Our topic is Hirschsprung's disease.
In other words, this
is toxic megacolon.
Now, Hirschsprung's disease is
quite, quite straightforward
for the pediatric population.
There something called the
enteric nervous system,
do you remember that from physio?
That enteric nervous
very much like your
parasympathetic nervous system,
and by that, we mean you've
heard of rest and digest.
You need the parasympathetic
with having its own
pacemaker known as your --
you've heard of the cell -- the
interstitial cells of Cajal?
And that pacemaker allows for the intestine
and really the GI to move forward,
And allows for the sphincters to relax so
that you move the food forward, right?
Welcome to parasympathetic.
This muscle contraction that you find,
let's say in the esophagus, in
the stomach, and in the intestine,
all of that is a particular plexus
of your enteric nervous system
and that plexus that
I'm referring to is –
What is it?
The myenteric plexus,
a.k.a. Auerbach plexus.
That's the plexus that you should be
focusing upon in Hirschsprung's disease
and specifically enteric nervous system
because that's the muscle plexus
that allows for contraction.
What gives rise to enteric
nervous system embryologically?
It's called the
neural crest cells?
If the neural crest cells do not migrate
properly down in the intestine,
You are not going to develop
your myenteric plexus properly.
So if myenteric plexuses are not
present in that part of the intestine,
you’re not going to have contraction.
You tell me. Is this a
functional type of constipation
or is this going to be an
obstructive type of disease.
This is actual functional
obstruction, not mechanical.
You've lost your plexus.
Failure of neural crest cells.
Therefore, this is a functional obstruction
because you can't move forward.
Welcome to toxic megacolon.
Constipation in a neonate should be
considered Hirschsprung's disease
until proven otherwise.
That is how important this is.
Constipation in a neonate.
Look at your population here.
Remember the three populations,
you have your neonate
and had your infant and
then you had your child
going into adolescence.
What do you want to do to confirm
your diagnosis of Hirschsprung?
You do a biopsy.
So now, use common sense,
here's your intestine and the
enteric nervous system isn’t there.
The myenteric plexus is absent.
Therefore, upon biopsy
of that region,
that has now become
damaged or is not moving,
you'd expect to find
no ganglion cells.
Absence of ganglionic cells
or aganglionic segment.
So what then happens, here's
my functional obstruction.
If things don’t move forward, what
are you going to find proximally?
Anytime you have obstruction
distally, proximal dilation.
Hence, we call this toxic megacolon.
Now, it's one cause of toxic megacolon.
There are other causes and, for example,
you could have an adult who then
suffers from Chagas' disease
and that will be obviously
But here specifically
with pediatric neonate,
and you're thinking about Hirschsprung,
failure of neural crest cells.
You'll notice the
following here on x-rays.
The first on your left pretty
much showing a massive megacolon.
And on the right, you'll
notice there as well,
that is a massive megacolon.
And distally, you'll find that things
are a little bit more narrowed.
If you were to then take
the area that's narrowed,
that's the area of the pathology,
not the dilated part.
The dilated part
wants to contract,
but it can't move forward
because the distal portion
doesn’t have the
So that area that is
You do a biopsy of that and
you're not going to find what?
Surgical resection of
affected segment of bowel,
really it's the only option
that you have at this point.
of ganglionic cells,
so therefore you've lost
–- or the intestine --
has lost the autonomic innervation and
thus, resulting in functional obstruction.
Signs and symptoms is because this
is failure of neural crest cells,
You are looking at congenital issues,
so therefore there's no
passage of that early stool.
In other words, within the first 24
hours, the meconium is not passed.
Obstruction leads to bowel
dilation as I've shown you
both on x-ray and on
physical specimen as well.
Your barium swallow would show you
exactly as to what you'd expect
with an enlarged
And biopsy once again will show
you absent ganglionic cell.