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Repeat expansions in the C9orf72 gene are a common cause of amyotrophic lateral sclerosis and frontotemporal lobar degeneration, two devastating neurodegenerative disorders. One of the proposed mechanisms of GGGGCC repeat expansion is their translation into non-canonical dipeptide repeats, which can then accumulate as aggregates and contribute to these pathologies. There are five different dipeptide repeat proteins (polyGA, polyGR, polyPR, polyPA and polyGP), some of which are known to be neurotoxic. In the present study, we used BioID2 proximity labelling to identify the interactomes of all five dipeptide repeat proteins consisting of 125 repeats each. We identified 113 interacting partners for polyGR, 90 for polyGA, 106 for polyPR, 25 for polyPA and 27 for polyGP. Gene Ontology enrichment analysis of the proteomic data revealed that these target interaction partners are involved in a variety of functions, including protein translation, signal transduction pathways, protein catabolic processes, amide metabolic processes and RNA-binding. Using autopsy brain tissue from patients with C9orf72 expansion complemented with cell culture analysis, we evaluated the interactions between polyGA and valosin containing protein (VCP). Functional analysis of this interaction revealed sequestration of VCP with polyGA aggregates, altering levels of soluble valosin-containing protein. VCP also functions in autophagy processes, and consistent with this, we observed altered autophagy in cells expressing polyGA. We also observed altered co-localization of polyGA aggregates and p62 in cells depleted of VCP. All together, these data suggest that sequestration of VCP with polyGA aggregates contributes to the loss of VCP function, and consequently to alterations in autophagy processes in C9orf72 expansion disorders., (© The Author(s) (2021). Published by Oxford University Press on behalf of the Guarantors of Brain.)

Many studies report an overlap of MRI and clinical findings between patients with relapsing-remitting multiple sclerosis (RRMS) and secondary progressive multiple sclerosis (SPMS), which in part is reflective of inclusion of subjects with variable disease duration and short periods of follow-up. To overcome these limitations, we examined the differences between RRMS and SPMS and the relationship between MRI measures and clinical outcomes 30 years after first presentation with clinically isolated syndrome suggestive of multiple sclerosis. Sixty-three patients were studied 30 years after their initial presentation with a clinically isolated syndrome; only 14% received a disease modifying treatment at any time point. Twenty-seven patients developed RRMS, 15 SPMS and 21 experienced no further neurological events; these groups were comparable in terms of age and disease duration. Clinical assessment included the Expanded Disability Status Scale, 9-Hole Peg Test and Timed 25-Foot Walk and the Brief International Cognitive Assessment For Multiple Sclerosis. All subjects underwent a comprehensive MRI protocol at 3 T measuring brain white and grey matter (lesions, volumes and magnetization transfer ratio) and cervical cord involvement. Linear regression models were used to estimate age- and gender-adjusted group differences between clinical phenotypes after 30 years, and stepwise selection to determine associations between a large sets of MRI predictor variables and physical and cognitive outcome measures. At the 30-year follow-up, the greatest differences in MRI measures between SPMS and RRMS were the number of cortical lesions, which were higher in SPMS (the presence of cortical lesions had 100% sensitivity and 88% specificity), and grey matter volume, which was lower in SPMS. Across all subjects, cortical lesions, grey matter volume and cervical cord volume explained 60% of the variance of the Expanded Disability Status Scale; cortical lesions alone explained 43%. Grey matter volume, cortical lesions and gender explained 43% of the variance of Timed 25-Foot Walk. Reduced cortical magnetization transfer ratios emerged as the only significant explanatory variable for the symbol digit modality test and explained 52% of its variance. Cortical involvement, both in terms of lesions and atrophy, appears to be the main correlate of progressive disease and disability in a cohort of individuals with very long follow-up and homogeneous disease duration, indicating that this should be the target of therapeutic interventions., (© The Author(s) (2021). Published by Oxford University Press on behalf of the Guarantors of Brain.)

See Stankoff and Louapre (doi:10.1093/brain/awy114) for a scientific commentary on this article.Grey matter atrophy is present from the earliest stages of multiple sclerosis, but its temporal ordering is poorly understood. We aimed to determine the sequence in which grey matter regions become atrophic in multiple sclerosis and its association with disability accumulation. In this longitudinal study, we included 1417 subjects: 253 with clinically isolated syndrome, 708 with relapsing-remitting multiple sclerosis, 128 with secondary-progressive multiple sclerosis, 125 with primary-progressive multiple sclerosis, and 203 healthy control subjects from seven European centres. Subjects underwent repeated MRI (total number of scans 3604); the mean follow-up for patients was 2.41 years (standard deviation = 1.97). Disability was scored using the Expanded Disability Status Scale. We calculated the volume of brain grey matter regions and brainstem using an unbiased within-subject template and used an established data-driven event-based model to determine the sequence of occurrence of atrophy and its uncertainty. We assigned each subject to a specific event-based model stage, based on the number of their atrophic regions. Linear mixed-effects models were used to explore associations between the rate of increase in event-based model stages, and T2 lesion load, disease-modifying treatments, comorbidity, disease duration and disability accumulation. The first regions to become atrophic in patients with clinically isolated syndrome and relapse-onset multiple sclerosis were the posterior cingulate cortex and precuneus, followed by the middle cingulate cortex, brainstem and thalamus. A similar sequence of atrophy was detected in primary-progressive multiple sclerosis with the involvement of the thalamus, cuneus, precuneus, and pallidum, followed by the brainstem and posterior cingulate cortex. The cerebellum, caudate and putamen showed early atrophy in relapse-onset multiple sclerosis and late atrophy in primary-progressive multiple sclerosis. Patients with secondary-progressive multiple sclerosis showed the highest event-based model stage (the highest number of atrophic regions, P < 0.001) at the study entry. All multiple sclerosis phenotypes, but clinically isolated syndrome, showed a faster rate of increase in the event-based model stage than healthy controls. T2 lesion load and disease duration in all patients were associated with increased event-based model stage, but no effects of disease-modifying treatments and comorbidity on event-based model stage were observed. The annualized rate of event-based model stage was associated with the disability accumulation in relapsing-remitting multiple sclerosis, independent of disease duration (P < 0.0001). The data-driven staging of atrophy progression in a large multiple sclerosis sample demonstrates that grey matter atrophy spreads to involve more regions over time. The sequence in which regions become atrophic is reasonably consistent across multiple sclerosis phenotypes. The spread of atrophy was associated with disease duration and with disability accumulation over time in relapsing-remitting multiple sclerosis.

