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  • Integration of structural and functional magnetic resonance imaging in amyotrophic lateral sclerosis.

    24 October 2018

    Amyotrophic lateral sclerosis as a system failure is a concept supported by the finding of consistent extramotor as well as motor cerebral pathology. The functional correlates of the structural changes detected using advanced magnetic resonance imaging techniques such as diffusion tensor imaging and voxel-based morphometry have not been extensively studied. A group of 25 patients with amyotrophic lateral sclerosis was compared to healthy control subjects using a multi-modal neuroimaging approach comprising T(1)-weighted, diffusion-weighted and resting-state functional magnetic resonance imaging. Using probabilistic tractography, a grey matter connection network was defined based upon the prominent corticospinal tract and corpus callosum involvement demonstrated by white matter tract-based spatial statistics. This 'amyotrophic lateral sclerosis-specific' network included motor, premotor and supplementary motor cortices, pars opercularis and motor-related thalamic nuclei. A novel analysis protocol, using this disease-specific grey matter network as an input for a dual-regression analysis, was then used to assess changes in functional connectivity directly associated with this network. A spatial pattern of increased functional connectivity spanning sensorimotor, premotor, prefrontal and thalamic regions was found. A composite of structural and functional magnetic resonance imaging measures also allowed the qualitative discrimination of patients from controls. An integrated structural and functional connectivity approach therefore identified apparently dichotomous processes characterizing the amyotrophic lateral sclerosis cerebral network failure, in which there was increased functional connectivity within regions of decreased structural connectivity. Patients with slower rates of disease progression showed connectivity measures with values closer to healthy controls, raising the possibility that functional connectivity increases might not simply represent a physiological compensation to reduced structural integrity. One alternative possibility is that increased functional connectivity reflects a progressive loss of inhibitory cortical influence as part of amyotrophic lateral sclerosis pathogenesis, which might then have relevance to future therapeutic strategies.

  • The internet for self-diagnosis and prognostication in ALS.

    24 October 2018

    Persons with ALS, and those close to them, may use the internet to explore symptoms prior to formal diagnosis, and as a source of information about prognosis and treatment thereafter. We used an internet search engine to rank the sensitivity of a variety of symptom search terms a patient might use for the diagnosis of ALS/MND. We also studied search engine responses to questions about life expectancy and possible 'cure'. An internet search engine in relation to ALS currently lacks sensitivity, and results varied greatly with only minor differences in the search terms used. The prognostic information did not reflect the inherent heterogeneity. Results in relation to 'cure' were misleading and may promulgate false hopes. There is a need to guide those with ALS (and particularly their children) to sources of reliable web-based information in addition to open discussion.

  • The borderland of neuromyelitis optica.

    24 October 2018

    Neuromyelitis optica (NMO), also known as Devic's disease, is an emerging clinical and pathological entity originally thought to be a variant of multiple sclerosis. Characterised by episodes of demyelination confined to the optic nerve and spinal cord, the discovery in such patients of antibodies to the aquaporin-4 channel has been largely responsible for defining the phenotype to date. Recently it has become clear that there is a borderland where there are patients with optic neuritis-only and myelitis-only forms of the disease, and these may be seronegative in the early phase. We describe two cases of optic neuritis-only NMO, and explore the current understanding of the diagnosis and spectrum of NMO disorders.

  • Volumetric cortical loss in sporadic and familial amyotrophic lateral sclerosis.

    24 October 2018

    Patients homozygous for the D90A mutation of the SOD1 gene (homD90A) demonstrate markedly slower progression of disease than those patients with sporadic ALS (SALS). PET studies have demonstrated a different cortical vulnerability in the two groups, reflected also in neurophysiological studies showing reduced cortical excitability in homD90A. Voxel-based morphometric analysis of magnetic resonance images (MRIs) enables the detection of regional differences in grey matter volume, and can be used to localize cortical atrophy in vivo. In this study, segmented, spatially normalized, modulated and smoothed grey matter portions of the MRIs from 23 SALS and seven homD90A patients with similar disability, were compared with those from 28 healthy control subjects. The SALS group showed bilateral areas of atrophy mainly confined to motor and pre-motor cortices. Cortical changes in the homD90A group were more pronounced within the frontal lobes when both were compared with healthy controls. This study provides further evidence for a different pattern of cortical neuronal vulnerability in homD90A versus SALS patients that may provide insight as to their slower rate of disease progression.

  • Fractional anisotropy in the posterior limb of the internal capsule and prognosis in amyotrophic lateral sclerosis.

