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

Enhanced visualization of axonopathy in EAE using thy1-YFP transgenic mice

It is widely accepted that chronic disabilities in multiple sclerosis (MS) patients are due in part to neuronal damage. The central aim of this study was to characterize axonal disruption in the spinal cord of mice with myelin oligodendrocyte glycoprotein-induced experimental autoimmune encephalomyelitis (MOG-EAE), a model of progressive MS. To accomplish this goal, we induced MOG-EAE in thy1-yellow fluorescent (thy-YFP)-transgenic mice in which all spinal motorneurons express the YFP reporter protein. We demonstrate that a build-up of YFP fluorescence occurs in profiles reminiscent of tortuous fragmented axons and axonal spheroids/globules as seen in various neurodegenerative/neuroinflammatory diseases. Approximately two-thirds of these damaged axons were decorated by the monoclonal antibody SMI 32, which recognizes hypophosphorylated neurofilament-H (hypoP-NF-H), an established marker of CNS axonal pathology. Unexpectedly, one third of damaged axons were hypoP-NF-H negative but could be visualized by their expression of the YFP transgene, whilst the remaining profiles were hypoP-NF-H positive but did not exhibit YFP fluorescence. Thus, using YFP transgenic mice in conjunction with hypoP-NF-H immunoreactivity provides a more comprehensive depiction of axonopathy in the ventral-lateral aspect of lumbosacral spinal cord in MOG-EAE. When YFP fluorescence was used in conjunction with a monoclonal antibody that recognizes CD11b; a marker of subsets of inflammatory cells, we were able to discern evidence of an early inflammatory attack on white matter axons. Finally, we show the accumulation of hyperphosphorylated neurofilament-H (hyperP-NF-H) expression in YFP+, lesioned WM areas and in a subpopulation of neuronal perikarya in the lumbar spinal cords of EAE mice.

Transcranial brain sonography findings related to neuropsychological impairment in multiple sclerosis

Cognitive dysfunction, fatigue and mood disorder contribute to the neuropsychological impairment that is common in multiple sclerosis (MS). The present paper reviews application of transcranial brain sonography (TCS) in MS patients and TCS findings related to neuropsychological dysfunction. TCS is a new neuroimaging method displaying tissue echogenicity of the brain through the intact skull. Whereas the cortex can not be discriminated from the subcortical white matter with TCS, subcortical brain structures such as ventricles and basal ganglia can be adequately displayed. Even though TCS proved sensitive and reliable in measuring widths of third and lateral ventricles in a number of neurodegenerative diseases, relatively few TCS studies on MS patients have been reported. Data of these studies suggest a good correlation of cognitive dysfunction and width of third ventricle which can be measured reliably with TCS. Moreover, abnormal TCS findings of basal ganglia were associated with cognitive impairment. However, TCS findings of midbrain structures, basal ganglia and ventricles did not correlate with fatigue or depression in MS patients. TCS has the advantages of low costs, short investigation times and unlimited repeatability. The use of third-ventricle and basalganglia TCS for predicting and monitoring neuropsychological impairment in MS patients, however, needs to be elucidated in further studies.

Acute metabolic brain changes following traumatic brain injury and their relevance to clinical severity and outcome

BACKGROUND

Conventional MRI can provide critical information for care of patients with traumatic brain injury (TBI), but MRI abnormalities rarely correlate to clinical severity and outcome. Previous magnetic resonance spectroscopy studies have reported clinically relevant brain metabolic changes in patients with TBI. However, these changes were often assessed a few to several days after the trauma, with a consequent variation of the metabolic pattern due to temporal changes.

METHODS

Proton magnetic resonance spectroscopic imaging (1H-MRSI) examinations were performed in 10 patients with TBI 48-72 h after the trauma, to obtain early measurements of central brain levels of N-acetylaspartate (NAA), choline (Cho), creatine (Cr) and lactate (La). Metabolite values were expressed as ratios to (1) a metabolic pattern, given by the sum of the resonance intensities of all metabolites detected in the same voxel and (2) intravoxel Cr.

RESULTS

NAA ratios were found to be significantly lower in patients with TBI than in normal controls. In contrast, Cho ratios were significantly higher in patients with TBI than in normal controls. Increased La levels were found in 5 of 10 patients with TBI. Both NAA and La values correlated closely with those of the Glasgow Coma Scale at presentation (r = 0.73 and -0.62, respectively; p<0.01 for both) and the Glasgow Outcome Scale at 3 months (r = -0.79 and 0.79, respectively; p<0.01 for both).

CONCLUSION

Spectroscopic measures of neuro-axonal damage occurring soon after a brain trauma are clinically relevant. Significant increases in cerebral La level also may be detected when 1H-MRSI is performed early after the trauma and, at this stage, can represent a reliable index of injury severity and disease outcome in patients with TBI.

N-acetylaspartic acid in cerebrospinal fluid of multiple sclerosis patients determined by gas-chromatography-mass spectrometry

BACKGROUND

Axonal degeneration is considered to play a major role in the development of clinical disability in multiple sclerosis (MS). N-AcetylAspartic Acid (NAA) is a neuron-specific marker constantly identified in MR-spectroscopy studies of the normal and MS brain. To our knowledge there are no studies available that evaluated NAA in cerebrospinal fluid (CSF) as a possible marker for disease severity.

OBJECTIVE

To evaluate CSF concentrations of NAA in MS in relation to disease phenotype, clinical measures of disability and MRI markers of disease burden.

METHODS

NAA concentrations were determined in CSF of 46 patients with MS (26 relapsing remitting (RRMS), 12 secondary progressive (SPMS) and 8 primary progressive (PPMS)). Prior to lumbar puncture, MS-patients underwent MRI and clinical examination, including the Expanded Disability Status Scale (EDSS) and the MS Functional Composite (MSFC). Additionally, CSF concentrations of NAA were determined in 12 patients with other neurological diseases (OND).

RESULTS

Median CSF NAA concentration was 0.74 (IQR: 0.59-0.94) in RRMS , 0.54 (IQR: 0.35-0.73) in SPMS and 0.83 mumol/l (IQR: 0.56-1.03) in PPMS patients. SPMS patients had a significantly lower NAA concentration than RRMS patients. NAA concentrations correlated with EDSS (r = )0.37, p = 0.016), MSFC (r = 0.41, p = 0.010), normalised brain volume (r = 0.49, p = 0.001), T2 lesion load (r = )0.35, p = 0.021) and black hole lesion load (r = )0.47, p = 0.002). No differences were observed between OND (median: 0.57 IQR: 0.28-0.73) and MS patients.

CONCLUSION

CSF NAA concentration in MS patients is related to clinical performance and MRI measures of disease burden and may therefore be an important neuron specific marker of disease severity and possibly progression.

MR Spectroscopy in Multiple Sclerosis

In the last decade, the use of magnetic resonance imaging (MRI) has led to a reevaluation of the pathogenesis and the natural history of multiple sclerosis (MS). This has been driven to a significant degree by results of proton magnetic resonance spectroscopy (1H-MRS) studies. By providing evidence of early neurodegeneration (based on levels of N-acetylaspartate), results of 1H-MRS studies have led to a reconsideration of the role of axonal damage in MS. By measuring brain changes of metabolites such as choline and myo-inosol, 1H-MRS has confirmed the importance of assessing myelin damage and repair. However, despite the pathological specificity of 1H-MRS and the relatively large number of clinical 1H-MRS studies on patients with MS, measures provided by this MR technique are not used routinely for assessing and monitoring MS patients. This is due to technical difficulties and limitations that are at present not entirely solved. We will review here the most relevant results in MS studies that have used 1H-MRS measures, the clinical importance of these results and the pending issues that need to be solved for a larger and more reliable use of 1H-MRS in clinical MS studies.

