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    ABSTRACT: This study explores the magnetostatic properties of the Alzheimer's disease brain using a recently proposed, magnetic resonance imaging, postprocessed contrast mechanism. Quantitative susceptibility mapping (QSM) has the potential to monitor in vivo iron levels by reconstructing magnetic susceptibility sources from field perturbations. However, with phase data acquired at a single head orientation, the technique relies on several theoretical approximations and requires fast-evolving regularisation strategies. In this context, the present study describes a complete methodological framework for magnetic susceptibility measurements with a review of its theoretical foundations. The regional and whole-brain cross-sectional comparisons between Alzheimer's disease subjects and matched controls indicate that there may be significant magnetic susceptibility differences for deep brain nuclei - particularly the putamen - as well as for posterior grey and white matter regions. The methodology and findings described suggest that the QSM method is ready for larger-scale clinical studies.
    PLoS ONE 11/2013; 8(11):e81093. DOI:10.1371/journal.pone.0081093
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    ABSTRACT: Purpose To analyse mortality for spontaneous intracerebral haemorrhage (ICH), myasthenia gravis (MG) and Guillain–Barré syndrome (GBS) from 1996 to 2009 in UK intensive care units (ICUs). Methods We used the Intensive Care National Audit & Research Centre (ICNARC) database. We identified specialised neurosciences critical care units (NCCUs) (n = 16), general ICUs with full neurological support (n = 48) and general ICUs with limited neurological support (n = 138) and undertook descriptive analyses for each condition. Poisson regression was used to identify trends in admission rates, median regression to identify trends in lengths of stay (LOS), and logistic regression (Wald test) to analyse interaction between unit type and time period; odds ratios were calculated for hospital mortality associated with unit types. Results For ICH (n = 10,313 cases), overall ICU mortality was 42.4 %, and acute hospital mortality 62.1 %. In NCCU, LOS was longer, but mortality lower, and over time, mortality from ICH decreased faster. For MG (n = 1,064 cases) and GBS (n = 1,906 cases), overall mortality was relatively high (MG: 8.7 % ICU mortality and 22 % acute hospital mortality; GBS: 7.7 and 16.7 %, respectively); overall mortality did not decrease over time. Conclusions This first large-scale analysis of outcomes in acute neurological disease in the UK demonstrates real-life mortality higher than published series. NCCU care is associated with increased survival in conditions requiring highly specialised intensive care techniques, but high-quality step-down care is pivotal in others. Strategies that truly improve outcomes must integrate emergency department management, ICU admission criteria, NCCU treatment, high-quality step-down care and neurorehabilitation.
    Intensive Care Medicine 08/2013; 39(8). DOI:10.1007/s00134-013-2960-6
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    ABSTRACT: We review the latest literature on the neuropharmacological treatments for acquired nystagmus. Nystagmus may have a significantly impact on health, yet there is little scientific evidence on which to make firm recommendations for treatment. Acquired pendular nystagmus may respond to gabapentin or memantine; downbeat and upbeat nystagmus to aminopyridines; and periodic alternating nystagmus to baclofen. To improve treatment we need multi-centre, randomised controlled trials using standardised techniques in reporting objective outcomes, with good follow-up duration and careful reporting of side effects.
    Practical Neurology 06/2012; 12(3):147-53. DOI:10.1136/practneurol-2011-000181
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    ABSTRACT: Primary progressive aphasia (PPA) has been proposed to comprise 3 discrete clinical subtypes: semantic, agrammatic/nonfluent, and logopenic. Recent consensus recommendations suggest a diagnostic framework based primarily on clinical and neuropsychological findings to classify these variants. Our objective was to evaluate the extent to which patients with PPA would conform to the proposed tripartite system and whether the clustering pattern of elements of the linguistic profile suggests discrete clinical syndromes. A total of 46 patients with PPA were prospectively recruited to the Cambridge Longitudinal Study of PPA. Sufficient data were collected to assess all consensus-proposed diagnostic domains. By comparing patients' performances against those of 30 age- and education-matched healthy volunteers, z scores were calculated, and values of 1.5 SDs outside control participants' means were considered abnormal. Raw test scores were used to undertake a principal factor analysis to identify the clustering pattern of individual measures. Of the patients, 28.3%, 26.1%, and 4.3% fitted semantic, nonfluent/agrammatic, and logopenic categories respectively, and 41.3% did not fulfill the diagnostic recommendations for any of the 3 proposed variants. There was no significant between-group difference in age, education, or disease duration. Furthermore, the outcome of the factor analysis was in keeping with discrete semantic and nonfluent/agrammatic syndromes but did not support a logopenic variant. Taken together, the results of this prospective data-driven study suggest that although a substantial proportion of patients with PPA have neither the semantic nor the nonfluent variants, they do not necessarily conform to a discrete logopenic variant.
