Table 1.

Key Definitions

• Penetrating traumatic brain injury (pTBI): a head injury with violation of, at minimum, the skull and likely dura and brain by a foreign body. Linear non-displaced skull fractures alone will NOT be included.

• pTBI encompasses penetrating, tangential, and perforating injuries as follows:

○ Penetrating: a foreign object penetrates skull and dura and remains within the skull. This wounding mechanism lacks an exit wound.

○ Tangential: a foreign object glances off the skull, which often drives skull fracture fragments into the brain.

○ Perforating: a “through-and through” injury, characterized by entry and exit wounds. Of these three, perforating brain injuries are associated with a worse outcome.

• pTBI will be subclassified as:

○ Missile injuries (such as gunshot wounds)

○ Blast fragment injuries (such as type II blast injury—blast overpressure plus fragment injury)

○ Low-velocity injuries (such as knives)