Diffuse Axonal Injury
The brain consists of billions of nerve cells
located in the gray matter which communicate with distant nerve cells
through long nerve fibers called axons, composing the white matter.
Severe sudden twisting or torquing of the brain, as occurs in a sudden
acceleration/deceleration - whiplash -- accident, can stretch, twist,
and damage these delicate axonal fibers. Under the microscope the axonal
damage is called Diffuse Axonal Injury (DAI). Although diffuse axonal
injury generally results from a severe whiplash injury that renders a
patient comatose, recent studies have shown that diffuse axonal injury
can also occur - but to a lesser degree -- when there has been only
brief loss of consciousness (LOC). Because Diffuse Axonal Injury causes
microscopic damage, it cannot be visualized on CT or MRI scans.
A
second method of how the brain can be injured in high speed velocity
change scenarios (a fall from a great height, high speed car accident)
is called “Isotropic Stress.” Whereas diffuse axonal injury involves the
deforming or stretching of the brain tissue, resulting in tearing,
isotropic stress causes damage through a “pulse” or “pressure wave” that
moves through the brain at extraordinarily high speeds. The damage is
caused by a sudden change in the density of the inside of an individual
brain cell. The instant compression causes damage to the internal
structures of the brain cells.
Many of these same types of
injuries have been discovered and treated in veterans returning from the
Iraq war. They have often been exposed to the proximity blast of
explosive charges. The pressure or pulse from the explosion moves
through their body and as it move through the brain it causes damage to
the cells. Although many of these soldiers look “fine” and have no
bleeding, they can and will suffer serious brain injury as a result.
Because
of the large number of veterans injured in this way, lots of research
is being done on this type of brain injury at the present time and there
should be studies available for an update on this new insight into TBI
in mid-2008.
Braininjury.com
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