A concussion may occur when the head hits an object, or a moving object strikes the head. A concussion is a minor or less severe type of brain injury, which may also be called a traumatic brain injury.
A concussion can affect how the brain works for a awhile. It may lead to headaches, changes in alertness, or loss of consciousness.
Brain injury - concussion; Traumatic brain injury - concussion; Closed head injury - concussion
A concussion can result from a fall, sports activities, or car accidents. A big movement of the brain (called jarring) in any direction can cause a person to lose alertness (become unconscious). How long the person stays unconscious may be a sign of how bad the concussion is.
Concussions do not always lead to loss of consciousness. Most people never pass out. They may describe seeing all white, all black, or stars. A person can also have a concussion and not realize it.