The purpose of this study is to determine if lowering the body temperature to 89°F (32°C) (hypothermia) may improve outcome following severe head injury.  There is laboratory evidence that cooling might be helpful.  Early studies in adult patients with head injuries also have suggested some beneficial effects from hypothermia.  Because of this and the finding that cooling adults and children can be done safely, we believe that it may be of benefit for children with severe head injury.