In multiple sclerosis, microstructural damage of normal-appearing brain tissue is an important feature of its pathology. Understanding these mechanisms is vital to help develop neuroprotective strategies. The visual pathway is a key model to study mechanisms of damage and recovery in demyelination. Anterograde trans-synaptic degeneration across the lateral geniculate nuclei has been suggested as a mechanism of tissue damage to explain optic radiation abnormalities seen in association with demyelinating disease and optic neuritis, although evidence for this has relied solely on cross-sectional studies. We therefore aimed to assess: (i) longitudinal changes in the diffusion properties of optic radiations after optic neuritis suggesting trans-synaptic degeneration; (ii) the predictive value of early optic nerve magnetic resonance imaging measures for late optic radiations changes; and (iii) the impact on visual outcome of both optic nerve and brain post-optic neuritis changes. Twenty-eight consecutive patients with acute optic neuritis and eight healthy controls were assessed visually (logMAR, colour vision, and Sloan 1.25%, 5%, 25%) and by magnetic resonance imaging, at baseline, 3, 6, and 12 months. Magnetic resonance imaging sequences performed (and metrics obtained) were: (i) optic nerve fluid-attenuated inversion-recovery (optic nerve cross-sectional area); (ii) optic nerve proton density fast spin-echo (optic nerve proton density-lesion length); (iii) optic nerve post-gadolinium T1-weighted (Gd-enhanced lesion length); and (iv) brain diffusion-weighted imaging (to derive optic radiation fractional anisotropy, radial diffusivity, and axial diffusivity). Mixed-effects and multivariate regression models were performed, adjusting for age, gender, and optic radiation lesion load. These identified changes over time and associations between early optic nerve measures and 1-year global optic radiation/clinical measures. The fractional anisotropy in patients' optic radiations decreased (P = 0.018) and radial diffusivity increased (P = 0.002) over 1 year following optic neuritis, whereas optic radiation measures were unchanged in controls. Also, smaller cross-sectional areas of affected optic nerves at 3 months post-optic neuritis predicted lower fractional anisotropy and higher radial diffusivity at 1 year (P = 0.007) in the optic radiations, whereas none of the inflammatory measures of the optic nerve predicted changes in optic radiations. Finally, greater Gd-enhanced lesion length at baseline and greater optic nerve proton density-lesion length at 1 year were associated with worse visual function at 1 year (P = 0.034 for both). Neither the cross-sectional area of the affected optic nerve after optic neuritis nor the damage in optic radiations was associated with 1-year visual outcome. Our longitudinal study shows that, after optic neuritis, there is progressive damage to the optic radiations, greater in patients with early residual optic nerve atrophy, even after adjusting for optic radiation lesions. These findings provide evidence for trans-synaptic degeneration., (© The Author (2016). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Neurodegeneration is thought to be the major cause of ongoing, irreversible disability in progressive stages of multiple sclerosis. Gamma-aminobutyric acid is the principle inhibitory neurotransmitter in the brain. The aims of this study were to investigate if gamma-aminobutyric acid levels (i) are abnormal in patients with secondary progressive multiple sclerosis compared with healthy controls; and (ii) correlate with physical and cognitive performance in this patient population. Thirty patients with secondary progressive multiple sclerosis and 17 healthy control subjects underwent single-voxel MEGA-PRESS (MEscher-GArwood Point RESolved Spectroscopy) magnetic resonance spectroscopy at 3 T, to quantify gamma-aminobutyric acid levels in the prefrontal cortex, right hippocampus and left sensorimotor cortex. All subjects were assessed clinically and underwent a cognitive assessment. Multiple linear regression models were used to compare differences in gamma-aminobutyric acid concentrations between patients and controls adjusting for age, gender and tissue fractions within each spectroscopic voxel. Regression was used to examine the relationships between the cognitive function and physical disability scores specific for these regions with gamma-aminobuytric acid levels, adjusting for age, gender, and total N-acetyl-aspartate and glutamine-glutamate complex levels. When compared with controls, patients performed significantly worse on all motor and sensory tests, and were cognitively impaired in processing speed and verbal memory. Patients had significantly lower gamma-aminobutyric acid levels in the hippocampus (adjusted difference = -0.403 mM, 95% confidence intervals -0.792, -0.014, P = 0.043) and sensorimotor cortex (adjusted difference = -0.385 mM, 95% confidence intervals -0.667, -0.104, P = 0.009) compared with controls. In patients, reduced motor function in the right upper and lower limb was associated with lower gamma-aminobutyric acid concentration in the sensorimotor cortex. Specifically for each unit decrease in gamma-aminobutyric acid levels (in mM), there was a predicted -10.86 (95% confidence intervals -16.786 to -4.482) decrease in grip strength (kg force) (P < 0.001) and -8.74 (95% confidence intervals -13.943 to -3.015) decrease in muscle strength (P < 0.006). This study suggests that reduced gamma-aminobutyric acid levels reflect pathological abnormalities that may play a role in determining physical disability. These abnormalities may include decreases in the pre- and postsynaptic components of gamma-aminobutyric acid neurotransmission and in the density of inhibitory neurons. Additionally, the reduced gamma-aminobutyric acid concentration may contribute to the neurodegenerative process, resulting in increased firing of axons, with consequent increased energy demands, which may lead to neuroaxonal degeneration and loss of the compensatory mechanisms that maintain motor function. This study supports the idea that modulation of gamma-aminobutyric acid neurotransmission may be an important target for neuroprotection in multiple sclerosis.See De Stefano and Giorgio (doi:10.1093/brain/awv213) for a scientific commentary on this article., (© The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Spinal neurodegeneration is an important determinant of disability progression in patients with primary progressive multiple sclerosis. Advanced imaging techniques, such as single-voxel (1)H-magnetic resonance spectroscopy and q-space imaging, have increased pathological specificity for neurodegeneration, but are challenging to implement in the spinal cord and have yet to be applied in early primary progressive multiple sclerosis. By combining these imaging techniques with new clinical measures, which reflect spinal cord pathology more closely than conventional clinical tests, we explored the potential for spinal magnetic resonance spectroscopy and q-space imaging to detect early spinal neurodegeneration that may be responsible for clinical disability. Data from 21 patients with primary progressive multiple sclerosis within 6 years of disease onset, and 24 control subjects were analysed. Patients were clinically assessed on grip strength, vibration perception thresholds and postural stability, in addition to the Expanded Disability Status Scale, Nine Hole Peg Test, Timed 25-Foot Walk Test, Multiple Sclerosis Walking Scale-12, and Modified Ashworth Scale. All subjects underwent magnetic resonance spectroscopy and q-space imaging of the cervical cord and conventional brain and spinal magnetic resonance imaging at 3 T. Multivariate analyses and multiple regression models were used to assess the differences in imaging measures between groups and the relationship between magnetic resonance imaging measures and clinical scores, correcting for age, gender, spinal cord cross-sectional area, brain T2 lesion volume, and brain white matter and grey matter volume fractions. Although patients did not show significant cord atrophy when compared with healthy controls, they had significantly lower total N-acetyl-aspartate (mean 4.01 versus 5.31 mmol/l, P = 0.020) and glutamate-glutamine (mean 4.65 versus 5.93 mmol/l, P = 0.043) than controls. Patients showed an increase in q-space imaging-derived indices of perpendicular diffusivity in both the whole cord and major columns compared with controls (P < 0.05 for all indices). Lower total N-acetyl-aspartate was associated with higher disability, as assessed by the Expanded Disability Status Scale (coefficient = -0.41, 0.01 < P < 0.05), Modified Ashworth Scale (coefficient = -3.78, 0.01 < P < 0.05), vibration perception thresholds (coefficient = -4.37, P = 0.021) and postural sway (P < 0.001). Lower glutamate-glutamine predicted increased postural sway (P = 0.017). Increased perpendicular diffusivity in the whole cord and columns was associated with increased scores on the Modified Ashworth Scale, vibration perception thresholds and postural sway (P < 0.05 in all cases). These imaging findings indicate reduced structural integrity of neurons, demyelination, and abnormalities in the glutamatergic pathways in the cervical cord of early primary progressive multiple sclerosis, in the absence of extensive spinal cord atrophy. The observed relationship between imaging measures and disability suggests that early spinal neurodegeneration may underlie clinical impairment, and should be targeted in future clinical trials with neuroprotective agents to prevent the development of progressive disability., (© The Author (2015). Published by Oxford University Press on behalf of the Guarantors of Brain. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

The impact of traumatic spinal cord injury on structural integrity, cortical reorganization and ensuing disability is variable and may depend on a dynamic interaction between the severity of local damage and the capacity of the brain for plastic reorganization. We investigated trauma-induced anatomical changes in the spinal cord and brain, and explored their relationship to functional changes in sensorimotor cortex. Structural changes were assessed using cross-sectional cord area, voxel-based morphometry and voxel-based cortical thickness of T1-weighted images in 10 subjects with cervical spinal cord injury and 16 controls. Cortical activation in response to right-sided (i) handgrip; and (ii) median and tibial nerve stimulation were assessed using functional magnetic resonance imaging. Regression analyses explored associations between cord area, grey and white matter volume, cortical activations and thickness, and disability. Subjects with spinal cord injury had impaired upper and lower limb function bilaterally, a 30% reduced cord area, smaller white matter volume in the pyramids and left cerebellar peduncle, and smaller grey matter volume and cortical thinning in the leg area of the primary motor and sensory cortex compared with controls. Functional magnetic resonance imaging revealed increased activation in the left primary motor cortex leg area during handgrip and the left primary sensory cortex face area during median nerve stimulation in subjects with spinal cord injury compared with controls, but no increased activation following tibial nerve stimulation. A smaller cervical cord area was associated with impaired upper limb function and increased activations with handgrip and median nerve stimulation, but reduced activations with tibial nerve stimulation. Increased sensory deficits were associated with increased activations in the left primary sensory cortex face area due to median nerve stimulation. In conclusion, spinal cord injury leads to cord atrophy, cortical atrophy of primary motor and sensory cortex, and cortical reorganization of the sensorimotor system. The degree of cortical reorganization is predicted by spinal atrophy and is associated with significant disability.

Clinically isolated syndromes (CIS), such as optic neuritis, brainstem or spinal cord syndromes are frequently the first clinical presentations of multiple sclerosis. However, not all CIS patients develop multiple sclerosis and in those who do, disability is highly variable. In previous follow-up studies, brain lesions on T2-weighted MRI are associated with increased risk of multiple sclerosis and to an extent disability. We evaluated the longitudinal relationships between the MRI lesions and clinical course over a period of 20 years. CIS patients were recruited between 1984 and 1987 and previously followed up after 1, 5, 10 and 14 years. Of the 140 subjects who were initially recruited with a CIS for a baseline MRI study, we followed up 107 patients after a mean of 20.2 years (range 18-27.7). Multiple sclerosis was diagnosed as clinically definite on clinical grounds only and disability determined using the Expanded Disability Status Scale (EDSS) and Multiple Sclerosis Functional Composite (MSFC) score. Clinically definite multiple sclerosis developed in 67 out of 107 (63%) overall: 60 out of 73 (82%) with abnormal and 7 out of 34 (21%) with normal baseline MRI. Multiple sclerosis was still relapsing-remitting in 39 (58%)--including 26 (39%) with a 'benign' course (EDSS < or = 3)--whilst 28 (42%) had developed secondary progression. T2 lesion volume at all time-points correlated moderately with 20-year EDSS (r(s) values 0.48 to 0.67; P < 0.001) and MSFC z-score [r(s) values (-0.50) to (-0.61); P < 0.001]. In those developing multiple sclerosis, a concurrent correlation of change in T2 lesion volume with change in EDSS was most evident in years 0-5 (r(s) = 0.69, P < 0.001). The estimated rate of lesion growth over 20 years was 0.80 cm3/year in those who retained a relapsing remitting multiple sclerosis course, and 2.89 cm3/year in those who developed secondary progressive multiple sclerosis, a difference of 2.09 cm3/year (95% CI: 0.77, 2.96; P < 0.001). This study extends previous follow-up of CIS patients and sheds new light on how the lesions evolve according to the natural history. Baseline MRI findings are predictive for development of clinically definite multiple sclerosis. Lesion volume and its change at earlier time points are correlated with disability after 20 years. Lesion volume increases for at least 20 years in relapse-onset multiple sclerosis and the rate of lesion growth is three times higher in those who develop secondary progressive than in those who remain relapsing remitting multiple sclerosis.

