A concussion happens when a blow to the head or the body causes the brain to shake inside the skull. This can result in bleeding or swelling in or around the brain.
Concussion can be mild, serious or somewhere in between.
Causes :
A single, forceful movement of the head
An explosion
A forceful blow to the body
A blunt force to the head
Shaking
Signs and Symptoms :
The person may say that he " blacked out " or " saw stars".