Increased Intima Media Thickness and Atherosclerotic Plaques in the Carotid Artery as Risk Factors for Silent Brain Infarcts

Abstract

The presence of silent cerebral infarcts (SCIs), defined as lesions > or = 3 mm in diameter on magnetic resonance imaging (MRI), is considered a predictor of symptomatic cerebrovascular disorders (CVDs). Similarly, SCI-like lesions < 3 mm in diameter, lesions which often occur in the deep white matter and basal ganglia, also may be a risk factor for CVD. This study evaluated the relationships between SCI and SCI-like brain lesions, as defined by MRI, and 2 findings on extracranial carotid ultrasonography: intima-media thickness (IMT) and atherosclerotic plaque. We studied data obtained by carotid ultrasonography and cerebral MRI in 448 consecutive subjects without a history of stroke who had undergone comprehensive brain screening (mean age, 51.1 years). The subjects were classified into 4 groups according to the presence of increased (> or = 1 mm) IMT (I) and plaque (P). A total of 110 subjects demonstrated increased IMT (24.6%), and 54 subjects had increased plaque (12.1%). SCI-like lesions were found in 38 subjects (8.5%); single SCI, in 24 (5.4%); and multiple SCIs, in 51 (11.4%). Frequencies of SCI-like lesion(s), single SCI, and multiple SCIs were 6.1%, 12.2%, and 8.7%, respectively, in the I(-)P(-) group; 14.6%, 22.0%, and 13.4% in the I(+)P(-) group; 7.7%, 30.8%, and 26.9% in the I(-)P(+) group; and 17.9%, 39.3%, and 21.4% in the I(+)P(+) group. Multivariate analysis found that the presence of carotid plaques was significantly associated with (1) SCI-like lesion(s) and SCI (odds ratio [OR] = 2.20; 95% confidence interval [CI] = 1.17-4.34), (2) single and multiple SCI (OR = 2.33; 95% CI = 1.16-4.67), and (3) multiple SCIs (OR = 2.31; 95% CI = 1.06-5.03). However, the presence of increased carotid IMT was not significantly associated with any of these 3 categories. Coexistence of increased IMT and plaque was more strongly correlated with SCI than with either lesion alone.