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Biomedical subjects

Alan J Thompson

Publications and source records attributed to Alan J Thompson.

At least 19 recordsLinked to original sources

Cannabinoids inhibit neurodegeneration in models of multiple sclerosis.

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

Animals↗

Interferon beta-1a in primary progressive multiple sclerosis.

There is currently no disease-modifying treatment proven to be of efficacy in primary progressive multiple sclerosis (PPMS). However, a number of therapeutic trials have recently been specifically designed for this group. These include a randomised controlled trial of interferon beta-1a which is discussed here. It is hoped that therapeutics in primary progressive multiple sclerosis will continue to expand and effective therapeutic agents will be developed.

Adjuvants, Immunologic↗

New T2 lesions enable an earlier diagnosis of multiple sclerosis in clinically isolated syndromes.

In clinically isolated syndromes, the new McDonald criteria for multiple sclerosis diagnosis require new gadolinium-enhancing lesions for dissemination in time at a 3-month follow-up magnetic resonance imaging scan. In a cohort of 56 patients, these criteria were specific (95%) but less sensitive (58%) for clinically definite multiple sclerosis at 3 years. If new T2 lesions were allowed as an alternative for dissemination in time, sensitivity increased (74%) with maintained specificity (92%), enabling an accurate diagnosis of multiple sclerosis in more patients.

Adolescent↗

Guidelines for using quantitative magnetization transfer magnetic resonance imaging for monitoring treatment of multiple sclerosis.

Quantitative evaluation of brain magnetic resonance imaging (MRI) scans is now an accepted part of the trial of new putative treatments for multiple sclerosis (MS). However, conventional MRI is not pathologically specific, and it does not reveal the details of the pathological processes that underlie the progression of the disease. Magnetization transfer (MT) imaging is a relatively new quantitative technique that appears to offer some pathological specificity, and can be used to monitor the changes over time in both individual lesions and the central nervous system as a whole. This paper considers the case for incorporating MT imaging into new clinical trials, so that the utility of MT for monitoring the modification of MS progression by treatment can be assessed. Specific guidelines for implementing MT imaging as part of a large multicenter clinical trial are given, and practical considerations when planning such a trial are detailed. It is anticipated that MT imaging will be incorporated into many new trials in the near future.

Brain↗

Application of a B-spline active surface technique to the measurement of cervical cord volume in multiple sclerosis from three-dimensional MR images.

PURPOSE: To evaluate the ability of a B-spline active surface technique to detect cervical spinal cord atrophy due to multiple sclerosis (MS) compared with intensity-based contouring. MATERIALS AND METHODS: In a previously reported study, the cervical spinal cords of 28 MS patients and 13 age-matched controls were imaged with a volume-acquired inversion-prepared fast spoiled gradient echo sequence at baseline and after one year. The images were reanalyzed using the B-spline technique and the results compared with the results obtained in the original report using intensity-based contouring. RESULTS: The mean cervical spinal cord volume determined by the active surface programme was 6487 mm(3) in 28 patients compared with 7117 mm(3) in controls (P = 0.002, corrected for age and gender). The patients' cervical spinal cord volumes were associated with expanded disability status scale scores (parameter estimate = -1.21 x 10(-3), r(2) = 0.39, P = 0.001). The patients' cervical spinal cord volumes did not decrease significantly over one year, unlike the mean cervical spinal cord areas at C2/3 calculated using intensity-based contouring. CONCLUSION: The active surface technique can detect cervical spinal cord atrophy due to MS, which has functional significance. However, this methodology is less sensitive at detecting small serial changes compared with the previously reported method.

Atrophy↗

A study of the mechanisms of normal-appearing white matter damage in multiple sclerosis using diffusion tensor imaging--evidence of Wallerian degeneration.

Diffusion tensor imaging (DTI) investigates brain tissue microstructure in vivo. In multiple sclerosis (MS) Wallerian degeneration of axons traversing focal lesions is a potential mechanism of damage in normal-appearing white matter. In vivo evidence for this hypothesis is limited. The present study investigated the relationship between DTI-derived indices in the normal-appearing corpus callosum (CC) and the lesion loads (LLs) in connected cerebral regions. DTI was performed in 39 MS patients and in 21 age-matched controls. Fractional anisotropy (FA) and mean diffusivity (MD) were estimated in the genu, body and splenium of CC. Patients showed lower FA and higher MD in the CC than controls and both correlated with the total LL (r = -0.56 and r = 0.54, p < 0.0001). The LL of individual cerebral lobes correlated with both FA and MD in the corresponding callosal regions, with the body showing the strongest correlations with frontal and parietal LL (p < 0.0001). The strong correlations between DTI indices in the CC and the extent of lesions in connected brain regions support the hypothesis that Wallerian degeneration of axons transected by remote, but connected focal lesions, is an important pathogenic mechanism of damage in MS.

