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WHAT IS A CONCUSSION?
Concussion is a word that is used to describe a
brain injury which has been caused by violent and sudden shaking of the
brain inside the skull. This shaking usually results in the brain striking
against the rough inside surface of the skull with significant impact and
often includes twisting caused by rotational forces. This creates a brief
deformity in the shape of the brain which produces biomechanical changes
in the brain that disrupt the brain’s synapses causing a temporary loss
or impairment of brain function which produces a variety of physical,
cognitive and emotional symptoms. This impairment can be relatively mild
or it can leave the person in a state of unconsciousness. It should be
pointed out that the majority of concussions do not involve a loss of
consciousness.
It is generally accepted that a concussion results
in functional deficiencies or symptoms may in fact be the result of
“structural” damage to the axons and synaptic connections which
transmit signals between the neurons. Therefore, while the symptoms may be
functional they may be caused by “structural” damage that is too
microscopic to be detected by most normal scanning technology, therefore
the only way of knowing that most concussions have occurred is by
identifying signs, symptoms and behaviours that are consistent with
concussion. That being said, one of the difficulties with brain injury is
that it is not always easy to identify the signs, symptoms and behaviours.
This is one of the main reasons why we are going to spend so much time
examining the signs, symptoms and behaviours consistent with concussion.
Nevertheless, it must be pointed out that a
concussion may be accompanied by structural damages such as a fractured
skull, increased intracranial pressure caused by the swelling of the
brain, ruptured blood vessels inside the brain and damaged muscle tissues
to the neck area. Some of these structural damages may be life-threatening
and need to be either ruled out or attended to immediately. They are
usually easily identified by a medical practitioner who has access to
imaging machines or who is familiar with such injuries.
A concussion is also often referred to as a mild
traumatic brain injury (MTBI), a traumatic brain injury (TBI), or an
acquired brain injury (ABI), so when you see those terms used they all
mean pretty much the same. However, we wish to point out that the use of
the words mild, moderate or severe are beginning to be eliminated from the
description of most brain injuries since there is really nothing mild
about a concussion and the severity of the injury is extremely hard to
determine. Hence, it is said that all concussions are serious since they
are all brain injuries.
A CONCUSSION IS A BRAIN
INJURY!!!!
Before we get into the specific signs, symptoms and
behaviours consistent with concussion, I think it is important for us to
have a clear understanding and to totally accept that a concussion is an
“injury” to the brain. Many people would like to drop the term
“concussion” and simply call it a “brain injury”. Then everyone
might take the injury more seriously.
In fact, a concussion is one of the injuries that
falls under the general scope of a “head injury”. For example, when we
say a person has a head injury, he/she may have a laceration to the face;
an injured eye; a broken nose; a fractured jaw bone; damaged teeth; a
bleeding nose; a fractured skull; a bump on the skull; muscle damage in
the neck region; or a brain injury. So if you say that you have a head
injury, you really haven’t told me anything. You have to be more
specific by identifying exactly which part of your head was injured and
describe the signs or symptoms.
This is no different from a leg injury, a shoulder
injury or a back injury. You must point out which part of the leg is
injured and then detail the injury in order for us to understand the
extent of the damage. If you just say you have a leg injury, I may pass it
off by default as a minor pain or discomfort. If you may say you have
injured your knee, then that makes it more serious and I may suspect that
you will have trouble moving around. Nevertheless, it could be a torn
cartilage, a bruise, a strain, etc. so I may once again pass it off as a
minor knee injury that doesn’t have much of an affect on your movement.
The natural tendency is for us to assume that an injury is minor unless
you tell me otherwise. I automatically assume that if you had a broken
leg, you would have said you had a broken leg and you would not have just
said you had a leg injury. If you say you hurt your hamstring, I will
assume that you have a slight pain or stretching of the muscles. I will
assume that if you had a torn hamstring you would have told me that since
it then establishes the level of seriousness.
