concussion drawingYou may be surprised to know that there is no uniform definition of concussion. The American Academy of Neurology defines concussion as “a trauma-induced alteration in mental status that may or not involve a loss of consciousness.” In fact in greater then 90% of all concussions there is no loss of consciousness.  During the traumatic event biomechanical forces (rotational and angular) cause rotation of the brain’s cerebral hemispheres around the upper part of the brainstem, the part of the brain that is involved in attention and arousal. This results in complex and somewhat poorly understood electrical and chemical changes and the patient may experience a very brief alteration of awareness which is usually described as being “dazed” or “seeing stars”, or in rare occasions a prolonged loss of consciousness.  Concussions portrayed in cartoons and movies, in which the front or back of the head is struck by a blunt object and no rotational or lateral force is induced are not possible. In fact many suggest that if the neck is restrained, concussion is difficult to produce.  Most concussions are short lived and resolve within seven to ten days, however children and adolescents usually take longer to recover.


"Concussion is a brain injury and should be taken seriously. Learn about the signs and symptoms of concussion and safe return to play."


The most common cause of concussion in the adult population (18-65) are motor vehicle accidents, where as in the elderly it is falls. Sports and bicycle accidents account for most of the concussions in children.  In the United States alone there are and estimated 1.4 to 3.6 million sports related concussions annually. This number is likely higher as many athletes fail to report symptoms of concussion for fear that they will not be allowed to return to play. At the high school level more than four hundred thousand children who participate in sports such as Ice Hockey, Football, Rugby, Lacrosse, Soccer and Cheerleading suffer concussions. Overall, sports with the highest rates of concussion include women’s ice hockey, despite the fact that hitting is not allowed, followed by Men’s Ice Hockey and Football. With respect to the later 4% of all college football players are estimated to have suffered a concussion during their career and studies show one and five (20%) of all high school football players suffer concussion during their high school career. More troubling is almost half of these athletes return to play prematurely setting them up for further injury and even death. In fact 5 out of every 7 deaths from football related injuries are deemed to be secondary to head trauma and the risk of a second concussion increases significantly after the first and even more so after a second event. Second Impact Syndrome is a rare condition in which the brain swells rapidly and catastrophically after a person suffers a second concussion before symptoms from an earlier one have subsided. This deadly second blow may occur days or weeks after an initial concussion. The condition is often fatal, and if not so usually leeds to severe disability. The cause of SIS is unknown however may be secondary to a sudden disregulation of cerebral blood flow. Most cases of Second Impact Syndrome have occurred in young people, who are thought to be particularly vulnerable.


Finally, researchers at Boston University School of Medicine studied the brains of deceased retired professional athletes and found premature neuropathological changes similar to those seen in older individuals who carry a diagnosis of dementia.  Furthermore, many retired NHL and NFL athletes are now beginning to report memory difficulties in their 40’s and 50’s.