A traumatic brain injury (TBI) may be caused by a violent blow to the head, sudden jolt, or impact of the head with the ground in a fall. It may occur during a car accident or due to being thrown from a bicycle, falling while skiing or colliding with someone or something while playing football, hockey or another contact sport. Professional medical evaluation should be sought immediately after a person sustains trauma to their head, even though symptoms may take days or more to develop. Such symptoms may include nausea and vomiting, a persistent and worsening headache, dilated pupils, slurring of words, seizures, and weakness in the extremities. A thorough neurological exam is necessary to determine whether a patient has sustained a concussion or other serious brain injury.