The concept of concussion can been found woven throughout the history of human societies since antiquity. The image of David knocking Goliath unconscious with a stone to the head is but one early example. A formal definition of cerebral concussion emerged in 1787 when Benjamin Bell, a British surgeon, who described it as,
“every affection of the head attended with stupefaction, when it appears as the immediate consequence of external violence, and when no mark or injury is discovered, is in general supposed to proceed from commotion or concussion of the brain, by which is meant such a derangement of this organ as obstructs its natural and usual functions, without producing such obvious effects on it as to render it capable of having its real nature ascertained by dissection.” (Shaw 2002)
That definition accurately describes the essence of the concussion as we know it today. In high school sports, there are an estimated 136 000 concussions every year in the US. The majority (53%) are a result of contact to the head and in most cases (83%) the symptoms subside within a week. Girls appear to be at higher risk than boys and generally experience different types of symptoms (see Concussion discussion II: differences between girls and boys). A small number of students (5%) lost consciousness during their injury and 1.5% experience symptoms that last beyond 1 month. A review of high school athletes determined 16 year old students reported the highest number of concussions (see Fig.1; Meehan et al., 2011)
In a study of high school football players, dizziness at the time of injury was a significant predictor of a prolonged recovery. Loss of consciousness and vomiting were possibly related to longer recoveries, whereas other symptoms like headaches, amnesia and visual problems were not (Lau et al., 2011).