injury of the brain or of its soft tissue or bony coverings may also be detected in
adjacent structures of the head (eyes, ears, and nose) or even in portions of the body
that are remote from it.
b. Brain Injuries. Most brain injuries occur due to movement of the brain inside
the skull. The level of damage to the brain depends on the speed the head was
traveling and the head's position just prior to contact.
c. Responses to Brain Injury. The base of the skull is rough; therefore,
movement over this area will cause various degrees of injury to the brain or blood
vessels. Possible responses to brain injury include the following:
Initial response to a bruised brain is swelling. The swelling is caused by:
(a) Increased blood volume due to vasodilation and increased cerebral
blood flow to the injured areas.
(b) Buildup of extra blood volume putting pressure on the brain and
decreasing blood flow to the injured part.
Since the edema builds over a period of 24 to 48 hours, early care and efforts
to decrease the vasodilation is important.
(2) Carbon dioxide may build up, having a critical effect on cerebral vessels.
This buildup causes more vasodilation.
(3) Hyperventilation may occur, causing a decrease in the carbon dioxide,
vasoconstriction, and better perfusion (passage of a fluid through the vessels of an
organ) for the brain.
Hyperventilation -- a condition marked by fast, deep breathing, which tends to
remove increased amounts of carbon dioxide from the body and lower the
partial pressure of the gas, causing buzzing in the ears, and tingling of the lips
Unconsciousness may occur due to injury to the cerebral cortex or the
(5) If there is increased intracranial pressure (ICP) and decreasing cerebral
blood flow, no matter what the cause, the level of consciousness is depressed.
(6) The intracranial cavity is filled to capacity with contents that cannot be
compressed -- cerebral spinal fluid, intravascular blood, brain tissue water (interstitial
fluid). If the volume of one of the constituents of the intracranial cavity increases, a
reciprocal decrease in volume of one or both of the others must occur. Otherwise, the
result is an increase in intracranial pressure.