There is a need to assess spinal cord involvement in multiple sclerosis with new imaging techniques in order to understand better the underlying pathology. We aimed to evaluate whether quantitative MRI measures, obtained using single-voxel (1)H-MR spectroscopy of the cervical cord and diffusion-based tractography of the major spinal cord pathways, in patients with a cervical cord relapse, differed from controls and correlated with acute disability. Fourteen patients at the onset of a cervical cord relapse with at least one lesion between C1 and C3 were imaged on a 1.5 T scanner and clinically assessed on the Expanded Disability Status Scale (EDSS), 9-hole peg test (HPT) and timed 25-foot walk test. Thirteen age- and gender-matched control subjects were also scanned. Metabolite concentrations, including total N-acetyl-aspartate (tNAA), choline-containing compounds (Cho), creatine plus phosphocreatine (Cr) and myo-Inositol (m-Ins), were quantified at C1-C3. Probabilistic tractography was performed at C1-C3 to track the lateral cortico-spinal tracts in the lateral columns, the anterior cortico-spinal tracts and the anterior spino-thalamic fasciculi in the anterior columns, and the bilateral fasciculus gracilis and cuneatus in the posterior columns. Diffusion- and tractography-derived measures of these tracts, including fractional anisotropy and voxel-based connectivity, which reflect fibre integrity, were obtained. These MRI measures were compared between patients and controls using the Mann-Whitney test. Univariate correlations between MRI measures and disability were assessed using the Spearman's rho correlation coefficient. Multiple regression analyses were performed to investigate which MRI measures independently correlated with the clinical scores, adjusting also for cross-sectional cord area, age and gender. Patients showed lower tNAA of the cervical cord, lower connectivity and lower fractional anisotropy of the lateral cortico-spinal tracts and posterior tracts, than controls. In patients, there were significant correlations between: (i) EDSS and m-Ins, Cho, Cr and radial diffusivity of the lateral cortico-spinal tracts; (ii) HPT and Cr, radial diffusivity of the lateral cortico-spinal tracts, connectivity and fractional anisotropy of the posterior tracts, and connectivity of the anterior tracts. M-Ins was independently associated with the EDSS, while Cr, tNAA and connectivity of the posterior tracts were independently associated with the HPT. MR spectroscopy and diffusion-based tractography of the cervical cord provide measures that are sensitive to the tissue damage occurring in this area in patients with a cervical cord relapse. These measures were found to correlate with acute disability. Our findings suggest that it would be worthwhile performing longitudinal studies and extending these novel techniques to other neurological diseases affecting the spinal cord.

The goal of probabilistic tractography is to obtain a connectivity index along a white matter pathway that reflects fibre organization and is sensitive to pathological abnormalities contributing to disability. Here, we present the development of voxel-based connectivity measures along the tractography-derived corticospinal tract (CST). We investigated whether these connectivity measures are different in patients with amyotrophic lateral sclerosis (ALS) and correlate with the rate of disease progression. We also investigated whether fractional anisotropy (FA), which reflects directional coherence of fibre tracts, is reduced in the CST of ALS patients and relates to disease progression rate. Thirteen patients with probable or definite ALS and 19 healthy subjects were studied. The probabilistic tractography algorithm segmented the bilateral CST, along which FA and connectivity values were obtained. To take into account the asymmetric distribution of connectivity values, two summary statistic measures that focused on voxels with higher connectivity values were selected and then used in the analysis, together with the mean connectivity and the mean FA. To complete the analysis, the same summary measures for FA were included. Differences in all these indices between patients with moderate or rapid disease progression rate and controls were investigated using linear regression, adjusted for age and white matter fraction. The association between FA or connectivity in the CST and the disease progression rate was assessed using linear regression. Patients with a rapid disease progression rate had significantly lower summary connectivity measures than controls in the left CST, but there was only a borderline statistical difference in mean connectivity. Patients with rapid progression had a significantly lower mean FA, and any other FA measure, in both CSTs than controls. When only patients were considered, strong associations between the rate of disease progression and all the connectivity measures in the left CST were found (P-values between P < 0.001 and P = 0.002, partial correlation coefficients between -0.90 and -0.82). However, there was no evidence of an association between disease progression rate and any of the FA measures in the bilateral CST. Our findings suggest that FA and connectivity provide complementary information, since FA is sensitive to the detection of all the group differences, whereas the summary connectivity measures correlate with disease progression rate. The development of such connectivity measures raises their potential as markers of disease progression in ALS, and provides guidance for their use in other neurological diseases.

Patients with clinically isolated syndromes suggestive of multiple sclerosis have evidence for abnormality in normal appearing grey matter detected using the magnetization transfer ratio (MTR), a quantitative MRI measure. One potential mechanism for the decreased grey matter MTR (GM MTR) observed is trans-synaptic morphological abnormality secondary to demyelinating lesions that are in an anatomically linked pathway but remote location. We investigated this potential association by studying the location of abnormalities using voxel-based analysis of GM MTR maps in a group of 80 patients studied within 6 months of presenting with isolated optic neuritis and compared the findings with those seen in 50 age- and sex-matched healthy controls. Occipital cortex and whole brain analysis comparing all optic neuritis patients and controls revealed a selective decrease of MTR bilaterally in the visual cortex in patients [Brodmann area (BA) 17]. Whole brain analysis of patients fulfilling the McDonald criteria for multiple sclerosis (n = 20) showed a lower MTR compared to controls bilaterally in the visual cortex (BA 17/18), left hippocampus, bilateral superior temporal gyrus, bilateral lenticular nuclei and the right cerebellum. There was no significant difference in the percentage of grey matter between patients and controls in the regions of abnormal MTR detected in the visual cortex. The intrinsic MTR decrease seen in patients suggests that there are structural changes in the visual cortex following an attack of optic neuritis. Potential mechanisms for this include trans-synaptic neuronal degeneration and cortical synaptic morphological changes; such abnormalities may also contribute to MTR abnormalities observed in the normal appearing grey matter in multiple sclerosis.

Movement-related brain activation patterns after subcortical stroke are characterized by relative overactivations in cortical motor areas compared with controls. In patients able to perform a motor task, overactivations are greater in those with more motor impairment. We hypothesized that recruitment of motor regions would shift from primary to secondary motor networks in response to impaired functional integrity of the corticospinal system (CSS). We measured the magnitude of brain activation using functional MRI during a motor task in eight chronic subcortical stroke patients. CSS functional integrity was assessed using transcranial magnetic stimulation to obtain stimulus/response curves for the affected first dorsal interosseus muscle, with a shallower gradient representing increasing disruption of CSS functional integrity. A negative correlation between the gradient of stimulus/response curve and magnitude of task-related brain activation was found in several motor-related regions, including ipsilesional posterior primary motor cortex [Brodmann area (BA) 4p], contralesional anterior primary motor cortex (BA 4a), bilateral premotor cortex, supplementary motor area, intraparietal sulcus, dorsolateral prefrontal cortex and contralesional superior cingulate sulcus. There were no significant positive correlations in any brain region. These results suggest that impaired functional integrity of the CSS is associated with recruitment of secondary motor networks in both hemispheres in an attempt to generate motor output to spinal cord motoneurons. Secondary motor regions are less efficient at generating motor output so this reorganization can only be considered partially successful in reducing motor impairment after stroke.

Spasticity is most commonly defined as an inappropriate, velocity dependent, increase in muscle tonic stretch reflexes, due to the amplified reactivity of motor segments to sensory input. It forms one component of the upper motor neuron syndrome and often leads to muscle stiffness and disability. Spasticity can, therefore, be measured through electrophysiological, biomechanical and clinical evaluation, the last most commonly using the Ashworth scale. None of these techniques incorporate the patient experience of spasticity, nor how it affects people's daily lives. Consequently, we set out to construct a rating scale to quantify the perspectives of the impact of spasticity on people with multiple sclerosis. Qualitative methods (in-depth patient interviews and focus groups, expert opinion and literature review) were used to develop a conceptual framework of spasticity impact, and to generate a pool of items with the potential to convert this framework into a rating scale with multiple dimensions. This item pool was administered, in the form of a questionnaire, to a sample of people with multiple sclerosis and spasticity. Guided by Rasch analysis, we constructed and validated a rating scale for each component of the conceptual framework. Decisions regarding item selection were based on the integration and assimilation of seven specific analyses including clinical meaning, ordering of thresholds, fit statistics and differential item functioning. The qualitative phase (17 patient interviews, 3 focus groups) generated 144 potential scale items and a conceptual model with eight components addressing symptoms (muscle stiffness, pain and discomfort and muscle spasms,), physical impact (activities of daily living, walking and body movements) and psychosocial impact (emotional health, social functioning). The first postal survey was sent to 272 people with multiple sclerosis and had a response rate of 88%. Findings supported the development of scales for each component but demonstrated that five item response options were too many. The 144-item questionnaire, reformatted with four-item response options, was administered with four validating instruments to an independent sample of 259 people with multiple sclerosis (response rate 78%). From the responses, an 88-item instrument with eight subscales was developed that satisfied criteria for reliable and valid measurement. Correlations with other measures were consistent with predictions. The 88-item Multiple Sclerosis Spasticity Scale (MSSS-88) is a reliable and valid, patient-based, interval-level measure of the impact of spasticity in multiple sclerosis. It has the potential to advance outcomes measurement in clinical trials and clinical practice, and provides a new perspective in the clinical evaluation of spasticity.

In established multiple sclerosis, magnetization transfer ratio (MTR) histograms reveal abnormalities of normal-appearing white matter (NAWM) and grey matter (NAGM). The aim of this study was to investigate for such abnormalities in a large cohort of patients presenting with clinically isolated syndromes suggestive of multiple sclerosis. Magnetization transfer imaging was performed on 100 patients (67 women, 33 men, median age 32 years) a mean of 19 weeks (SD 3.8, range 12-33 weeks) after symptom onset with a clinically isolated syndrome and in 50 healthy controls (34 women, 16 men, median age 32.5 years). SPM99 software was used to generate segmented NAWM and NAGM MTR maps. The volumes of T2 lesions, white matter and grey matter were calculated. Eighty-one patients were followed up clinically and with conventional MRI after 3 years (n = 61) or until they developed multiple sclerosis if this occurred sooner (n = 20). Multiple regression analysis was used to investigate differences between patients and controls with age, gender and volume measures as covariates to control for potential confounding effects. The MTR histograms for both NAWM and NAGM showed a reduction in the mean (NAWM, 38.14 versus 38.33, P = 0.001; NAGM 32.29 versus 32.50, P = 0.009; units in pu) and peak location, with a left shift in the histogram. Mean NAWM and NAGM MTR were also reduced in the patients who developed clinically definite multiple sclerosis and multiple sclerosis according to the McDonald criteria but not in the 24 patients with normal T2-weighted brain magnetic resonance imaging (MRI). MTR abnormalities occur in the NAWM and NAGM at the earliest clinical stages of multiple sclerosis.