Gray and normal-appearing white matter in multiple sclerosis: an MRI perspective

Besides focal white matter lesions, multiple sclerosis brain tissue also displays abnormalities in the gray matter and the normal-appearing white matter. Recent advances in magnetic resonance imaging studies of both types of tissue are discussed. Herein, normal-appearing white matter abnormalities are being found in quantitative magnetic resonance investigations, consistent with a limited degree of axonal damage and/or demyelination, and an increase of glial cells, but the specific nature of the histopathological changes underlying the quantitative magnetic resonance abnormalities remains unclear. Gray matter studies have demonstrated that much of the disease process remains undetected by conventional magnetic resonance imaging. Although newly developed techniques, such as 3D double-inversion recovery, may greatly improve detection of cortical pathology, it remains important to investigate the resultant effects on the cortical tissue alongside this, by studying integrity of normal-appearing cortical tissue through quantitative magnetic resonance studies, as well as the net neurodegenerative effect through measurements of cortical thickness and cortical atrophy (rates). To improve our understanding of normal-appearing white and gray matter changes, their mutual relations, and their relations to clinical changes, further in vivo magnetic resonance imaging studies are required. Specifically, it is proposed that more spatially specific investigations, ideally utilizing subject-specific anatomical information from, for example, diffusion fiber-tracking techniques, could be used to gain more insight into the relations between normal-appearing white matter changes, cortical changes, magnetic resonance visible focal-lesions, and physical and cognitive deficits.

Discordant white matter N-acetylasparate and diffusion MRI measures suggest that chronic metabolic dysfunction contributes to axonal pathology in multiple sclerosis

Diffusion MRI and magnetic resonance spectroscopic measurements of selectively neuronally localised N-acetylaspartate (NAA) both have been used widely to assess white matter integrity and axonal loss. We have tested directly the relationship between changes in diffusion MRI parameters and NAA concentrations in the corpus callosum (CC) in an in vivo study of patients with MS. Fifteen MS patients (median EDSS 2.5, range 1-4) were studied with T(1) anatomical, T(2)-weighted, and diffusion-sensitised MRI and PRESS single-voxel MRS. A recently described method, tract-based spatial statistics (TBSS) [Smith, S.M., Jenkinson, M., Johansen-Berg, H., Rueckert, D., Nichols, T.E., Mackay, C.E. et al., 2006. Tract-based spatial statistics: voxelwise analysis of multi-subject diffusion data. Neuroimage 31, 1487-1505] also was used to perform exploratory voxelwise whole-brain analysis of white matter diffusion fractional anisotropy (FA). We found a strong correlation between callosal size and both mean FA (r=0.68, p<0.005) (related specifically to changes in the radial tensor component) and mean inter-hemispheric motor tract connectivity probability (r=0.74, p<0.001). TBSS confirmed that the diffusion anisotropies of white matter voxels specifically within the callosum were correlated with the callosal size. Individual patient global T(2) lesion volumes were correlated with both the probability of callosal connectivity (r=-0.69, p<0.005) and fractional anisotropy across the callosum (r=-0.76, p<0.001). However, absolute concentrations of NAA from the voxel showed no correlation with callosal cross-sectional area, mean connectivity or fractional anisotropy within the callosal pathway. We conclude that diffusion MRI shows changes consistent with sensitivity to axonal loss, but that relative NAA changes are not necessarily related directly to this. Axonal metabolic function, independent of structural integrity, may be a major determinant of NAA measures in MS.

Progression in multiple sclerosis: further evidence of an age dependent process

The relapsing-remitting phase and the progressive phase of multiple sclerosis (MS) seem to be the result of distinct pathophysiological processes. Previous research on the natural history of MS was largely focussed on relapses and disability scores. In this study we evaluated 438 patients with secondary or primary progressive MS. The influence of gender, initial disease course, onset manifestation and age at disease onset on age at progression and time to progression were evaluated with Kaplan-Meier survival analysis and Cox multivariate regression models. The analysis of these data showed that the initial disease course (SPMS or PPMS) had no influence on the age at progression. Gender had no influence on age at progression in PPMS and SPMS patients nor on time to progression in SPMS patients. PPMS patients with visual or brainstem/cerebellar onset had a significantly younger age at progression. SPMS patients with motor onset had a significantly higher age at progression and longer time to progression. Time to progression was significantly shorter in SPMS patients with higher age at disease onset. Our data give further support to the notion that progression in MS is an age dependent process independent of relapses.

Elevated intrathecal antibodies against the medium neurofilament subunit in multiple sclerosis

Neurofilaments are cytoskeletal proteins localized within axons, which may interact with the immune system during and following tissue destruction in multiple sclerosis (MS). Antibodies against the medium neurofilament subunit synthesized intrathecally may reflect axonal damage in MS patients. Both immunoglobulin G (IgG) and M (IgM) responses against the purified native medium subunit of neurofilaments (NFM) using enzyme-linked immunosorbent assay (ELISA) were determined in paired serum and cerebrospinal fluid samples obtained from 49 MS patients, 16 normal controls (CN), 21 control patients with miscellaneous diseases (CD) and 14 patients with neurodegenerative disorders (CDEG). Intrathecal production of IgM and IgG antibodies to NFM were elevated in MS patients compared with the CN or CD groups (p<0.04 for IgM, p<0.01 for IgG). The increase was present in all the MS courses (relapsing-remitting, primary and secondary progressive). Similar local anti-NFM IgG and IgM synthesis occurred in the MS and CDEG groups. MS patients with short and long disease duration did not differ in terms of their anti-NFM IgM and IgG responses. Repeated examinations showed stable intrathecal anti-NFM production. Intrathecal IgG and IgM antibodies against NFM were increased in MS patients and may serve as a potential marker for axonal pathology. The extent of anti-NFM levels did not correspond to any individualized clinical profiles of MS patients.

N-Acetylaspartate in the CNS: from neurodiagnostics to neurobiology

The brain is unique among organs in many respects, including its mechanisms of lipid synthesis and energy production. The nervous system-specific metabolite N-acetylaspartate (NAA), which is synthesized from aspartate and acetyl-coenzyme A in neurons, appears to be a key link in these distinct biochemical features of CNS metabolism. During early postnatal central nervous system (CNS) development, the expression of lipogenic enzymes in oligodendrocytes, including the NAA-degrading enzyme aspartoacylase (ASPA), is increased along with increased NAA production in neurons. NAA is transported from neurons to the cytoplasm of oligodendrocytes, where ASPA cleaves the acetate moiety for use in fatty acid and steroid synthesis. The fatty acids and steroids produced then go on to be used as building blocks for myelin lipid synthesis. Mutations in the gene for ASPA result in the fatal leukodystrophy Canavan disease, for which there is currently no effective treatment. Once postnatal myelination is completed, NAA may continue to be involved in myelin lipid turnover in adults, but it also appears to adopt other roles, including a bioenergetic role in neuronal mitochondria. NAA and ATP metabolism appear to be linked indirectly, whereby acetylation of aspartate may facilitate its removal from neuronal mitochondria, thus favoring conversion of glutamate to alpha ketoglutarate which can enter the tricarboxylic acid cycle for energy production. In its role as a mechanism for enhancing mitochondrial energy production from glutamate, NAA is in a key position to act as a magnetic resonance spectroscopy marker for neuronal health, viability and number. Evidence suggests that NAA is a direct precursor for the enzymatic synthesis of the neuron specific dipeptide N-acetylaspartylglutamate, the most concentrated neuropeptide in the human brain. Other proposed roles for NAA include neuronal osmoregulation and axon-glial signaling. We propose that NAA may also be involved in brain nitrogen balance. Further research will be required to more fully understand the biochemical functions served by NAA in CNS development and activity, and additional functions are likely to be discovered.

Decreased Expression of VEGF-A in Rat Experimental Autoimmune Encephalomyelitis and in Cerebrospinal Fluid Mononuclear Cells from Patients with Multiple Sclerosis

Vascular endothelial growth factor A (VEGF-A) stimulates angiogenesis, but is also pro-inflammatory and plays an important role in the development of neurological disease, where it can have both attenuating and exacerbating effects. VEGF-B, a related molecule, is highly expressed in the central nervous system and seems to be important in neurological injury. A few studies have indicated that VEGF-A may play a role in the pathogenesis of multiple sclerosis (MS), but the role of VEGF-B has not been studied. We have studied the expression of VEGF-A, -B and their receptors by mRNA in situ hybridization, immunohistochemistry and real-time PCR in spinal cord from LEW rats with experimental autoimmune encephalomyelitis (EAE) and in cerebrospinal fluid (CSF) and blood samples from MS patients. Whereas VEGF-A is downregulated in glia in EAE, the infiltrating inflammatory cells are positive for VEGF-A. Expression of VEGF-B and the VEGF receptors is unaltered. In addition, the levels of VEGF-A mRNA in mononuclear cells [corrected] in CSF are lower in MS patients compared with controls. These results demonstrate a complex regulation of VEGF-A during neuroinflammation and suggest that VEGF-B is not involved in the pathogenesis of MS.