The problem with brain injuries is that they are
unlike any other kind of injury you can experience anywhere else on your
body. A brain injury is indeed a type of head injury. However, a brain
injury may have an impact on other areas of your body that were not
injured in the first place. And to make matters worse, a brain injury may
have been caused by a force that does not have to have been applied to the
head. All that is needed to cause a brain injury is for the brain to have
been sufficiently shaken or twisted to the point where it struck the
inside surface of the skull or was somehow temporarily deformed, causing
stretching and shearing of axons and synaptic connections which then
disrupt the chemical balance and communication system that is so critical
to the functioning of the brain, our central nervous system.
The consequences of damage to the brain may be far
reaching and could affect coordination, balance, vision, reaction time,
etc. that render us somewhat disabled in areas that were not injured in
the first place.
So when a person says they have a concussion, we
tend to assume that it is a minor injury that will resolve in a few days
because that is what usually happens. We once again assume that it is
minor. If you say you were unconscious, then it raises our image of the
injury to a higher level. The fact is that being rendered unconscious is
no indication of the severity of the concussion. Some people who lose
consciousness recover from their injury faster than those who do not. Such
is the nature of traumatic brain injury.
But despite everything else we still assume the
“least damage” position and will expect that everything will be fine
in a week or so. To put it in context, if someone approaches you and
simply says they have a leg injury, you may ask them if they would like to
go on a hike with you in a few days. However, if that person is on
crutches and says they have a broken leg, you will likely not invite the
person to go on a hike. So if someone tells you they have a concussion,
but otherwise they look healthy, it is hard to understand what limitations
that person is under. It is even hard for the person with the concussion
to understand why he/she must avoid activity if he/she feels well enough.
The other problem with an injury to the brain is
that it turns the body into a “minefield”. It is very difficult to
know exactly how a brain injury is going to present itself. The symptoms
are unpredictable and every concussion is different. They are like
snowflakes – no two are alike!
Once you go beyond the usual headache, dizziness,
and fogginess, the damages to the neurons, axons and synapses, coupled
with the chemical imbalance and the interruption of normal communication
between the neurons, a brain injury may prevent you from performing
functions that you once took for granted. And you won’t be aware of
these problems until you try to perform those functions.
For example, until you try to tie your shoelaces,
you may not be aware that you cannot remember what to do. You may not be
aware that the brain injury has changed your ability to recall material
for exams until you write an exam. You may not be aware that your brain
injury has affected your ability to catch a baseball until someone throws
a baseball at you and routine catch becomes a real challenge.
The other problem with a brain injury is that some
of the symptoms take a long time to resolve. While your brain is in
recovery or rehabilitation mode, you are more vulnerable to further
damage, not necessarily to the area of the brain that was damaged in the
first place, but to other parts of the brain that escaped the first
injury. Imagine if you twisted your left ankle and decided to rest that
ankle until it felt better. Then imagine that once it felt a bit better
you tried walking on it before it healed fully. You find that you can walk
very gingerly but you know that the ankle has not healed yet. Now imagine
that while you were testing your ankle your wrist suddenly broke for no
apparent reason. There is no connection between your wrist and your ankle,
but you now have a strained ankle and a broken wrist, so you are even more
disabled than you were in the first place. You realize that if you would
have waited a bit longer for your ankle to heal fully your wrist
wouldn’t have broken.
That is how it is with a second brain injury that
occurs before the first brain injury has healed. In the ankle example, you
would have understood if the ankle became more painful and your injury was
confined to the original location. That means that your functional
disabilities would continue and your actions would be limited due to the
ankle injury. But if your wrist breaks because you tried to test your
ankle, then you have a whole other set of symptoms that are going to cause
much more widespread dysfunction. Now you’ve got an injured ankle and a
broken wrist. This time you are definitely going to take longer to heal
and you are going to be a little more hesitant to try to return to normal
too quickly for fear of causing some other damage to another unknown part
of your body.
Keeping with the analogy of the injured ankle and
the wrist, imagine if you were resting your ankle and while you put
pressure on your wrist by lifting a heavy object, your ankle started to
hurt again. That is what happens with a concussion. The only way to make
sure that your ankle doesn’t suffer any further damage is for you to do
nothing – to go through a period of time when you are at complete
physical rest. So when you have a concussion, the only way to be sure you
won’t do any further damage to the injured parts of your brain is for
you to do nothing – physically or mentally.