There are few longitudinal studies of cognition in patients with multiple sclerosis, and the results of these studies remain inconclusive. No serial neuropsychological data of an exclusively primary progressive series are available. Cross-sectional analyses have revealed significant correlations between cognition and magnetic resonance imaging (MRI) parameters in primary progressive multiple sclerosis (PPMS). This study investigated cognitive and MRI change in 99 PPMS patients from five European centres for 2 years. They were assessed at 12 month intervals using the Brief Repeatable Battery, a reasoning test, and a measure of depression. The MRI parameters of T1 hypointensity load, T2 lesion load, and partial brain volume were also calculated at each time point. There were no significant differences between the mean cognitive scores of the patients at year 0 and year 2. However, one-third of the patients demonstrated absolute cognitive decline on individual test scores. Results indicated that initial cognitive status on entry into the study was a good predictor of cognitive ability at 2 years. There was only a small number of significant correlations between changes in cognition and changes on MRI, notably T1 hypointensity load with the two attentional tasks (r = -0.266, P = 0.017; r = -0.303, P = 0.012). It is probable that multiple factors underlie this weak relation between the cognitive and MRI measures.

We have recently reported brain atrophy in the early stages of primary progressive multiple sclerosis (PPMS), affecting both grey and white matter (GM and WM). However, to date no clinical or radiological predictors of GM and WM atrophy have been identified. The aim was to investigate short-term changes in GM and WM volumes and to assess the predictive value of demographic, clinical and radiological variables in order to gain a better understanding of the pathological substrate underlying these changes. Thirty-one subjects with PPMS within 5 years of symptom onset were studied at baseline and after 1 year. At baseline, patients underwent neurological examination and were scored on the Expanded Disability Status Scale (EDSS) and Multiple Sclerosis Functional Composite. They had 3D inversion-prepared fast spoiled gradient recalled (FSPGR), dual-echo and triple-dose post-contrast T1-weighted spin echo MRI scans. Proton density and enhancing lesion loads were determined. The 3DFSPGR sequence was repeated after 1 year and brain volume changes were calculated using two techniques, SPM99 (statistical parametric mapping) and SIENA (structural image evaluation, using normalization, of atrophy). Stepwise linear regression models were applied to baseline variables to identify independent predictors of atrophy development. Using SPM99, a decrease in brain parenchymal fraction (-1.03%; P < 0.001) and GM fraction (-1.49%; P < 0.001) was observed. The number of enhancing lesions independently predicted decrease in brain parenchymal fraction (P = 0.019) and decrease in WM fraction (P = 0.002). No independent predictors of GM fraction decrease were found. A mean brain volume change of -0.63% (range -4.27% to +1.18%; P = 0.002) was observed using SIENA, which was independently predicted by EDSS (P = 0.004). Global and GM atrophy can be detected over a 1-year period in early PPMS. The former may be predicted by the degree of inflammation, while the latter seems to be independent of it. SIENA and SPM-based methods appear to provide complementary information.

This study assessed optic nerve mean area on serial MRI in a cohort of patients with a first episode of acute unilateral optic neuritis to assess the effects of a single acute inflammatory demyelinating lesion. Twenty-nine patients with a median delay from onset of visual symptoms of 13 days (range 7-24 days) were recruited. After a clinical examination and visual evoked potential (VEP) measurement, each patient had their optic nerves imaged with a coronal fat-saturated short echo fast fluid-attenuated inversion recovery sequence. Twenty-one patients had serial examinations after 2, 4, 8, 12, 26 and 52 weeks. In addition, 32 control subjects had their optic nerves imaged up to three times. The mean cross-sectional area of the intra-orbital portion of each optic nerve was calculated by a blinded observer using a computer-assisted contouring technique. At baseline, the mean area of diseased optic nerves was 16.1 mm2 compared with 13.4 mm2 for healthy contralateral optic nerves (20.1% higher, P < 0.0001) and 13.6 mm2 for controls (18.4% higher, P = 0.0003). The diseased optic nerve mean area declined over time, from initial swelling to later atrophy. The mean decline at 52 weeks was -0.0018 mm2/day (95% confidence interval -0.0038 to -0.00051). At 52 weeks, the mean area of diseased optic nerves was 11.3 mm2 compared with 12.8 mm2 for healthy contralateral optic nerves (11.7% lower, P = 0.032) and 13.1 mm2 for controls (13.7% lower, P = 0.008). The 52 week diseased optic nerve mean area was not significantly affected by the baseline mean area. There was an association between baseline optic nerve mean area and logMAR visual acuity (rS = 0.46, P = 0.012) and visual field mean deviation (rS = -0.55, P = 0.002), but there was no evidence of an association between 1 year mean area and visual outcome. There was no evidence of association between baseline, rates of decline or 1 year diseased optic nerve mean areas and any of the baseline, 1 year or time-averaged VEP variables. The present study shows a consistent pattern of changes associated with individual inflammatory demyelinating lesions in the optic nerve. Acutely, there was swelling, consistent with the presence of acute inflammation, which was related to visual impairment. Over the longer term, there was loss of tissue. The lack of association between 1 year optic nerve mean area and visual outcome may reflect a mild loss of tissue, redundancy or remodelling of function.

Normal-appearing white matter (NAWM) in established multiple sclerosis has been shown to be abnormal using a variety of magnetic resonance (MR) techniques, including proton MR spectroscopy ((1)H-MRS), although the stage at which these changes first appear is less clear. Using a 1.5 T scanner and single-voxel (1)H-MRS [TR 3000 ms, TE 30 ms, point-resolved spectroscopy (PRESS) localization], we determined NAWM metabolite concentrations in 96 patients a mean of 19 weeks (range 12-28 weeks) after onset of a clinically isolated syndrome (CIS) suggestive of multiple sclerosis and in 44 healthy control subjects. Absolute concentrations of N-acetyl-aspartate, total creatine and phosphocreatine (Cr), choline-containing compounds, glutamate plus glutamine, and myo-inositol (Ins) were estimated automatically using the LCModel. Compared with control subjects, the concentration of Ins was elevated in CIS NAWM (mean 3.31 mM, SD 0.86 versus mean 3.82 mM, SD 1.06; P = 0.001). The increase in Ins was also seen in the patient subgroup with abnormal T2-weighted MRI (mean 3.88 mM, SD 1.10; P = 0.001) and in those who satisfied the McDonald criteria for multiple sclerosis (mean 4.04 mM, SD 1.31; P = 0.001). An increase in Cr was also observed in CIS NAWM (P = 0.023), but other metabolites did not significantly differ between the whole CIS group and control subjects. There was no significant correlation between NAWM Ins and T2 lesion load. The early increase in Ins may reflect a process of pathogenic importance in multiple sclerosis NAWM. Follow-up studies will investigate whether the increase in NAWM Ins is of prognostic importance for future relapses and disability.

While brain atrophy occurs early in the clinical course of multiple sclerosis, exactly how early, which tissues are affected and the rate at which early atrophy occurs are unclear. Regional brain atrophy was investigated in 58 patients recruited within 3 months of onset of a clinically isolated syndrome (CIS) suggestive of multiple sclerosis, who were followed-up for 3 years. At 3 years, 31 subjects had developed multiple sclerosis as defined by the McDonald criteria, while 27 had not (13 had MRI-visible brain lesions and 14 did not). In those who developed multiple sclerosis, the mean decrease in grey matter fractional volume (GMF, as a fraction of total intracranial volume) was -0.017 (-3.3%) and was significantly larger than in the combined lesion-positive and lesion-negative CIS subjects [-0.005 (-1.1%), P = 0.001]. No decrease in white matter fractional volumes (WMF) was seen. Change in GMF correlated only modestly with the change in T2 lesion volume from baseline to year 3 (r = -0.428, P = 0.004). These results suggest that progressive grey matter, but not white matter, atrophy is seen in the earliest clinically observable stages of relapse onset multiple sclerosis, and this is only moderately related to lesion accumulation. Longer-term follow-up is required to determine whether early grey matter atrophy is associated with subsequent disability or cognitive impairment.

In serial studies of multiple sclerosis lesions, reductions in magnetization transfer ratio (MTR) are thought to be due to demyelination and axonal loss, with later rises due to remyelination. This study followed serial changes in MTR in acute optic neuritis in combination with clinical and electrophysiological measurements to determine if the MTR changes over time mirror the picture in multiple sclerosis lesions, further validating MTR as a marker of tissue integrity. Twenty-nine patients were recruited who had acute optic neuritis for a median of 13 days (range 7-24 days) since the onset of visual symptoms. A clinical examination and measurement of visual evoked potentials (VEP) was performed on each patient. Their optic nerves were imaged with a fat-saturated fast spin echo (FSE) sequence and a magnetization transfer sequence. Twenty-one had multiple subsequent examinations over the course of 1 year. In addition, 27 control subjects had their optic nerves imaged up to three times over 1 year. A blinded observer segmented the optic nerves from the MTR maps. Lesions were defined on the acute FSE images and, from the coordinates, the ratio of mean lesion MTR : healthy nerve MTR (lesion ratio) was calculated for each dataset. The time-averaged mean MTR in control optic nerves was 47.7 per cent units (pu). In diseased optic nerves, baseline mean MTR was 47.3 pu, with a mean lesion ratio of 0.98. The diseased optic nerve MTR and lesion ratio declined over time with a nadir at about 240 days at a mean MTR value of 44.2 pu and mean lesion ratio of 0.91. Subsequently, diseased optic nerve MTR appeared to rise; after 1 year the diseased optic nerve mean MTR was 45.1 pu (mean lesion ratio 0.93), although the difference was not significant compared with the nadir value. For each 0.01 increase in time-averaged lesion ratio logMAR visual acuity recovery improved by 0.03 (95% CI, 0.002, 0.08, P = 0.02). Time-averaged VEP central field latency was shorter by 6.1 ms (95% CI 1.5, 10.7, P = 0.012) per 1 pu rise in time-averaged diseased optic nerve MTR. The early fall in diseased optic nerve MTR is consistent with demyelination and Wallerian degeneration of transected axons. The late nadir compared with studies of multiple sclerosis lesions may have been due to slow clearance of myelin debris. Remyelination may have influenced subsequent MTR changes. The observations support using MTR to monitor symptomatic demyelinating lesions.

