Strokes occur either because an artery in the brain has burst (cerebral hemorrhage) or because a blood clot or other material has blocked an artery (cerebral thrombosis and cerebral embolism). You can suspect a stroke if a middle-aged or older person suddenly collapses or loses consciousness. His face may become very red and the eyeballs prominent. One side of the body may become paralyzed. Speech may be affected and the mouth drown ot one side.Call a doctor or ambulance immediately. While you are waiting for medical help, place the person in a position halfway between lying down and sitting up, or at least prop up his head. Loosen ant tight clothing. It is important to maintain a calm attitude yourself. If the person should vomit, turn his head to one side to prevent his choking. Otherwise, do not try to move him.