Brain : a journal of neurology
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Multicenter Study Comparative Study
Assessment of metabolic brain damage and recovery following mild traumatic brain injury: a multicentre, proton magnetic resonance spectroscopic study in concussed patients.
Concussive head injury opens a temporary window of brain vulnerability due to the impairment of cellular energetic metabolism. As experimentally demonstrated, a second mild injury occurring during this period can lead to severe brain damage, a condition clinically described as the second impact syndrome. To corroborate the validity of proton magnetic resonance spectroscopy in monitoring cerebral metabolic changes following mild traumatic brain injury, apart from the magnetic field strength (1.5 or 3.0 T) and mode of acquisition, we undertook a multicentre prospective study in which a cohort of 40 athletes suffering from concussion and a group of 30 control healthy subjects were admitted. ⋯ Results indicate that N-acetylaspartate determination by proton magnetic resonance spectroscopy represents a non-invasive tool to accurately measure changes in cerebral energy metabolism occurring in mild traumatic brain injury. In particular, this metabolic evaluation may significantly improve, along with other clinical assessments, the management of athletes suffering from concussion. Further studies to verify the effects of a second concussive event occurring at different time points of the recovery curve of brain metabolism are needed.
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Biography Historical Article
Lockhart Clarke's contribution to the description of amyotrophic lateral sclerosis.
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. ⋯ 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.
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Comparative Study
Short echo time proton magnetic resonance spectroscopy in Alzheimer's disease: a longitudinal multiple time point study.
Short echo time localized proton magnetic resonance spectroscopy provides quantification of brain metabolites, including N-acetyl-aspartate, myo-inositol, creatine/phosphocreatine and choline-containing compounds, which may be useful biomarkers for monitoring Alzheimer's disease. We aimed to quantify the rate of metabolite change in Alzheimer's disease, to assess factors influencing changes and to investigate the potential for serial magnetic resonance spectroscopy as an Alzheimer's disease trial biomarker. A total of 42 patients and 22 controls each had up to six magnetic resonance spectroscopy examinations over a 2-year period, using a midline posterior cingulate single-voxel point resolved spectroscopy sequence (1.5 T; time to repetition = 2000 ms; echo time = 30 ms; 192 averages). ⋯ These results confirm that magnetic resonance spectroscopy can be used to quantify excess metabolite decline in Alzheimer's disease, which may provide a useful measure of disease progression. We found no evidence that age, disease severity or acetylcholinesterase inhibitor use influenced rate of decline, although numbers were small. The substantial variability in longitudinal measurements that drives sample size requirements is principally within-subject and technique related: technical developments to reduce this variability may make serial magnetic resonance spectroscopy a viable biomarker in clinical trials for Alzheimer's disease.
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Comparative Study
Clinical, functional and structural determinants of central pain in syringomyelia.
The present study aimed to investigate the relationship between neuropathic symptoms (i.e. pain and paraesthesia/dysaesthesia) and structural damage and functional alterations of spinal sensory tracts in patients with syringomyelia. Three-dimensional fibre tracking of the cervical spinal cord (at level C3-C4), electrophysiological assessments of nociceptive (laser-evoked potentials) and non-nociceptive (somatosensory-evoked potentials) pathways and quantitative sensory testing were carried out in 37 patients with syringomyelia, 27 with neuropathic pain and 21 controls. Four regions of the body (both hands and shoulders) were systematically examined with laser-evoked potentials and quantitative sensory testing, and somatosensory-evoked potentials were induced from both hands. ⋯ Patients with spontaneous pain only had more severe spinal cord damage, and the correlation between average daily pain intensity and fractional anisotropy of the full spinal cord was particularly strong in this subgroup of patients (Spearman's ρ = -0.93, P = 0.008). By contrast, patients with both spontaneous and evoked pain had not only less structural spinal cord damage, but also better preserved spinothalamic and lemniscal tracts on quantitative sensory testing and electrophysiological testing. These data showed, for the first time, a direct relationship between central neuropathic pain and objective markers of spinal cord damage, and confirmed the clinical relevance of 3D fibre tracking for the sensory assessment of patients with a spinal cord lesion.
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Comparative Study
Brain beta-amyloid measures and magnetic resonance imaging atrophy both predict time-to-progression from mild cognitive impairment to Alzheimer's disease.
Biomarkers of brain Aβ amyloid deposition can be measured either by cerebrospinal fluid Aβ42 or Pittsburgh compound B positron emission tomography imaging. Our objective was to evaluate the ability of Aβ load and neurodegenerative atrophy on magnetic resonance imaging to predict shorter time-to-progression from mild cognitive impairment to Alzheimer's dementia and to characterize the effect of these biomarkers on the risk of progression as they become increasingly abnormal. A total of 218 subjects with mild cognitive impairment were identified from the Alzheimer's Disease Neuroimaging Initiative. ⋯ Our results are consistent with a model of Alzheimer's disease in which Aβ deposition initiates the pathological cascade but is not the direct cause of cognitive impairment as evidenced by the fact that Aβ load severity is decoupled from risk of progression at high levels. In contrast, hippocampal atrophy indicates how far along the neurodegenerative path one is, and hence how close to progressing to dementia. Possible explanations for our finding that many subjects with mild cognitive impairment have intermediate levels of Aβ load include: (i) individual subjects may reach an Aβ load plateau at varying absolute levels; (ii) some subjects may be more biologically susceptible to Aβ than others; and (iii) subjects with mild cognitive impairment with intermediate levels of Aβ may represent individuals with Alzheimer's disease co-existent with other pathologies.