A traumatic brain injury (TBI) is defined as a blow or jolt to the head, or a penetrating head injury that disrupts the normal function of the brain. TBI can result when the head suddenly and violently hits an object, or when an object pierces the skull and enters brain tissue. Symptoms of a TBI can be mild, moderate or severe, depending on the extent of damage to the brain. Mild cases (mild traumatic brain injury, or mTBI) may result in a brief change in mental state or consciousness, while severe cases may result in extended periods of unconsciousness, coma or even death.
The 4th International Conference on Concussion in Sport held in Zurich, Switzerland in 2012 defined concussion, a subset of mTBI, as the following:
Concussion is the historical term representing low velocity injuries that cause brain ‘shaking’ resulting in clinical symptoms and that are not necessarily related to a pathological injury. Concussion is a subset of TBI and will be the term used in this document. It was also noted that the term commotio cerebri is often used in European and other countries. Minor revisions were made to the definition of concussion, which is defined as follows:
Concussion is a brain injury and is defined as a complex pathophysiological process affecting the brain, induced by biomechanical forces. Several common features that incorporate clinical, pathologic and biomechanical injury constructs that may be utilised in defining the nature of a concussive head injury include:
1. Concussion may be caused either by a direct blow to the head, face, neck or elsewhere on the body with an "impulsive" force transmitted to the head.
2. Concussion typically results in the rapid onset of short-lived impairment of neurological function that resolves spontaneously. However, in some cases, symptoms and signs may evolve over a number of minutes to hours.
3. Concussion may result in neuropathological changes, but the acute clinical symptoms largely reflect a functional disturbance rather than a structural
injury and, as such, no abnormality is seen on standard structural neuroimaging studies.
4. Concussion results in a graded set of clinical symptoms that may or may not involve loss of consciousness. Resolution of the clinical and cognitive symptoms typically follows a sequential course. However, it is important to note that in some cases symptoms may be prolonged.
To view peer reviewed literature related to sports concussions, the Sports Concussion Library can be found here.
The U.S. Consumer Product Safety Commission (CPSC) tracks product-related injuries through its National Electronic Injury Surveillance System (NEISS).
According to CPSC data, there were an estimated 446,788 sports-related head injuries treated at U.S. hospital emergency rooms in 2009. This number represents an increase of nearly 95,000 sports-related injuries from the prior year. All of the 20 sports noted below posted increases in the number of injuries treated in 2009, except for trampolines, which posted 52 fewer injuries in 2009. Sports that exhibited substantial increases from 2008 to 2009 included water sports (11,239 to 28,716*), cycling (70,802 to 85,389), baseball and softball (26,964 to 38,394) and basketball (27,583 to 34,692).
*Four categories were tabulated by the AANS in the current analysis that were not reflected in the 2008 injury data analysis, but together, these account for only 1,397 injuries.
The actual incidence of head injuries may potentially be much higher for two primary reasons. 1). In the 2009 report, the CPSC excluded estimates for product categories that yielded 1,200 injuries or less, those that had very small sample counts and those that were limited to a small geographic area of the country; 2). Many less severe head injuries are treated at physician's offices or immediate care centers, or are self-treated.
Included in these statistics are not only the sports/recreational activities, but the equipment and apparel used in these activities. For example, swimming-related injuries include the activity as well as diving boards, equipment, flotation devices, pools and water slides.
The following 20 sports/recreational activities represent the categories contributing to the highest number of estimated head injuries treated in U.S. hospital emergency rooms in 2009.