Ipsilateral silent period: A marker of callosal conduction abnormality in early relapsing–remitting multiple sclerosis?

OBJECTIVE

The corpus callosum (CC) is commonly affected in multiple sclerosis (MS). The ipsilateral silent period (iSP) is a putative electrophysiological marker of callosal demyelination. The purpose of this study was to re-assess, under recently established optimised protocol conditions [Jung P., Ziemann U. Differences of the ipsilateral silent period in small hand muscles. Muscle Nerve in press.], its diagnostic sensitivity in MS, about which conflicting results were reported in previous studies.

METHODS

ISP measurements (onset, duration, and depth) were obtained in the abductor pollicis brevis (APB) muscle of either hand in 49 patients with early relapsing-remitting MS (RRMS) (mean EDSS, 1.3). Standard central motor conduction times to the APB (CMCT(APB)) and tibial anterior muscles (CMCT(TA)), and magnetic resonance images (MRI) were also obtained.

RESULTS

ISP measurements showed a similar diagnostic sensitivity (28.6%) as CMCT(APB) (24.5%), while diagnostic sensitivities of CMCT(TA) (69.4%) and MRI of the CC (78.6%) were much higher. Prolongation of iSP duration was the most sensitive single iSP measure. ISP prolongation occurred more frequently when CMCT(APB) to the same hand was also prolonged (40.0% vs. 8.4%, p<0.0001). The correlation between iSP duration and CMCT(APB) was significant (Pearson's r=0.24, p<0.02), suggesting that iSP duration can be contaminated by demyelination of the contralateral corticospinal tract. ISP duration did not correlate with MRI abnormalities of the CC.

CONCLUSIONS

ISP measures are neither a sensitive nor a specific marker of callosal conduction abnormality in early RRMS.

Effects of Alzheimer disease on fronto-parietal brain N-acetyl aspartate and myo-inositol using magnetic resonance spectroscopic imaging

Previous magnetic resonance (MR) spectroscopy studies of Alzheimer disease (AD) reporting reduced N-acetyl aspartate (NAA) and increased myo-Inositol (mI) used single voxel techniques, which have limited ability to assess the regional distribution of the metabolite abnormalities. The objective of this study was to determine the regional distribution of NAA and mI alterations in AD by using MR spectroscopic imaging. Fourteen patients with AD and 22 cognitively normal elderly were studied using structural MR imaging and MR spectroscopic imaging. Changes of NAA, mI, and various metabolite ratios were measured in frontal and parietal lobe gray matter (GM) and white matter. This study found: (1) when compared with cognitively normal subjects, AD patients had increased mI and mI/creatine (Cr) ratios primarily in parietal lobe GM, whereas frontal lobe GM and white matter were spared; (2) in the same region where mI was increased, AD patients had also decreased NAA and NAA/Cr ratios, replicating previous findings; (3) however, increased mI or mI/Cr ratios did not correlate with decreased NAA or NAA/Cr ratios; and (4) using mI/Cr and NAA/Cr together improved sensitivity and specificity to AD from control as compared with NAA/Cr alone. In conclusion, decreased NAA and increased mI in AD are primarily localized in parietal lobe GM regions. However, the NAA and mI changes are not correlated with each other, suggesting that they represent different processes that might help staging of AD.

[Multiple sclerosis. An update with practical guidelines for ophthalmologists]

Multiple sclerosis (MS) is the most frequent chronic inflammatory disease of the central nervous system. Mostly young adults present with a variety of different symptoms due to the multiple localisations of the inflammatory lesions. Up to one-third of MS patients experience symptoms of optic neuritis as the initial symptom. That is the reason why the ophthalmologist often is the first physician contacted by patients later on diagnosed with MS. Today, it is known that there is already a significant irreversible axonal loss in MS patients progressing from the beginning of the disease. Therefore early, diagnosis and application of available therapeutic options are necessary for the patient's benefit. The therapeutic aim in early immunomodulatory treatment is to decrease the number of relapses and to slow down the development of clinical disability. This interdisciplinary overview presents guidelines for the clinical routine: how to assess the individual risk of each patient and how to treat the patient in accordance with current pathogenic, diagnostic and therapeutic knowledge.

The brain as a target of inflammation: common pathways link inflammatory and neurodegenerative diseases

Classical knowledge distinguishes between inflammatory and non-inflammatory diseases of the brain. Either the immune system acts on the CNS and initiates a damage cascade, as in autoimmune (e.g. multiple sclerosis) and infectious conditions, or the primary insult is not inflammation but ischemia or degeneration, as in stroke and Alzheimer's disease, respectively. However, as we review here, recent advances have blurred this distinction. On the one hand, the classical inflammatory diseases of the brain also exhibit profound and early neurodegenerative features - remarkably, it has been known for more than a century that neuronal damage is a key feature of multiple sclerosis pathology, yet this was neglected until very recently. On the other hand, immune mechanisms might set the pace of progressive CNS damage in primary neurodegeneration. Despite differing initial events, increasing evidence indicates that even in clinically heterogeneous diseases, there might be common immunological pathways that result in neurotoxicity and reveal targets for more efficient therapies.

The role of CD8+ T-cells in lesion formation and axonal dysfunction in multiple sclerosis

The etiology of multiple sclerosis (MS) remains unknown. However, both genetic and environmental factors play important roles in its pathogenesis. While demyelination of axons is a hallmark histological feature of MS, axonal and neuronal dysfunction may correlate better with clinical disability. All major immune cell types have been implicated in the pathogenesis of MS, with the CD4+ T-cells being the most commonly studied. In this review, we discuss the involvement of CD8+ T-cells in MS. In addition, we review the contribution of CD8+ T-cells to the pathogenesis of experimental autoimmune encephalitis (EAE) and Theiler's murine encephalomyelitis virus (TMEV) mouse models of MS, including the concept of CD8+ T-cell mediated axonal damage.

Diffuse metabolic changes in the brain of patients with familial amyloid polyneuropathy. A proton MRSI study

OBJECTIVES

To assess brain metabolic abnormalities in patients with familial amyloid polyneuropathy (FAP) due to the transthyretin (TTR) gene mutations.

BACKGROUND

The TTR-FAP has variable phenotypic expression, which includes abnormalities of the central nervous system (CNS). Several conventional MRI studies have shown brain abnormalities, probably secondary to amyloid accumulation in leptomeningeal and subarachnoid vessels. However, TTR-related amyloid deposits do not seem to significantly affect the brain parenchyma and a prominent CNS impairment is considered to be rare in TTR amyloidosis.

METHODS

We performed proton MR spectroscopic imaging (1H-MRSI) in the central brain of four unrelated TTR-FAP patients with either minimal or no signs of neurological involvement and eight age- and sex-matched normal controls (NC). Metabolic changes were assessed in the entire volume of interest (VOI) and in the frontal, periventricular and posterior white matter (WM).

RESULTS

Conventional MRI was normal in 2 patients and showed minimal WM lesions in the remaining 2 patients. 1H-MRSI showed N-acetylaspartate to creatine ratio (NAA/Cr) decreases in the central brain VOI in all TTR-FAP patients (p < 0.005). These NAA/Cr decreases were homogeneous in all WM regions (p < 0.05 for all).

CONCLUSIONS

1H-MRSI findings suggest that diffuse metabolic changes, probably related to axonal damage, are present in brains of TTR-FAP patients even when they have no or minimal clinical and MRI signs of CNS involvement. The mechanism leading to sub-clinical metabolic brain changes needs to be identified.

