the brain is the most complex part of
the human body this three-pound organ is
the seat of intelligence database of
memories interpreter of the senses
and the director of all movement
lying in its bony shell and washed by
protective fluid the brain is also the
most fragile organ in the body with the
same texture and consistency as gelatin
within the brain are over 100 billion
nerve cells called neurons sending
electrical and chemical signals to and
from the body each neuron has a cell
body a long nerve fiber called an axon
and projections of the cell body called
dendrites dendrites extend out from the
cell body to receive messages from other
nerve cells axons in the brain connect
neurons with each other which in turn
provide extensive interconnections with
other brain areas
because the brain and it's nerve cells
are so fragile sudden rapid movements of
the head can cause injuries
during one such injury called coup
contrecoup or acceleration deceleration
injury the brain bounces back and forth
against the bony interior wall of the
skull in high-speed coup contrecoup
injury the impact may be violent enough
to cause swelling and bruising of the
brain tissue called a contusion however
in cases involving low-speed coup
contrecoup injury the resulting damage
may not be visible to the naked eye
as the brain moves back and forth within
the skull areas of varying density in
the brain slide over each other at
different speeds
axons crossing these junctions
experienced tremendous shearing forces
causing them to stretch and tear from
the cell body
this event is called axonal shearing or
diffuse axonal injury
brain damage can continue to occur for
hours or days after the initial injury
damage to the axons can lead to a
breakdown of communication among neurons
in the brain the torn axons quickly
degenerate releasing toxic levels of
chemicals called neurotransmitters into
the extracellular space in turn many of
the surrounding neurons begin to die
over the next 24 to 48 hours worsening
the initial effects of the injury
mild to moderate cases of diffuse axonal
injury or Dai may result in symptoms
such as brief loss of consciousness
impaired long-term memory
reduced problem-solving ability
lower social inhibition and problems
with attention and perception
severe cases of diffuse axonal injury
may result in coma
or a persistent vegetative state
in the United States over 1 million
cases of mild traumatic brain injuries
including diffuse axonal injury are
reported each year of this number over
300,000 patients suffer long-term
effects from the damage computed
tomography or CT and magnetic resonance
imaging or MRI are tests that can be
performed to check for mild traumatic
brain injury the results of these tests
usually show a normal reading therefore
doctors must rely on patient history and
a clinical exam to diagnose mild
traumatic brain injury