Lt Col Reynolds
A hematoma is bleeding in or around the brain. There are several different types of hematomas that can happen in TBI. Dr. Green, can you tell us more about hematomas?

Dr. Green
Of course, Dr. Reynolds. A pocket of blood that forms between the skull and the tough outer layer of the brain’s protective cover, called the dura mater, is known as an epidural hematoma, or EDH. An EDH is most often the result of bleeding from higher-pressure arteries. The bleeding forms a pocket of blood that increases the pressure inside the skull. As the hematoma grows, the pressure pushes on the brain. This pressure can damage the brain, and in some cases even push part of the brain through the hole in the bottom of the skull where the spinal column passes through. This is called herniation, which is likely to be fatal.

If the bleeding occurs one layer down, between the dura mater and the next protective layer, the arachnoid mater, it’s called a subdural hematoma, or SDH. A slight impact to the head or even a fall to the ground without hitting the head may be enough to cause an SDH. Subdural hematomas may cause no obvious symptoms at all or can be life threatening. Small subdural hematomas may not be very serious, and the blood can be slowly absorbed over several weeks. In other cases, small or medium subdural hematomas may slowly grow in size over weeks to months. This growth can compress the brain, possibly leading to death if the blood is not drained. Larger hematomas may require immediate surgery to reduce pressure on the brain.

Based on when the symptoms appear, subdural hematomas can be divided into acute or chronic. Acute subdural hematomas are those with symptoms that appear quickly after the injury. If weeks pass before symptoms appear, the hematoma is called a chronic subdural hematoma, and is often the result of a slow-bleeding, small tear of a blood vessel. Children and the elderly are most likely to experience a chronic subdural hematoma. This chronic form is less risky, because it happens slowly, and the brain is often able to adjust to the bleeding. However, if the bleeding continues and the hematoma is not treated, the condition can become very serious.

Bleeding in the next layer, between the arachnoid mater and the pia mater, is called subarachnoid hemorrhage, or SAH. Some people with SAH recover fully, but it can be a life-threatening condition even with treatment. The outcome of a subarachnoid hemorrhage varies widely depending on the location and amount of bleeding. Surgery may be done to relieve pressure on the brain.

Finally, bleeding into the brain itself is called an intracerebral hematoma, or ICH. These injuries occur after a trauma literally tears axons in the brain's white matter. Axons are the connections that carry electrical impulses, or messages, from one part of the brain to another. When this connection is sheared, serious brain damage can result because the neurons can no longer communicate.