Cognitive changes in early MS: A call for a common framework

Cognitive dysfunction is among the main symptoms of multiple sclerosis (MS) and adversely affects patients' quality of life. The occurrence of cognitive impairment early in the disease process raises crucial issues related to definition of the impairment and its magnitude as well as to the tools applied to the assessment. To date there is little evidence concerning the reliability and validity of cognitive measures in early MS and their predictive long-term role. As MS is a complex disease, multidimensional approaches should be further developed and validated to study the cognitive sphere in the early stages of the disease. Considering that none of the available tests performed in isolation is able to provide a complete picture of the cognitive impairment in early MS, this calls for the definition of phase duration, impairment and tools appropriate for use by clinicians and researches. The present review proposes a framework aimed to help neurologists in approaching cognitive impairment in early MS and stimulate discussions and evaluations of the suggested recommendations.

The relationship between MRI and PET changes and cognitive disturbances in MS

Cognitive dysfunction in multiple sclerosis (MS) is present in approximately 50% of the patients. Only moderate correlations have been found between cognitive dysfunction and T(2) lesion load, black holes or atrophy. Cognitive dysfunction in MS is probably related to the overall disease burden of the brain including abnormalities in normal appearing white matter (NAWM) and cortical grey matter, which is undetected with conventional magnetic resonance imaging (MRI). Hence, imaging techniques that embrace such abnormalities are needed to achieve better correlation with cognitive dysfunction. MR spectroscopy (MRS) performed with multi-slice echo planar spectroscopic imaging (EPSI) and PET measurements of brain metabolism as the cortical cerebral metabolic rate of glucose are imaging methods that are able to provide information on axonal loss or dysfunction in both MS lesions and in NAWM and cortical grey matter. Measurements of global NAA using multi-slice EPSI is a new promising method for measurement of the global neuron capacity and can be repeated with only little discomfort and without any risk for the patient.

Early macrophage MRI of inflammatory lesions predicts lesion severity and disease development in relapsing EAE

Magnetic resonance imaging (MRI) is of great utility in diagnosis and monitoring of multiple sclerosis (MS). Axonal loss is considered the main cause of accumulating irreversible disability. MRI using ultrasmall-super-paramagnetic-iron-oxide (USPIO) nanoparticles is a new technique to disclose in vivo central nervous system (CNS) inflammatory lesions infiltrated by macrophages in experimental autoimmune encephalomyelitis (EAE). Here, we raised the question of whether USPIO-enhanced MRI could serve as a tool to predict disease severity. We investigated, in a relapsing EAE model with various degrees of disease severity, the interindividual differences at the beginning of CNS inflammation as revealed in vivo by MRI with USPIO in correlation to the severity of both acute and chronic tissue damage including axonal loss. At the onset of the disease, observation of MRI alterations with USPIO allowed assignment of animals into USPIO+ and USPIO- groups. In 54.5% of diseased rats, MRI with USPIO+ at first attack revealed signal abnormalities mainly localized in the brainstem and cerebellum. Although animals did not present any clinically significant differences during the first attack, USPIO+ rats presented significantly more important tissue alterations at the first attack (onset and initiated recovery phase) and, at the second attack, more severe clinical disease with axonal loss compared to USPIO- rats. MRI lesion load and volume at the first attack correlate significantly with inflammation, macrophage recruitment, demyelination, acute axonal damage and, at the second attack, extent of axonal loss. This new MRI application of in vivo monitoring of macrophage infiltration provides a new platform to investigate the severity of inflammatory demyelinating CNS diseases.

Secondary progressive multiple sclerosis: current knowledge and future challenges

The secondary progressive phase of multiple sclerosis (MS), which is characterised by a steady accrual of fixed disability after an initial relapsing remitting course, is not clearly understood. Although there is no consensus on the mechanisms underlying such a transition to the progressive phase, epidemiological and neuroimaging studies indicate that it is probably driven by the high prevalence of neurodegenerative compared with inflammatory pathological changes. This notion is lent support by the limited efficacy of available immunomodulating and immunosuppressive treatment strategies, which seems to be further decreased in the late stages of secondary progressive MS. No established clinical or paraclinical predictors of the transition from relapsing remitting to secondary progressive MS have been described. However, the use of quantitative MRI-derived measures is warranted to monitor natural history studies and therapeutic trials of secondary progressive MS with increased reliability. In view of the small effects of immunomodulating and immunosuppressive treatments in preventing the transition to secondary progression, the development of treatments promoting neuroaxonal repair remains an important goal in this disease.

Prolonged intracortical delay of long-latency reflexes: electrophysiological evidence for a cortical dysfunction in multiple sclerosis

Convincing evidence suggests that long-latency reflexes (LLRs) are capable of testing the transcortical sensorimotor reflex arch. By subtracting the sum of the latencies of N20 (afferent branch) and transcranially elicited motor evoked potentials (MEP; efferent branch) from the LLR II latency, the cortical relay time (CRT) can also be obtained, which is alleged to represent the time required for the cortical sensorimotor integration. The aim of the present study was to investigate if a cortical dysfunction occurs in multiple sclerosis (MS). Median nerve somatosensory evoked potentials (SEPs), MEPs and LLRs were recorded from the upper limbs of 23, not severely disabled MS patients in acute phases of the disease. Eighteen age and sex matched healthy volunteers served as controls. N20, MEP, LLR II latencies were measured, and the CRT was calculated for each limb. The statistical comparison between patients and controls was only weakly significant by taking into account conduction times along either the afferent (N20) or the efferent (MEP) pathways. On the contrary, it turned out to be considerably significant if both branches of the transcortical sensorimotor reflex arch, together with the intracortical pathway, were simultaneously tested by means of the LLRs. Moreover, the patients showed a significantly higher CRT compared with that found in the control subjects. These findings are consistent with a prolonged intracortical delay of LLRs in the MS group and suggest the occurrence of conduction velocity slowing and/or synaptic transmission impairment along the sensorimotor intracortical pathway in MS.

Diffuse structural and metabolic brain changes in Fabry disease

OBJECTIVES

To assess structural and metabolic brain changes in subjects affected by Fabry disease (FD) or carrying the disease mutation.

BACKGROUND

FD is an X-linked metabolic disorder due to alpha-galactosidase A deficiency, which leads to storage of glycosphingolipids in many tissues and organs. Previous MR studies have shown structural and metabolic brain abnormalities in FD patients. It is not clear, however, whether tissue damage can be seen in both the brains of hemizygous and heterozygous and whether quantitative MR metrics are useful to monitor disease evolution.

DESIGN/METHODS

We studied 4 males and 4 females with FD. Each subject underwent brain proton MRI/MR spectroscopic imaging (MRSI) examinations to obtain measures of total brain volumes, total brain lesion volumes, magnetization transfer ratios (MTr) in WM and central brain levels of N-acetylaspartate (NAA) to creatine (Cr). A second MR examination was performed in five subjects after 2 years.

RESULTS

Focal WM lesions were found in 2 males and 1 female. The MTr values were always low in the WM lesions of FD subjects (p < 0.001) and also were low in the normal-appearing WM of 2 affected males. Total brain volumes were never decreased in FD subjects. Brain NAA/Cr values were significantly (p = 0.005) lower in FD subjects than in normal controls and correlated closely with Rankin scale measures (r = -0.79). On follow-up examinations, no significant MR changes were found. However, the small changes in NAA/Cr correlated closely with changes in Rankin scores (r = -0.86).

CONCLUSIONS

Subtle structural and metabolic tissue damage can extend beyond WM lesions in FD subjects. Diffuse brain NAA/Cr decrease can be found in FD subjects in relation to the degree of their CNS involvement and its evolution over time.

Magnetic resonance spectroscopy in the monitoring of multiple sclerosis

In addition to providing information on tissue structure, magnetic resonance (MR) technology offers the potential to investigate tissue metabolism and function. MR spectroscopy (MRS) offers a wealth of data on the biochemistry of a selected brain tissue volume, which represent potential surrogate markers for the pathology underlying multiple sclerosis (MS). In particular, the N-acetylaspartate peak in an MR spectrum is a putative marker of neuronal and axonal integrity, and the choline peak appears to reflect cell-membrane metabolism. On this basis, a diminished N-acetylaspartate peak is interpreted to represent neuronal/axonal dysfunction or loss, and an elevated choline peak represents heightened cell-membrane turnover, as seen in demyelination, remyelination, inflammation, or gliosis. Therefore, MRS may provide a unique tool to evaluate the severity of MS, establish a prognosis, follow disease evolution, understand its pathogenesis, and evaluate the efficacy of therapeutic interventions, which complements the information obtained from the various forms of assessment made by conventional MR imaging.

