Natural History of Atherothromboembolic Occlusion of Cerebral Arteries: Carotid Versus Vertebrobasilar Territories

Abstract

Although Natural history studies are often used as “historical controls” for evaluating new therapeutic modalities, their proper role is to help determine sample size for prospective, randomized trials. These studies can also provide important insights into variables impacting on prognosis following stroke. Unfortunately, natural history data pertinent to thrombolytic therapy for acute stroke are scant since we are most interested in lesion-specific outcome rather than outcome related solely to clinical parameters. Clinical and computed tomography (CT) data alone cannot be used to localize precisely the site of arterial occlusion in patients with acute cerebral infarction, and virtually all studies of acute stroke therapy lack angiographic or even noninvasive data. Furthermore, thrombolytic trials carry out treatment in the very early stages of evolving infarction, i.e., less than 8h from onset, making it even more difficult to use existing data related to outcome since the average time from onset to stroke therapy in most trials exceeds 24 h [25].