Recovery of motor function after stroke may occur over weeks or months and is often attributed to cerebral reorganization. We have investigated the longitudinal relationship between recovery after stroke and task-related brain activation during a motor task as measured using functional MRI (fMRI). Eight first-ever stroke patients presenting with hemiparesis resulting from cerebral infarction sparing the primary motor cortex, and four control subjects were recruited. Subjects were scanned on a number of occasions whilst performing an isometric dynamic visually paced hand grip task. Recovery in the patient group was assessed using a battery of outcome measures at each time point. Task-related brain activations decreased over sessions as a function of recovery in a number of primary and non-primary motor regions in all patients, but no session effects were seen in the controls. Furthermore, consistent decreases across sessions correlating with recovery were seen across the whole patient group independent of rate of recovery or initial severity, in primary motor cortex, premotor and prefrontal cortex, supplementary motor areas, cingulate sulcus, temporal lobe, striate cortex, cerebellum, thalamus and basal ganglia. Although recovery-related increases were seen in different brain regions in four patients, there were no consistent effects across the group. These results further our understanding of the recovery process by demonstrating for the first time a clear temporal relationship between recovery and task-related activation of the motor system after stroke.

Longitudinal imaging studies of primary progressive multiple sclerosis (PPMS) have shown significant changes in MR measures over 1 to 2 years. Correlation with clinical change over the same period has not been evident; we investigated the possibility that this is because the period of observation was insufficient for these associations to become apparent. Forty-one patients with PPMS were followed prospectively for 5 years. Patients had clinical [Expanded Disability Status Scale (EDSS) and Multiple Sclerosis Functional Composite Measure (MSFC)] and MRI assessment (brain and spinal cord) at baseline, 1, 2 and 5 years. At 5 years, significant deterioration was seen in all clinical and MRI measures (P<0.01, P<0.001 respectively). Associations were seen between increase in EDSS score and decrease in cord area (r=0.31, P<0.05) and between increase in MSFC and both rate of ventricular enlargement (r=0.31, P<0.05) and increase in T2 load (r=0.31, P<0.05). The rates of change of MR measures were not associated with age or disease duration and were more consistent within than between patients. Longer duration of follow-up demonstrates modest associations between change in clinical and MR measures and provides new insights into the pattern of change within and between individuals with PPMS.

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.

Recovery of motor function after stroke may occur over weeks or months and is often attributed to neuronal reorganization. Functional imaging studies investigating patients who have made a good recovery after stroke have suggested that recruitment of other motor-related networks underlies this recovery. However, patients with less complete recovery have rarely been studied, or else the degree of recovery has not been taken into account. We set out to investigate the relationship between the degree of recovery after stroke and the pattern of recruitment of brain regions during a motor task as measured using functional MRI. We recruited 20 patients who were at least 3 months after their first ever stroke, and 26 right-handed age-matched control subjects. None of our patients had infarcts involving the hand region of the primary motor cortex. All subjects were scanned whilst performing an isometric, dynamic visually paced handgrip task. The degree of functional recovery of each patient was assessed using a battery of outcome measures. Single-patient versus control group analysis revealed that patients with poor recovery were more likely to recruit a number of motor-related brain regions over and above those seen in the control group during the motor task, whereas patients with more complete recovery were more likely to have 'normal' task-related brain activation. Across the whole patient group and across stroke subtypes, we were able to demonstrate a negative correlation between outcome and the degree of task-related activation in regions such as the supplementary motor area, cingulate motor areas, premotor cortex, posterior parietal cortex, and cerebellum. This negative correlation was also seen in parts of both contralateral and ipsilateral primary motor cortex. These results further our understanding of the recovery process by demonstrating for the first time a clear relationship between task-related activation of the motor system and outcome after stroke.

While much work has concentrated on focal white matter (WM) lesions in multiple sclerosis, there is growing evidence to suggest that normal-appearing WM (NAWM) and grey matter (GM) are also involved in the disease process. This study investigated multiple sclerosis disease effects on NAWM and cortical GM (CGM) metabolite concentrations, and the relationships between these metabolite concentrations and clinical impairment. Proton magnetic resonance spectroscopic imaging ((1)H-MRSI) data acquired using point resolved spectroscopic (PRESS) localization (echo time 30 ms, repetition time 3000 ms, nominal voxel volume 2.3 ml) from 27 relapsing-remitting multiple sclerosis and 29 normal control (NC) subjects were processed using LCModel to estimate metabolite concentrations in millimoles per litre. (1)H-MRSI voxel tissue contents were estimated using SPM99 tissue and semi-automatic lesion segmentations of three-dimensional fast spoiled gradient recall scans acquired during the same scanning session. NAWM and CGM metabolite concentrations estimated were: choline-containing compounds (Cho); creatine and phosphocreatine (Cr); myo-inositol (Ins); N-acetyl-aspartate plus N-acetyl-aspartyl-glutamate (tNAA); and glutamate plus glutamine (Glx). CGM data came from 24 of the multiple sclerosis (mean age 35.2 years, mean disease duration 1.7 years) and 25 of the NC (mean age 34.9 years) subjects. NAWM data came from 25 of the multiple sclerosis (mean age 35.0 years, mean disease duration 1.7 years) and 28 of the NC (mean age 36.7 years) subjects. Metabolite concentrations were compared between multiple sclerosis and NC subjects using multiple (linear) regression models allowing for age, gender, (1)H-MRSI voxel tissue and CSF contents, and brain parenchymal volume. At a significance level of P < 0.05, CGM Cho, CGM and NAWM tNAA, and CGM Glx were all significantly reduced, and NAWM Ins was significantly elevated. Spearman correlations of multiple sclerosis functional composite scores with tissue metabolite concentrations were significant for the following: CGM Cr (r(s) = 0.524, P = 0.009), CGM Glx (r(s) = 0.580, P = 0.003) and NAWM Ins (r(s) = -0.559, P = 0.004). These results indicate that metabolite changes in NAWM and CGM can be detected early in the clinical course of multiple sclerosis, and that some of these changes relate to clinical status. The correlation of clinical impairment with CGM Cr and Glx but not tNAA suggests that it is more closely associated with neuronal metabolic dysfunction rather than loss in clinically early relapsing-remitting multiple sclerosis. The correlation of clinical impairment with a raised NAWM Ins may indicate that glial proliferation also relates to function at this stage of the disease.

MRI methods are widely used to follow the pathological evolution of multiple sclerosis in life and its modification by treatment. To date, measures of the number and volume of macroscopically visible lesions have been studied most often. These MRI outcomes have demonstrated clear treatment effects but without a commensurate clinical benefit, suggesting that there are other aspects of multiple sclerosis pathology that warrant investigation. In this context, there has been considerable interest in measuring tissue loss (atrophy) as a more global marker of the adverse outcome of multiple sclerosis pathology, whether it arises in macroscopic lesions or in the normal appearing tissues. An International Workshop recently considered the measurement of atrophy in multiple sclerosis and provided the basis for this review. Brain white matter bulk consists predominantly of axons (46%) followed by myelin (24%), and progressive atrophy implies loss of these structures, especially axons, although variable effects on tissue volumes may also arise from glial cell proliferation or loss, gliosis, inflammation and oedema. Significant correlations found between brain volume and other putative MR neuronal markers also indicate that atrophy reflects axonal loss. Numerous methods are available for the measurement of global and regional brain volumes and upper cervical cord cross-sectional area that are highly reproducible and sensitive to changes within 6-12 months. In general, 3D-T(1)-weighted acquisitions and largely automated segmentation approaches are optimal. Whereas normalized volumes are desirable for cross-sectional studies, absolute volume measures are adequate for serial investigation. Atrophy is seen at all clinical stages of multiple sclerosis, developing gradually following the appearance of inflammatory lesions. This probably reflects both inflammation-induced axonal loss followed by Wallerian degeneration and post-inflammatory neurodegeneration that may be partly due to failure of remyelination. One component of atrophy appears to be independent of focal lesions. Existing immunomodulatory therapies have had limited effects on progressive atrophy, concordant with their modest effects on progressive disability. Atrophy provides a sensitive measure of the neurodegenerative component of multiple sclerosis and should be measured in trials evaluating potential anti-inflammatory, remyelinating or neuroprotective therapies.

