People who have silent strokes, without symptoms, run an increased risk of later having a major stroke, according to a new study.
The Asymptomatic Carotid Atherosclerosis Study (ACAS) has been looking at whether clearing the carotid arteries serving the brain from plaque is helpful in preventing stroke. This turns out to be so, and the study has also yielded up a mass of other data on stroke risk and prevention.

One major finding, reported by lead researchers at Wake Forest University, is that having a silent stroke leads to an eight to 12 per cent risk in having a major stroke in the next year. In a silent stroke, an artery in the brain gets blocked, but there are no symptoms. But the silent stroke does show up on a brain scan, which is how it became apparent in this study.

People can have silent strokes with no other risk factors. But the study also showed that a combination of diabetes and high cholesterol did raise the risk of silent stroke. The researchers say that the new findings should also place more emphasis on transient ischemic attacks (TIAs). These are a bit like silent strokes, only they do have symptoms - such as temporary limb weakness or momentary loss of speech. These symptoms usually resolve, but the TIA is a warning sign and, rather than wait for another one to occur, preventive measures should be put into place as soon as possible.