No abstract

Background: The investigation of ischemic stroke etiology is commonly limited to the heart and extracranial vessels. However, the diagnosis of intracranial stenosis may carry important therapeutic implications. We aimed to determine the prevalence of intracranial stenosis and compare the predictors of intracranial and extracranial stenosis in patients with ischemic stroke. Methods: Consecutive patients admitted to a university-based outpatient stroke clinic were submitted to 64-slice CT angiography (CTA) of the intracranial and extracranial brain vessels. Clinical, demographic and laboratory characteristics were compared between patients with or without a critical (>70%) intracranial or extracranial arterial stenosis. Ankle-brachial index (ABI) was measured to quantify peripheral arterial disease, defined by a low ABI (<=0.9). Multivariable logistic regression analysis was performed including variables with a possible (P<0.1) association in univarible analyses, searching for predictors of intracranial and extracranial stenosis. Results: One hundred-five patients were studied, mean age 59 +/- 14 years, 55% female. Intracranial stenosis occurred in 13% of the sample, while extracranial stenosis occurred in 14%. Clinical characteristics such as age, sex and major cerebrovascular risk factors did not discriminate between patients with or without intracranial stenosis. No association was found between intracranial and extracranial stenosis. The predictors of intracranial stenosis in the multivariable analysis were low ABI (OR=21.2; 95% CI 1.8-250.0) and abdominal circumference (OR=1.11 for every 1 cm increase; 95% CI=1.01-1.22), while the only predictor of extracranial stenosis was smoking history (OR 1.02 for every 1 pack-year; 95% CI 1.01-1.04). Low ABI was the best screening tool for intracranial stenosis (sensitivity 89%, specificity 70%, positive predictive value 32%, negative predictive value 98%). Conclusion: Classical cerebrovascular risk factors do not discriminate between patients with or without intracranial stenosis. Abdominal circumference and ABI may be useful clinical screening tools for intracranial stenosis.