Noninvasive detection of cuprizone induced axonal damage and demyelination in the mouse corpus callosum

Previously, we tested the prediction that axonal damage results in decreased axial diffusivity (lambda(parallel)) while demyelination leads to increased radial diffusivity (lambda(perpendicular)). Cuprizone treatment of C57BL/6 mice was a highly reproducible model of CNS white matter demyelination and remyelination affecting the corpus callosum (CC). In the present study, six C57BL/6 male mice were fed 0.2% cuprizone for 12 weeks followed by 12 weeks of recovery on normal chow. The control mice were fed normal chow and imaged in parallel. Biweekly in vivo DTI examinations showed transient decrease of lambda(parallel) in CC at 2-6 weeks of cuprizone treatment. Immunostaining for nonphosphorylated neurofilaments demonstrated corresponding axonal damage at 4 weeks of treatment. Significant demyelination was evident from loss of Luxol fast blue staining at 6-12 weeks of cuprizone ingestion and was paralleled by increased lambda(perpendicular) values, followed by partial normalization during the remyelination phase. The sensitivity of lambda(perpendicular) to detect demyelination may be modulated in the presence of axonal damage during the early stage of demyelination at 4 weeks of cuprizone treatment. Our results suggest that lambda(parallel) and lambda(perpendicular) may be useful in vivo surrogate markers of axonal and myelin damage in mouse CNS white matter.

Inflammation and neurodegeneration

Many CNS diseases of primarily noninflammatory origin, such as chronic neurodegenerative diseases, stroke and trauma, display inflammatory features. Conversely, damage to nerve cells and axons has emerged as a clinically important parameter of autoimmune neuroinflammatory conditions such as multiple sclerosis. Experimental data are conflicting as to whether neuroinflammatory reactions should be regarded as detrimental, or as an apt response serving to minimize nervous tissue damage. Despite this, modulation of inflammation is one of the most dynamic areas in the search for new therapeutic targets for a spectrum of CNS diseases. Recent developments in the field have unravelled an intricate regulation of neuroinflammation and disclosed several avenues that, with further exploration, may result in new ways of treating common and disabling CNS diseases.

Intrathecal immunoglobulin G synthesis and brain injury by quantitative MRI in multiple sclerosis

OBJECTIVES

It was the aim of this study to evaluate if the quantitative intrathecal immunoglobulin G (IgG) synthesis correlates with the brain atrophy and the total lesion volume (TLV) in brain magnetic resonance imaging (MRI) of multiple sclerosis (MS) patients.

METHODS

A total of 50 patients with relapsing-remitting MS were included in this study. MRIs were performed and cerebrospinal fluid samples were collected during the diagnostic determination when patients were in remission without treatment.

RESULTS

At study baseline, IgG index values were elevated in 36 patients (72%), and oligoclonal IgG bands were positive in 42 of 50 patients (84%). Brain MRI was abnormal in 94% of patients, and, compared with healthy controls, brain atrophy was observed in MS patients. A positive correlation among IgG index, cerebrospinal fluid leukocyte count and TLV was observed; the Expanded Disability Status Scale correlated positively with TLV and the number of lesions, although a significant relationship between disability and brain atrophy was not demonstrated.

CONCLUSIONS

Although new parameters will be necessary in longitudinal studies to characterize the axonal injury in various stages of the disease, the data suggest that the high intrathecal IgG synthesis may predict a greater brain lesion burden.

Genomics and proteomics: role in the management of multiple sclerosis

Epidemiological studies and neuro-imaging have provided important insights into the natural course and prognostic factors of multiple sclerosis (MS), but our ability to predict different courses of the disease, and especially its response to treatment, is still very limited. Pharmacogenetic, pharmacogenomic and proteomic studies aim to assess gene and protein function in disease and promise to help to fill this important gap in our knowledge. Such studies may increase our understanding of disease mechanisms and responses to therapeutic compounds. Large-scale transcriptional expression profiling can be performed using gene chip microarrays; this technology allows screening for differentially expressed genes without having well-defined underlying hypotheses ("discovery-driven research"). To complement the technique, real time reverse transcription and polymerase chain reaction (RT-PCR) can be used for more targeted profiling and provides quantitative data on pre-selected genes. However, to maximise their clinical utility, expression profiling results need to be combined with well-documented clinical and imaging data. Two forthcoming studies will investigate the long-term effects of early treatment with interferon beta-1b (IFNbeta) on the course of MS. The BENEFIT (BEtaseron/Betaferon in Newly Emerging MS for Initial Treatment) study will incorporate pharmacogenetic and pharmacogenomic analyses to determine the genetic elements controlling treatment response. BEST-PGx (Betaferon/Betaseron in Early relapsing-remitting MS Surveillance Trial-Pharmacogenomics) is an exploratory 2-year study that will investigate the value of RNA expression profiling and pharmacogenetics in predicting treatment response to IFNbeta in patients with early relapsing MS. The main goal of BEST-PGx is the identification of differences in gene expression profiles of patients showing differential treatment responses. In addition, this study may reveal new information relevant to the mechanism of action of interferon treatment in MS and also to differences in the underlying pathology of the immune system. These data may help us approach the goal of a really "individualised therapy" with increased efficacy, reduced adverse drug reactions and more efficient use of health care resources.

Measuring injury and repair of myelin and neurons in multiple sclerosis

Neuroprotection in MS needs to be considered in the context of several pathological processes: limitation of acute inflammatory injury to myelin and axons, remyelination, survival of demyelinated axons, and limitation of more diffuse, nonlesional pathology that affects myelin and axons. Advanced MRI techniques are capable of reporting on all of these different pathological features of MS and will be an important aspect of the assessment of neuroprotection strategies in MS, when these become available.

Metabolite changes in early relapsing-remitting multiple sclerosis. A two year follow-up study

Previous in vivo proton magnetic resonance spectroscopic imaging ((1)H-MRSI) studies have found reduced levels of N-acetyl-aspartate (NAA) in multiple sclerosis (MS) lesions, the surrounding normal-appearing white matter (NAWM) and cortical grey matter (CGM), suggesting neuronal and axonal dysfunction and loss. Other metabolites, such as myoinositol (Ins), creatine (Cr), choline (Cho), and glutamate plus glutamine (Glx), can also be quantified by (1)H-MRSI, and studies have indicated that concentrations of these metabolites may also be altered in MS. Relatively little is known about the time course of such metabolite changes. This preliminary study aimed to characterise changes in total NAA (tNAA, the sum of NAA and N-acetyl-aspartyl-glutamate), Cr, Cho, Ins and Glx concentrations in NAWM and in CGM, and their relationship with clinical outcome, in subjects with clinically early relapsing-remitting MS (RRMS). Twenty RRMS subjects and 10 healthy control subjects underwent (1)H-MRSI examinations yearly for two years. Using the LCModel, tNAA, Cr, Cho, Ins and Glx concentrations were estimated both in NAWM and CGM. At baseline, the concentration of tNAA was significantly reduced in the NAWM of the MS patients compared to the control group (-7%, p = 0.003), as well as in the CGM (-8.7%, p = 0.009). NAWM tNAA concentrations tended to recover from baseline, but otherwise tissue metabolite profiles did not significantly change in the MS subjects, or relatively between MS and healthy control subjects. While neuronal and axonal damage is apparent from the early clinical stages of MS, this study suggests that initially it may be partly reversible. Compared with other MR imaging measures, serial (1)H-MRSI may be relatively less sensitive to progressive pathological tissue changes in early RRMS.