Imagine a major fire breaking out in a part of the
city which requires virtually all of the firefighters to be called out to
battle the blaze. While they are fighting the first fire, it puts the rest
of the city at greater risk. If another fire breaks out on the other side
of the city while the fire crews are fighting the first fire, not only
will it take longer to get to the other fire, but the attention that is
available to give to the first fire will be reduced and the damages will
be greater to both areas.
Now imagine what happens in the brain when a
student-athlete suffers his/her first brain injury and no one spots the
signs, symptoms or behaviours consistent with concussion. The
student-athlete may inadvertently go back into the game and receive a
second brain injury which has much more serious consequences because of
the vulnerability of the brain from the first injury.
That is why it is so important to identify that
first injury.
Keep in mind that your brain is the central nervous
system of your entire body. When you disrupt the communication system you
are causing problems that are widespread in scope and it is very difficult
to know exactly what symptoms that disruption is going to cause. And if a
second disruption occurs while the brain is repairing the first damaged
areas, then all of the other connections are at risk.
For example, you may buy an airplane ticket to fly
from
Toronto
to
Japan
. Imagine how frustrated
you would be if it is sunny in
Toronto
and
Japan
, but there is a storm
in
Vancouver
. Since you were
supposed to stop in
Vancouver
on your way to
Japan
, the storm in
Vancouver
will delay your flight
from
Toronto
and you will not be
able to get to
Japan
. You will have to wait
until the storm clears up in
Vancouver
before flying out. But
then, once the storm clears up in
Vancouver
, it may still be a
while before you can take off from
Toronto
because there may be a
back up of flights that have to get to
Vancouver
before you.
Your only other choice is to see if there is another
way to get to Japan, so you may try to get a flight to
San Francisco
and then go to Japan
from there. It is possible, but it may take a bit longer for the flight
and you may need to wait to get a ticket to
San Francisco
to make the connection
to
Japan
. While you are doing
this,
Vancouver
may open up and now you
don’t know what to do because you already have your new ticket to
San Francisco
. You may decide that
you will use the
San Francisco
route to
Japan
from now on, but that
means that future flights may be longer and more costly. Eventually, you
may try to go back to your normal route through
Vancouver
. However, if enough
people thought the way you did about establishing a new connection through
San Francisco
, the airlines may have
decided to cancel the route from
Toronto
to
Japan
and you will have no
other choice but to follow the new path forever. That is what happens in
the brain to the connections between neurons as a result of a brain
injury.
HOW IS A CONCUSSION
CAUSED?
We are obviously focusing our attention on
sport-related concussions, but we should remember that a concussion can be
caused by any kind of activity that causes the head to move rapidly and
change speed or direction. This sudden change in speed and/or direction of
the head is what causes the brain to shift inside the skull. The brain is
a soft, jelly-like substance that is suspended in cerebrospinal fluid, so
if you move the “container” rapidly enough, the brain will push
through the protective cushion provided by the fluid and will smash
against the surface of the skull, crushing and deforming its normal shape.
It will momentarily bounce and twist until the movement of the head
ceases. All of this can happen in a split second.
It is important to note that this rapid movement of
the head does not necessarily have to be the result of a blow to the head.
In fact, the actual contact can be made anywhere on the body. If that
contact with the body causes the head to change direction rapidly, then
damage to the brain inside the skull may result. Admittedly, the blows to
the head are the ones that cause the most damage, but any blow to the body
should be cause for concern when it comes to identifying the signs,
symptoms and behaviours consistent with concussion.
No matter what definition you use, the fact remains that a concussion
changes the way the brain functions. What is not known at this time is how
long or how permanent the damage will remain.
Many people refer to a concussion as a "mild Traumatic Brain
Injury" or a temporary TBI. You will often see the definition include
reference to the "rapid onset of short-lived impairment of
neurological function that resolves spontaneously". However, there is
great debate going on now as research points that the impairment of
neurological function may not repair as rapidly as once thought and the
resolution may not be as spontaneous as we had hoped.
