[Clinical aspects of silent cerebral infarction--MRI findings and its distribution]

High-field MR scans have often showed patchy incidental findings especially in the elderly. We examined 91 patients, without episodes of cerebrovascular disorders previously, who had silent cerebral lesions noted by the 1.5 tesla superconductive system T2 weighted magnetic resonance imaging. They were divided into three subtypes by the localization of foci. The 23 subjects (25%) showed confined lesions to thalamus and/or internal capsule and/or basal ganglia (the basal ganglia type). The 39 subjects (43%) had lesions predominantly in cerebral cortex and/or subcortical white matter and/or cerebellum (the diffuse subcortical type). Finally, the 29 subjects (32%) had both features of above-mentioned two groups (the mixed type). These subtypes were correlated with age, sex and some of the other risk factors, such as systolic blood pressure, diastolic blood pressure, serum total cholesterol and uric acid, for stroke. The mean age of the basal ganglia type was significantly younger than that of the diffuse subcortical type (p less than 0.001) and than that of the mixed type (p less than 0.001). The diffuse subcortical type consisted of 11 men and 28 women. In the mixed type, it was composed of 21 men and 8 women. These two subtypes had the significant sex differences (the diffuse subcortical type, p less than 0.05 and the mixed type, p less than 0.025). Systolic and diastolic pressures of the basal ganglia type were lower than those of the diffuse subcortical type (systolic, p less than 0.001 and diastolic, p less than 0.025) and than those of the mixed type (systolic, p less than 0.001 and diastolic, p less than 0.025).(ABSTRACT TRUNCATED AT 250 WORDS)