Spine Ultrasound – How I do it - HD

Introduction

Hi, I'm Mike DiPietro,
pediatric radiologist at the University of Michigan.
I'm a professor of radiology and of pediatrics.
Today I'm gonna be talking to you about
spinal canal ultrasound, which I've been doing
for almost 30 years.
And the emphasis of this talk is basically how I do it.
Rather than showing a number
of various different cases
and entities, which I've done at other times,
this is really gonna emphasize on basically how
to perform the study.
I hope you'll find it useful. Thank you.

Spine Ultrasound: How I Do It

Spine ultrasound, how I do it,
this is a talk I presented at the Society for Radiologists
in Ultrasound in October, 2014.
Another line could be, what's the line on the spine?
Some tips for good picks.
And you can see from the start that
although it's often referred to as spine sonography
or sonography of the spine, it's really of the spinal canal.
So now let's begin.

Disclosures and Background

I have no disclosures to make,
and I've been doing this for almost 30 years,
and I give credit for getting me interested in.
This was a pediatric neurosurgeon, Dr.
Joan Venes, who has since passed away,
but she was a pioneer in pediatric neurosurgery.
I think she might've been the first
woman pediatric neurosurgeon, if not perhaps even the first
or one of the first neurosurgeons.
And one day, in the evening, a little bit late
after work, she saw me in the hallway
and said, did you ever think about using ultrasound
to look at the spinal canal?
And we just went from there.
And it was a great collaboration. I learned a lot.
It was very interesting. And
I always state this for young people
who are earlier in their careers,
to always keep your eyes and ears open.
You never know when some opportunity might arise.

Purpose: Occult Tethered Spinal Cord

Most of the cases are done
and the studies are done to look
for the occult tethered spinal cord.
And features of that are
that the spinal cord is low.
The conus medullaris is more caudal than it should be.
It's often eccentric within the canal.
And for that reason, I coined the expression,
called it the low down, stuck up spinal cord.
You will find a lesion that caused the tethering,
such as the things you see
before you lipoma thick filum, filum lipoma,
and other features that the cordal oscillations of the canal
and roots of the cauda equina, which,
which I'll demonstrate, will sometimes become damped
and reduced, as you approach the area of the tethering.
And these old pictures from the literature,
you can see that this, the baby has a small hump at the
top of the back.
This is not the same child,
but this could very well be the same depiction.
You can see the spinal cord is low coming down
to the lumbosacral junction, and that there's a fatty mass.
And this case is also the hairy patch, which
that could really match that.
And this is a case I did back number of years ago,
which is almost exactly a representation of this.
This is the spinal cord.
We're down at the lumbosacral junction,
and you can see this echogenic fat,
which then the arrowheads are showing, a hump,
on the lower back just like this.
Although even this is far from being state-of-the-art
ultrasound for the present time
that it is,
still even this vintage image really shows you the
information and is a clear representation of
what you see in this drawing.
Here's a case that was a little bit later, though,
still an older image in which you can see that the
the ultrasound represented here in long axis,
which actually preceded the MR.
And you can see the spinal cord is
is down low in the canal.
And the this is invested here with the fat.
This is the lipoma.
And really later on an MR was done,
which it showed exactly the same findings.
And I like to show this case again with earlier
ultrasound.
I don't think this is any greater than
perhaps seven megahertz.
You could still see things quite well and in short axis.
This is a nice depiction
because this is the spinal cord here,
which is hypoechoic.
In this picture. Here's the lipoma.
And notice how on this, on this side, this,
which is actually the right side, that the
spinal cord is rather flat, which matches exactly
what the appearance that you see on the MR.

Technique: How I Get These Studies

So basically, what this talk is about is how do I do it?
How do I get these studies?
What's, what, what are some tips
for getting successful studies?
So most of it's gonna be about getting it.
There's also gonna be some discussion about
how you word the report,
and basically then how you actually show it and depict it
and present it to the clinicians.
As with any ultrasound,
and especially in musculoskeletal and
and pertinent also to a spinal canal, being aware
of your orientation
and having a clear orientation on the image
and technique is of utmost importance.
We use appropriate high frequency transducers.
Most of the time they tend to be linear array.
There's some features, which are a little bit newer,
like the extended field of view
and the ability to store dynamic cine loops,
is actually very helpful, especially in children,
which might be moving targets for you.
So basically, the most important thing with the technique,
as I've found over the years, is that you really have
to get the child adequately flexed
to separate the posterior spinal elements.
And you'll see, and if you are successful in doing that,
you can actually use ultrasound to look at the spinal canal
much beyond in older children than what is conventionally
taught and mentioned.
Images are obtained from the back on the dorsal surface.
It's your ability to use ultrasound is because the posterior elements are less ossified in kids
than they are when you're older,
but you still need adequate flexion
to separate the elements.
This is an extended field of view image, which,
which now we have it.
But at the time that we didn't have this feature,
I was working, so this is from Cincinnati
Children's, and you can see how you can,
you're seeing the low thoracic and lumbar canal.
This is the lumbosacral junction,
very much like you'd see in a lateral radiograph,
how you're going from lumbar to then sacral.
These lines down here are the backs of the
the posterior aspects of the vertebral bodies.
These are the spinous processes are in the midline.
They look like upside down U shape.
And there's the dorsal dura, the ventral dura.
This hypoechoic tapering
structure kinda looks like a carrot is the spinal cord.
And then normal tapering the conus medullaris.
And these echogenic kind
of hair-like structures extending down are the cauda equina.
If you don't have extended field of view,
you can use the old obstetrical ultrasound trick,
which is basically just do a split image
and you just have a very steady hand and you can line it up.
You scan down to here,
and then you pick up where you left off,
and you can accomplish the same thing.

