SKYAID
New
Mission
Overview
Details
Medical
Watch
Heart attack
Stroke
World health
Emergency
Cost effective
Media
- Site Map
SKYCAR
Details
Overview
VTOL
Airline
Military
Transportation
Images
- Site
Map
Search
Translate
8
languages
( Medical Post ) Kylie Taggart; 03-13-2001 added 06/05/01
FORT LAUDERDALE, FLA. -- The U.S. has an "epidemic" of undetected brain infarctions on its hands, researchers said here. The so-called "silent strokes" are associated with an increased risk for symptomatic ischemic stroke.
"Our current estimates are that in 1998, nine million Americans had an ischemic silent stroke. We also estimate that in 1998, about 1.9 million Americans had a silent hemorrhagic stroke," said Dr. Megan Leary, a clinical instructor at the University of California at Los Angeles stroke center.
Since one person can have numerous silent strokes, Dr. Leary estimated there are a total of 17 million ischemic silent strokes a year in the U.S., and five million silent hemorrhagic strokes. There are about 750,000 symptomatic strokes yearly in the U.S., Dr. Leary said. The estimates were based on data collected from population studies and U.S. census data.
"Silent stroke is at epidemic proportions in our country and greater resources and research should be allocated to stroke prevention and treatment," she said.
Prior brain infarcts are present on the MRIs of many elderly people who show up at hospital with their first ischemic stroke. They are often also present in the MRIs of healthy elderly people.
Dr. Leary said the term "silent stroke" is a misnomer, since they are associated with vascular dementia, mood disorders and other cognitive impairments. They also put people at risk for future symptomatic strokes.
The latest results from the multicentre Cardiovascular Health Study were presented here also, and showed that 7% of 923 people with silent strokes had a clinically symptomatic stroke during the four-year trial.
The 67 patients mostly suffered silent infarcts in the subcortical region of the brain. Of those with subcortical infarcts, 16% had a subsequent hemorrhagic stroke and 84% had an ischemic stroke. These results suggest patients with silent strokes are at risk for both hemorrhagic and ischemic symptomatic strokes.
The risk factors for silent strokes are similar to symptomatic strokes: hypertension and age. Whether there is an increased risk of silent strokes for women, diabetics or smokers is not clear.
Shedding even more light on silent stroke was a study presented by Dutch researchers. The Rotterdam Scan Study assessed cardiovascular risk factors and presence of silent stroke in 1,077 participants age 60 to 90. All participants were interviewed, received a physical examination and an MRI of the brain. Pulse pressure, a measurement of large artery function, was calculated.
Age was the strongest predictor of a silent infarct on the MRI. "The prevalence of these silent lesions increased from 8% in the youngest group in our cohort to 35% in the age group of 85 to 90," said Dr. Sarah Vermeer, a principal investigator of the study and a research physician at Erasmus Medical Center in Rotterdam.
"We did not see any association with diabetes or smoking, but we did see one with pulse pressure, or large artery thickening," she said.
Another finding was that women were more likely to have silent strokes than men. Dr. Vermeer said this is probably not due to any pathophysiological differences in women's brains, but rather because women don't report strokes as frequently as men.
"If you experience some speaking problems for an hour or so and it is OK after that, then a lot of people think, 'I'll live,' especially if you don't have a partner who gets scared to death and says 'You' ve got to go to a physician with that,' " Dr. Vermeer said.
The only way to treat silent strokes is to control the risk factors for a symptomatic stroke.
"Right now stroke prevention treatments are recommended but patients aren't compliant. I think telling them about silent strokes gives us some leverage to convince them that compliance is important," Dr. Leary said.