This temporary impairment may be true for the most obvious symptoms such
as headache and dizziness, but the long-term impact of a concussion may
result in impairment of emotional and psychological functions as a result
of the changes that occur in the brain.
In fact, there are studies that have found middle aged adults who
suffered concussions while in college exhibiting premature brain aging and
deficiencies in concentration, balance and motor control many years after
suffering their concussions. It is most likely that most people who are
suffering from these kinds of functional deficits may simply attribute
them to normal aging and getting older, not even relating any symptom or
deficit to their history of concussions. And yet, there may be things they
could have done during rehabilitation that might have reduced or
eliminated these functional deficits, thus impacting on their quality of
life many years after the injury. Our goal in developing the most
effective student-athlete concussion management program possible is to
reduce the long-term consequences of sport-related concussions.
A
CONCUSSION IS A PROCESS – NOT AN EVENT
Evidence is being produced by researchers which proves clearly that a
"concussion is a process". It is not an event. And this process
does not simply involve "healing and recovery". Many symptoms of
concussion do not present themselves for hours, days, weeks or months. In
fact some people admit to experiencing concussion-like symptoms for many
years following an injury.
We will concede that there may well be a rapid onset of short-lived
impairment of neurological function in some areas that resolve
spontaneously, but what about the long-term impairment that does not
resolve. What about personality changes? What about anxiety and mood
disorders? What about interpersonal relationship skills? What about one's
attitude towards life? These are all recognized as signs and symptoms of
concussion but they are also unfortunately accepted by most people as part
of growing up and normal development. They may not be that normal after
all.
Admittedly, we all change our personality slightly from time to time. We
all have periodic bouts of anxiety and we are all moody from time to time.
We all have some difficulties with relationships and our attitude towards
life is often affected by our environment and the people around us. But
for young people who suffer a concussion, are these changes part of their
natural evolution, or are they consequences of their brain injury? And is
there something we can do to reduce the risk of life-altering
consequences?
Symptoms of a concussion may also not be evident until you are required
to perform a specific task. For example, you may not even know that you
are no longer able to recall math facts until you are asked to recite your
times table. You may not realize that you get dizzy riding a bike until
you have a chance to ride a bike. You may not know you have problems
adjusting your vision when things are being thrown quickly in your
direction from the side until this actually happens. These symptoms take
time to present themselves and they will only be noticed if you have
people around you who are looking for signs and symptoms of concussion.
That is why we recommend using the "partner approach" to
concussion management.
WHAT HAPPENS DURING A CONCUSSION?
Axons get their shape from internal structures called microtubules which
look like a string of sausages strung together. As the shape of the brain
gets temporarily deformed from the twisting or rapid acceleration and/or
deceleration, the axons may stretch or break. Normally, since your brain
is constantly jiggling like a mold of jello, axons are often stretched
gently with no damage to any of the internal skeletal structure that is
found inside axons. This is what is often referred to as a “slow
stretch”.
If the axons are stretched too quickly, they tend to stiffen up causing
their internal skeletons to become destroyed and the axons will shear,
causing a total interruption of signals. In most cases, concussions are
mild traumatic brain injuries where the axons do not actually shear, but
rather are stretched with enough force that they don’t quite rip apart
but still sustain significant damage to their internal skeletal structure.
For example, if the axon is stretched hard enough, the microtubules that
act like conveyor belts carrying nutrients from one end of the axon to the
synaptic connections in its network may break at some point. When this
“conveyor belt” is broken, the supplies that are being carried will
continue to flow but they will basically “fall off” at the break and
will collect inside the axon. This causes a “bulb” to form inside the
axon. More importantly, it may prevent the part of the axon beyond the
break from receiving the nourishment and supplies it needs to survive.
Eventually, the part of the axon that is not receiving nourishment will
wither away and die, thus disconnecting from the original axon. That means
that signals that would normally have gone along that axon will no longer
get through. This then causes the axons with the bulbs of protein to also
shrivel up and die because they can no longer do what they are supposed to
do and the neuron will die as well. All communication that was conducted
that one neuron will then cease.