    Neurology 05/2012; 78(21):1670-7. DOI:10.1212/WNL.0b013e3182574f79
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    ABSTRACT: Alemtuzumab is a lymphocyte depleting monoclonal antibody that has demonstrated superior efficacy over interferon β-1a for relapsing-remitting multiple sclerosis (MS), and is currently under investigation in phase 3 trials. One unresolved issue is the duration and significance of the lymphopenia induced. The long term effects on lymphocyte reconstitution of a single course, and the consequences that this has on disability, morbidity, mortality and autoimmunity, were examined. The lymphocyte reconstitution (n=36; 384 person years) and crude safety data (n=37; 447 person years) are reported for the first patients with progressive MS to receive alemtuzumab (1991-1997). Reconstitution time was expressed as a geometric mean or, when a non-negligible number of individuals failed to recover, as a median using survival analysis. Geometric mean recovery time (GMRT) of total lymphocyte counts to the lower limit of the normal range (LLN; ≥1.0×10(9) cells/l) was 12.7 months (95% CI 8.8 to 18.2 months). For B cells, GMRT to LLN (≥0.1×10(9)/l) was 7.1 months (95% CI 5.3 to 9.5); median recovery times for CD8 (LLN ≥0.2×10(9) cells/l) and CD4 lymphocytes (LLN ≥0.4×10(9) cells/l) were 20 months and 35 months, respectively. However, CD8 and CD4 counts recovered to baseline levels in only 30% and 21% of patients, respectively. No infective safety concerns arose during 447 person years of follow-up. Lymphocyte counts recovered to LLN after a single course of alemtuzumab in approximately 8 months (B cells) and 3 years (T cell subsets), but usually did not recover to baseline values. However, this long lasting lymphopenia in patients with a previously normal immune system was not associated with an increased risk of serious opportunistic infection.
    Journal of neurology, neurosurgery, and psychiatry 11/2011; 83(3):298-304. DOI:10.1136/jnnp-2011-300826
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    ABSTRACT: Multiple sclerosis (MS) is an inflammatory neurodegenerative disease with complex aetiology. A haplotype within the major histocompatibility region is the major risk factor for MS, but despite clear evidence for a genetic component additional risk variants were not identified until the recent advent of genome-wide association studies (GWAS). At present, 10 GWAS have been conducted in MS, and together with follow-up studies these have confirmed 16 loci with genome-wide significance. Many of these common risk variants are located at or near genes with central immunological functions and the majority are associated with other autoimmune diseases. However, evidence from pathway analyses on more modestly associated variants also supports the involvement of neurological genes. Although the mechanisms by which the associated variants exert their effects are still poorly understood, some have been shown to correlate with expression of nearby genes. Further studies are required to define the functionally relevant variants in the identified regions and to investigate their effects at the molecular and cellular level. Finally, many genetic risk variants for MS remain to be identified. In order to expose some of the loci with more modest effects, a GWAS in nearly 10,000 MS patients has recently been completed.
    Briefings in functional genomics 02/2011; 10(2):61-70. DOI:10.1093/bfgp/elr004
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    Journal of Neurology 10/2010; 258(4):686-8. DOI:10.1007/s00415-010-5788-9
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    ABSTRACT: Not only finger tapping speed, but also tapping regularity can be impaired after stroke, contributing to reduced dexterity. The neural substrates of impaired tapping regularity after stroke are unknown. Previous work suggests damage to the dorsal premotor cortex (PMd) and prefrontal cortex (PFCx) affects externally-cued hand movement. We tested the hypothesis that these two areas are involved in impaired post-stroke tapping regularity. In 19 right-handed patients (15 men/4 women; age 45-80 years; purely subcortical in 16) partially to fully recovered from hemiparetic stroke, tri-axial accelerometric quantitative assessment of tapping regularity and BOLD fMRI were obtained during fixed-rate auditory-cued index-thumb tapping, in a single session 10-230 days after stroke. A strong random-effect correlation between tapping regularity index and fMRI signal was found in contralesional PMd such that the worse the regularity the stronger the activation. A significant correlation in the opposite direction was also present within contralesional PFCx. Both correlations were maintained if maximal index tapping speed, degree of paresis and time since stroke were added as potential confounds. Thus, the contralesional PMd and PFCx appear to be involved in the impaired ability of stroke patients to fingertap in pace with external cues. The findings for PMd are consistent with repetitive TMS investigations in stroke suggesting a role for this area in affected-hand movement timing. The inverse relationship with tapping regularity observed for the PFCx and the PMd suggests these two anatomically-connected areas negatively co-operate. These findings have implications for understanding the disruption and reorganization of the motor systems after stroke.
    NeuroImage 12/2009; 50(1):1-6. DOI:10.1016/j.neuroimage.2009.12.012
  • Neurology 12/2009; 73(23):2039-40. DOI:10.1212/WNL.0b013e3181c55e9b
  • Practical Neurology 05/2009; 9(2):118-26. DOI:10.1136/jnnp.2008.171132
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Top publications last week

Nature Genetics 09/2013; 45(11). DOI:10.1038/ng.2770
Journal of neurology, neurosurgery, and psychiatry 11/2013; 84(11):e2. DOI:10.1136/jnnp-2013-306573.54
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