A diagnosis may be made when symptoms last for more than three months after the injury, or it may be made starting within a
week or ten days of trauma. In late, persistent, or prolonged PCS,
symptoms last for over six months, or by other standards, three.
The nature of the symptoms tends to change over time. They are most commonly of a physical nature (headache) following the injury, but tend to become predominantly psychological (difficulty concentrating, irritability) later.