A serious head injury occurs when the brain hits against the inside of the skull with enough force to cause brain damage. A serious head injury may result from a hard blow to the head, from severe jarring or shaking of the head, or when an object pierces the head.
With this type of injury, the brain tissue may bruise, swell, or tear. Nerves or blood vessels within or around the brain may stretch, pull apart, or tear.
Serious injury to the brain may occur even when there is no visible bleeding or injury on the outside of the skull.
Symptoms of a serious head injury may include:
A difference in the size of the pupils of the eyes.
New vision problems.
A person with a serious head injury should visit a doctor immediately.
It can be hard right after a head injury to tell the difference between a mild concussion and a more serious injury. A brain bruise (contusion) or bleeding within the skull at first may cause only mild symptoms. If a person with a head injury is seen by a doctor, he or she should still be closely watched for any changes in behavior or symptoms for the next 24 hours or longer.