A brain injury is any injury occurring in the brain of a living organism. Brain injuries can be classified along several dimensions. Primary and secondary brain injury are ways to classify the injury processes that occur in brain injury, while focal and diffuse brain injury are ways to classify the extent or location of injury in the brain. Specific forms of brain injury include:
- Brain damage, the destruction or degeneration of brain cells.
- Traumatic brain injury, damage that occurs when an outside force traumatically injures the brain.
- Stroke, a vascular event causing damage in the brain.
- Acquired brain injury, damage to the brain that occurs after birth, regardless of whether it is traumatic or nontraumatic, or whether due to an outside or internal cause.