Stroke; a journal of cerebral circulation
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The effects of acute smoking on cerebral circulation are controversial. This study was designed (1) to clarify any differences between the effects of cigarette smoking and nicotine infusion and between the effects of single- and multiple-cigarette smoking on cerebral vessels and (2) to probe the mechanism(s) underlying the vascular responses. ⋯ Single-cigarette smoking had a significant biphasic effect on cerebral arteriolar tone. The vasodilation was attenuated by repeated smoking. The vasodilation is most likely an effect of nicotine, at least in part mediated via sympathetic activation, NO production, and K+ channel activation. The vasoconstriction is partially due to thromboxane A2 induced by cigarette smoke.
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Comparative Study
Vasopressin combined with epinephrine decreases cerebral perfusion compared with vasopressin alone during cardiopulmonary resuscitation in pigs.
It is unknown whether a combination of vasopressin and epinephrine may be superior to vasopressin alone by targeting both nonadrenergic and adrenergic receptors. ⋯ Comparison of vasopressin with vasopressin and epinephrine resulted in comparable left ventricular myocardial blood flow but significantly increased cerebral perfusion.
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In normal subjects, regional cerebral blood flow (rCBF) is greatly increased by neuronal activity, whereas the cerebral metabolic rate for O2 is increased only slightly. However, it is not clear what kinds of cerebral blood oxygenation and hemodynamic changes can be induced by language activities in language-relevant areas of poststroke aphasics. In the present study, we investigated the difference in the changes of cerebral blood oxygenation and hemodynamics in the left prefrontal cortex induced by language activities between normal subjects, poststroke nonaphasic patients, and nonfluent aphasic patients using near-infrared spectroscopy (NIRS). ⋯ The present results demonstrate a multiplicity of language-activated cerebral blood oxygenation and hemodynamic changes in the left prefrontal cortex in the nonaphasic and aphasic groups. The increase of deoxy-Hb with increases of oxy-Hb and total-Hb in the aphasics during language tasks suggests that the left prefrontal cortex of the aphasics utilizes more oxygen than the nonaphasics during language tasks. Finally, functional MRI, which images the activation area in the brain by detecting the reduced concentration of deoxy-Hb during neuronal activation, should be performed on the patients with cerebral dysfunction, giving special consideration to the possible multiplicity of the rCBF and cerebral oxygen metabolism responses to functional tasks.
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The alteration of regional cerebral blood flow (CBF) during and after hyperventilation was measured using positron emission tomography (PET) to determine the circulatory response induced by daily respiratory changes in the cerebral area under chronic hemodynamic stress. ⋯ Vasodilatation after the termination of hyperventilation in the normal areas induces a steal response in the cerebral area suffering from hemodynamic stress and may cause profound hypoperfusion in everyday situations. This phenomenon may be important to our understanding of the clinical symptoms and the natural course of chronic cerebral occlusive disease bearing hemodynamic stress.
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Although several factors have been identified that predict outcome after intracerebral hemorrhage (ICH), no previous study has investigated the impact of hydrocephalus. The purpose of this study was to determine whether the presence of hydrocephalus after ICH would predict mortality and functional outcome. ⋯ We conclude that hydrocephalus is an independent predictor of mortality after ICH.