World Stroke Day Underlines Risk from "Silent" Strokes

Susan Jeffrey

October 29, 2008

October 29, 2008 — October 29 is World Stroke Day, and the theme for this year is "little strokes, big trouble," underlining the importance of the subtle neurological and neuropsychological deficits associated with subclinical strokes.

World Stroke Day arose from the World Stroke Congress in Vancouver in 2004, when a working group was organized to develop a global agenda on stroke. In 2006, this agenda was articulated in the World Stroke Proclamation, launched in Cape Town, South Africa, at that year's congress.

This year, World Stroke Day emphasizes 1 of the items on that stroke agenda, subclinical strokes, which, the document notes, "occur 5 times as often as clinical strokes and may affect thinking, mood, and behavior."

Dr. Vladimir Hachinski (Source: University of Western Ontario)

At the recent 6th World Stroke Congress, in Vienna, Austria, Vladimir Hachinksi, MD, DSc, from the University of Western Ontario, and editor-in-chief of the American Heart Association journal Stroke, pointed out that subclinical strokes tend to affect executive function and the ability to plan and to abstract and have been associated with late-life depression.

"We have chosen this theme because this is not well-known," Dr. Hachinski told a press conference at the congress in Vienna. "It's beginning to emerge among those of us who specialize in treating stroke, and it's just beginning to be publicized among physicians, and certainly the public is not aware."

These so-called "silent" strokes are by far the most common type of stroke, he wrote in a recent editorial. Results of 3 longitudinal studies, for example, showed that in 1998, 770,000 clinical strokes occurred in the United States, along with 9 million silent infarcts and about 2 million silent hemorrhages. A recent paper from the Framingham Study showed that among stroke-free individuals with an average age of 63 years who were living in the community, 1 in 10 had already had a clinically silent stroke.

"Silent" Strokes Not Silent

However, that they are "silent" is a misnomer, Dr. Hachinski writes. "If ignored, little strokes could spell big trouble. One subclinical stroke is associated with increased chance of having others and of experiencing a clinical stroke and/or dementia." In addition, the combination of subclinical stroke and subclinical Alzheimer's lesions may present a background for the association of stroke and dementia, he added, "given that the lifetime risk of either or both is 1 in 3."

"From a practical viewpoint, it becomes important to recognize that some of the symptoms that elderly individuals manifest, such as changes in judgment, in intellectual ability, and personality change, particularly depression, may be associated with subclinical strokes and white-matter changes," Dr. Hachinski writes.

At the meeting, Dr. Hachinski emphasized that changes — in personality, in the ability to organize oneself to do multiple tasks, in mood — should not be simply attributed to old age but should signal the need for screening and more vigorous risk-factor modification.

"Most people would rather die from a stroke than live and linger with a faulty brain, and I think the important message here is that we should intervene and prevent both little and big strokes, before the little strokes cause big trouble," he said.

Finally, Dr. Hachinski also called for more research into the difference between clinical and subclinical strokes. "It may not simply be a question of infarct size, but of mechanisms and actions on different brain substrates," he writes. For example, experimentally, the presence of amyloid in the brain can magnify the size and inflammatory response of cerebral infarction.

Stroke. 2008;39:2407-2408. Abstract

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