Orofacial Pain--Part II: Assessment and management of vascular, neurovascular, idiopathic, secondary, and psychogenic causes

Chronic orofacial pain is a common health complaint faced by health practitioners today and constitutes a challenging diagnostic problem that often requires a multidisciplinary approach to diagnosis and treatment. The previous article by the same authors in this issue discussed the major clinical characteristics and the treatment of various musculoskeletal and neuropathic orofacial pain conditions. This second article presents aspects of vascular, neurovascular, and idiopathic orofacial pain, as well as orofacial pain due to various local, distant, or systemic diseases and psychogenic orofacial pain. The emphasis in this article is on the general differential diagnosis and various therapeutic regimens of each of these conditions. An accurate diagnosis is the key to successful treatment of chronic orofacial pain. Given that for many of the entities discussed in this article no curative treatment is available, current standards of management are emphasized. A comprehensive reference section has been included for those who wish to gain further information on a particular entity.

Early B-cell Factor gene association with multiple sclerosis in the Spanish population

Background

The etiology of multiple sclerosis (MS) is at present not fully elucidated, although it is considered to result from the interaction of environmental and genetic susceptibility factors. In this work we aimed at testing the Early B-cell Factor (EBF1) gene as a functional and positional candidate risk factor for this neurological disease. Axonal damage is a hallmark for multiple sclerosis clinical disability and EBF plays an evolutionarily conserved role in the expression of proteins essential for axonal pathfinding. Failure of B-cell differentiation was found in EBF-deficient mice and involvement of B-lymphocytes in MS has been suggested from their presence in cerebrospinal fluid and lesions of patients.

Methods

The role of the EBF1 gene in multiple sclerosis susceptibility was analyzed by performing a case-control study with 356 multiple sclerosis patients and 540 ethnically matched controls comparing the EBF1 polymorphism rs1368297 and the microsatellite D5S2038.

Results

Significant association of an EBF1-intronic polymorphism (rs1368297, A vs. T: p = 0.02; OR = 1.26 and AA vs. [TA+TT]: p = 0.02; OR = 1.39) was discovered. This association was even stronger after stratification for the well-established risk factor of multiple sclerosis in the Major Histocompatibility Complex, DRB1*1501 (AA vs. [TA+TT]: p = 0.005; OR = 1.78). A trend for association in the case-control study of another EBF1 marker, the allele 5 of the very informative microsatellite D5S2038, was corroborated by Transmission Disequilibrium Test of 53 trios (p = 0.03).

Conclusion

Our data support EBF1 gene association with MS pathogenesis in the Spanish white population. Two genetic markers within the EBF1 gene have been found associated with this neurological disease, indicative either of their causative role or that of some other polymorphism in linkage disequilibrium with them.

1H-MRS quantification of tNA and tCr in patients with multiple sclerosis: a meta-analytic review

Meta-analysis was performed on the results of 75 comparisons from the 30 peer-reviewed publications that used proton magnetic resonance spectroscopy (1H-MRS) or spectroscopic imaging to (i) quantify the mean concentrations of total creatine (tCr, found in neurons, astrocytes and oligodendrocytes), and/or total N-acetyl groups (tNA, found only in neurons), in the lesional and/or non-lesional white matter (WM) and/or the grey matter (GM) of patients with multiple sclerosis (MS) and (ii) compare these values with those in the homologous tissues of normal controls (NC). For mean [tNA] values, there was (i) a large-effect-sized overall decrease in patients' lesional WM relative to NC WM (25 comparisons), (ii) a medium-effect-sized overall decrease in patients' non-lesional WM relative to NC WM (36 comparisons) and (iii) a medium-effect-sized overall decrease in patients' GM relative to NC GM (14 comparisons). Patients' mean [tNA] values were sometimes statistically normal but were never statistically increased. For mean [tCr] values, there was (i) no statistically significant overall change in the patients' lesional WM relative to NC WM (24 comparisons), although statistically significant increases and decreases were sometimes found, (ii) a medium-effect-sized overall increase in patients' non-lesional WM relative to NC WM (33 comparisons) and (iii) no statistically significant overall change in patients' GM relative to NC GM (12 comparisons), although a significant decrease was found in one comparison. Of 41 comparisons with statistically significant changes, 38 combined in a way that would probably result in decreased mean [tNA]/[tCr] ratios such that (i) 66% had statistically decreased mean [tNA] and statistically unchanged mean [tCr] values, (ii) 13% had statistically decreased mean [tNA] and statistically increased mean [tCr] values and (iii) 21% had statistically unchanged mean [tNA] values and statistically increased mean [tCr] values. Of the 25 comparisons that came from studies that also analysed [tNA]/[tCr] ratios, the direction of change in mean [tNA] values and mean [tNA]/[tCr] ratios was concordant in 84%. In comparisons that quantified both [tNA] and [tCr], there was a similar amount of variability in both measures in each of the different tissue types studied, both in patients and NCs. Together, these results suggest that within-voxel tNA/tCr ratios can be interpreted as valid and accurate surrogate measures of 'cerebral tissue integrity'-with decreased tNA/tCr ratios indicating some combination of neuroaxonal disturbance, oligodendroglial disturbance, and astrocytic proliferation. These results also suggest that, although within-voxel tNA/tCr ratios are not perfect indicators of [tNA] content, they do represent a practical compromise to acquiring surrogate measures of within-voxel neuroaxonal integrity.

MRI evidence for multiple sclerosis as a diffuse disease of the central nervous system

The classical view of MS as a chronic inflammatory demyelinating disease leading to the formation of focal central nervous system (CNS) white matter (WM) lesions has been recently challenged by pathological studies and by the extensive application of modern MRI-based techniques. There is now overwhelming evidence supporting the following statements: MS causes widespread tissue damage in the normal-appearing white matter (NAWM) of the brain and spinal cord, whose extent and severity is more strictly associated to the clinical manifestations of the disease than the extent of focal pathology. Discrete, macroscopic lesions are just the tip of the iceberg of MS pathology. Grey matter (GM) damage is a consistent feature of all MS phenotypes, which is progressive from the start of the relapsing-remitting phase of the disease. As is the case for WM, GM damage is also a mixture of focal lesions and diffuse pathology. High-field strength MR scanners are improving our ability to image focal GM lesions and modern MR-based techniques are enabling us to quantify in vivo the extent and severity of GM pathology, which have been shown to correlate only moderately with the amount of WM changes. At least part of GM pathology in MS is not secondary to retrograde degeneration of fibers traversing WM lesions. The neurodegenerative component of the disease is not a late phenomenon and it is not completely driven by inflammatory demyelination. In fact, neurodegeneration occurs very early in the course of MS and the correlation between MRI measures of inflammation and neurodegeneration is weak in all disease phases. The interplay of inflammation and neurodegeneration is a complex and still poorly understood phenomenon. At least part of MS-related neurodegeneration is not directly driven by Wallerian degeneration. Functional cortical changes can be seen in virtually all MS patients and are likely to play a central role in the ability of the MS brain to respond to tissue injury and, hence, limit the functional consequences of structural damage. MS disability is not just the result of tissue destruction but rather a balance between tissue destruction, tissue repair and adaptive cortical reorganization. All of this calls for the concept of MS as a focal, inflammatory demyelinating, WM disease to be reexamined and to start viewing MS as a diffuse CNS disease with an important neurodegenerative component. This is central for identifying novel and effective treatment strategies.

Quality of life and its assessment in multiple sclerosis: integrating physical and psychological components of wellbeing

Health-related quality of life (HRQoL) has been more intensively studied in multiple sclerosis (MS) than in any other neurological disorder. Traditional medical models of impairment and disability are an incomplete summary of disease burden. Quality of life can be thought of as the sum of all sources of satisfaction (including anticipated sources) minus all threats (including anticipated threats). Many psychosocial factors-including coping, mood, self-efficacy, and perceived support-influence the quality of life of patients with MS more than biological variables such as weakness or extent of MRI lesions. Neuropsychiatric complications such as cognitive impairment and fatigue are also important predictors, even in those patients in the early stages of the disease. We review generic and specific HRQoL measures to help clinicians choose the most appropriate therapies. Subjective (self-report) HRQoL measures may serve to alert clinicians to areas that would otherwise be overlooked. Studies of new interventions should include an assessment of HRQoL not just impairment or disability alone.

