4 Primary Types of Damage:
Hematomas, or bleeding in or around the brain:
Epidural Hematoma (EDH): When bleeding occurs into the area between the skull and the dura mater.
Subdural Hematoma (SDH): When bleeding occurs between the dura mater and the arachnoid mater.
Subarachnoid Hemorrhage (SAH): When the bleeding is beneath the arachnoid mater
Intra-cerebral Hematoma (ICH): Bleeding into the brain tissue its self.
Bleeding into the brain or between the layers will cause swelling which will then lead to an increase in Intracranial Pressure. This is a very serious condition
2. Focal Contusion:
Bruising of the brain tissue as a result of the brain tissue being in direct contact with the skull.
3. Diffuse Axonal Injury (DAI):
When the brain rapidly moves and rotates inside the skull at the time of injury. The long connecting fibers in the brain, which are called axons, are sheared as the brain is rapidly accelerating or decelerating inside the hard bone of the skull.
DAI usually causes injury to multiple parts of the brain, therefore people who suffer DAI are usually in a coma.
The changes in the brain may be minute and can be difficult to detect using CT or MRI scans.
It is one of the most common types of Traumatic Brain Injury but also one of the most devastating.
e.g. Car accidents, violent attacks, falling, sports injuries and child abuse (shaken baby syndrome)
4. Ischemic:
When an insufficient blood supply to the brain is a result of the Traumatic Brain Injury.
Traumatic Brain Injuries are usually classified as FOCAL or DIFFUSE injuries.
FOCAL injuries are usually caused by direct contact:
Scalp injury
skull fracture
surface contusion
DIFFUSE injuries are usually caused by acceleration-deceleration events:
DAI
Hypoxic-ischemic damage
Meningitis
Vascular injury
Focal and diffuse injuries frequently present at the same time in Traumatic Brain Injury.