Adult↗

Effects of a short outpatient rehabilitation treatment on disability of multiple sclerosis patients--a randomised controlled trial.

It is well known that neurorehabilitation can reduce disability or improve handicap of people with multiple sclerosis (MS). The aim of this study was to evaluate the effectiveness of a short period (6 weeks) of a tailored, individualised outpatient rehabilitation program in people with progressive MS. A randomised-controlled trial was undertaken in patients with primary and secondary progressive MS referred to the Centro Sclerosi Multipla of Catania. One hundred and eleven patients were assessed at baseline and at 12 weeks with validated measures of disability (Functional Independence Measure (FIM)) and impairment (Expanded Disability Status Scale (EDSS) and Functional Systems Scale). Of the 111, 58 were randomly assigned to the treatment group and 53 to the control group. All patients had been previously trained in a home exercise program. Both groups were well matched for age, sex, disease duration and severity, disability and quality of life (Short Form-36). At the end of 6 weeks patients allocated to the rehabilitation treatment group showed significant improvement in their level of disability compared with the control group,while the level of impairment did not change. Thirty-two patients of the treatment group and four of the control group improved on the FIM by two or more steps at 12 weeks (p<0.0001). An improvement by 1 EDSS step occurred in only two patients of the treatment group and in one patient of the control group. Benefits were maintained for a further six weeks. This study demonstrates that a short outpatient rehabilitation treatment improves disability of MS patients, without changing their impairment and confirms the effectiveness of rehabilitation in people with MS.

Adult↗

The therapeutic potential of cannabis.

Research of the cannabinoid system has many similarities with that of the opioid system. In both instances, studies into drug-producing plants led to the discovery of an endogenous control system with a central role in neurobiology. Few compounds have had as much positive press from patients as those of the cannabinoid system. While these claims are investigated in disorders such as multiple sclerosis spasticity and pain, basic research is discovering interesting members of this family of compounds that have previously unknown qualities, the most notable of which is the capacity for neuroprotection. Large randomised clinical trials of the better known compounds are in progress. Even if the results of these studies are not as positive as many expect them to be, that we are only just beginning to appreciate the huge therapeutic potential of this family of compounds is clear.

Cannabinoids↗

A longitudinal study of abnormalities on MRI and disability from multiple sclerosis.

BACKGROUND: In patients with isolated syndromes that are clinically suggestive of multiple sclerosis, such as optic neuritis or brain-stem or spinal cord syndromes, the presence of lesions as determined by T2-weighted magnetic resonance imaging (MRI) of the brain increases the likelihood that multiple sclerosis will develop. We sought to determine the relation between early lesion volume, changes in volume, and long-term disability. METHODS: Seventy-one patients in a serial MRI study of patients with isolated syndromes were reassessed after a mean of 14.1 years. Disability was measured with the use of Kurtzke's Expanded Disability Status Scale (EDSS; possible range, 0 to 10, with a higher score indicating a greater degree of disability). RESULTS: Clinically definite multiple sclerosis developed in 44 of the 50 patients (88 percent) with abnormal results on MRI at presentation and in 4 of 21 patients (19 percent) with normal results on MRI. The median EDSS score at follow-up for those with multiple sclerosis was 3.25 (range, 0 to 10); 31 percent had an EDSS score of 6 or more (including three patients whose deaths were due to multiple sclerosis). The EDSS score at 14 years correlated moderately with lesion volume on MRI at 5 years (r=0.60) and with the increase in lesion volume over the first 5 years (r=0.61). CONCLUSIONS: In patients who first present with isolated syndromes suggestive of multiple sclerosis, the increases in the volume of the lesions seen on magnetic resonance imaging of the brain in the first five years correlate with the degree of long-term disability from multiple sclerosis. This relation is only moderate, so the volume of the lesions alone may not be an adequate basis for decisions about the use of disease-modifying treatment.

Adolescent↗

Application of the new McDonald criteria to patients with clinically isolated syndromes suggestive of multiple sclerosis.

