Primary Brain Injury occurs at time of injury due to impact, and is irreversible. It may be the result of either:
- A shear injury to axons, and/or,
- Laceration or contusion of brain tissue
Secondary Brain Injury evolves after the primary injury and is potentially preventable and treatable. It can occur by a number of mechanisms:
- Intracranial hematoma
- Increased intracranial pressure
- Hypoxia
- Ischemia
- Fluid and electrolyte abnormalities
- Infection