In this lecture, we'll discuss
a variety of problems
that happen structurally with
children's brain and skulls.
In particular, we'll focus on hydrocephalus
So, let's start by remembering
the basic pathophysiology
of increased inter cranial pressure.
When you see a patient with inter cranial
there are is an expansion of one
of the three major components of the brain.
One maybe brain tissue,
another maybe blood within the brain,
and another maybe cerebral spinal fluid.
The normal ICP is about 8-12mm of mercury
If this goes up,
because of an excessive amount of either
blood tissue or cerebral spinal fluid,
the problem is that the skull
has encased the brain
and the only way out for that brain
with its increased pressure is down to
the foramen magnum.
The reason why that is a problem is
several of the vital areas
of the brain such as the pons
breathing and heartrate
will be damaged as that brain
herniates and it can cause
even an instant death.
increased intercranial pressure or increased
CSF is made by the lateral ventricles.
so, those side ventricles
are where it is made.
It flows down through the ventricles
in a system of collecting ducts
into the spinal cord.
It flows down to the spinal column
and then if flows over the top
and it is reabsorbed back to
in the dural venous
Adults make and reabsorb
a half a litre of spinal fluid a day.
children a bit less.
But the point is we are all day long
making and reabsorbing
this cerebral spinal fluid
in large amounts.
So, you can imagine if there is
stricture in the system.
or a problem with the adequate
drainage or reabsorption
you can have a problem with increased
and that in turn results in
increased intercranial pressure
And this leads us to hydrocephalus.
Hydrocephalus has two major
Communicating and non-communicating.
Non-communicating is where the
Cerebral Spinal Fluid
simply cannot get out of the brain.
It is stuck for some reason.
There are several causes and
many of those are congenital
and show up in childhood.
An example would be Aqueduct stenosis.
Or atresia of the outflow foramina
of the 4th ventricle.
This is called a Dandy Walker cyst.
Also patients may have a Chiari malformation.
I'll talk about what these are
in a bit.
Also, patients can develop acquired causes
of non communicating hydrocephalus.
Example would be a posterior fossa
or a vascular malformation that arises.
Babies may have communicating
CSF in utero.
But then on their way out suffer
an intraventricular hemorrhage.
that can cause scarring and edema,
which can then obstruct the flow of CSF
and cause hydrocephalus.
Also, patients can have
a communicating hydrocephalus.
This is essentially an inability to
reabsorb the CSF
that's already been produced.
So, in hydrocephalus, how do patients
Well, children are more likely
to have this than really at any age
in the age group. This presents
with poor feeding
But what's key is they will actually have
an enlarged head.
This is one of the major reasons
why we screen all children
by following their head circumference
through the first several years of life.
This exam will usually show
macrocephaly as you can see in this child.
So, if we are worrying about hydrocephalus,
we have an abnormally
large head circumference,
we then want to scan the child's brain
to see what is going on.
This diagnosis can be made
by CT or by MRI.
CT has the risk of
Whereas MRI may have the risk
there are new techniques being
developed in MRI, where we can assess the
vague areas of where the
ventricles are enlarged
without delving into the
details of tissue abnormalities
and this can be done relatively quickly.
Sometimes we can get it done on a baby
without sedation at all.
And that is now becoming our
to both avoid sedation and
If a child has a problem
with draining CSF out of their brain,
regardless of the cause,
We are going to help them drain that
Because the size of the brain will
continue to increase
inside the enclosed
skull and problems will arise.
This is where VP shunts come in.
A ventricular peritoneal shunt
is a tube that is implanted into the
area of the brain which needs assistance
and then that shunt
is tunneled underneath the skin
along the back of the skull
down along the neck.
And then it burrows underneath
the clavicle and down through the chest
into the peritoneal cavity.
Typically, when they place this,
they would put
an extra amount of tubing into
the peritoneal cavity
because as the child grows, this tube
is going to be stretched
and they need some room for growth.
After placement, we expect this child
to be able to drain the csf
and have a cessation of symptoms
that is caused by the hydrocephalus
such as perhaps vomiting, altered mental
status or seizure.
There is some risk with VP shunt
The first is infection.
Children with fever and a recent
need to be evaluated for a potential
of a shunt infection.
And this is a tricky thing
because checking the shunt directly
for infection with a needle
and sampling some of
that cerebral spinal fluid out of that shunt
actually bears a risk of introducing
infection into that shunt.
So, we need to very careful about who
are we evaluating for shunt infections
and who we aren't.
Almost always shunt infections will
happen within six months
of the operative procedure that placed
or revised that shunt.
In other words, if a patient hasn't had
a shunt problems in years,
and now they're
presenting with fever,
it is much less likely that this is
a shunt problem.
Shunts can and do often fail.
Failed shunts are a common problem
for these patients.
Basically, proteinaceous material are some
reason why the shunt either breaks
as the child has grown.
Or there is trauma or it gets clogged up by
and the CSF stops draining.
In a patient with a shunt, if they represent
the findings of increased ICP,
we have to check for shunt failure.
If the shunt is suspected to have failed,
then we will obtain something
called the shunt series.
The shunt series is a series of X-rays
including the skull and neck
chest and abdomen, where we look
at the integrity of the shunt
through multiple views to look for
cracks, or kinks or disconnections.
If the shunt series is normal,
we can say that there hasn't been
a disruption in the line
but we can't say whether or not
a child in fact
has a proteinaceous clog that is
preventing the flow of the fluid.
So, on the back of the child's head
as you palpate the shunt,
you will notice a small reservoir.
This is a pump.
The pump has a valve in it.
And there are many different type of shunts.
And I can't go through all the different
types of shunts, and how they are designed
and how they are pumped.
But typically there is either a one pump
or a two pump system.
You can pump this shunt
through guidance. I wouldn't try it yourself
for the first time
and what that would do
is it will allow you to test
whether cerebral spinal fluid is both flowing
and distantly to that valvular
This is a good quick way to check
if the child's CSF is draining
through the shunt.
The problem is that pumping the shunt
can itself lead to shunt failure.
So, we don't want to pump the shunt
unless we absolutely have to.
And even then, some practitioners suggests
that we should really leave the shunt pumping
to the neurosurgeon so that it is
accessed less frequently.
So, don't pump the shunt
unless you're stucked.
Let's move on to the Dandy-Walker variant.
The Dandy-Walker variant is an unusual
type of obstruction of CSF.
It results on a cystic dilation of that 4th
as you can see in this patient here.
Very remarkable dilation
of the 4th ventricle.
It is associated with teratogens,
and chromosomal abnormalities
such as say down syndrome.
These patients will present very early with
Usually, within the first three months.
Again, it is treated with shunt placement
but it is different because it is not
the lateral ventricles that are affected
it's that 4th ventricle.