It is estimated that over two million people suffer traumatic brain injuries in the United States each year. Motor vehicle accidents account for approximately one half of traumatic brain injuries. Other causes include falls, assaults, and accidents related to sports and recreation. The total economic cost of traumatic brain injury in the United States is over $25 billion annually. The cost of long-term rehabilitation of each victim may exceed $4 million over a 5-10 year period. Each year, between 70,000 and 90,000 of the survivors are often left with some kind of chronic sequelae due to their original injuries (Department of Health and Human Services, 1989).