There are some injuries where the damage is beyond repair, but the
communication is still continuing in a faulty manner. The signals are
getting through but they are not clear. In this case the damaged
connection may end up corrupting the entire system with static
communication.
Dr. Douglas Smith of the
University
of
Pennsylvania
and a number of his colleagues have done extensive research on concussions
and axonal damage. What they found is that if you stretch an axon gently
the first time, it produces an increase in the number of tiny pores that
line the outside skin of an axon. These pores allow sodium and calcium to
come inside. If you stretch the axon gently a second time shortly after
the first time, these tiny pores became enlarged and sodium and calcium
came rushing in.
Other scientists had previously discovered that increased levels of
calcium in an axon created an enzyme that actually ate away the internal
structure of the axon. Therefore, the implication is that if a person
suffers a seemingly minor blow to the head or body, there may not be any
obvious symptoms of concussion present, but the stretched axons will be
extremely vulnerable if there is another minor blow. That is why some
people are surprised when they receive serious concussion-like symptoms
from what seemed like a very small force. It’s because the axons were
vulnerable at the time from the stretching caused by the first blow.
“THE
METABOLIC CASCADE”
When
the brain suffers from a force as a result to a blow to the head or some
other part of the body, it experiences a "power surge" producing
an extreme amount of chemical neurotransmitters, effectively
"lighting" up the entire brain with electrical charges. This
surge only lasts a minutely brief period of time and seems like a
mini-seizure. The physical movement causes neurons and axons all over the
brain to be pulled, twisted and stretched. Doctors call this a “diffuse
axonal injury” because it causes injury to axons from a number of
different places in the brain. It doesn’t affect a single area of the
brain.
The
neurons send out signals through the axons to allow sodium and calcium to
enter through the tiny pores on the outer skin that have been enlarged by
the twisting and stretching. At the same time potassium is allowed to rush
out of the neurons through the axon openings. The problem with too much
sodium is that it also brings in water which can cause swelling of the
axons and thus dangerously increase intracranial pressure. Calcium
produces an enzyme that eats away at the internal structure of the axons.
Once
the initial power surge is over, the brain immediately attempts to restore
the equilibrium and get things back to normal levels. The first thing the
neurons do is send a signal to pump potassium back into the axon and pump
sodium back out. The potassium counteracts the effects of sodium by
neutralizing its electrical charge. This process requires a lot of energy
which is usually produced inside the neuron by something called the
mitochondria, which acts like an internal power plant for each cell.
The
mitochondria require fuel in the form of glucose to produce energy.
Glucose is carried to the neurons by the blood flow in the brain. The
demand on the cell for energy causes a drain on the supply which causes
the brain to lose power and operate on a slower speed. The brain then
demands for an increase in blood flow in order to bring in more glucose to
the mitochondria to repair the damaged areas. However, the message somehow
is disrupted and the blood flow to the brain is actually slowed down. No
matter how many signals the neurons send out for more fuel, there is no
increase in blood flow and the cells are in danger of dying. Because of
this the brain releases high quantities of potassium in order to try to
calm things down even more.
It
is common for student-athletes who have suffered a concussion to complain
about feeling groggy or fatigued. This is because the brain is placing
such a high demand on the energy being produced by the body. Consider that
under normal circumstances, almost 25% of the energy being burned up in
your body is being used by the brain. When the brain suffers a trauma, the
demand goes up even higher, but the body refuses to provide that energy,
actually reducing the flow to the brain. Hence, you feel very tired and
disoriented.
Since
each
dendrite or axon may be part of a communication line that carries impulses
to thousands of nerve cells as it winds its way around the brain, any
damage to an axon or a synaptic connection can impact many areas of the
brain in the network other than just the area where the original damage
was caused. This domino affect can cause symptoms that may seem unusual
based on the point of impact, but neurons in one part of the brain connect
to neurons in other parts of the brain and may be part of a communication
link with many other functions.
This is why we often see a variety of symptoms when a person suffers a
concussion. The damage can affect your cognitive, physical, emotional and
psychological functioning and it can play havoc with your sleep patterns
and relationships.
Please
go to the following link on Signs, Symptoms & Behaviours for more
detailed explanations about how to identify a concussion. CLICK
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