A coma is when a person is in such a deep state of unconsciousness that the individual is unable to be awakened. Severe illness and injuries such as concussions and brain trauma are the most frequent causes of comas. It derives from the Greek word koma, meaning 'deep sleep."
As Arizona residents may know, mild head injuries are often deceptive. The trauma may be slight, and the injured individual may seem shaken but not hurt. If brain injury occurred, the signs and symptoms may develop gradually. The onset of injury differs from person to person.