Head injury can be classified as either closed or penetrating. In closed head injury, the head sustains a blunt force by striking against an object. In penetrating head injuries, a high velocity object breaks through the skull and enters the brain. The signs and symptoms of a head injury may occur immediately or develop slowly over several hours.
Review Date 9/23/2019
Updated by: Jacob L. Heller, MD, MHA, Emergency Medicine, Emeritus, Virginia Mason Medical Center, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.