Stroke

Stroke happens when blockage or breakage of a blood vessel interrupts the blood supply to an area of the brain. Brain cells in the immediate area usually die within a few hours. Strokes can impair speech, vision, movement or memory, depending on where in the brain it happens. Some people recover completely, while others die after very severe strokes.

Coloured CT scan of the brain of a stroke patient. Dark areas indicate reduced activity. Wellcome Photo Library