A concussion is a disturbance in brain function that occurs following either a blow to the head or as a result of the violent shaking of the head.
In the United States, the annual incidence of sports-related concussion is estimated at 300,000. Estimates regarding the likelihood of an athlete in a contact sport experiencing a concussion may be as high as 19% per season.
Although the majority of athletes who experience a concussion are likely to recover, an unknown number of these individuals may experience chronic cognitive and neurobehavioral difficulties related to recurrent injury. Symptoms may include:
Personality changes (e.g. increased irritability, emotionality)
Sensitivity to light or noise
Dizziness when standing quickly
Deficits in short-term memory, problem solving, and general academic functioning
This constellation of symptoms is referred to "Post-Concussion Syndrome" and can be quite disabling for an athlete. In some cases, such difficulties can be permanent and disabling.
In addition to Post-Concussion Syndrome, suffering a second blow to the head while recovering from an initial concussion can have catastrophic consequences as in the case of "Second Impact Syndrome," which has led to approximately 30-40 deaths over the past decade.
Upon ruling out more severe injury, acute evaluation continues with assessment of the concussion.