Locating the Conus Medullaris

Very important to locate the conus medullaris.
And as you just saw, it has a tapered shape,
and these are the roots of the cauda equina.
And you wanna see it,
to localize the tip in both long axis and in short axis.
And here it is right here. And these are dorsal roots.
And these are ventral roots.
Now, I tend to, on my short axis, have this
as the patient's right side,
and this as the patient's left side,
you can do whatever you want as long as you're oriented and you realize it.
And I do that
because usually I'm over here on the patient's
left, I'm reaching across.
And I found that it has helped me in some complicated cases
where you're seeing something
and there's some asymmetry,
and then I'll realize, oh,
was that on the right or the left?
And then I remember that, yes,
I was reaching across the child's back
and spending a lot of time on the far side away from me,
which is therefore the right side.
So I tend to have it
that this is the right, and this is the left.

Patient Positioning

Really you can almost have any position of the patient,
but the most critical thing is
that the back is adequately flexed.
Very often the patients are prone and it can,
and you may put a pillow or a towel roll
or something under it to facilitate
flexion of the back.
Actually, sometimes if you elevate the head
and the upper body a little bit, that can promote distension
of the caudal thecal sac.
These are all techniques that you may be familiar with
for any of you that do myelography.
And then you want a
nice distended caudal thecal sac
to which inject the contrast.
So this is basically the same principle as that.
You may have the child sitting,
and then of course you want them to bend forward
or fall forward, or
or if they're just a little infant,
they may be falling forward anyhow
because they haven't yet achieved the ability
to sit up straight.
Sometimes
it can hold the child over the parent's shoulder, kind of,
I call it the burping position,
as though you're gonna burp the child
after the child had been fed.
And I'm gonna show pictures of all these positions.
Or you may put the child in a lateral decubitus position
so the patient is recumbent on his side
and as though you're gonna perform a lumbar puncture.
So any of these views will work.
Sometimes I'll do a few of them.
And
but as long as the back is adequately flexed,
that's the most critical feature.

Examples of Positioning

So here's some examples.
Now, this child is already four months of age,
and you can see that she's exploring her world.
She has her head up, she's able
to lift up her head and neck.
She's actually arching her back in the wrong position.
And this is gonna be very difficult to scan.
You can see you're trying it, but
but then what you would like
to do is get the back flex a little bit better.
You may put some rolls underneath the abdomen to kind
of get the back to open up a little bit more
and flex a little bit more.
The burp position, the child is kind
of held up over the shoulder sometimes if the
the child is a little bit anxious,
although the young infants don't usually act
that way, but it can be comforting the kid
to be over the parent's shoulder,
and then they will kind of naturally just drape themselves
over the shoulder and flex the back.
And that can be very helpful.
And also the parent and the child
feel more comfortable because they have control over things.
And you can see here as we're scanning in both long axis
and short axis to the body, the sitting position can work
and actually the child has to be supported.
'cause the child might fall over
and you want them to fall a little bit forward with flexion.
And the lateral decubitus posture can work.
So the child is on his or her side,
but again, you wanna make sure that you flex the back
somewhat to open up the spinal elements.
As with any time with flexion,
and this is a warning to
pediatricians in performing lumbar punctures,
you wanna be sure that you don't have a small infant
and you're so vigorous with your flexion
that you actually make it hard for the child to breathe.
You certainly don't want that to happen.
And that amount of flexion is not necessary.
And you can see here that how we're scanning
with from the side,
and this is actually from a top down look here,
the child's still lateral decubitus,
but I photographed it from the top
to show getting the short axis view.
And of course, this is a view that won't work
because you have no access to the back.

