Which of the following is one of the four main mechanisms of TBI injury?

• A. Epidural hematoma
• B. Closed head injury
• C. Seizures
• D. Diffuse axonal injury

Answer: (B)

The main idea here is how energy from a head impact reaches and injures the brain. A common way to classify traumatic brain injuries is by whether the skull is breached. A closed head injury means the skull stays intact, but the brain is damaged by the forces of impact—such as rapid acceleration or deceleration, or rotational forces—that transmit energy to brain tissue without an open wound.

This category is counted among the primary mechanisms because it describes the mode of energy transfer to the brain without penetration of the skull, distinguishing it from injuries where the skull is fractured or penetrated.

The other options describe specific injury outcomes or occurrences rather than the broad mechanism of injury: an epidural hematoma is a particular bleed, seizures are a secondary event that can occur after injury, and diffuse axonal injury is a common damage pattern resulting from shear forces, not a standalone mechanism of energy transfer.