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Percent of Each Stroke Type
Preceded by TIA
Every year approximately 50,000 people in the
United States experience transient ischemic attacks (TIAs)
and about a third of them will develop a stroke [Feinberg
WM, et al, 1994.]
TIAs have bee vigorously defined. According
to the Ad Hoc Committee on Guidelines for the Management of
Transient Ischemic Attacks of the Stroke Council of the American
Heart Association, TIAs are "temporary focal brain or
retinal deficits caused by vascular disease that clear completely
in less than 24 hours." The Committee notes, however,
that the 24-hour limit is arbitrary and that most TIAs are
much shorter, the majority clearing within 1 hour.
In the Cooperative Study of Transient Ischemic
Attacks, the median duration of carotid distribution TIAs
was 14 minutes and that of vertebrobasilar TIAs was 8 minutes
[Dyken ML, et all. JAMA. 1977;237:882.]
TIAs have diverse causes. In older patients
and those with cerebrovascular risk factors, atheroscelerosis
of the arteries supplying the brain is the most frequent cause.
TIAs are most common in patients with large-artery atherothrombotic
disease, with embolism being the second most likely type of
stroke to be preceded by a TIA. The attacks can occur
days, weeks, or even months before a major stroke.
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Stroke Education
