Updated Thinking About Tias - What Is A Stroke: Stroke

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Updated thinking about TIAs

Transient ischemic attacks (TIAs) were once considered less dangerous than full-blown strokes because symptoms tend to disappear within 24 hours, and in most cases no permanent disability remains. However the thinking about TIAs has changed considerably, as evidenced by stroke guidelines updated in 2006 by the American Heart Association and the American Stroke Association.

The consensus now is that a TIA should be regarded, and treated, every bit as seriously as a full-blown stroke. TIAs usually last several minutes to hours and are caused by partial or temporary obstruction of an artery by the same pathological process that causes an ischemic stroke. For this reason, although the symptoms of a TIA may disappear, take it as a warning of an impending serious ischemic stroke.

But TIAs may also last longer, and in such cases the potential for brain damage is significant even if the TIA never progresses to a full-blown stroke. If the TIA lasts as long as 24 hours (at which point a TIA technically becomes a full-blown stroke) it is likely that it has caused some type of brain infarction, or tissue death. Advances in brain imaging have revealed that brain infarction may occur even in TIAs that end much earlier — and even if symptoms have abated. Here the infarcted tissue is in a "silent" area of the brain, one not currently being used, and so there are no symptoms. Or the damaged area may be adjacent to a part of the brain that produced symptoms following the initial injury, but then recovered, so that the symptoms disappeared.

What's more, as many as 10% of people who have a TIA will suffer a full-blown stroke within 90 days, with the greatest risk in the first week. That's why it's so important to seek medical help promptly: The fact that symptoms have disappeared does not mean that the danger is over.

Last updated:	September 05, 2008