1. Concussionby Chris Gralapp, MA
In the headlines
Concussion is a hot topic
currently in the news, especially
as it relates to high school,
college and professional sports.
Laws in the U.S. are being
passed now to address how
contact sports shall be played
to avoid brain injury. But what is
concussion?
Also called Mild Traumatic
Brain Injury, concussion results
from a blow to the head or a
fall, and causes a variety of
physical, cognitive, and
emotional symptoms, some of
which may be subtle.
Physical damage
Concussion is a complex injury.
During a concussion, there is
both linear and rotational
motion to the brain. As the
brain shifts and deforms, the
density differential between
the denser gray matter of the
cerebral cortex (where the
neuron bodies reside) and the
less dense white matter of the
cerebrum’s interior (where the
axons deliver impulses one
region to another) cause
stretching and damage to the
axons, and also to capillaries.
This damage is often the result
of a shearing motion at the
interface of the two layers.
Cascade of changes
This shearing and damage
cause the neurons to depolar-
ize and discharge abnormally,
somewhat like a seizure.
Neurons are not necessarily
destroyed, but the connections
between them can be
disrupted as the axons are
stretched and broken. This
damage leaves the axons
swollen and weak. Damage is
incurred not only at the time of
injury, but also thereafter, as a
cascade of pathophysiological
changes occur over a period of
days. Abnormal neurotransmit-
ter release, ionic shifts (Ca++),
glucose metabolism, cerebral
blood flow, and axonal function
are part of the cascade.
Symptoms and treatment
Signs of a concussion include
loss of consciousness or
amnesia, headache, slow
reaction times, emotional
irritability, sleep disturbance,
feelings of detachment or
inability to concentrate.
Treatment is rest, both physical
and cognitive, as well as
monitoring of the patient. A
concussed brain is particularly
vulnerable to further injury,
Adequate time is necessary to
avoid permanent impairment.
Symptoms usually clear up in
Differences in density between the gray matter layer and the
deeper white matter contribute to stretching of the axons at
the interface, when acceleration forces of a blow are incurred
Gray matter (more dense)
Neuron cell bodies
Axons
Stretching damage
White matter (less dense)
Understanding the Brain: The Neurobiology of Everyday Life has provided
a comprehensive overview of the workings of the brain and nervous system, and the
spectrum of pathologies that can affect our families and communities. My understanding of the
complexities of brain health and disease has grown, particularly in the areas of perception and the
special senses of vision and hearing. I will be more sensitive to the differences in others, as I reflect on the
learning I have done in this course. Also, we can all take better care of ourselves when we know the deeper
mechanisms of potential damage to our own brains. Protection is paramount!