Stroke

Stroke is a sudden loss of neuronal function that can be ischemic or hemorrhagic. Ischemic stroke can be thrombotic, embolic, and due to diffuse hypoperfusion whereas hemorrhagic stroke can be intraparenchymal and subarachnoid. By convention, an ischemic event is classified as a transient ischemic attack (TIA) when the neurologic symptoms have resolved within 24 hours (although most neurologic symptoms lasting >20 minutes have positive findings on magnetic resonance imaging [MRI] suggesting permanent tissue damage); if the symptoms persist for more than 24 hours, the attack is termed an ischemic stroke.