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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