Brain atrophy measured by MRI is a potentially useful tool for monitoring disease progression in multiple sclerosis. The location, extent and mechanisms of brain atrophy in early disease are not well documented. Using quantitative MRI, this study investigated whole brain, grey and white matter atrophy in clinically early relapsing-remitting multiple sclerosis and its relationship to lesion measures. Data came from 27 normal control subjects (14 females and 13 males, mean age 36.1 years) and 26 subjects with clinically definite multiple sclerosis (18 females and eight males, mean age 35.1 years, mean delay from first symptom to scan 1.8 years, median Expanded Disability Status Scale score 1.0). All had three-dimensional fast spoiled gradient recall (3D FSPGR), T(1)-weighted pre- and post-gadolinium-enhanced and T(2)-weighted scans. The 3D FSPGR images were automatically segmented into grey and white matter and cerebrospinal fluid using SPM99. 3D FSPGR hypo-intense, T(2) hyper-intense, T(1) hypo-intense and T(1) post-gadolinium-enhancing lesion volumes were determined by semi-automatic lesion segmentation. The SPM99 output was combined with the 3D FSPGR lesion segmentations to quantify tissue volumes as fractions of total intracranial volumes, producing values for the brain parenchymal fraction (BPF), white matter fraction (WMF) and grey matter fraction (GMF). Comparing multiple sclerosis with control subjects, BPF, GMF and WMF were significantly reduced (P < 0.001 for all tissue fractions). Using Pearson correlations, T(2) hyper-intense and T(1) hypo-intense lesion volumes were inversely related to BPF (T(2) r = -0.78, P < 0.001; T(1) r = -0.59, P = 0.002) and GMF (T(2) r = -0.73, P < 0.001; T(1) r = -0.53, P = 0.006), but not WMF (T(2) r = -0.30, P = 0.134; T(1) r = -0.26, P = 0.199). T(1) post-gadolinium-enhancing lesion volumes were not correlated with any fractional volumes. These results indicate that significant brain atrophy, affecting both grey and white matter, occurs early in the clinical course of multiple sclerosis. The lack of correlation between lesion load measures and WMF suggests that pathological changes in white matter may occur by mechanisms which are at least partly independent from overt lesion genesis in early multiple sclerosis.

The clinical and laboratory phenotype of a paraproteinaemic neuropathy syndrome termed chronic sensory ataxic neuropathy with anti-disialosyl IgM antibodies is described in a series of 18 cases. Previous single case reports have outlined some features of this syndrome. All 18 cases were defined by the presence of serum IgM antibodies which react principally with NeuAc (alpha2-8)NeuAc(alpha2-3)Gal-configured disialosyl epitopes common to many gangliosides including GDlb, GD3, GTlb and GQlb. In 17 out of 18 cases, the serum contained benign IgM paraproteins, and in four of these cases at least two IgM paraproteins were present. The IgM antibodies were also cold agglutinins in 50% of cases. The clinical picture comprised a chronic neuropathy with marked sensory ataxia and areflexia, and with relatively preserved motor function in the limbs. In addition, 16 out of 18 cases had motor weakness affecting oculomotor and bulbar muscles as fixed or as relapsing-remitting features. When present in their entirety, these clinical features have been described previously under the acronym CANOMAD: chronic ataxic neuropathy, ophthalmoplegia, IgM paraprotein, cold agglutinins and disialosyl antibodies. This distribution of clinical features is reminiscent of Miller Fisher syndrome, in which acute-phase anti-disialylated ganglioside IgG antibodies are found. Clinical electrophysiology and nerve biopsy show both demyelinating and axonal features. A partial response to intravenous immunoglobulin and other treatments is reported in some cases.

Recently, the clinical efficacy of interferon beta-1b (IFNbeta-1b) was demonstrated for secondary progressive (SP) multiple sclerosis in a European multicentre study. We evaluated the effect of IFNbeta-1b treatment on the rate of development of hypointense T(1) MRI lesions, a putative marker of axonal damage. Unenhanced T(1)-weighted images were obtained in a subgroup of 95 multiple sclerosis patients from five centres at 6-month intervals; this subgroup was similar to the total study population for all demographic, clinical and MRI parameters. An experienced observer blinded to the clinical data and treatment allocation measured volumes. The median baseline lesion load for hypointense T(1) lesions was 5.1 cm(3) for placebo-treated and 4.9 cm(3) for IFNbeta-1b-treated patients (P = 0.56). Placebo-treated patients showed an increase in T(1) lesion load by a median of 14% per year (P = 0.0002 compared with baseline); this was reduced to 7.7% per year in the IFNbeta-1b-treated patients (P = 0.003 versus placebo). In the IFNbeta-1b arm there was a statistically significant correlation between absolute change in Expanded Disability Status Scale scores and T(1) lesion load by month 36 (r = 0.38, P = 0.0015). In patients with SP multiple sclerosis, IFNbeta-1b treatment reduces the development of hypointense T(1) lesions, suggesting that reduced axonal damage in lesions may play a part in the beneficial effect that is observed clinically.

The recently completed European trial of interferon beta-1b (IFNbeta-1b) in patients with secondary progressive multiple sclerosis (SP multiple sclerosis) has given an opportunity to assess the impact of treatment on cerebral atrophy using serial MRI. Unenhanced T(1)-weighted brain imaging was acquired in a subgroup of 95 patients from five of the European centres; imaging was performed at 6-month intervals from month 0 to month 36. A blinded observer measured cerebral volume on four contiguous 5 mm cerebral hemisphere slices at each time point, using an algorithm with a high level of reproducibility and automation. There was a significant and progressive reduction in cerebral volume in both placebo and treated groups, with a mean reduction of 3.9 and 2.9%, respectively, by month 36 (P = 0.34 between groups). Exploratory subgroup analyses indicated that patients without gadolinium (Gd) enhancement at the baseline had a greater reduction of cerebral volume in the placebo group (mean reduction at month 36: placebo 5.1%, IFNbeta-1b 1.8%, P < 0.05) whereas those with Gd-enhancing lesions showed a trend to greater reduction of cerebral volume if the patient was on IFNbeta-1b (placebo 2.6%, IFNbeta-1b 3.7%; P > 0.05). These results are consistent with ongoing tissue loss in both arms of this study of secondary progressive multiple sclerosis. This finding is concordant with previous observations that disease progression, although delayed, is not halted by IFNbeta. The different pattern seen in patients with and without baseline gadolinium enhancement suggests that part of the cerebral volume reduction observed in IFNbeta-treated patients may be due to the anti-inflammatory/antioedematous effect of the drug. Longer periods of observation and larger groups of patients may be needed to detect the effects of treatment on cerebral atrophy in this population of patients with advanced disease.

The idea that the initiating event in the formation of all new multiple sclerosis lesions is a focal blood-brain barrier (BBB) leakage associated with perivascular inflammation has been challenged recently by the observation of subtle abnormalities in some quantitative magnetic resonance (MR) parameters (including the magnetization transfer ratio) prior to lesion enhancement. MR diffusion imaging can non-invasively quantify the average apparent diffusion coefficient (ADC(av)), a measure of water molecule random motion that is sensitive to pathological change in multiple sclerosis lesions and to abnormalities in the normal-appearing white matter (NAWM). We therefore used MR diffusion imaging to investigate the dynamic evolution of water diffusion measurements in new enhancing multiple sclerosis lesions, in the NAWM from which they arise, and in anatomically matched contralateral NAWM regions from which no visible lesions develop. Gadolinium diethylenetriaminepentaacetic acid (Gd)-enhanced MRI and MR diffusion studies were performed monthly for 1 year in five multiple sclerosis patients with clinically and radiologically active disease. The ADC(av) was calculated at each time point of the study (before, during and after lesion appearance on Gd-enhanced scans) for each new enhancing lesion, and for regions matched for size and position in the contralateral NAWM. A steady and moderate increase in ADC(av) in prelesion NAWM was observed, which was followed by a rapid and marked increase at the time of Gd enhancement and a slower decay after the cessation of enhancement. In matched contralateral NAWM regions there was a significant but milder increase in ADC(av) at the time of the first noted lesion enhancement. These findings indicate that new focal lesions associated with frank BBB leakage are preceded by subtle, progressive alterations in tissue integrity beyond the resolution of conventional MRI. The increases in ADC(av) in anatomically matched contralateral regions after lesions have appeared supports the concept that structural damage in lesions causes damage or dysfunction in connected areas of NAWM.

The relative rarity of primary progressive (PP) and transitional progressive (TP) multiple sclerosis has meant that little documentation of cognitive function in such patients is currently available. The aim of this study was to investigate the cognitive skills of patients with PP and TP multiple sclerosis relative to matched healthy controls, and to examine the relationship of this impairment to MRI parameters. Sixty-three patients (43 PP, 20 TP) were individually matched with healthy controls, who undertook the same cognitive tasks as the patient group. The neuropsychological assessment comprised Rao's brief repeatable battery, a reasoning test, and a measure of depression. Patients also underwent T1- and T2-weighted brain MRI. These patients were taken from a larger cohort (158 PP, 33 TP) in whom it had been demonstrated that the re were no significant differences between the mean scores of the PP and TP groups on any of the cognitive variables. The 63 patients were therefore taken as one group for comparison with the healthy controls. These patients performed significantly worse than the controls in tests of verbal memory, attention, verbal fluency and spatial reasoning. An impairment index was constructed and applied to the patient data. This correlated modestly with T2-lesion load (r = 0.45, P = 0.01), T1-hypointensity load (r = 0.45, P = 0.01) and cerebral volume (r = -0.35, P = 0.01). Thus, PP and TP multiple sclerosis patients demonstrate significant cognitive dysfunction when compared with matched healthy controls. The relationship between this impairment and MRI parameters is moderate, suggesting that cognitive dysfunction in PP and TP multiple sclerosis has a complex and multifactorial aetiology, which is not adequately explained by pathology as demonstrated on conventional MRI.

The purpose of this study was to relate abnormalities of motor conduction time to the presence of spinal cord MRI lesions in progressive multiple sclerosis and to investigate the relationship between changes in motor conduction over time and clinical and MRI changes. Central motor conduction time (CMCT), serial MRI of the brain and spinal cord, and clinical evaluations were carried out in 20 patients with primary and secondary progressive multiple sclerosis. CMCT was carried out at the beginning and end of the study whilst the clinical and MRI examinations occurred at monthly intervals for 12 months. Median CMCT to abductor pollicis brevis was 14.8 ms (range 8.8-27.4 ms). The response latency to tibialis anterior correlated with disability measured on the Expanded Disability Status Scale. Latencies to upper limb muscles correlated with cervical MRI lesion load and the presence of atrophy of the cervical cord. Over the 12-month study period, 15 of 19 patients deteriorated clinically. However, an increase in motor response latencies occurred only in the four patients who had developed new cord lesions. The results suggest that prolonged CMCT is related to spinal cord lesion load and that, over time, changes in the CMCT occur only when spinal cord lesion load increases. Clinical change in progressive multiple sclerosis may therefore occur without either the development of new lesions on MRI scans or an increase in motor conduction time. This suggests that clinical deterioration in these patients may occur by a mechanism other than increasing demyelination. This may be progressive axonal degeneration.

