[HTML][HTML] Epidemiology of stroke

CP Warlow - The Lancet, 1998 - thelancet.com
CP Warlow
The Lancet, 1998thelancet.com
A stroke is a clinically defined syndrome of rapidly developing symptoms or signs of focal
loss of cerebral function with no apparent cause other than that of vascular origin, but the
loss of function can at times be global (applied to patients in deep coma and to those with
subarachnoid haemorhage). Symptoms last more than 24 h or lead to death/The syndrome
varies in severity from recovery in a day, through incomplete recovery, to severe disability, to
death. Whether it is for clinical or epidemiological purposes, the definition has not changed …
A stroke is a clinically defined syndrome of rapidly developing symptoms or signs of focal loss of cerebral function with no apparent cause other than that of vascular origin, but the loss of function can at times be global (applied to patients in deep coma and to those with subarachnoid haemorhage). Symptoms last more than 24 h or lead to death/The syndrome varies in severity from recovery in a day, through incomplete recovery, to severe disability, to death. Whether it is for clinical or epidemiological purposes, the definition has not changed for over 20 years, and there is no reason to change it in the foreseeable future. If the definition depended heavily on technology, such as brain imaging, it would be useless to epidemiologists because the technology may be unavailable in many parts of the world where stroke is a major burden. Even if the technology were available, it may evolve rapidly, so that accurate comparison of the burden of stroke in different places and at different times becomes impossible. Like other clinical syndromes, such as pneumonia or meningitis, stroke is highly heterogeneous, and its numerous causes influence the prognosis, the type of treatment required, and the preventive strategies. For the definition of many of the types and subtypes of stroke, technology is certainly necessary (see page 6).
The epidemiology of" all strokes" lumped together is one matter, whereas the epidemiology of the various stroke types and subtypes may be quite another. Ideally, all require study. But, until the quite recent past, most epidemiological studies and clinical trials were based mainly on all strokes, sometimes with separate analysis of the rather distinct clinical syndrome of spontaneous subarachnoid haemorrhage. Even nowadays the most fundamental classification of strokes as primary intracerebral haemorrhage (PICH) or ischaemic stroke may not be practicable because computed tomographic scanning is unavailable. Moreover, even where computed tomography is available, it may be difficult to get scans on all the patients, and quickly enough to exclude PICH, especially in community-based studies.
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