A severe head injury is any injury which occurs to a person's head which has the potential to cause "traumatic brain injury", which is another term which is often used by medical professionals. This may include any head injury in which the skull is penetrated, or any injury in which the head is hit hard enough to cause internal damage without penetration. Severe head injuries may have different consequences depending on which area of the brain is damaged, and to what extent. Symptoms which indicate that a severe head injury may have been sustained include headaches, dizziness, double-vision, vomiting, loss of consciousness, changes in mental functioning, seizures, ringing in the ears, sleepiness, numbness in the arms and legs and slurred speech. Any person who has sustained a severe head injury should immediately seek medical help.