What is a stroke?

A stroke occurs when the blood flow in the brain is suddenly disturbed. As a consequence the nerve cells in the brain are starved of oxygen and nutrients, and they die if blood flow is not re-established. Other terms for a stroke are apoplexy, brain insult or cerebral infarction.

The stroke may be caused by an obstruction (termed ischemic stroke) or rupture (hemorrhagic stroke) of a blood vessel.

Stroke due to thrombosis

In this case, an artery is occluded by a blood clot – a thrombus that has formed in a larger or smaller vessel in the brain. Such occlusions usually do not occur in healthy brain vessels; they occur in vessel walls already damaged by atherosclerosis.

Stroke caused by an embolus

This is caused primarily by blood clots that form in the heart or in the large vessels leading to the brain, for example in the carotid artery. Pieces that become detached from a blood clot can pass through the bloodstream into the brain and occlude a major blood vessel.

Rupture of a Blood Vessel (Hemorrhagic Stroke or Bleeds)

Bleeds account for about 15 % of strokes. Blood flows into the brain tissue.