There are three main types of Traumatic Brain Injury (TBI) i.e. closed TBI, open or penetrating TBI and blast TBI.
Closed TBI describes an injury where no object penetrates the skull. The injury may or may not be associated with a fracture of the skull. If there is a skull fracture, the broken bone does not directly impinge upon the brain tissue. Significant brain damage may be present without any obvious injury to the skull.
Open (i.e. penetrating) TBI describes an injury in which an object(s) penetrates the skull and impinges upon brain tissue. Examples include:
- Pieces of bone from a fracture directly causing brain injury.
- Bullets causing high velocity brain injury.
- Knife injuries causing low velocity brain injury.
Open TBI can provide a route for bacteria to enter the brain potentially leading to a serious infection. In open TBI, where the dura is torn, a potential route for infection occurs. Bacteria can then get access to the brain to form an abscess or infect the meninges causing meningitis. Both require urgent and appropriate antibiotic treatment and abscesses need to be drained via a neurosurgical procedure.
Blast TBI occurs in people exposed to bombing and warfare. The brain injury is caused by a combination of factors:
- Contact injuries which may cause closed or open/penetrating blast injuries,
- High pressure caused by shock waves that are significantly above normal atmospheric pressure. These can result in direct trauma to the brain.
Mechanisms of Brain Injury refers to the processes which cause damage to brain tissue. Mechanisms of traumatic brain injury may be focal or diffuse. Please click on the following links:
Focal Brain Injury (This term refers to areas of localised damage to the brain).
Diffuse Brain Injury (This term refers to widespread, non-localised brain damage).
Another mechanism of brain injury following trauma includes anoxia. This can occur as a result of reduced blood supply to the tissues of the brain following a TBI. Please click on the following links for information on other mechanisms of brain injury: