American Heart Association Prevention Conference. IV. Prevention and Rehabilitation of Stroke. Etiology of stroke.

Abstract

The diagnosis of arterial stroke differentiates ischemia from hemorrhage. The former may be due to arterial occlusion or stenosis, the latter to leakage or rupture of an artery. Computed tomography (CT) and magnetic resonance imaging (MRI) have shown that this basic differentiation cannot be reliably made from the history and clinical examination alone. Of the clinical stroke syndromes, only Wallenberg’s syndrome has not been reported to be due to hemorrhage. When CT or MRI is not available for diagnosis, spinal tap is reliably positive only when the aneurysm or arteriovenous malformation has ruptured into the subarachnoid space; the results are often normal when a small hemorrhage occurs in the parenchyma. For some therapies, notably neuroprotective agents, the potential benefits for ischemia do not seem to be offset by potential harm in the case of hemorrhage. However, because fibrinolytics, antithrombotic agents, or surgery are treatment options, diagnostic certainty is essential to avoid harming the patient. Most—but not all—strokes have a sudden or rapidly evolving onset. Differential diagnosis of sudden change in focal neurological status includes seizures or postepileptic paralysis, hemorrhage into a tumor (itself a form of stroke), and migraine. Neuroimaging helps to differentiate between these and the cause of short-lived symptoms (transient ischemic attack [TIA]) usually presumed due to ischemia but possibly due to new-onset infarction or hemorrhage. More precise classification of stroke into a pathogenic subtype (embolism, thrombosis, decreased perfusion or “lacunar” infarction, leakage, or rupture) evades the best clinical skills. The classification of stroke mechanism depends on the presence of risk factors for stroke (preexisting condition or circumstance epidemiologically related to stroke) and etiologies (disease directly causing the mechanism) that implicate the cause of stroke in a given patient. However, more than one risk factor and etiology are frequently present in the same patient and may be related …