Early treatment and dose optimisation

The use of interferon beta (IFNbeta) in the treatment of multiple sclerosis (MS) has not changed greatly since its introduction. However, two new treatment paradigms have recently emerged-initiation of treatment as early in the course of the disease as possible and the use of higher doses with greater frequency to gain maximum therapeutic effect. The rationale for early treatment comes from evidence showing that early and irreversible pathology exists in very early stages of relapsing remitting MS (RRMS) often before significant disability is apparent and continues during remission. In addition, irreversible axonal damage begins early in the course of MS. Two relatively short-term studies indicate that it is possible to delay the onset of MS by early treatment with low-dose IFNbeta-1a. The BENEFIT (BEtaferon/Betaseron in Newly Emerging MS For Initial Treatment) study is being undertaken to investigate whether early intervention with a high-dose and more frequent administration of IFNbeta-1b (250 microg [8 MIU] every other day [eod]) has the ability to affect long-term clinical and magnetic resonance imaging (MRI) outcomes even more favourably. In addition, together with its follow-up study, BENEFIT will address the open question of long-term effects of early treatment on disease progression. Results from the pivotal IFNbeta-1b study, together with data from PRISMS (Prevention of Relapses and Disability by Interferon beta-1a Subcutaneously in Multiple Sclerosis) showed the presence of a dose-response relationship for IFNbeta in the treatment of RRMS. This finding was confirmed by the results of INCOMIN (INdependent COMparison of INterferons) and EVIDENCE (EVidence of Interferon Dose-response: European North American Comparative Efficacy), direct comparative studies of high-dose (250 microg IFNbeta-1b, 44 microg IFNbeta-1a), high-frequency versus lower dose (30 microg IFNbeta-1a) and less frequent IFNbeta regimens. Results from a pilot study in patients with RRMS have indicated that increasing the dose of IFNbeta-1b to 500 microg (16 MIU) had a more pronounced biological effect compared with the standard 250 microg dose. The BEYOND (Betaferon/Betaseron Efficacy Yielding Outcomes of a New Dose) study is being undertaken to investigate whether IFNbeta-1b 500 microg eod is superior to the standard 250 microg eod dose in treatment-naïve patients with RRMS. A third treatment arm will provide a comparison with glatiramer acetate 20mg subcutaneously once daily.

Axonal injury in the cerebral normal-appearing white matter of patients with multiple sclerosis is related to concurrent demyelination in lesions but not to concurrent demyelination in normal-appearing white matter

We assessed axonal injury and demyelination in the cerebral normal-appearing white matter (NAWM) of MS patients in a pilot study using proton magnetic resonance spectroscopic imaging and quantitative magnetization transfer (MT) imaging. Resonance intensities of N-acetylaspartate (NAA) relative to creatine (Cr) were measured in a large central brain volume. NAA/Cr in NAWM was estimated by regression of the NAA/Cr in each voxel against white matter fraction and extrapolation to a white matter fraction of 1. The fractional size of the semi-solid pool (F) was obtained from the binary spin bath model of MT by computing the model parameters from multiple MT-weighted and relaxometry acquisitions. F in NAWM was significantly smaller in the patients [0.109 (0.009)] relative to controls [0.123 (0.007), P = 0.011], but did not differ between RR [0.1085] and SP [0.1087] patients [P > 0.99]. NAA/Cr and F in the NAWM were not correlated (r = 0.16, P > 0.7), mainly due to a lack of variation in F among patients. This may indicate a floor to the extent of myelin pathology that can occur in NAWM before a lesion appears, or that axonal damage is not strictly related to demyelination. The correlation between NAWM NAA/Cr and T2w lesion volume was not significant (P > 0.1). However, dividing the lesion volumes by the mean F in T2w lesions resulted in a quantity that correlated well with NAWM NAA/Cr (r = -0.78, P = 0.038), possibly reflecting the association of Wallerian degeneration in the NAWM with axonal transection associated with demyelination within lesions.

Autoantigen specific T cells inhibit glutamate uptake in astrocytes by decreasing expression of astrocytic glutamate transporter GLAST: a mechanism mediated by tumor necrosis factor‐α

Glutamate excitotoxicity is increasingly being recognized as a pathogenic mechanism in autoimmune inflammatory disorders of the central nervous system (CNS). Astrocytes are the predominant players in clearing the extracellular space from glutamate and normally have extensive spare capacities in terms of glutamate uptake. We asked what might be the basis of glutamate accumulation in T cell triggered autoimmune inflammation. In vitro, coculture of primary rat astrocytes with activated myelin basic protein (MBP)-specific T cells resulted in a decrease of astrocytic glutamate uptake rates (Vmax). In parallel, the amount of the Na+-dependent glutamate transporter GLAST was reduced within 48-60 h. Significant decreases of GLAST protein were observed in astrocytes harvested after incubation with T cells activated by MBP during coculture or after incubation with T cell blasts preactivated in the presence of splenocytes beforehand. Since exposure of astrocytes to cell-free supernatant of MBP-activated T cells also resulted in reduced expression of GLAST, a humoral factor appeared to be the driving agent. In blocking experiments using neutralizing antibodies and by incubation of astrocytes with recombinant cytokines, tumor necrosis factor-alpha (TNF-alpha) was identified as being responsible for the down-modulation of GLAST. GLAST was also down-regulated in the CNS of autoimmune encephalomyelitic rats but not in animals suffering from systemic inflammation. Since the loss of GLAST was not confined to inflammatory infiltrates, here too, a humoral factor seemed to be causative. In conclusion, T cell derived TNF-alpha impairs glutamate clearance capacity of astrocytes in vitro and probably also in vivo providing a pathogenic link to glutamate excitotoxicity that may contribute to early axonal dysfunction remote from active autoimmune inflammatory demyelination.

Macrophages and neurodegeneration

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS). Demyelination is a classical feature of MS lesions, and neurological deficits are often ascribed to the reduced signal conduction by demyelinated axons. However, recent studies emphasize that axonal loss is an important factor in MS pathogenesis and disease progression. Axonal loss is found in association with cellular infiltrates in MS lesions. In this review, we discuss the possible contribution of the innate immune system in this process. In particular, we describe how infiltrated macrophages may contribute to axonal loss in MS and in experimental autoimmune encephalomyelitis (EAE), the animal model for MS. An overview is given of the possible effects of mediators, which are produced by activated macrophages, such as such as pro-inflammatory cytokines, free radicals, glutamate and metalloproteases, on axonal integrity. We conclude that infiltrated macrophages, which are activated to produce pro-inflammatory mediators, may be interesting targets for therapeutic approaches aimed to prevent or reduce axonal loss during exacerbation of inflammation. Interference with the process of infiltration and migration of monocytes across the blood-brain barrier is one of the possibilities to reduce the damage by activated macrophages.

Demyelination increases radial diffusivity in corpus callosum of mouse brain

Myelin damage, as seen in multiple sclerosis (MS) and other demyelinating diseases, impairs axonal conduction and can also be associated with axonal degeneration. Accurate assessments of these conditions may be highly beneficial in evaluating and selecting therapeutic strategies for patient management. Recently, an analytical approach examining diffusion tensor imaging (DTI) derived parameters has been proposed to assess the extent of axonal damage, demyelination, or both. The current study uses the well-characterized cuprizone model of experimental demyelination and remyelination of corpus callosum in mouse brain to evaluate the ability of DTI parameters to detect the progression of myelin degeneration and regeneration. Our results demonstrate that the extent of increased radial diffusivity reflects the severity of demyelination in corpus callosum of mouse brain affected by cuprizone treatment. Subsequently, radial diffusivity decreases with the progression of remyelination. Furthermore, radial diffusivity changes were specific to the time course of changes in myelin integrity as distinct from axonal injury, which was detected by betaAPP immunostaining and shown to be most extensive prior to demyelination. Radial diffusivity offers a specific assessment of demyelination and remyelination, as distinct from acute axonal damage.

