Headaches often occur after injuries to the head or neck, and are very common after rear-end collisions (whiplash-related headaches). For some people, headaches occur immediately, and for others, onset may take a few hours or days. Depending on the nature and severity of the trauma, headaches may resolve quickly or may persist for years. Although it is difficult to ascertain who will suffer chronic post-traumatic headaches, people with pre-existing headache or migraine issues are at an increased risk. Factors that influence headache pain include the type of accident, angle of impact, location of the person in the car, and the brain trauma inside the skull. Symptoms of post-traumatic headaches may include irritability, dizziness, vertigo, fatigue, depression, anxiety, insomnia, memory problems, trouble with concentration and trouble solving problems. Diagnosis of headaches involves medical history, physical exam, and diagnostic testing and imaging, if necessary. The treatment of headaches depends on the type of headaches, but may involve medication such as painkillers or anti-inflammatories, behavioral therapy, and physical therapy.