Epidemiology of athletic head injury.

Although more common in collision sports, head injuries (for this article confined to cerebral neurotrauma) may occur in virtually any form of athletics. A few such injuries result in death, especially the second-impact syndrome and subdural hematoma. The more minor cerebral injuries, mostly concussions, have wide-spread misunderstanding in definition and severity. These misunderstandings in the field have contributed to a paucity of reliable epidemiological information about its actual frequency. The concerns accompanying cerebral insult are discussed more than studied, but much can be gained in principle from the history of attention to concussions in football.