THE MECHANISM OF A TRAUMATIC BRAIN INJURY
There are two types mechanisms that cause head injuries: a coup injury and a contrecoup injury. Coup and contrecoup injuries are associated with cerebral contusions, a type of traumatic brain injury in which the brain is bruised. The contusion may have resulted from a strong blow to the head, causing the brain to slam against the inside of the skull. A coup injury occurs under the site of the impact from an object. A contrecoup injury occurs on the side opposite the area that was hit and causes the brain to impact the side the of the skull opposite of the point of impact.
A coup-contrecoup injury occurs when the brain ricochets inside the skull, which results in widespread damage to the brain. The brain can be compared to jello, in that when it shakes it will not be in tact.
There are two classifications of traumatic brain injury: open and closed. Open head injury is when the skull is penetrated by an external instrument such as a sharp knife or explosive. Closed head injury is caused by a blunt impact or blow to the head, which more commonly leads to brain damage.
A laceration occurs when there is tearing of the brain, usually from a skull fracture or gunshot wound, ruptures large blood vessels causing bleeding into the brain and subarachnoid space. This can result in hematomas, edema and increased intracranial pressures. Objects like bullets can also ricochet within the skull, which can widen the area of damage.
Hematoma occurs when the wall of a blood vessel, artery, vein, or capillary has been damaged and blood has leaked into tissues where it does not belong. Hematoma is swelling or a mass of blood in the brain caused by a break in a blood vessel. A collection of clotted blood in the brain is usually due to a severe TBI and may be life threatening.
Anoxic brain injury occurs when the brain does not receive any oxygen. Cells in the brain need oxygen to survive and function.
Hypoxic brain injury results when the brain receives some, but not enough oxygen.