Brain in stroke. Coloured computed tomography (CT) scan of an axial section through the brain of a 53-year-old patient affected by hemiplegia (paralysis) of the right side of the body following a stroke (cerebral vascular accident, cva). Strokes occur when the blood supply to an area of the brain is restricted, or cut off completely, resulting in cell death of the affected tissue. Here, a blood clot (thrombosis) is visible at the termination of the left internal carotid artery.