You suffer a head injury in a car accident or a fall. You wind up in the hospital, and the doctors know it's serious. They diagnose you with edema. What exactly does this mean?
Essentially, it is swelling of your brain tissue. The biggest issue with edema, other than the initial injury that caused it, is that the skull is too rigid to accommodate it. As a result, the tissue presses dangerously against the inside of your skull, which can lead to further injury or even death in the worst cases. The pressure buildup is too much for the fragile organ to withstand.
If you study injuries in general, you'll find that swelling is response to injuries that happen all over the body and is part of the body's response and the healing process. An impact to your knee could cause swelling around the joint while a laceration on your arm may cause the skin around the cut to swell.
Of course, those other tissues have more room to expand. They can swell freely, heal and then return to their normal size as the swelling goes down. The confines in which the brain exists mean that it does not have this same ability, which is why doctors must work quickly to reduce swelling.
A similar problem is bleeding on the brain. As the blood builds up between the brain and skull, it also puts pressure on your brain that can cause serious complications.
A head injury of any kind can lead to high medical bills and related costs, so you need to know if you have a right to financial compensation.