- [Voiceover] So, someone with cerebral palsy can fall
kinda anywhere along this really wide
spectrum of movement impairments,
and what sort of dictates where
they'll end up on the spectrum,
so how severe their movement impairments will be,
well that really boils down to two things,
so, one, where the brain is damaged
or underdeveloped or impaired,
and two, how severe the damage is.
And just to jog your memory, this damage,
it occurs because of some event
like an infection or a stroke that happens
during really critical periods of early development,
anywhere from in utero, as a fetus,
to the first few years of life.
So, there are actually three main
movement areas in the brain that,
when damaged or impaired in some way,
can cause cerebral palsy, and,
depending on which movement area is primarily affected,
well, that's what will determine
what type of cerebral palsy the person has,
because remember, cerebral palsy is actually
an umbrella term that describes a few
different disorders that affect movement.
So, let's check out these different types,
and the first movement area that we'll look at
to see what type of cerebral palsy
generally develops if it's damaged
or impaired in some way is the motor cortex.
So, here's the motor cortex here,
and the motor cortex, what it is really important for
is helping us plan and control and make voluntary movements,
and in order to do that, in order to
help us accomplish our voluntary movements,
the motor cortex uses these special
neurons called upper motor neurons,
and it uses these to communicate messages to our muscles.
So these upper motor neurons, what they do is
they head off from different parts of the motor cortex,
and they come together with neighboring
upper motor neurons to form these highways
that we call the pyramidal tracks,
pyramidal because the neurons go through
these structures called the medullary pyramids
in order to reach their destinations
in the brain stem or the spinal cord,
and tract just means a bundle of axons,
so the axons of these upper motor neurons.
So it's these tracts, these highways
of upper motor neurons that our
motor cortex uses to control our muscles.
So, when the motor cortex itself
or these pyramidal tracts are damaged
or underdeveloped or impaired in some way,
some of our muscles might not be able
to get the right messages from the motor cortex,
the messages that control their activity,
and when this happens, the sort of net result
is that the affected muscles get too active
and their muscle tone increases.
Now, muscle tone, when we say that,
what we're talking about is the
amount of tension in the muscle.
Think of it when you're stringing
a guitar or a tennis racket.
The tighter you pull the strings,
the more tone, the more tension that they have.
So, this increase in muscle tone is kind of like that.
It makes the muscles really tight,
really stiff, and difficult to move.
So, let's actually write this down, stiff,
because stiff actually describes
our first type of cerebral palsy,
this type of cerebral palsy that's
caused by damage to the motor cortex
or the upper motor neurons in the pyramidal tracts.
So, the official, sort of medical name
for this stiff type of cerebral palsy
is spastic cerebral palsy, and spastic
is just describing the person's tight, stiff muscles.
Now where someone with this stiff type of cerebral palsy
falls on our severity spectrum, here,
that largely depends on how many of their muscles
are affected by this stiffness.
And we actually see a few patterns
of this muscles stiffness in people with cerebral palsy,
so let's check some of these out.
So, sometimes the muscles on both sides
of the lower body are affected by the stiffness,
so, when this is the case, what often happens
is that some of the muscles in the legs or the thighs,
they can become more active than
other muscles in those areas,
and so the overactive muscles,
they kinda override the less active ones.
So, one of the more common examples of this
are the muscles in the inner thigh.
These muscles are what we use to
pull our thighs together and rotate them inward,
but in spastic cerebral palsy,
what often happens is these muscles,
they get really active, so they start to
constantly pull the legs together,
and constantly rotate them inwards like this,
and if this gets really bad, the knees can actually
start to cross over each other,
sort of like a pair of scissors.
So, because of this, we call this scissoring,
or we may say that the person has a scissored gait.
So, these overactive muscles, they're really stiff, right,
so it's really hard for the person
to get out of these positions,
and another pattern that we commonly see
is that the person with spastic cerebral palsy
in both of their legs here, they walk around
on their toes, on their tiptoes almost,
and this happens because the muscles in the calves
get really tight and they pull the heel up like this,
so this forces the person onto their toes.
So, another sort of pattern of cerebral palsy
distribution that we can see with this stiffness
is stiffness in the arm and the
leg on just one side of the body.
So, let's say it's the person's right side here,
but it could be on their left instead.
So, in this case, the person will often
still have the same sort of gait problems,
like scissor walking and toe walking,
but this time it will just be on
the one side here, the side that's affected,
and on their upper body, we'll see
the same sort of thing that we see in the legs.
Some of the muscles become more active than others
and they kind of override the less active muscles in the arm
So, the muscles that bend the elbow
and bend the wrist like this, these are the ones
that get really active, and so they get really stiff,
and they pull the arm and the hand into these
flex positions that are really difficult to move out of.
Now, the most severe version of
this stiff type of cerebral palsy
happens when the muscles in the arms
and the legs on both sides of the body
are affected by the stiffness,
and often muscles other than the limbs
are affected as well, like the muscles of the tongue,
maybe the face, the vocal cords,
and you can imagine, with these muscles also being stiff,
this can make it hard for the person
to eat and swallow and speak.
So, these are some of the main patterns
that we see of this stiffness.
So, in these first two cases, if the upper motor neurons
that are helping to control these affected muscles
aren't too badly impaired, these people might be able
to get around okay without too much assistance.
They just might be walking a little bit slower
or they might have some trouble
with running or jumping or walking on tricky terrains
like those that are uneven or steep,
but otherwise they can get around okay,
so maybe they'd be around here
on our severity spectrum, on the more mild side,
but if the upper motor neurons controlling these muscles
are really impaired, then these people might need
a little bit more help getting around.
They might need crutches or maybe a walker or a wheelchair,
and this would put them a little bit more
towards the sever end of our spectrum,
maybe somewhere around here, and for these people here
with the stiffness on one side of the body,
if this stiffness is pretty bad,
this could make it more difficult
to operate crutches or operate manual wheelchair,
so they might need a powered wheelchair
which would put them a little bit further
down our severity spectrum, here,
and for someone with this stiffness
in all of their limbs, they'll usually be all the way
over here on the far end of our spectrum,
the most severe end.
They'll likely need to be in a wheelchair.
They'll need assistance getting around,
help with things like eating and getting dressed,
because their muscles stiffness is too widespread,
it's too severe, and it makes it too hard
to move all the affected body parts.
So that's our stiff or spastic type of cerebral palsy,
and this, actually, is the most common type.
The vast majority of people with cerebral palsy,
about 70% to 80% have one of these
stiff types of cerebral palsy.