Traditionally, multiple sclerosis (MS) has been diagnosed on the basis of clinical evidence of dissemination in time and space. Previously, it could not be diagnosed in patients with single clinical episodes of demyelination known as clinically isolated syndromes. New diagnostic criteria from the International Panel of McDonald and colleagues incorporate MRI evidence of dissemination in time and space to allow a diagnosis of MS in patients with clinically isolated syndromes. From clinical and MRI examinations performed prospectively at baseline, 3 months, 1 year, and 3 years of follow-up, the frequency of developing MS was ascertained by the application of both the new McDonald criteria and the Poser criteria for clinically definite MS. The specificity, sensitivity, positive and negative predictive value, and accuracy of the new criteria for the development of clinically definite MS were assessed. At 3 months, 20 of 95 (21%) patients had MS with the McDonald criteria, whereas only 7 of 95 (7%) had developed clinically definite MS. After 1 year, the corresponding figures were 38 of 79 (48%) and 16 of 79 (20%), and after 3 years, they were 29 of 50 (58%) and 19 of 50 (38%). The development of MS with the new MRI criteria after 1 year had a high sensitivity (83%), specificity (83%), positive predicative value (75%), negative predictive value (89%), and accuracy (83%) for clinically definite MS at 3 years. Use of the new McDonald criteria more than doubled the rate of diagnosis of MS within a year of presentation with a clinically isolated syndrome. The high specificity, positive predictive value, and accuracy of the new criteria for clinically definite MS support their clinical relevance.

Adolescent↗

The reproducibility and sensitivity of brain tissue volume measurements derived from an SPM-based segmentation methodology.

PURPOSE: To investigate the reproducibility of SPM99-based whole brain, gray matter, and white matter volume measurements with and without image inhomogeneity correction, subsequently exploring age and gender effects on absolute and fractional (proportional to intra-cranial) volumes. MATERIALS AND METHODS: Twenty-seven control subjects (aged 23.2 to 55.2 years) had three-dimensional fast spoiled gradient recall scans. Ten subjects were scanned about 197 days later. RESULTS: Coefficients of variation (CV) for absolute and fractional volumes determined from images processed with inhomogeneity correction ranged from 1.2% to 0.5%. Inhomogeneity correction reduced the CV for all measures except gray matter fractional (GMF) volumes. Significantly lower white matter absolute (WM) and fractional (WMF) volumes, and higher GMF were found in females compared with males, overlying age-related reductions (in decreasing order of significance) in brain parenchymal fraction, GMF, WMF, brain parenchymal, and gray matter volumes. CONCLUSION: SPM99 segmentations are sufficiently reproducible to detect age and gender effects in limited cohorts.

Adult↗

Disability and lesion load in MS: a reassessment with MS functional composite score and 3D fast FLAIR.

The correlation between T2 lesion load (LL) detected on conventional MR sequences and disability assessed by the Expanded Disability Status Scale (EDSS) in multiple sclerosis (MS) is, at best, moderate. The present study was performed to determine whether the correlation between disability and LL is improved by (i) use of the more sensitive three-dimensional fast fluid-attenuated inversion recovery (3D-fast FLAIR) sequence; (ii) application of the newly devised MS functional composite (MSFC) score. Forty-one patients with clinically definite or probable MS were studied. All had been followed prospectively for 14 years since their first symptom. EDSS and MSFC score were assessed. Imaging was performed with 3D-fFLAIR, fast spin-echo (FSE), and T1 weighted SE sequences. 3D-fFLAIR detected a 34% higher LL than FSE, but did not improve the correlation between T2 LL and EDSS (r = 0.51 and r = 0.53); the correlation was stronger with T1 LL (r = 0.57). The MSFC score did not significantly correlate with T2 LL or T1 LL. The robust correlation in this cohort between T2 LL and EDSS may reflect the homogeneous disease duration and the wide spread of disability. This correlation was not improved by the increased detection of T2 lesions with the 3D-fFLAIR sequence. The stronger correlation between T1 LL with EDSS is consistent with the finding that this subgroup of lesions represent areas of more severe tissue damage. The MSFC score did not improve the clinico-radiological paradox that is found in MS, despite including information on cognitive function.

Adolescent↗

Monitoring disease activity and progression in primary progressive multiple sclerosis using MRI: sub-voxel registration to identify lesion changes and to detect cerebral atrophy.

