TBI patients who have a hematoma, contusion, or excessive brain swelling, called edema, can have secondary complications that cause further damage to the brain. Three of these complications are hemorrhagic progression of a contusion, or HPC, elevated intracranial pressure, or ICP, and breakdown of the blood-brain barrier. Dr. Freeman, can you tell us more about these three complications?
Sure, Dr. Hemstad. HPCs occur when an initial contusion from the primary injury continues to bleed and expand over time. This creates a new or larger lesion, or area of damaged tissue. This increased exposure to blood, which is toxic to brain cells, leads to swelling and further brain cell death.
Poor blood flow to the brain can also cause secondary damage. When the brain receives a powerful blow, swelling occurs just as it would in other parts of the body. Because the skull cannot expand, the brain tissue swells and the pressure inside the skull rises. This is known as increased intracranial pressure, or ICP, which can prevent blood from flowing to the brain. This can permanently damage brain function.
The blood-brain barrier preserves the separation between the brain fluid and the very small capillaries that bring nutrients and oxygen to the brain. If a contusion or hematoma causes the blood-brain barrier to break down, blood, plasma proteins, and other foreign substances leak into the space between neurons in the brain and cause the brain to swell. This causes multiple biological systems to go into overdrive, which can be harmful to the body if they continue for an extended period of time. It also permits the release of neurotransmitters, which are chemicals used by brain cells to communicate. The release of neurotransmitters can damage or kill nerve cells.