Silent brain infarctions in patients with first-ever stroke. A community-based study in Umbria, Italy

The relative frequency of computed tomographic evidence of old cerebral infarctions without prior history of stroke, and their effect on short- and long-term outcome of patients with first-ever ischemic stroke, are currently unknown. Silent infarctions may relate to specific risk factors and may influence the rate of survival free of handicap.

We studied the prevalence of such lesions in patients registered with SEPIVAC, a community-based survey of stroke incidence and outcome in the Sixth Local Health Unit of Umbria, Italy. Of 375 first-ever strokes, 209 patients with cerebral infarction (computed tomogram done within 30 days after the stroke) were included in this study. Computed tomograms were reviewed blindly, and cases were classified as having a single lesion or multiple lesions; in the latter case, it was assumed that at least one silent brain infarction was present. The two groups were compared in terms of risk factors and outcome. To avoid a selection bias, these patients were also compared with 68 patients who were not submitted to computed tomography but were judged on clinical grounds to have a > 90% probability of having suffered a cerebral infarction.

Risk factors and outcome did not differ between patients without and with a computed tomogram. In the latter group, 80 patients (38.3%; 95% confidence interval, 31.7%-44.9%) had silent brain infarction. Male sex (odds ratio, 1.84; 95% confidence interval, 1-3.4), ischemic changes on an electrocardiogram (odds ratio, 2.5; 95% confidence interval, 1.3-4.9), and--in the multivariate analysis--hypertension (odds ratio, 1.46; 95% confidence interval, 1.1-2) were significantly more frequent in these patients. Outcome at 1, 6, and 12 months was not influenced by the presence of silent infarctions.

This community-based study shows that silent brain infarctions in patients with first-ever stroke are not significantly related to risk factors commonly described in hospital-based series (atrial fibrillation, transient ischemic attack, etc.); rather, silent infarctions seem to be a marker of widespread vascular disease.