Open brain injuries occur when an object penetrates the skull. A gunshot is a common example.
Closed brain injuries happen through blunt force trauma that does not penetrate the skull.
Focal or localized brain injuries occur to a single region of the brain.
Diffuse brain injuries affect several regions of the brain. Diffuse axonal injuries (DAIs) happen when the brain is injured on both sides as it is twisted, shaken, or rotated in the skull.
Coup-contrecoup brain injuries affect two areas of the brain on opposite sides.
Brain contusions are bruises on the brain that cause swelling and bleeding.
Intracranial hematomas happen when a brain contusion fails to heal or results in a large blot clot. It can also happen as pressure on the brain increases.