Stroke; a journal of cerebral circulation
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Mx is an index of cerebrovascular autoregulation. It is calculated as the correlation coefficient between slow spontaneous fluctuations of cerebral perfusion pressure (cerebral perfusion pressure=arterial blood pressure-intracranial pressure) and cerebral blood flow velocity. Mx can be estimated noninvasively (nMxa) with the use of a finger plethysmograph arterial blood pressure measurement instead of an invasive cerebral perfusion pressure measurement. We investigated the agreement between nMxa and the previously validated index Mx. ⋯ The noninvasive index of autoregulation nMxa correlates with Mx and is sensitive enough to detect autoregulation asymmetry. nMxa is proposed as a practical tool to assess cerebral autoregulation in patients who do not require invasive monitoring.
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Statistical sciences have recently made advancements that allow improved precision or reduced sample size in clinical research studies. Herein, we review 4 of the more promising: (1) improvements in approaches for dose selection trials, (2) approaches for sample size adjustment, (3) selection of study end point and associated statistical methods, and (4) frequentist versus Bayesian statistical methods. Whereas each of these holds the opportunity for more efficient trials, each are associated with the need for more stringent assumptions or increased complexity in the interpretation of results. The opportunities for these promising approaches, and their associated "costs," are reviewed.
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Brain inflammation holds promise as a therapeutic target in subacute stages of ischemic stroke. At the cellular level, postischemic inflammation is dominated by cells of the innate immune system with resident microglia/brain macrophages and blood-derived monocytes/macrophages being the most important cell types involved. ⋯ USPIO-laden macrophages cause typical signal changes in MRI of infarcted brain parenchyma, which has been demonstrated in studies of both experimental ischemia and human stroke. USPIO-enhanced MRI may therefore represent an important tool to address the role of macrophages for ischemic lesion development both in basic science and clinical studies.
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Induced hypothermia is one of the most promising neuroprotective therapies. Technological limitations and homeostatic mechanisms that maintain core body temperature have impeded the clinical use of hypothermia. Recent advances in intravascular cooling catheters and successful trials of hypothermia for cardiac arrest and neonatal asphyxia renewed interest in hypothermia for stroke, resulting in early phase clinical trials and plans for further development. This review elaborates on the clinical implications of hypothermia research in stroke and technical and logistical issues associated with the application of hypothermia.