Serum uric acid, dehydroepiandrosterone sulphate, and apolipoprotein E genotype in benign vs. progressive multiple sclerosis

The majority of patients with multiple sclerosis (MS) experience gradual progression of disability, either as secondary progressive MS (SPMS) or primary progressive MS (PPMS). A subgroup with relapsing-remitting MS shows a benign course with little or no disease progression and minimal disability decades after the first manifestations, so called benign MS (BMS). In our search to identify factors that are associated with progression of MS, we investigated serum levels of uric acid and dehydroepiandrostenedione sulphate (DHEAS), and apolipoprotein (apo)E genotype in 28 patients with BMS, 33 with SPMS, 21 with PPMS, and 29 healthy individuals. We found no significant changes in uric acid levels and apoE genotype between the four groups. Mean DHEAS levels were lower in MS patients compared with healthy controls (P = 0.049), but there were no significant differences between the clinical subgroups of MS. In patients with SPMS and PPMS there was no correlation between progression rate and serum levels of either uric acid or DHEAS. Our results suggest that serum levels of uric acid and DHEAS, and apoE genotype do not differ between patients with a benign and progressive course of MS.

Evolving management of optic neuritis and multiple sclerosis

PURPOSE

To review the relation of optic neuritis to multiple sclerosis (MS) and the indications, modalities, and results of therapy for optic neuritis, for both visual and general neurologic function.

DESIGN

Literature review and author's experience.

METHODS

Analysis of both laboratory and clinical evidence supporting the use of corticosteroids, immunomodulation agents, and other modalities in the treatment of optic neuritis and MS.

RESULTS

Although treatment of optic neuritis with corticosteroids may hasten visual recovery to a minor degree, it has no long-term beneficial effect on visual outcome. Optic neuritis is frequently the initial manifestation of multiple sclerosis. The risk of later development of clinically definite MS (CDMS) correlates with white matter demyelinative lesions on magnetic resonance imaging (MRI). The role of corticosteroid therapy alone in reducing the risk of subsequent MS is unclear, but recent studies suggest that the combination of immunomodulation agents (IMAs) and corticosteroids significantly reduces the later development of MS. Current research indicates that, contrary to previous doctrine, axonal damage is an early finding in MS.

CONCLUSIONS

The risk of MS after optic neuritis may be predicted. The use of corticosteroids and IMAs, particularly in those at substantial risk, reduces the frequency and severity of developing CDMS. Earlier, more aggressive therapy in optic neuritis may be proven to reduce permanent axonal injury and progressive disability in MS.

Trigeminal neuralgia in a patient with multiple sclerosis and chronic inflammatory demyelinating polyneuropathy

BACKGROUND

Trigeminal neuralgia (TN) is characterized by unilateral, severe, brief, stabbing, recurrent pain in the distribution of one or more branches of the fifth cranial nerve. Symptomatic or secondary TN involves TN-like pain that develops owing to a central nervous system lesion (benign or malignant) or to multiple sclerosis (MS).

CASE DESCRIPTION

The authors present a report of a unique case of a 43-year-old patient with unilateral TN, MS and concomitant chronic inflammatory demyelinating polyneuropathy. The facial pain preceded any other manifestations of the systemic disorders, and only after repeated neurological examinations were these diagnoses established.

CLINICAL IMPLICATIONS

Magnetic resonance imaging of the brain and repeated neurological evaluations should be implemented in all patients with TN to rule out the presence of underlying disease. The dental practitioner should be familiar with TN to avoid unnecessary dental interventions and ensure prompt initiation of appropriate treatment.

Motor neuron pathology in experimental autoimmune encephalomyelitis: studies in THY1-YFP transgenic mice

Using adult male C57BL/6 mice that express a yellow fluorescent protein transgene in their motor neurons, we induced experimental autoimmune encephalomyelitis (EAE) by immunization with myelin oligodendrocyte glycoprotein peptide 35-55 (MOG peptide) in complete Freund's adjuvant (CFA). Control mice of the same transgenic strain received CFA without MOG peptide. Early in the course of their illness, the EAE mice showed lumbosacral spinal cord inflammation, demyelination and axonal fragmentation. By 14 weeks post-MOG peptide, these abnormalities were much less prominent, but the mice remained weak and, as in patients with progressive multiple sclerosis, spinal cord atrophy had developed. There was no significant loss of lumbar spinal cord motor neurons in the MOG peptide-EAE mice. However, early in the course of the illness, motor neuron dendrites were disrupted and motor neuron expression of hypophosphorylated neurofilament-H (hypoP-NF-H) immunoreactivity was diminished. By 14 weeks post-MOG peptide, hypoP-NF-H expression had returned to normal, but motor neuron dendritic abnormalities persisted and motor neuron perikaryal atrophy had appeared. We hypothesize that these motor neuron abnormalities contribute to weakness in this form of EAE and speculate that similar motor neuron abnormalities are present in patients with progressive multiple sclerosis.

MR spectroscopic evidence for glial increase but not for neuro-axonal damage in MS normal-appearing white matter

Quantitative single-voxel, short echo-time (TE) MR spectroscopy (MRS) was used to determine metabolite concentrations in the cerebral normal-appearing white matter (NAWM) of 76 patients with multiple sclerosis (MS), and the WM of 25 controls. In NAWM of all MS disease types (primary progressive, relapsing-remitting, and secondary progressive), the concentration ratio of total N-acetyl-aspartate (tNAA)/total creatine (tCr) was decreased compared to controls. Remarkably, this was entirely due to an increase of tCr in MS patients, whereas there was no difference in tNAA. Separate quantification of the two tNAA components yielded no significant difference in NAA (N-acetyl-aspartate), while the concentration of NAAG (N-acetyl-aspartyl-glutamate) was slightly-but significantly-elevated in MS patients. Myo-inositol (Ins) was strongly increased in MS patients, and choline-containing compounds (Cho) were mildly increased. There were no metabolite differences between disease types, and no correlations with disability scores. The results are supported by measures of spectral quality, which were identical for patients and controls. In conclusion, MS NAWM containing very little perilesional tissue is characterized by increased glial cell numbers (increase of Ins and tCr) without evidence of axonal dysfunction (normal NAA). Further studies should elucidate the mechanism underlying increased NAAG in MS NAWM.

A Practical Approach to Immunomodulatory Therapy for Multiple Sclerosis

This article provides a current overview of the definition and pathogenesis of the disease, the different types of MS, a new diagnostic criteria, the rationale for early therapy, a review of the approved MS therapies, the strategies to evaluate ongoing treatment efficacy,the management of suboptimal treatment responders, and the prospects for future therapies. The article focuses on relapsing remitting MS because most of the therapeutic data deal with this type of MS. The role of mitoxantrone as a "rescue therapy" for suboptimal responders to IMTs is discussed.

Magnetic resonance spectroscopy as a measure of brain damage in multiple sclerosis

Recent MR studies have emphasised the importance of neuronal and axonal damage in multiple sclerosis. In this respect, proton MR spectroscopy (by monitoring levels of N-acetylaspartate, a putative marker of axonal integrity) has been particularly illuminating by showing indirect evidence of neurodegeneration in both lesional and non-lesional brain tissues from the earliest stages of the disease. The importance of these changes to patients' clinical disability argues for the primary role of neuronal pathology in the pathogenesis of the disease.

Imaging of multiple sclerosis: role in neurotherapeutics

Magnetic resonance imaging (MRI) plays an ever-expanding role in the evaluation of multiple sclerosis (MS). This includes its sensitivity for the diagnosis of the disease and its role in identifying patients at high risk for conversion to MS after a first presentation with selected clinically isolated syndromes. In addition, MRI is a key tool in providing primary therapeutic outcome measures for phase I/II trials and secondary outcome measures in phase III trials. The utility of MRI stems from its sensitivity to longitudinal changes including those in overt lesions and, with advanced MRI techniques, in areas affected by diffuse occult disease (the so-called normal-appearing brain tissue). However, all current MRI methodology suffers from limited specificity for the underlying histopathology. Conventional MRI techniques, including lesion detection and measurement of atrophy from T1- or T2-weighted images, have been the mainstay for monitoring disease activity in clinical trials, in which the use of gadolinium with T1-weighted images adds additional sensitivity and specificity for areas of acute inflammation. Advanced imaging methods including magnetization transfer, fluid attenuated inversion recovery, diffusion, magnetic resonance spectroscopy, functional MRI, and nuclear imaging techniques have added to our understanding of the pathogenesis of MS and may provide methods to monitor therapies more sensitively in the future. However, these advanced methods are limited by their cost, availability, complexity, and lack of validation. In this article, we review the role of conventional and advanced imaging techniques with an emphasis on neurotherapeutics.