ABSTRACT
The incidence, topology, and risks of clinically silent cerebral ischemia were studied in a series of stroke patients entering the Klosterneuburg Stroke Data Bank, a prospective single-center stroke registry in Lower Austria that was established in 1988. Among 462 first-ever stroke patients, 340 (74%) showed only one lesion, which corresponded to the syndrome of their presenting stroke. However, 57 (12%) patients either showed an additional or a noncorresponding lesion, or both. Most silent strokes in our study were singular, deep, small infarctions (52%) by their location known to be asymptomatic, whereas eight additional cases with cortical involvement and one deep, large infarction could have been either unreported or largely asymptomatic. No significant difference was found for age, sex, or the hemispheric side of any lesion type (deep, small, or cortical), nor for the etiology of the presenting stroke. Silent cerebral infarctions were not associated with known additional or disproportional risk factors. The differing incidences and risks of silent stroke known from previous studies probably are not only due to the differing accuracy of neuroimaging techniques to detect small ischemic lesions but also to differences in awareness of unspecific and transient symptoms. Therefore, a continuum between clinically silent infarcts, unspecific symptoms, and short-lasting transient ischemia must be acknowledged.