We studied the electrophysiological parameters of motor performance in eight patients with multiple sclerosis and troublesome fatigue, before and after treatment with 3,4-diaminopyridine. Symptomatic fatigue was evaluated by the Krupp Fatigue Severity Score and motor performance of adductor pollicis by transcranial magnetic stimulation, rapid voluntary movements and a fatiguing exercise test of a sustained 45-s isometric contraction. The motor tests revealed baseline abnormal motor function and substantial central fatigue. After a 3-week course of 3,4-diaminopyridine (25-60 mg/day), six out of the eight patients reported substantial improvement in fatigue and the group showed slightly less fatigue on the exercise test. Other electrophysiological tests of motor function were unchanged. The findings suggest that 3,4-diaminopyridine may play a role in the symptomatic treatment of fatigue in multiple sclerosis. However, the mechanism behind such a benefit in fatigue remains unclear and the discrepancy between subjective and more objective responses underlines the probable multifactorial nature of the pathogenesis of this symptom in multiple sclerosis.

A definitive diagnosis of multiple sclerosis cannot be made at presentation on patients with a clinically isolated syndrome of the optic nerve, spinal cord or brainstem suggestive of demyelination, as dissemination in time is not established. To determine the long-term risk of abnormalities on brain MRI for the development of multiple sclerosis and disability we performed a 10-year follow-up on 81 such patients who had T2-weighted brain MRI at presentation. Initial brain MRI was abnormal in 54 (67%). Follow up of those patients with an abnormal MRI revealed progression to clinically definite multiple sclerosis in 45 out of 54 (83%), of whom 11 (20%) had relapsing/remitting disease (EDSS > 3), 13 (24%) secondary progressive and 21 (39%) benign (relapsing/remitting with EDSS < or = 3) disease. For those with a normal MRI progression to clinically definite multiple sclerosis occurred in only three out of 27 (11%), all benign. There was a significant relationship between the number of lesions at presentation and both EDSS (r = 0.45, P < 0.001) and the type of disease at follow-up (P < 0.0001). Brain MRI at presentation with a clinically isolated syndrome is predictive of the long-term risk of subsequent development of multiple sclerosis, the type of disease and extent of disability.

We report the findings in 60 patients with secondary progressive multiple sclerosis who had monthly brain MRI studies for 4 months (one baseline and three follow-up scans). The purpose was to define the short-term MRI natural history in a large cohort with secondary progressive disease and to ascertain its relationship with other clinical and MRI features. The patients were participating in either a natural history study or the placebo arm or non-treatment phase of a therapeutic trial. The cohort had clinical features typical of secondary progressive disease: thus, all had moderate or severe locomotor disabilities [Expanded Disability Status Scale (EDSS), score 3.5-8], with a median disease duration of 12 years. There was equal representation of males and females. During the 3 months of follow-up there was a total of 362 new enhancing lesions seen in 42 patients, and there were 24 relapses in 20 patients. There was no correlation between new enhancing lesions and age at study entry, age of disease onset, gender disease duration or EDSS, but there was a strong correlation with the number of enhancing lesions on the baseline scan (r = 0.65, P < 0.0001) and subsequent activity. There was a non-significant trend for higher numbers of new enhancing lesions in those having relapses during the 3 months of scanning (P = 0.14) or in the preceding 6 months (P = 0.06). The 34 patients who did not relapse in either period had significantly fewer new active lesions (P = 0.02) than those who relapsed at some stage during the 9 months. Nevertheless, considerable activity was seen in the non-relapsing cohorts: there was a mean of 3.5 (median 2) new enhancing lesions in those not relapsing during the 3 month study, and 5.5 (median 2) in those not relapsing in the previous 6 months. We conclude that short-term MRI activity is generally high in secondary progressive disease, confirming a useful role for the technique in exploratory trials. Further work should concentrate on elucidating the mechanisms of secondary progression by longer term follow-up studies of larger cohorts using multiple MRI and clinical measurements.

Although clinical end points remain the definitive measure of therapeutic efficacy in multiple sclerosis, more sensitive markers of disease activity are required to screen potential disease-modifying agents. The use of gadolinium contrast-media in MRI studies increases both the reliability and sensitivity of detecting active lesions in multiple sclerosis. We studied three potential methods for further improving sensitivity; the use of 0.3 mmol/kg (triple dose) gadolinium-diethylenetriaminepenta-acetic acid (Gd-DTPA), magnetization transfer (MT) contrast imaging and the introduction of a delay between contrast-medium injection and imaging. Fifty patients were studied (seven with benign, 14 with relapsing-remitting, 10 with secondary progressive, 16 with primary progressive and three with transitional multiple sclerosis). Imaging was performed on two occasions, 24-72 h apart, with triple- and single-dose Gd-DTPA. Pairs of contrast-enhanced T 1-weighted studies, with and without MT, were obtained at three different times, i.e. within early (0-20 min), short-delay (20-40 min) and long-delay (40-60 min) time-windows. Nineteen patients did not have the full complement of studies. Seven patients suffered minor self-limiting adverse events possibly related to triple-dose Gd-DTPA. Overall, triple-dose Gd-DTPA resulted in a 75% increase in the number of enhancing lesions detected compared with the single dose (P < 0.002). The use of MT or delay alone did not significantly increase the sensitivity of either single- or triple-dose studies. The combination of MT and short delay increased the number of enhancing lesions detected with single-dose Gd-DTPA by 47% (P < 0.05) and with triple-dose Gd-DTPA by 27% (P < 0.01). Detection was not significantly further improved by a long delay. The most sensitive modality was MT imaging with a long delay following triple-dose Gd-DTPA, resulting in the detection of 126% more enhancing lesions than in standard single-dose imaging (P < 0.05). This applies to all subgroups except for primary progressive multiple sclerosis, in which none of these methods alone or in combination improved the sensitivity. We conclude that for relapsing-remitting and secondary progressive multiple sclerosis, the combination of triple-dose Gd-DTPA and delayed MT imaging more than doubles the sensitivity to contrast-enhancing lesions.

Patients with multiple sclerosis who develop progressive disability from onset without relapses or remissions pose difficulties in diagnosis, monitoring of disease activity and treatment. There is a need to define the diagnostic criteria for this group more precisely and, in particular, to describe a comprehensive battery of investigations to exclude other conditions. The mechanisms underlying the development of disability and the role of MRI in monitoring disease activity in this clinical subgroup require elucidation, particularly in view of the lack of change on conventional imaging in the presence of continuing clinical deterioration. The prognosis is poor and there are currently no treatment trials for this form of the disease.

Fatigue is a common and disabling symptom in multiple sclerosis but is poorly understood. We investigated 'physiological' fatigue in 21 patients with multiple sclerosis who complained of disabling fatigue by measuring the decline in strength during a 45 s maximal contraction of the adductor pollicis muscle. The results were compared with those from a control group of 19 healthy subjects. The strength of control subjects declined by approximately 20% during the contraction; twitch interpolation showed central drive remained almost maximal throughout, and therefore that the fatigue was peripheral in origin. Patients had normal baseline strength, but developed greater fatigue (approximately 45%), which was central in origin. In both cases, the decline in strength followed a roughly linear time course suggesting that the patients, like the normals, were trying to maintain a maximum voluntary effort. Evidence for frequency-dependent conduction block (FDCB) in the patients' central motor pathways was sought by measuring the EMG responses to single and paired transcranial magnetic stimuli. Fatigue had no effect on the latency or size of EMG responses to transcranial magnetic stimulation, suggesting that FDCB was unlikely to have occurred. This was supported by measurements of the maximum speed of voluntary muscle contraction; although the patients showed relatively slow speeds before exercise, the decline in speed after fatigue was no greater than in normal subjects. We conclude that excessive 'physiological' fatigue contributes to the symptom of fatigue in multiple sclerosis and is central in origin. However, since the degree of exercise-induced fatigue did not correlate with the baseline complaint of fatigue, other factors must also be operating to produce the full range of clinical symptoms. We found no conclusive evidence that central fatigue is related to increased dysfunction in the primary central motor pathways and no evidence that FDCB is the pathophysiological mechanism. We postulate that central fatigue in multiple sclerosis is due to impaired drive to the primary motor cortex and several lines of evidence strongly suggest that this is not due to a lack of motivation.

