Cerebrovascular accident

A stroke or cerebrovascular accident (CVA) occurs when the blood supply to a part of the brain is suddenly interrupted by occlusion (called an ischemic stroke -- approximately 90% of strokes), by hemorrhage (called a hemorrhagic stroke -- about 10% of strokes) or other causes. Ischemia is a reduction of blood flow most commonly due to occlusion (an obstruction). On the other hand, hemorrhagic stroke (or intracranial hemorrhage), occurs when a blood vessel in the brain bursts, spilling blood into the spaces surrounding the brain cells or when a cerebral aneurysm ruptures. The mortality and long-term morbidity prognosis is generally worse for hemorrhagic strokes than for ischemic strokes. A small proportion of strokes are watershed strokes caused by hypoperfusion (usually due to hypotension) or other vascular problems including vasculitis.

Causes

Ischemic stroke

Ischemic stroke is usually caused by atherosclerosis (fatty lumps in the artery wall), embolism (obstruction of blood vessels by blood clots from elsewhere in the body), or microangiopathy (small artery disease, the occlusion of small cerebral vessels).

Related Topics:
Atherosclerosis - Embolism - Microangiopathy

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Risk factors (for atherosclerosis and small vessel disease) are age, hypertension (high blood pressure), diabetes mellitus, elevated cholesterol levels and cigarette smoking. High blood pressure is the most important modifiable risk factor of stroke. Atrial fibrillation and other arrhythmias can lead to clot formation in the heart, which embolize to the brain. Some forms of thrombophilia (increased coagulation tendency) have a predilection for arterial thrombosis and stroke; these include polycythemia vera and the rare paroxysmal nocturnal hemoglobinuria. Sickle cell anemia predisposes to strokes.

Related Topics:
Hypertension - Diabetes mellitus - Elevated cholesterol - Cigarette smoking - Atrial fibrillation - Arrhythmia - Thrombophilia - Polycythemia vera - Paroxysmal nocturnal hemoglobinuria - Sickle cell anemia

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Hemorrhagic stroke

Hypertension increases the risk of cerebral bleeding. Other causes include arteriovenous malformation (cerebral AVM), cerebral aneurysms, cerebral arteriosclerosis, brain injury, head injury, congophilic angiopathy, congenital artery defects and prematurity.

Related Topics:
Hypertension - Arteriovenous malformation - Cerebral AVM - Cerebral aneurysm - Congophilic angiopathy - Prematurity

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Watershed stroke

As opposed to hemorrhagic stroke or embolic (or other atherogenic) stroke, watershed strokes occur in parts of the brain that lie at the boundary between zones of arterial distribution from different arteries. When there is hypotension from any cause, these watershed areas are more susceptible to damage than other areas of the brain.

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