Very small cerebrovascular lesions warrant concern

By Eleanor McDermid, Senior medwireNews Reporter

Subclinical cerebrovascular smaller than 3 mm are associated with an increased risk of stroke and stroke mortality, report researchers.

These very small lesions were associated with a 3.47-fold increased risk of stroke among stroke-free participants of the Atherosclerosis Risk in Communities (ARIC) study, aged between 50 and 73 years. The risk increase was equivalent to that associated with larger lesions, which was 1.94-fold.

But the largest risk increase was found in people who had lesions in both size categories, at 8.59-fold, report B Gwen Windham (University of Mississippi Medical Center, Jackson, USA) and co-researchers.

“Although clinicians and researchers tend to dismiss very small cerebral lesions, our findings provide evidence that this practice could warrant reconsideration”, the team writes in the Annals of Internal Medicine.

The smallest lesions also increased participants’ risk of stroke mortality, at a 3.05-fold increase, but did not significantly increase the risk of all-cause mortality. Larger lesions had the opposite effect, conferring a nonsignificant 1.87-fold increase in stroke mortality but a significant 1.90-fold increase in all-cause mortality.

However, the researchers note that the confidence intervals for the effect of smaller and larger lesions overlapped, so the effect sizes may prove to be similar in a larger study. The team used data from 1884 ARIC participants who had baseline magnetic resonance imaging data. During an average follow-up of 14.5 years, these participants had 157 strokes, with 50 dying of stroke and 576 of other causes.

As with stroke risk, the presence of lesions in both size categories had the largest effect on stroke mortality, raising the risk of stroke and all-cause mortality a significant 6.97-fold and 1.89-fold, respectively.

“Our robust associations between lesions smaller than 3 mm and stroke and stroke-related mortality support the hypothesis that very small lesions are pathologic and clinically important”, say Windham et al.

The team also found that stroke and stroke mortality risk rose with increasing number of lesions identified, supporting a causal association.

“Future studies are needed to examine the effect of preventive treatment in asymptomatic persons, including those with even the smallest abnormalities”, say the researchers.

Hypertension was the most important predictor of lesions, being associated with around a doubled risk of having small or large lesions in isolation and a sixfold increased risk of having both simultaneously. Other established stroke risk factors, including older age, Black ethnicity and current smoking were also associated with lesions, while increased education was protective.

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