versus previously published WBNAA values for healthy subjects, disease duration, and age.

RESULTS

Analyses indicated three subgroups of WBNAA dynamics: Ten patients' conditions were "stable," exhibiting an insignificant change of about 0% (0.02/14.37) per year of clinically definite disease duration (P =.54); 27 patients showed "moderate" decline, -2.8% (-0.34/12.18) per year (P <.01); and 12 patients experienced "rapid" decline, -27.9% (-3.39/12.14) per year (P <.01). No correlation was found between WBNAA deficit, EDSS score, and age.

CONCLUSION

Ascertaining an individual's NAA concentration dynamics might enable early forecast of disease course, reflect disease severity and thus influence treatment decisions, and improve clinical trial efficiency by allowing selection of candidates on the basis of WBNAA dynamics in addition to clinical status.

The clinico-radiological paradox in multiple sclerosis revisited

The use of magnetic resonance imaging as a surrogate outcome measure in clinical trials, or even as a prognosticator in the assessment of the natural evolution, assumes a close relationship between extent and rate of development of magnetic resonance imaging abnormalities with the clinical status and rate of development of disability. While it may seem obvious that patients who develop new lesions are worse off than those without new lesions, the association between clinical findings and radiological extent of involvement is generally poor. In this review, various confounders are discussed, including inappropriate clinical rating, lack of histopathological specificity (especially for axonal loss), neglect of spinal cord involvement, underestimation of damage to the normal appearing brain tissue (both white and gray matter), and masking effects of cortical adaptation. It is concluded that much progression has been made in magnetic resonance techniques so that the clinico-radiological dissociation has indeed proved to be a paradox. Thus, the relevance of normal appearing brain tissue damage, residual brain volume, spinal cord damage and cerebral plasticity had to be reiterated. The increased awareness of the subtle interplay between these dimensions should be kept in mind when magnetic resonance is used as a surrogate outcome measure. This corroborates with conventional wisdom that one should not rely on a single magnetic resonance measure, but take full advantage of the fact that magnetic resonance is able to provide multidimensional information.

Magnetic resonance spectroscopy in multiple sclerosis: window into the diseased brain

Magnetic resonance spectroscopy provides noninvasive insight into the regional and global biochemical alterations that are concomitants of the dynamic processes that underlie the evolution of fundamental pathologic changes in multiple sclerosis. These include now well-recognized alterations of neuronal biochemical markers that accompany tissue destruction readily visualized by magnetic resonance imaging, but also dynamic changes in several metabolites that indicate pathological processes that precede the magnetic resonance imaging-defined lesion, or completely escape current high-resolution imaging.

Clinical trials and clinical practice in multiple sclerosis: conventional and emerging magnetic resonance imaging technologies

Conventional magnetic resonance imaging (cMRI) is widely used for diagnosing multiple sclerosis (MS) and as a paraclinical tool to monitor disease activity and evolution in natural history studies and clinical trials. However, the correlation between cMRI and clinical findings is far from strict, and such a discrepancy is even more evident when moving from the setting of large-scale studies to the management of individual patients. Among the reasons for this "clinical-MRI paradox" is the limited specificity of cMRI to the heterogeneous pathologic substrates of MS and its inability to quantify the extent of damage in the normal-appearing tissues. Modern quantitative MR techniques have the potential to overcome some of the limitations of cMRI. Although the application of modern MR techniques is changing dramatically our understanding of how MS causes irreversible disability, their use for clinical trial monitoring and clinical practice is still very limited. Whereas there is increasing perception that modern quantitative MR techniques should be more extensively employed in clinical trials to advance the understanding of MS and derive innovative information, their use in clinical practice should still be regarded as premature.

Quantitative 1H MRS imaging 14 years after presenting with a clinically isolated syndrome suggestive of multiple sclerosis

clinically isolated syndromes (CIS) are events suggestive for emerging multiple sclerosis (MS). A majority of patients develop MS within months or years whilst others remain clinically isolated. The goal of this study was to investigate whether biochemical metabolites detectable by 'H magnetic resonance spectroscopy (MRS) may serve to distinguish between these two groups. We investigated 41 patients 14 years after presentation with a CIS and 21 controls with combined quantitative short echo 'H MRS and magnetic resonance imaging (MRI) and assessed disability according to the Expanded Disability Status Scale (EDSS). At follow-up, 32 had developed MS, and 9 still had CIS. Compared with controls, MS patients demonstrated significantly higher concentrations of myo-inositol (Ins) in normal appearing white matter (NAWM) and lesions. Lesions also demonstrated a reduced N-acetyl-aspartate (NAA) level and an increase in choline-containing compounds (Cho). The NAWM Ins concentration was correlated with EDSS (r = 0.48, p = 0.005). MS normal appearing cortical grey matter (CGM) exhibited a decreased NAA. Patients who remained CIS did not differ significantly from controls in any MRS measure. Metabolite changes in normal appearing white and grey matter in MS indicate diffuse involvement of the entire MS brain, which was not seen in the persisting CIS patients. Elevated Ins in MS NAWM appeared functionally relevant It may indicate glial cell proliferation or gliosis.

MRI techniques to monitor MS evolution: the present and the future

Conventional MRI (cMRI) is limited in its ability to provide specific information about pathology in MS. Measures commonly derived from cMRI include T2 lesions, T1-enhanced lesions, atrophy, and possibly T1-hypointense lesions, which have been extensively investigated in many clinical trials. Better MRI measures are needed to advance our understanding of MS and design ideal clinical trials. This article reviews the strengths and weaknesses of the major MRI-based methods used to monitor MS evolution and submits that 1) metrics derived from magnetization transfer MRI, diffusion-weighted MRI, and proton MRS should be implemented to achieve reliable specific in vivo quantification of MS pathology; 2) targeted multiparametric MRI protocols rather than generic application of cMRI should be used in all possible clinical circumstances and trials; and 3) reproducible quantitative MR measures should ideally be used for the assessment of patients but are essential for clinical trials.

