Diagnosis: Sudden onset of focal neurological symptoms are the most common clinical presentation of stroke. This focal impairment represents injury to discreet brain areas that were perfused by the artery that is now occluded or affected by hemorrhage. Location of ischemia is the crucial factor in determining the sequelae of stroke. A small stroke in the brainstem can cause death; a similar stroke in the right hemisphere may result in virtually no clinical impairment.

The location of infarction is largely determined by clinical symptoms as radiological tests often do not show infarction in the acute phase. Since there must be a major change in brain density for CT and MRI to show lesions, these tests do not indicate areas of infarction. Hemorrhages are reliably observed on CT or MRI because of the presence of blood in areas not usually containing it.

Common clinical symptoms include language impairment (left hemisphere), visual-spatial disorder (right hemisphere) and contralateral hemiplegia (motor cortex or internal capsule lesions). Strokes involving the basilar system will produce ataxia (cerebellum) and visual field defects (occipital lobe).

Hemorrhages are largely detected using CT or MRI examination, and lumbar puncture. Blood appears distinct on these scans and its presence in the CSF is a reliable indication of cerebral hemorrhage. Single Proton Emission Computed Tomography (SPECT) may also be used to assess patients who have no structural lesion detectable by CT. SPECT measures the metabolic function of cells and will reveal areas that were damaged by the stroke.

Treatment: Treatment of stroke is generally supportive. Most patients make considerable recovery in six months following onset. Embolic strokes are often treated using anticoagulant medications such as Heparin. The use of anticoagulants is controversial. Antiplatelet agents, such as Aspirin, are also used as treatment. Carotid endarterectomy, a surgical procedure used to clean the arteries of atherosclerotic plaques, is often used to treat partial occlusion of carotid arteries. Surgical evacuation of hemorrhage is a common treatment following that type of stroke. Surgical resection or repair of aneurysm or AV malformations is also performed for defects that are in accessible locations.