Okay guys, we have a classic USMLE question here and it is difficult, so let’s jump right in.
A six-year-old boy is brought in for evaluation by his adoptive mother due to having trouble starting first grade.
His teacher has reported that he has been having trouble focusing on tasks and has been acting out while in class.
His family history is unknown as he was adopted two years ago.
His temperature is 36.2 °C, the pulse is 80, respirations are 20 and blood pressure is 110/70.
Visual inspection of the boys face shows a low set nasal bridge, a smooth philtrum, and a small lower jaw.
Which of the following findings would also likely be found on physical exam?
Answer choice A: Holosystolic murmur.
Answer choice B: Wide-notched teeth.
Answer choice C: Limb hypoplasia
Answer choice D: Cataracts
Or answer choice E: Congenital deafness.
Now take a moment to come to an answer by yourself before we go through it together.
Okay, this is a classic USMLE question and I have to say, this is the kind of question you will see on USMLE.
This is not the most common question, this is what separates the top, top scores from the normal scores
is getting these very challenging questions correct.
So let me show you how to get them so you can kill the exam.
Now, for the question characteristics, this is a pediatrics question.
We got a six year old kid coming in with problems, six year olds fall under peds.
Now, this is actually a three step question -- that’s right.
Not a one step, not a two step but a three step.
This is what separates, like I said, the top scores of USMLE from those that sit in the normal range.
And the stem of course is absolutely required, this is a three step question,
we got to pull a lot from the stem and figure out what's going on.
So, the three steps we have to do here are a bit complex.
The first thing we have to do is simply determine the diagnosis of what the patient has,
then based on the diagnosis we have to figure out associated symptoms with that diagnosis
and then the third step is to pair one of those associated symptoms with the appropriate answer choice.
So let’s start.
The first thing to do let’s figure out the diagnosis.
Now, we have a six year old male patient coming in and the chief complaint is that he's having difficulties in school.
Now that’s a very wide differential diagnosis.
This kid could have AHD, he could have behavioral problems, he could be having emotional problems,
or he could have a learning disability among others, so really a broad differential doesn’t help us very much.
So let me look at the question stem and see what it’s giving us.
Well, the first thing is we have a normal set of vitals -- that doesn’t help,
but there is really a description of a unique facial morphology in which the patient is described as having a low set nasal bridge,
a smooth philtrum and a small lower jaw.
When you see a few of these and I'm gonna give them all to you, a few of these morphology descriptions,
you need to be able to figure out what they’re trying to describe.
And in this case, these facial features are really quite typical of what's called fetal alcohol syndrome.
Now, this actually make sense because you're gonna read this and you're gonna think about this facial features
but then you have to think it doesn’t make sense with the clinical picture they're painting
and it does in this case because fetal alcohol syndrome does have a strong association with cognitive and behavioral difficulties
which is what we are seeing in this patient.
Well, of course, you can't diagnose fetal alcohol syndrome just by getting a bit of a story,
you need some family history but the clinical morphology in the story really tied together
and we can feel confident about the diagnosis.
Now that we know the diagnosis is fetal alcohol syndrome, we have to come up with the associated symptoms.
Now, of course, fetal alcohol syndrome has distinctive facial features that were described in the question stem.
But these people or patients excuse me, can also have deformities of their joints, their limbs, and their fingers.
They can have heart defects such as atrial septal defects or ventricular septal defects.
They can have difficulties with vision but not complete blindness or cataracts and they can have difficulties with hearing,
but again not complete deafness, what they do have is social and behavioral issues that’s described in this patient
and they even have CNS problems such as difficulty with memory and problem solving skills.
So really, the associated deficits with fetal alcohol syndrome are really quite various.
Now that we have seen the associated symptoms and defects that are associated with fetal alcohol syndrome,
we need to try to pair something with the answer choices.
And here we’ll see Answer choice A as being the most appropriate answer of a holosystolic murmur
since patients with fetal alcohol syndrome can either have a congenital heart defect
of a atrial septal defect or a ventricular septal defect.
Now let’s go to these answer choices in detail to learn more and also figure out
how you can eliminate all the other answer choices for this condition.
Now, starting with the very first one, which is the correct answer of holosystolic murmur.
You know when you look at a patient that has a fetal alcohol syndrome, they're going to have signs of cognitive impairment
and they're going to have characteristic facial abnormalities.
Now, in this patient we have cognitive and behavioral issues that are mentioned
and to kinda go over all of the facial anomalies and fetal alcohol syndrome, refer to the image of this young boy
that’s drawn that’s demonstrating many of the features of fetal alcohol syndrome which includes micropthalmia,
the patient has epicanthal folds, the patient has a thin upper lip, that’s very important.