The aim of this study was to assess neopterin, a marker of interferon gamma (IFN-gamma) induced macrophage activity, as a possible surrogate marker of inflammation in patients with multiple sclerosis. Urinary neopterin to creatinine ratios (UNCRs) were measured daily in 10 primary progressive (PP). 10 relapsing remitting (RR) and 11 secondary progressive (SP) patients with multiple sclerosis, and 14 normal control (NC) subjects, for periods of up to 12 weeks. After excluding measurements related to infection, the median of the individuals' average UNCRs was significantly higher in patients than in controls (P < 0.001 for all patients and P < 0.01 for each of the three groups of patients); the median UNCRs (and interquartile ranges) were 187 (135-231), 187 (165-277), 218 (164-517) and 134 (97-152) mumol/mol for PP, RR, SP patients and controls, respectively. Similarly, patients had a greater median proportion of days with a UNCR above normal (P < 0.001 for all patients and P < 0.01 for each group); the median percentage (and interquartile ranges) were 16 (6-62), 28 (21-36), 49 (14-86) and 0 (0-6)% for PP, RR, SP patients and controls, respectively. They also had a greater number of peaks in their serial UNCR measurements than controls (P < 0.001 for all patients and P < 0.01 for each group); the means +/- SD peaks/subject/month were: 2.1 +/- 1.8; 3.0 +/- 1.7; 3.3 +/- 2.3 and 0.2 +/- 0.6 for PP, RR, SP patients and controls, respectively. Nine relapses occurred in nine patients during the study, and all were associated with increased neopterin excretion, which tended to be greater than that on days not associated with a relapse. Three of the nine relapses were preceded by an upper respiratory tract infection. In eight out of 13 patients who had infections during the study, increased neopterin excretion was noted for periods of up to 6 weeks post-infection, significantly longer than that which occurred after infections in controls. This confirms infection as a potent inducer of symptomatic and asymptomatic disease activity in mutiple sclerosis, and provides further support of a pivotal role for IFN-gamma in te pathogenesis of mutiple sclerosis. Urinary neopterin excretion is increased in patients with both progressive and relapsing mutiple sclerosis, and therefore has potential as a surrogate marker of the inflammatory component of mutiple sclerosis disease activity.

Deficits in executive function and the relationship to frontal lesion load as detected on MRI were investigated in 42 multiple sclerosis patients. A battery of neuropsychological test examining executive skills including computerized tests of planning and spatial working memory was administered to all subjects. Performance on these tests was impaired in the patient group when compared with a group of matched controls, but not all executive skills were affected to the same extent. Although a number of executive test scores correlated with the severity of frontal lesion load, it was difficult to disentangle the specific contribution of frontal lobe pathology to the impairment on executive tasks. This study highlights the difficulties in attempting to attribute specific cognitive abnormalities to focal brain pathology in the presence of widespread disease such as in multiple sclerosis.

Recent studies of the spinal cord and cerebellum have highlighted the importance of atrophy in the development of neurological impairment in multiple sclerosis. We have therefore developed a technique to quantify the volume of another area commonly involved pathologically in multiple sclerosis: the cerebral white matter. The technique we describe extracts the brain from the skull on four contiguous 5 mm periventricular slices using an algorithm integrated in an image analysis package, and quantifies their volume. Intra-observer scan-rescan reproducibility was 0.56%. We have applied this technique serially to 29 patients with multiple sclerosis selected for an 18-month treatment trial with a monoclonal antibody against CD4+ lymphocytes (deemed clinically ineffective). A decrease in volume beyond the 95% confidence limits for measurement variation was seen in 16 patients by the end of the 18-month period. The rate of development of atrophy was significantly higher in those who had a sustained deterioration in their Kurtzke expanded disability status scale (EDSS) score compared with those who did not (respective means: -6.4 ml year-1 and -1.8 ml year-1, P < 0.05) but in both groups these changes differed significantly from baseline (P < 0.05). Baseline T2 lesion load, change in T2 lesion load over 18 months and the volume of new gadolinium enhancing lesions on monthly scans for the first 10 months showed no correlation with the development of atrophy. This study demonstrates that progressive cerebral atrophy can be detected in individual patients with multiple sclerosis, correlates with worsening disability and gives additional information to that obtained with conventional MRI. The effect of putative therapies aimed at preventing disability could be objectively assessed by this measure.

Although MRI detects the white matter lesions of multiple sclerosis within the brain with high sensitivity, a minority of patients have normal brain MRI. We describe 20 patients, selected from over 170 who had undergone brain imaging with minimal (n = 12) or no (n = 8) abnormalities (median number of lesions = I, range, 0-3) but in whom spinal MRI was abnormal. Twelve had clinically definite or laboratory supported definite multiple sclerosis according to the Poser criteria; one had clinically probable disease and seven, not fulfilling the Poser criteria, were classified as possible multiple sclerosis. All had presented with symptoms and signs referable to the spinal cord or optic nerves. Eleven had a primary progressive course, eight relapsing-remitting and only one secondary progressive. Moderate or severe disability was the rule in the primary progressive cases; all the relapsing-remitting patients had minimal disability. All had at least one lesion visible in the spinal cord (median 2; range 1-6). In patients in whom the diagnosis of multiple sclerosis is not supported by abnormalities on brain MRI, imaging of the spinal cord can be of considerable value.

Recent MRI studies in multiple sclerosis have highlighted the potential importance of spinal cord atrophy (implicating axonal loss) in the development of disability. However, the techniques applied in these initial studies have poor reproducibility which limits their application in the serial monitoring of patients. The aim of this study was to develop a highly reproducible and accurate method for the quantification of atrophy. The technique we describe demonstrates an intra-observer coefficient of variation (scan-rescan) of only 0.8%. When applied to 60 patients with clinically definite multiple sclerosis there was a strong correlation between spinal cord area and disability measured by Kurtzke's Expanded Disability Status Scale (EDSS) (r = -0.7, P < 0.001). The correlation was graded providing evidence for a causal connection. At levels 3 and 8 of the EDSS we observed a reduction in average cord area of 12 and 35%, respectively. Given its reproducibility, the magnitude of the change detected and the strong correlation with disability, this new technique should prove to be a sensitive measure of progressive neurological deterioration and could be readily incorporated into imaging protocols aimed at monitoring therapy.

Proton magnetic resonance spectroscopy (MRS) and MRI were carried out in 11 patients with multiple sclerosis who had clinical evidence of severe cerebellar involvement, 11 multiple sclerosis patients (of similar age and disease duration) who had minimal or no signs of cerebellar disease, eight patients with autosomal dominant cerebellar ataxia (ADCA) and 11 healthy controls. In all subjects MRS was localized to cerebellar white matter (volumes of interest 3-6 ml). Apparent metabolite concentrations were calculated using the fully relaxed water spectrum as an internal standard of reference. The patients also underwent MRI to assess cerebellar volume and (in the two multiple sclerosis groups) lesion volume within the posterior fossa. Magnetic resonance spectroscopy from cerebellar white matter showed a highly significant reduction in the concentration of N-acetyl groups (NA) [which consists predominantly of N-acetylaspartate (NAA), a neuronal marker] in the multiple sclerosis group with cerebellar deficit compared with the multiple sclerosis group with minimal or no signs of cerebellar involvement, and healthy controls. Follow-up MRS performed in six of the multiple sclerosis patients 9 months later showed no change in the median NA concentration. The ADCA group showed a significant reduction of NA from a region of cerebellar white matter and also a reduction in the concentration of choline-containing compounds. The multiple sclerosis group with severe cerebellar deficit and the ADCA group both had significant cerebellar atrophy (suggesting nerve cell body and axon loss) compared with the multiple sclerosis patients with minimal or no signs of cerebellar deficit and healthy controls. The multiple sclerosis patients with cerebellar deficit had a significantly greater lesion volume in the posterior fossa, although the proportion of the spectroscopic voxel occupied by lesions was small, suggesting that axonal loss from normal appearing white matter also contributes to the observed reduction in NA. These results support the hypothesis that axonal loss is important in the development of persistent clinical disability in multiple sclerosis.

In recent years, several segmentation techniques have been developed to quantify brain MRI lesion load in multiple sclerosis and are now being used increasingly for both evaluating the natural history of the disease and monitoring the efficacy of treatment. Such techniques have been applied extensively to conventional T2-weighted images; there is less experience to date with gadolinium-enhanced scans and newer MR parameters which are thought to reflect the more destructive aspects of the pathological process. Manual outlining of lesions on T2-weighted images is moderately accurate when performed by an experienced observer and has been validated in large clinical trials, but is very time consuming. Semi-automated intensity-based techniques appear to be more reproducible, but are still slow to perform. Faster techniques with higher reproducibility are still needed. The correlations between conventional T2 lesion load and clinical outcome is strong in patients seen at first presentation with clinically isolated syndromes suggestive of multiple sclerosis, but much weaker in established multiple sclerosis. The application of quantitative assessment of the MR parameters which are more specific for the disabling aspects of the pathological process (i.e. demyelination, axonal loss and spinal cord involvement) may improve the correlation with clinical status.

The dynamics of primary progressive multiple sclerosis differ from those of the more common secondary progressive form. The observation by MRI that the frequency of enhancement with gadolinium-DTPA, a marker for blood-brain barrier dysfunction, is significantly less in the primary progressive form, has led to the hypothesis that inflammation is less intense in this group. To test this, we have studied postmortem material from nine cases judged from a retrospective analysis of case notes to show clear clinical evidence of either primary progressive or secondary progressive disease. Five hundred and seventy-eight lesions were analysed. There was significantly more inflammation in secondary progressive multiple sclerosis (as judged by the frequency of perivascular cuffing and cellularity of the parenchyma) than in primary progressive disease. These observations have implications for therapeutic strategies in progressive multiple sclerosis.

Enhanced expression of beta-adrenoceptor densities on peripheral blood mononuclear cells (PBMCs) in progressive multiple sclerosis patients has been observed in a number of independent studies. A link between increased number of beta-adrenoceptors and inflammatory disease has been further indicated by studies in rheumatoid arthritis and relapsing-remitting multiple sclerosis patients. In a serial monthly assessment of relapsing-remitting multiple sclerosis patients, we have demonstrated that increased beta-adrenoceptors on PBMCs correlate with the expression of high affinity interleukin-2 receptors (IL-2Rs) and disease activity as determined by clinical and MRI findings. Magnetic resonance imaging activity was strongly correlated with IL-2R expression and it appears to be a sensitive marker of PBMC immunoactivation in multiple sclerosis. In vitro studies showed that beta-agonist stimulation of PBMCs reduces the IL-2R expression and suppresses cell proliferation following mitogenic stimulation. This observation may indicate a recovery role for the enhanced beta-adrenoceptor expression in multiple sclerosis. However, its therapeutic importance remains to be tested by appropriate trials using either beta-agonists or agents activating the second messenger system, c-AMP, in lymphocytes.