Every year an estimated 3.8 million people in the United states sustain mild traumatic brain injuries (MTBI) or concussions. Many of these injuries are due to sports related activities, work related injuries, motor vehicle accidents, and military operations. It is also estimated that as many as 50 percent of MTBIs are never reported because the patient does not seek medical attention. This makes it difficult to get a solid number on how many there actually are, but it is a prevalent condition.