They have ear abnormalities, they have a smooth philtrum, that’s very important;
they have shortened palpebral fissure, again very important; a low nasal bridge that’s always highlighted; and micrognathia.
Now these are the characteristic facial feature.
I would look at this picture a few times and really memorize it. This is very high yield.
They love fetal alcohol syndrome on the boards.
Now fetal alcohol syndrome patients are more likely to have heart defects such as an atrial septal defect or a ventricular septal defect.
Now, the diagnosis of fetal alcohol syndrome requires careful evaluation of maternal history
and asking to see if they'd had any kind of substance abuse, any physical exam abnormalities in the child,
or if we see any behavioral or cognitive abnormalities in the child.
And once we diagnose fetal alcohol syndrome, really what we're gonna be focusing on
is what's called repairing symptomatic deformities.
Things that bother the patient are what we are going to repair, in otherwise,
we then do behavioral management and social support.
Now, why does fetal alcohol syndrome occur?
What's so bad?
Well, alcohol and alcohol metabolites such as acetaldehyde readily cross the placenta and into the fetus and amniotic fluid.
Now, the fetal liver has very limited alcohol dehydrogenase activity and actually relies upon the mother’s liver for detoxification.
Now the amniotic fluid also acts as a reservoir for the alcohol and this is painful
and this then increases the exposure of the fetus to the harmful effects of alcohol.
Now there are several risk factors for mothers to do to develop a child with fetal alcohol syndrome.
This includes binge drinking, drinking with increase maternal age and drinking with multiple pregnancies.
Now, very important to know, the fetus is most sensitive to the effects of alcohol during the first trimester of pregnancy
and that makes sense, the first trimester you have so much origination in embryology moving in development
that of course alcohol is going to severely damage during the first trimester.
So that’s why that answer choice is correct, of a holosystolic murmur
which can be seen with our septal defects.
Now looking at Answer choice B, which is wide-notched teeth, another phrase for this is Hutchinson teeth.
Now these are wide and they're notched on their biting edge and they're associated with perinatal syphilis infection
and which is going to be caused by congenital syphilis of course.
Now, congenital syphilis is one of the TORCH infections and the O is the other and that’s where syphilis comes in and to stand in.
Now, mothers are more likely to transmit syphilis during the primary and secondary stages of the syphilis disease to their newborns.
Other symptoms of perinatal syphilis include a maculopapular rash on the hands and feet,
what is called snuffles; chorioretinitis; saber shins; hearing loss and a saddle nose.
Now maternal screening and early treatment are important to protect the developing fetus.
Screening involves getting an RPR or a VDRL, non-treponemal testing followed by true diagnostic treponemal testing.
And the treatment, again, very high yield because it’s odd,
the treatment for pregnant women with syphilis consist of benzylpenicillin.
Now, that’s for syphilis and alcohol fetal syndrome.
Now for Answer choice C, limb hypoplasia, this one is tricky.
Now, limb hypoplasia is likely to result of teratogens such as thalidomide or viruses such as an HSV infection.
Now, this is where it gets tricky.
Fetal alcohol syndrome can cause joint problems and radioulnar stenosis
but does not result in under development of limbs and this is the subtle point.
You can have joint problems but you don’t get limb hypoplasia.
Now, thalidomide, this is important to know, it’s oftenly tested,
was originally used previously to reduce nausea or morning sickness in pregnant women
but this was later then taken off of the market due to the teratogenic effects on fetuses.
But today, thalidomide is still used as chemotherapy for multiple myeloma.
Now looking at Answer choice D, cataracts. Congenital cataract are caused by several of the perinatal TORCH infections
including rubella and herpes, and the fetus again is at highest risk of developing this during the first trimester of pregnancy.
And then Answer choice E, congenital deafness. Congenital deafness can be caused by syphilis or rubella infections
and again, fetal alcohol syndrome can cause sensory neural hearing loss but it does not cause congenital deafness.
Now let’s review some high yield facts regarding fetal alcohol syndrome.
Now, this syndrome is cause by alcohol exposure in utero, and very important to know, no amount of alcohol is safe during pregnancy.
Now, a combination of signs and symptoms allow you to perform this diagnosis.
Now, of course you have to have some inkling of history and even if you don’t as in this question stem,
we can rely on the physical defects that is the morphology of the patient
which you can see in the diagram that’s drawn that shows all of the facial anomalies of fetal alcohol syndrome
and also mental disabilities and behavior abnormalities that you can see in these patients.
Now the diagnosis is usually performed at a young age and likely said,
it’s based on a combination of history and the clinical presentation of the child.
Unfortunately, the defects of fetal alcohol syndrome are irreversible and our treatment is directed at one preventing progression
that is using physiotherapy, talking to psychologist and using medication as necessary for certain problems.