Stroke; a journal of cerebral circulation
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Free radical scavengers enhance neuronal survival in some models of transient forebrain ischemia. Recent experiments have suggested that N-acetylcysteine prevents cellular injury after a reperfusion injury. No information is available regarding the neuroprotective potential of the free radical scavenger N-acetylcysteine after transient forebrain ischemia. In this study we evaluated the potential of N-acetylcysteine to improve hippocampal neuronal survival after transient forebrain ischemia in the rat. ⋯ N-Acetylcysteine partially improved neuronal survival when administered before or after ischemia following transient cerebral ischemia (mean arterial blood pressure, 45 mm Hg) but not with a more severe ischemic insult of 10 minutes of transient cerebral ischemia with a mean arterial blood pressure of 30 mm Hg.
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Although crossed cerebellar diaschisis is well recognized after stroke, there is controversy concerning its clinical correlations and serial changes, and little is known about its prognostic value. ⋯ This study shows that crossed cerebellar diaschisis is a functional phenomenon that correlates with both stroke severity and infarct hypoperfusion volume and persists despite neurological recovery. Although acute-stage crossed cerebellar diaschisis has no prognostic value independent of acute-stage hypoperfusion volume, it might indicate the proportion of nutritional to nonnutritional perfusion at the infarct site and hence be useful in the evaluation of reperfusion therapies in the acute stage.
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Autoregulation of cerebral blood flow is easily disrupted, and loss of this normal physiological reflex may worsen the neurological outcome for patients undergoing intensive care. We studied the response of cerebral blood flow velocity to changes in mean arterial blood pressure. ⋯ Computerized coherent averaging of the cerebral blood flow velocity response to spontaneous blood pressure transients offers a promising new method for noninvasive bedside assessment of autoregulation in patients undergoing intensive care. The time course for autoregulation, when present, is in agreement with that reported in adults.
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Comparative Study
Assessment of cerebral vasomotor reactivity by transcranial Doppler ultrasound and breath-holding. A comparison with acetazolamide as vasodilatory stimulus.
Evaluating cerebrovascular vasomotor reactivity seems to be of prognostic relevance for patients with occlusive internal carotid artery disease. To evaluate its clinical usefulness, the recently introduced breath-holding maneuver as a carbon dioxide-dependent vasodilatory stimulus was compared with the acetazolamide challenge by means of transcranial Doppler ultrasound and stable xenon-enhanced computed tomography. ⋯ The assessment of vasomotor reactivity by transcranial Doppler ultrasound correlates with cerebral blood flow changes even when different vasodilatory stimuli are used. In cooperative patients the breath-holding maneuver as vasodilatory stimulus seems clinically useful for a first estimation of cerebral vasomotor reactivity.
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Although stroke mortality has been declining in the United States for decades, recent trends in stroke incidence based on national data have not been described. We used Medicare hospitalization data to estimate national trends in the incidence of stroke among Americans aged 70 years or older, and we provide evidence of the validity of the estimate. ⋯ Stroke incidence declined steadily from 1985 to 1989 and then increased slightly to 1991. Several postulated potential sources of bias were investigated and found to be unlikely to account for the incidence decline, although some may have contributed to the subsequent incidence increase.