A stroke is when an artery that delivers blood to the brain is blocked by a blood clot, or when a blood vessel to the brain breaks, interrupting blood flow to an area of the brain. Without this blood flow, brain cells begin to die and brain damage occurs.
When a stoke starts to kill brain cells, the areas of your body controlled by those cells are affected – you may lose control of those areas, affecting your speech, movement and memory. How you are affected depends upon what part of the brain is affected by the lack of blood.
Someone who has a small stroke may have only minor problems, such as weakness in a leg or arm. People with larger strokes may be paralyzed on one side of their body, or lose their ability to speak.