    24 October 2018

    OBJECTIVE: To explore the value of diffusion tensor imaging applied to those specific cerebral white matter tracts consistently involved pathologically in amyotrophic lateral sclerosis as a source of prognostic biomarkers. DESIGN: Baseline clinical assessment and 3-T diffusion tensor imaging, repeated after approximately 6 months.Tract-based spatial statistics were used to assess voxel wise correlations of just the baseline diffusion tensor imaging indices with the progression rate (change in disability score/time interval) within the corticospinal tract and corpus callosum. PATIENTS: The study involved 21 patients with amyotrophic lateral sclerosis and 3 patients with primary lateral sclerosis. RESULTS: Correlation was observed between fractional anisotropy and progression rate for a region of the corticospinal tract spanning the posterior limb of the internal capsule, with a left hemisphere emphasis. Posterior limb of the internal capsule fractional anisotropy showed potential to distinguish those patients with rapid progression. Axial diffusivity significantly increased in this region in a paired t test analysis of baseline and follow-up diffusion tensor imaging, in keeping with axonal damage.No correlations were noted for the corpus callosum. CONCLUSIONS: Posterior limb of the internal capsule fractional anisotropy is a candidate prognostic marker in amyotrophic lateral sclerosis, with potential to identify incident cases with more rapid progression.

  • Fractional anisotropy in the posterior limb of the internal capsule and prognosis in amyotrophic lateral sclerosis

    24 October 2018

    Objective: To explore the value of diffusion tensor imaging applied to those specific cerebral white matter tracts consistently involved pathologically in amyotrophic lateral sclerosis as a source of prognostic biomarkers. Design: Baseline clinical assessment and 3-T diffusion tensor imaging, repeated after approximately 6 months. Tract-based spatial statistics were used to assess voxelwise correlations of just the baseline diffusion tensor imaging indices with the progression rate (change in disability score/time interval) within the corticospinal tract and corpus callosum. Patients: The study involved 21 patients with amyotrophic lateral sclerosis and 3 patients with primary lateral sclerosis. Results: Correlation was observed between fractional anisotropy and progression rate for a region of the corticospinal tract spanning the posterior limb of the internal capsule, with a left hemisphere emphasis. Posterior limb of the internal capsule fractional anisotropy showed potential to distinguish those patients with rapid progression. Axial diffusivity significantly increased in this region in a paired t test analysis of baseline and follow-up diffusion tensor imaging, in keeping with axonal damage. No correlations were noted for the corpus callosum. Conclusions: Posterior limb of the internal capsule fractional anisotropy is a candidate prognostic marker in amyotrophic lateral sclerosis, with potential to identify incident cases with more rapid progression. ©2012 American Medical Association. All rights reserved.

  • Biomarkers in amyotrophic lateral sclerosis: opportunities and limitations.

    24 October 2018

    Insights into the mechanisms of amyotrophic lateral sclerosis (ALS) have relied predominantly on the study of postmortem tissue. Modern technology has improved the ability of scientists to probe effectively the underlying biology of ALS by examination of genomic, proteomic and physiological changes in patients, as well as to monitor functional and structural changes in patients over the course of disease. While effective treatments for ALS are lacking, the discovery of biomarkers for this disease offers clinicians tools for rapid diagnosis, improved ways to monitor disease progression, and insights into the pathophysiology of sporadic ALS. The ultimate aim is to broaden the therapeutic options for patients with this disease.

  • Lockhart Clarke's contribution to the description of amyotrophic lateral sclerosis.

    24 October 2018

    The definition of the clinicopathological entity of amyotrophic lateral sclerosis evolved over half a century. Although the definitive term amyotrophic lateral sclerosis that acknowledged both upper and lower motor neuron involvement was attributed to Jean-Martin Charcot in 1874, his initial case was published nearly a decade earlier; and it is accepted that, from at least the 1830s, several others (including Charles Bell, François-Amilcar Aran and Jean Cruveilhier) had already recognized a progressive lower motor neuron-only syndrome within a broader, clinically-defined group of disorders, termed progressive muscular atrophy. Although William Gowers first grouped the three phenotypes of amyotrophic lateral sclerosis, progressive muscular atrophy and progressive bulbar palsy together as part of the same syndrome, the term motor neuron disease, as an over-arching label, was not suggested until nearly a century later by W. Russell Brain. Augustus Jacob Lockhart Clarke (1817-80) is best known for his descriptions of spinal cord anatomy. However, in two detailed case reports from the 1860s, he carried out rigorous post-mortem neuropathological studies of what appear to be classical cases of amyotrophic lateral sclerosis. Furthermore, he recognized the additional involvement of the corticospinal tracts that distinguished this from progressive muscular atrophy. Several aspects of the exquisite clinical histories documented as part of both studies, one by Charles Bland Radcliffe, resonate with contemporary debates concerning the evolution of disease in amyotrophic lateral sclerosis. These 'past masters' still have much to teach us.