A penetrating traumatic brain injury occurs when an object breaches or penetrates the skull and the dura matter, or the outer layer of the brain beneath the skull.   The penetrating brain injury causes a wound.  In penetrating traumatic brain injuries, brain damage is caused both by the velocity of the object and its destruction of the brain tissue with which it comes into contact, and damage from the shock wave and/or rotations stretching and bending brain tissue.

Gunshot wounds to the head are a classic example of a penetrating traumatic brain injury where the bullet does not exit the skull.  If an object penetrates the skull and also produces an exit wound, that is referred to as a perforating brain injury.

Because the penetrating injury leaves a wound, these injuries are often initially evaluated with a CT scan or x-ray.  Surgery may be indicated for the removal of the object or to repair damaged tissue.  As with other traumatic brain injuries, intracranial pressure is also usually monitored and I.V. fluids are given to maintain high blood oxygen levels.

Brain damage severity in a penetrating traumatic brain injury is usually associated with velocity of the object penetrating the skull.  The higher velocity the object, the worse the injury and prognosis tend to be.   Brain tissue can become packed up against the sides of the cavity formed by the missile or ejected through the entry or exit wound.

Penetrating traumatic brain injuries are serious medical emergencies that can lead to death or permanent disability.