Direct impacts to the head are caused by a foreign object or missile striking the head. The object need not penetrate the brain or skull to be considered a direct impact, but skull fractures are common. Any direct impact can put the injured person at risk for a concussion or other serious brain injuries.
Indirect impacts, in contrast, are caused by the movement of the brain inside the skull. An external force causes the movement but the head doesn’t come into contact with any object. Severe and sudden acceleration, deceleration or violent shaking, as common in car accidents, can cause the brain to strike the inside of the skull.
Both direct and indirect impacts can cause serious brain damage leading to memory loss, impaired motor and cognitive abilities, headaches and death.