A concussion occurs when force to the head or body causes the brain to strike the skull or twist upon itself.

How is a concussion medically defined?

Concussion is the mildest form of traumatic brain injury (TBI). There is no universally accepted definition of concussion, but it results in:

  • Rapid impairment in brain function that is temporary and gets better by itself

  • A variety of symptoms, but not necessarily loss of consciousness

  • Disturbance to the brain’s function rather than physical structure, which means that standard neuroimaging tests such as MRIs and CT scans can’t detect any changes

  • Symptoms that gradually improve over time, but which may be prolonged in a small percentage of people.

Who is most at risk from concussion?

The connection between contact sport and concussion has been widely publicised. In the general population, however, concussion is in fact extremely common. Typically caused by a fall or car accident, it can also be sustained by a wide variety of other activities.

The outcome of a blow to the head can be either mild or severe. While anyone who has been ‘knocked out’ has usually suffered concussion, you can be concussed without losing consciousness. When concussion occurs in sport, players in most cases remain conscious, and the condition often goes undiagnosed. And while protective headgear prevents skull damage during high-impact knocks, it doesn’t prevent the brain from moving inside the skull.

People in certain sports have a higher risk of being concussed than the general population – rugby players and boxers, for example. People in the military who are exposed to explosions and victims of domestic abuse are also at particularly high risk. These groups are also more likely to suffer repeated concussions.


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