Brain in ischemic stroke. Coloured magnetic resonance imaging (MRI) scans of sections through the brain of a 60-old patient five hours after an ischemic stroke of the middle cerebral artery. A stroke, or cerebrovascular accident (CVA), is the rapid loss of brain function due to disturbance in the blood supply to the brain. This can be due to haemorrhage (bleeding), or ischemia (lack of blood flow) caused by a blockage, as seen here. Here, the stroke has caused complete paralysis (hemiplegia) of the left side of the body.