What Happens to the Brain?

Traumatic brain injury differs from other types of brain damage (genetic, drug or alcohol included, degenerative disease, strike, etc.) in a number of ways:
  • Damage is acquired in the course of what may well have been normal development.
  • It happens suddenly, bringing significant change immediately.
  • Damage is usually diffuse, widespread, not confined to one area of the brain. Thus the effects are multiple.
  • TBI results from some trauma to the head, causing damage to the brain. The head may be hit or strike a stationary object or be shaken violently. Alternatiively, the brain may actually be penetrated from the outside.

    Open Head Injury. The brain is penetrated from outside, as in a bullet wound.
    Closed Head injury. The brain is damaged within the head, without external penetration.

    The brain is a soft mass of jelly-like constistency. Its volume cannot be compressed, but it can shift and move when violently disturbed. It "floats" in a bath of cerebral spinal fluid within a hard, unyielding skull. The protuberances froming vaults and ridges. When, because of trauma to the head, the brain moeseithin the skull, the camage prouces predictable patients of TBI. While open head injuries cause destruction of the penetrated brain tissue, closed head injuries may result in three other types of damage:

    Diffuse.
    Widespread damage results from the strectching and tearing of nerve fibers. When the brain mass twists and shifts, billions of thread-like nerve connections are pulled and stretched. Some actually snap and never function again. Some that are stretched may recover but others degenerate and finally fall apart.
    Concussive.
    The brain mass collides with the sharp ridges indside the skull. As it bounces off hard bone, it is torn and bruised. Contusions (bruises) are the most likely to occur at the tips and base of the frontal and temporal lobes, because these areas are closest to sharp ridges of bone.
    Coup/Countercoup.
    If the head is struck in a particular way, the skull may bend in, bruising the brain, then diving the brain mass against the opposite wall of the skull so that brain tissue on the other side is bruised as well.

    There also may be secondary damage to the brain after injury. Bleeding of the damaged vessels can cause an internal buildup of blood, which can cause pressure and harm the tissue. The injured brain may swell with fluid, causing intracranial pressure and herniation or tissue death as a result of loss of oxygen. If surgery is necessary, additional brain tissue may be destroyed in the process.

    A Very Thorough and Resourceful TBI Page