Identification of new therapeutic targets for prevention of CNS inflammation

Multiple sclerosis (MS) is a disease of complex pathologies, which involves infiltration by CD4(+) and CD8(+) T cells of and response within the central nervous system. Expression in the CNS of cytokines, reactive nitrogen species and costimulator molecules have all been described in MS. Notably, the cytokines IFN-gamma and TNF are strongly expressed. Microglial cells in the CNS express costimulator molecules and it is assumed that they play a role in directing or inducing the T cell response. Transgenic experiments have tested the effects of overexpression of these molecules in mice and have shown that TNF has multiple effects in the CNS. These range from pro-inflammatory effects of soluble TNF signalling through one of its receptors TNF-RI, to protective/regenerative effects of membrane-associated TNF signalling through the other receptor, TNF-RII. Although IFN-gamma induces nitric oxide production via the enzyme inducible nitric oxide synthase, which is immunosuppressive, IFN-gamma is predominantly pro-inflammatory. In CNS disease in mice that involves CD8(+) T cells, IFN-gamma blockade is protective. Finally, microglial expression of the costimulator ligand B7.2 induces demyelinating pathology. Animal experiments therefore point to IFN-gamma and costimulatory microglia as logical targets of therapy for MS. IFN-gamma represents a more accessible target and should therefore be pursued at the earliest opportunity.

Adaptive functional changes in the cerebral cortex of patients with nondisabling multiple sclerosis correlate with the extent of brain structural damage

In multiple sclerosis, the mechanisms underlying the accumulation of disability are poorly understood. Recently, it has been suggested that adaptive cortical changes may limit the clinical impact of multiple sclerosis injury. In this study, functional magnetic resonance imaging and a general search method were used to assess patterns of brain activation associated with a simple motor task in 14 right-handed, nondisabled relapsing-remitting multiple sclerosis patients that were compared to those from 15 right-handed, sex- and age-matched healthy volunteers. Also investigated were the extent to which the functional magnetic resonance imaging changes correlated with T2 lesion volume and severity of multiple sclerosis pathology in lesions and normal-appearing brain tissue, measured using magnetisation transfer and diffusion tensor magnetic resonance imaging. Compared to controls, multiple sclerosis patients showed increased activation in the contralateral primary sensorimotor cortex, bilaterally in the supplementary motor area, bilaterally in the cingulate motor area, in the contralateral ascending bank of the sylvian fissure, and in the contralateral intraparietal sulcus. T2 lesion volume was correlated with relative activation in the ipsilateral supplementary motor area, and in the ipsilateral and contralateral cingulate motor area. Average lesion magnetisaiton transfer ratio and average lesion water diffusivity were correlated with relative activation in the contralateral sensorimotor cortex. Average lesion magnetisation transfer ratio was also correlated with relative activation in the ipsilateral cingulate motor area. Average water diffusivity and peak height of the normal-appearing brain tissue diffusivity histogram were both correlated with relative activation in the contralateral intraparietal sulcus. This study shows that cortical activation occurs over a rather distributed sensorimotor network in nondisabled relapsing-remitting multiple sclerosis patients. It also suggests that increased recruitment of this cortical network contributes to the limitation of the functional impact of white matter multiple sclerosis injury.

Neuronal apoptosis induced by cerebrospinal fluid from multiple sclerosis patients correlates with hypointense lesions on T1 magnetic resonance imaging

Neuronal damage seems to be a major source of disability in multiple sclerosis (MS) patients and at present magnetic resonance imaging (MRI) is a sensitive method to evaluate lesion and disease activity. We studied the potential correlation between changes in MS patients' disability after relapse, the degree of T1 lesion hypointensity on MRI in vivo and neuronal apoptosis induced by cerebrospinal fluid (CSF) on neuron cultures. In this study, we included 24 MS patients with relapsing disease. Clinical recovery from relapse was measured by the Expanded Disability Status Scale (EDSS). T1-weighted MRI studies were done according to established standards and neuronal apoptosis was induced by treatment of neuronal cultures with CSF from patients while relapsing. Recovery after relapse is inversely correlated with neuronal apoptosis (r=-0.725, p<0.0001). A correlation was found between T1 lesion hypointensity and a poor recovery from relapse (r=0.656, p=0.0005) and such hypointensity correlated strongly with neuronal apoptosis (r=-0.779, p<0.0001). CSF from all patients with hypointense T1 lesions caused significantly increased neuronal apoptosis, whereas all CSF that did not induced such effects corresponded to patients without T1 lesions. The recovery from an acute MS relapse is significantly worse in patients with hypointense T1 lesions in MRI and in those whose CSF damaged neurons on cultures in vitro, phenomena that closely correlated each other.

The role of non-conventional MR techniques to study multiple sclerosis patients

Conventional magnetic resonance imaging (MRI) lacks pathological specificity to the heterogeneous substrates of multiple sclerosis (MS) lesions and is not able to detect subtle, disease-related changes in the normal-appearing white matter (NAWM). As a consequence, the correlation between MRI findings and the long-term evolution of MS is moderate at best. To overcome the limitations of conventional MRI, new quantitative magnetic resonance (MR) techniques, such as cell-specific imaging, magnetization transfer imaging (MTI), proton magnetic resonance spectroscopy (MRS), diffusion-weighted imaging (DWI) and functional MR imaging (fMRI) have all been recently applied to the study of MS. These techniques should provide more accurate and pathologically specific estimates of the MS lesion burden than conventional MR and should improve our understanding of the mechanisms leading to MS-related irreversible disability.