Stroke. Coloured computed tomography (CT) brain scan showing a cerebrovascular accident (CVA), or stroke. The red region is an area of internal bleeding, or haemorrhage. Stroke is brain damage caused by the interruption of the brain's blood supply or by the leakage of blood through blood vessel walls. The two main causes are high blood pressure and atherosclerosis (narrowing of the arteries due to fat deposition). Strokes vary in severity depending on the site and extent of damage, but can result in long-term paralysis, coma and death. A CT scan is a cross-sectional map of the body created by the computation of X-rays passed through the body at different angles.