Risk factors for silent cerebral infarcts in subcortical white matter and basal ganglia

Background and Purpose - The purpose of this study was to clarify whether the relevant risk factors for silent cerebral infarcts (SCIs) in subcortical white matter (WM) are different from those in the basal ganglia (BG). Methods - Subjects of this study were 219 adults without a history of stroke or transient ischemic attack and without any abnormality on a neurological examination who consecutively visited the neurology service in our hospital between January 1994 and November 1997 requesting medical evaluation for possible cerebrovascular diseases. Subjects included 141 men and 78 women ranging in age from 33 to 83 years (mean±SD, 63.2±9.5 years). We performed brain MRIs and cervical/cranial MR angiographies on all subjects. In this study, SCI was defined as a focal lesion ≥5 mm in diameter that was prolonged on both T2-weighted and proton density images. Results - SCIs in the WM and/or BG were detected in 88 (40.2%) of the 219 subjects. No SCI ≥15 mm was observed in this series. Fifty of the subjects had SCIs only in the WM, 32 subjects had SCIs in both the WM and BG, and 6 subjects had SCIs only in the BG. Thus, 82 (93.2%) of 88 subjects with SCIs had lesions in the WM. Most subjects with SCIs in the BG also had SCIs in the WM. Multiple logistic regression analyses revealed that age, female sex, and hypertension were significant and independent predictors of SCIs in the WM, and that age, a history of ischemic heart disease, and carotid artery stenosis were significant and independent predictors of SCIs in the BG. Conclusions - The present study indicated that the relevant risk factors for SCIs in the WM and those for SCI in the BG were different. Our results suggest that SCIs are prone to first appear in the WM in association with aging and hypertension, and the additional appearance of SCIs in the BG predicts a progression of generalized atherosclerosis that is manifested in the carotid and coronary arteries.