Cerebrovascular diseases
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Cerebrovascular diseases · Jan 2001
Circadian variation of stroke onset in Hong Kong Chinese: a hospital-based study.
Circadian variation of onset of transient ischaemic attack (TIA) or stroke during four 6-hourly periods starting from midnight was studied in Hong Kong Chinese patients admitted to a regional hospital between October 1996 and July 1999. The onset was classifiable into one of the 6-hourly periods in 832 of 905 patients; patients with unclassifiable onset were more likely to have lacunar infarct and less likely to have intracerebral haemorrhage (ICH). ⋯ There was no difference in the circadian variation between patients with and without prior TIA or stroke. This hospital-based study revealed a significant circadian variation of onset in different types and subtypes of stroke.
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Cerebrovascular diseases · Jan 2001
Clinical TrialAcetylsalicylic acid and microembolic events detected by transcranial Doppler in symptomatic arterial stenoses.
In patients with symptomatic carotid artery stenosis, high-intensity transient signals detected by transcranial Doppler (TCD) have been related to particulate microemboli originating at the stenotic lesion. The occurrence of these microembolic events within the Doppler spectrum should be influenced by antithrombotic agents of proven efficacy in these patients mainly by reducing cerebral embolism. ⋯ In patients with symptomatic arterial stenosis, the absence of an ASA medication is associated with the occurrence of TCD-detected microembolic events, suggesting a relation between these events and ASA-sensitive microemboli from the stenotic lesion.
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Cerebrovascular diseases · Jan 2001
Clinically silent circulating microemboli in 20 patients with carotid or vertebral artery dissection.
Carotid and vertebral artery dissections are frequently complicated by cerebral embolism. Detection of clinically silent circulating microemboli by transcranial Doppler sonography (TCD) is now widely investigated in patients with carotid artery disease in the hope to identify patients at increased risk for stroke. ⋯ Microembolic signals occur in patients with high-grade stenosis or occlusion due to acute cervical artery dissection. Patients with microemboli seem to be at increased macroembolic risk, i.e. stroke recurrence, and may require close-meshed clinical follow-up and possibly stronger antithrombotic treatment.
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Cerebrovascular diseases · Jan 2001
Historical ArticlePerfusion thresholds in human cerebral ischemia: historical perspective and therapeutic implications.
After middle cerebral artery occlusion (MCAO) in the laboratory animal, the ischemic penumbra has been documented as a severely hypoperfused, functionally impaired, but still viable cortex which can regain its function and escape infarction if it is reperfused before a certain time has elapsed. The penumbra surrounds the ischemic core of already irreversibly damaged tissue, and is progressively recruited into the core with increasing MCAO duration. In the animal, the threshold of cerebral blood flow (CBF) below which neuronal function is impaired and the tissue is at risk of infarction is around 22 ml/100 g/min (approximately 40% of normal) in the awake or lightly anesthetized monkey, and around 30--35 ml/100 g/min in the cat and the rat. ⋯ In the remaining patients, there was evidence of early extensive damage or early spontaneous reperfusion, which would make them inappropriate candidates for neuroprotective therapy. Recent evidence from PET studies of relative perfusion performed within 3 h of onset suggests that early thrombolysis indeed saves the tissue with CBF below a critical threshold of 12 ml/ 100 g/min, with a correlation between the volume of such tissue escaping infarction and subsequent neurological recovery. Thus, mapping the penumbra in the individual patient with physiologic imaging should allow to formulate a pathophysiological diagnosis, and in turn to design a rational management of the stroke patient and to increase the sensitivity of drug trials by appropriate patient selection.