OBJECTIVE: To explore the potential usefulness of two new magnetic resonance imaging (MRI) analysis techniques for assessment of progressive cerebral atrophy and T2 lesion activity in primary progressive multiple sclerosis (PPMS), and thereby assess the relationship between MRI activity and atrophy in this patient group. BACKGROUND: Measurements of cerebral atrophy and net change in T2 lesion volumes are currently used as surrogate markers of disease progression in multiple sclerosis (MS). However, manual implementation of these techniques is time-consuming and the pathological specificity of T2 lesion change is low. Advances in serial scan registration have facilitated the development of a new, fully-automated technique to measure cerebral volume (SIENA; Structural Image Evaluation, using Normalisation, of Atrophy), and a technique to measure the total new T2 lesion volume selectively (MRI difference imaging). METHOD: SIENA measures changes in cerebral size based on sub-voxel detection of shifts in edge contours. The lesion difference imaging method measures differences in lesion volumes over time as defined by a semi-automated outlining technique. The two new methods were validated against the T2 lesion volume contour technique and a previously described measure of partial brain volume (which uses six slices centred on the presumed area of greatest change around the lateral ventricles). All were applied to serially acquired MR images from a cohort of 39 patients with PPMS, who also underwent scoring on the expanded disability status scale (EDSS) twice, two years apart. RESULTS: The two measures reflecting cerebral atrophy correlated strongly (r = 0.58, p < 0.001). T2 lesion load measurements using the two techniques correlated very highly (r = 0.999, p < 0.001). 91% of the total new T2 lesion volume was from enlargement of pre-existent lesions and only 9 % from new, discrete, lesions. No relationship was seen between the traditional measure of net gain in T2 lesion load and either measure of atrophy. However, the fully-automated measure of total new T2 load correlated with both measures of atrophy (SIENA technique, r= -0.37, p= 0.02; six slice measure, r = -0.41, p = 0.01). There was no relationship between the MRI measures and changes in the EDSS. CONCLUSION: Both of the new image analysis techniques appear to be promising as sensitive markers for disease progression in PPMS. The correlation of total new T2 lesion volume with the progression of cerebral atrophy (which is known to be a consequence of axonal loss in progressive disease), compared with a lack of correlation with the traditional net gain in T2 lesion load is interesting and suggests that the total new T2 lesion volume may ultimately be the most useful measure.

Adult↗

The relationship between lesion and normal appearing brain tissue abnormalities in early relapsing remitting multiple sclerosis.

BACKGROUND: In multiple sclerosis (MS), pathological changes have been found both in macroscopic lesions and normal appearing tissue. Magnetisation transfer ratio (MTR) and T1 relaxation time are abnormal in normal appearing tissues in established MS. This study used these MR techniques in early MS to study normal appearing tissues and lesions. The purpose was to determine whether abnormalities are already detectable in normal appearing tissues in early MS, and if so how they correlate with lesion characteristics. METHODS: Twenty two patients with early relapsing remitting (RR) MS (median disease duration 2 years, range 7 months-3 years) and 11 age-matched controls were studied. MTR and T1 relaxation times were measured in 9 regions of normal appearing white matter (NAWM) and 7 of normal appearing grey matter (NAGM). Gadolinium enhancing, T1-hypointense and T2 lesion loads were measured in all patients. RESULTS: When all regions were combined, there was a significant difference between patient and control NAWM for both T1 and MTR; T1 was abnormal in 6/9 and MTR in 3/9 NAWM regions. Global assessment of NAGM revealed a significant difference between patients and controls for Ti but not for MTR; T1 was significantly abnormal only in frontal NAGM. There was no significant correlation between NAWM T1 or MTR and any of the lesion load measurements. CONCLUSIONS: This study reveals quantitative MR abnormalities in both NAWM and NAGM in early RR MS, with more extensive changes in the former. The lack of correlation between NAWM and lesion abnormalities suggests that they have developed by at least partly independent mechanisms. T1 may be more sensitive than MTR in detecting subtle pathological changes in NAWM and NAGM.

Adult↗

Measurement of atrophy in multiple sclerosis: pathological basis, methodological aspects and clinical relevance.

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.

Atrophy↗

Progress in neurorehabilitation in multiple sclerosis.

Despite being acknowledged as an important component in the overall management of multiple sclerosis, the relatively few evaluative studies in symptomatic treatment and rehabilitation have meant that the evidence base is still poor. The encouraging work on health outcome measures, together with an improved understanding of the mechanisms underlying disability, provide a useful base for improving the lot of patients with multiple sclerosis. These advances need to be associated with improved models of care which provide comprehensive and accessible services throughout the course of the disease.

Ataxia↗