The main types of ICH include epidural, subdural, intracerebral, and diffuse axonal injuries (DAI). Epidural hematomas occur when the bruising is beneath the skull, but still above the dura, or the tough lining of the brain. The problem with epidural hematomas is that they can keep growing, which places pressure on the brain. This pressure can eventually cause a person to lose consciousness. Epidural hematomas are also associated with skull fractures.
Subdural hematomas occur slightly deeper than epidurals. The dura, mentioned above, is actually composed of three layers. When a contusion, or bruise, happens within these three layers but still above the brain, it is called a subdural hematoma. Like an epidural, pressure placed on the brain from prolonged bleeding can cause a person to lose consciousness.
There are three types of subdural hematomas: chronic, subacute, and acute. Chronic contusions bleed very slowly, which means that you may not even notice the injury at first. Subacute injuries can also take several days or weeks to notice, but the bleeding is still more severe than chronic hematomas. Lastly, acute bruising occurs pretty much immediately. The bleeding is so severe that signs are almost instantly obvious. The level of bleeding makes these the most life-threatening subdural hematomas.
Intracerebral ICH, or intraparenchymal, are when the bruising happens to the brain itself. Not only does the brain suffer damage at the site of the injury, but the momentum of the brain can make it slide slightly in the skull and strike the opposite site. This results in axonal tearing, which destroys nerves' ability to communicate.
