A concussion occurs when the head sustains a hard blow and the impact jars or shakes the brain inside the skull, interrupting the brain's normal activities. Although there may be cuts or bruises on the head or face, there may be no other visible signs of a brain injury.
Symptoms of a concussion can include any of the following changes in the person's level of consciousness, such as:
Symptoms of a concussion can be mild to severe, depending on the severity of the injury. If the injury is more serious, symptoms will usually develop within the first 24 hours after the accident. Symptoms may last for days, weeks, or even months following the injury.
WebMD Medical Reference from Healthwise