Hi and welcome to Nursing School Explained!
Today's topic is spina bifida or neural tube defects. So let's take a look at
this. So spina bifida is defined as a neural
tube defect due to incomplete closure of the vertebra and the neural
tube in utero. So keep in mind when the embryo first develops, it's basically
just a, it starts as a tube that eventually grows and grows and
grows and then it develops into the brain, the spinal cord and then all
the limbs and so forth develop. And when there's a neural tube defect, it
usually happens in the first three to four weeks of pregnancy when the neural
tube starts to bend and fold in week five. Now the neural tube defect usually
occurs at the level of L5 to S1. Let's take a look at the different levels of
neural tube defects that can happen here. So I have drawn out the vertebra here in
pink, the nerve roots in blue, and then the layer of skin on the back basically
in green. So if you look at it here, the vertebra, every nerve root innervates a
vertebra, and then it's covered by a layer of skin. And in spina bifida
occulta, that basically just means there's kind of a gap here and there may
be a tuft of hair at the level of that L5 to S1. There is no herniation of the
spinal cord or the meninges. And remember the meninges is kind of like the lining
of the brain and the central nervous system including the brain and the
spinal cord. Where in spina bifida Cystica we have
to distinguish between meningocele and then myelomeningocele. So
in meningocele again we have our vertebra and the nerve roots and then
because the neural tube defect here, we have this sac-like protrusion here that
is filled with cerebral spinal fluid. Remember that the brain and spinal cord
are cushioned by cerebrospinal fluid to allow for movement and lubrication, so in
this case there's this protrusion here, this herniation that's filled with
cerebrospinal fluid. Now in myelomeningocele we again have this sac-like
protrusion but now there's not only CSF in here, but also some of these nerve
roots are coiled up in this sac and basically protruding, permeating into
there. And then the severity of symptoms that the patient will have will depend
on the level, so is there herniation, is there only CSF that's protruding or
are there also nerve roots that have escaped into the sac-like protrusion?
Now keep in mind that all the different vertebra control different levels of
organs and also controlling the lower extremities. So the more severe the nerve
roots are involved and kind of tangled up in this sac-like protrusion, the more
severe the patient symptoms will be. In at the level of L5 S1 is where the nerve
roots break off that also control the bladder and bowel and we'll come and
look at those complications in a bit here. Now causes: typically unknown but
neural tube defects are linked to maternal folic acid deficiency. And the problem
with this really is that this neural tube defect happened so early in the
pregnancy, in 3 to 4 weeks of gestation, that some women might not even know that
they are pregnant and they might not know that they are folic acid deficient,
which is why the recommendation is that any woman who is trying to conceive or of
childbearing age should either take prenatal vitamins including folic acid,
or just a folic acid supplement to make sure that they have enough folic acid in
their system to hopefully prevent that neural tube defect that happens early in
the pregnancy. Now for signs and symptoms: they will depend on the degree of the
protrusion, so it'll depend if it's spina bifida occulta or if it's cystica
with meningocele or myelomeningocele . So again, depending on if the nerve roots
are involved or not, the patient might have no motor impairment, they may might
have complete control over their lower extremities, or they might have
completely flaccid lower extremities, depending on how many nerve roots and
what nerve roots are really involved here. Now diagnosis of spina bifida
usually happens with an alpha-fetoprotein test at 16 to 18
weeks of gestation, and if that comes out positive, usually an amniocentesis and
fetal ultrasound are recommended to investigate
a little bit further. There are a couple of different treatment options: so first
this has to be surgically repaired. So first option is to do this in utero,
prenatally and this can be done at 19 to 25 weeks of gestation and you can
imagine what kind of complications can happen here when the baby is still in
utero and you're trying to have surgery on that embryo, or that infant in this
case. But the advantages, if it's done prenatally, there is a decreased
incidence of hydrocephalus and Chiari malformation. And hydrocephalus I'll be
discussing in more detail in a different video, but Chiari malformation basically
means that, this is the spinal cord here in blue and on top we have the brain. So
if there is now a protrusion over here, parts of the brain, depending on the
severity of the sac and the level of protrusion and herniation, it kind of
creates a suctioning effect, which means that part of the brain cannot get sucked
down into the spinal cord and this is called a Chiari malformation. And then
that might have complications as of developmental and cognitive
complications in the patient. So prenatal surgery which was discussed and the
benefit is that it would decrease that sucking of the brain down to the spinal
canal hopefully preventing some of those complications. Now we can also, surgery
is also performed postpartum, but there is an increased risk of infection and
death in the infant. Just imagine this is a very delicate
sac that sometimes even almost kind of like like see-through and we don't want
to, when this patient is born they are usually born by c-section because
squeezing the infant through the birth canal might disrupt this the sac
and then the contents will will spill and causing a whole lot of problems here.
But also postpartum surgery will put the patient at an increased risk of
infection and because again of the degree of the nerve root involvement
here, the patient will need lifelong management of their orthopedic, neuro
and urinary problems. And let's just skip down here to most common complications
are neurogenic bladder and neurogenic bowel. Again, because if these nerve roots
that usually control bladder and bowel function are impaired because of this
myelomeningocele, the bladder and bowel function are not going to be intact,
which a lot of times means that the patient won't have control or the
sensation that they need to urinate or defecate, which sometimes will lead them
to need to do, perform self catheterization in order to empty their
bladder. And another complication is constipation because again they don't
get the sensation that they have to defecate therefore there's going to be
very strict bowel regimen keeping them hydrated so that they can actually
defecate, hopefully normally. And then post-op management if this is done
postpartum, you definitely want to monitor for leakage from that repaired sac
because that could be cerebrospinal fluid
that's escaping there. We certainly want to assess for an infection. Imagine if
you have now surgically removed the sac and kind of repaired these nerve roots and now
you have an infection inside it's a direct pathway into the central nervous
system through the cerebral spinal fluid that can lead to an infection in the
brain, so meningitis, encephalitis. And then as well we want to assess distal
sensation because again these nerve roots control the lower extremities so
we want to make sure to see is there sensation, is there movement, how is the
patient doing post operatively? And another complication is hydrocephalus,
which I'll be discussing in a different video here in and on itself. So in
summary, spina bifida is a chronic neurological or orthopedic and
neurological disorder that happens early on in development, it can be linked to
maternal folic acid deficiency, so it is recommended that a women of childbearing
age have appropriate levels of folic acid in their system so that during
early fetal development this neural tube develops normally and spina bifida is
prevented. Thanks for watching Nursing School Explained, I look forward to
seeing you next time!