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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