Normal Anatomy

So look at some normal anatomy now.
So this is the view that you saw,
the combined image going from the low thoracic into the lumbar area.
And then you can see the posterior aspects
of the vertebra start ascending.
And the picture kind of like an escalator going up.
And that's usually your lumbosacral junction,
very much like a lateral radiograph, dorsal dura,
ventral dura, these white lines conus medullaris.
Here you can actually see the central echo complex.
You can see the roots of the cauda equina coming off.
You see the spinous processes back here.
Some of the black that's on the tip
of the spinous processes, like here and here,
and here is actually the cartilaginous tips, kind
of like the dorsal fin of a shark that you're seeing there.
But that's because the ossification is relatively low,
that enables you to get these really nice pictures in
these young babies.

Position of the Conus Medullaris

Just to reiterate, the position
of the conus medullaris is very important,
and you wanna make sure you've localized it in two views,
seeing both long axis.
And in short axis, some appearances
of the spinal cord as you look at the canal.
Most of the emphasis is around where the conus is,
but I often tend to look at the entire spinal canal.
I'm not demonstrating a cervical here, but notice,
and these are all at the same magnification.
I haven't changed it, but notice
how the thoracic cord is circular,
but tends to be smaller than the low thoracic
and lumbar cord, which is still kind of circular,
but almost like a kind of a box shape.
And then it starts getting smaller again
and tapering as you get down to the conus.
And then the cord is gone,
and all you have are roots of the cauda equina.
Other things you can see, especially in the thoracic,
you can see these horizontal lines
in the nine o'clock position
and in the three o'clock position,
these are the dentate ligaments.
And then using the one or two o'clock position, 10
or 11 o'clock position, seven or eight.
And four
and five o'clock positions are usually where you're
actually seeing the dorsal
and ventral roots coming off the cord
and extending down.
You can see them quite abundantly in this picture.
And then, of course, as you get lower,
this is just the tip of the conus
and the dorsal ventral roots are quite striking here.
They are here just below the conus.
And then as you go lower down in the canal,
you see fewer and fewer nerve roots
because they're being given off to the body.
Sometimes the appearance of the tip
of the conus almost kinda looks like a spider here
that you're seeing in this drawing.
And here's an example here,
and again, more just with the roots at the cauda equina.
Now in this movie loop, which is done in short axis,
and you can see you're just coming down.
So you see the hypoechoic cord in the center,
then you see it getting smaller
as you're coming more caudally notice, for orientation, you can see the
the kidney on the left side of the
on your left on the screen, in which the way I image
that actually is the left kidney.
And this is just showing you that you're
going from the cord down to the tip of the conus
and then into the roots of the cauda equina.
And this is the same area in long axis.
And you're seeing coming in
and out of the picture, the spinous processes,
the hypoechoic tips of the spinous processes.
And you can see all, they sort of look like the
dorsal fin of a shark white line.
That's continuous long hair.
That's the dorsal dura continuous white line down here,
the ventral dura, the backs of vertebral bodies.
You can see the tapering conus and the
roots of the cauda equina.

Lower Spinal Canal Anatomy

Okay, now we're gonna go on, this is just a still picture in
what you can notice on this combined image
that the black, which is the cerebral spinal fluid,
the thecal sac, really doesn't go all the way
down the spinal canal.
And we'll talk more about that in a moment.
As you come down, you can see the ascending vertebra,
kind of like an escalator.
And these are sacral elements.
And then you get into these hypoechoic areas
beyond the sacrum.
And these are actually elements of the coccyx.
And you should see a rectum right in front of it, right,
opposing it, lumbosacral junction area, we're down in here.
Again, you can see the thecal sac, and then it ends.
This is the sac itself tapering.
And I'll mention in a moment how
that's an important landmark, sort
of in the mid lumbar area.
And you're just seeing roots of the cauda equina all in here.
We're up by the conus, just as you saw
before, nice normal tapering.
And again, you can scan the entire canal,
but most of them, the requests are
to rule out an occult tethered spinal cord.

What is the Tethered Cord?

So what is the tethered cord?
This is a definition that I really like it,
it really says it rather concisely.
Don Reigel was head
of pediatric neurosurgery when I was at the Children's
Hospital, Pittsburgh, in the mid seventies.
And I think this is a nice quote
and it explains exactly what it is.
And we're really, in imaging, look
for the abnormal caudal position of the cord,
and showing evidence perhaps that it is being stretched,
which we'll see with some diminished oscillation.
You already saw this statement before.
The tethered cord, because of its low caudal
and eccentric, often dorsal position.
I like to refer to it as a teaching thing,
low down, stuck up spinal cord.
And again, usually we see something that's causing the
tethering now in this longitudinal picture.
So the patient's head is towards your left.
I'm kind of scanning slightly from left to right,
but pretty much in the midline, you can see the
hypoechoic tip of the conus medullaris.
However, look at where it is, it's way down
by the lumbosacral junction.
The tip of the conus should be probably no
more caudal than about L three, the mid lumbar level.
Most of 'em are around L one, L two very often, sometimes at L three.
But this is definitely low.
And not only is it low, has a reason for the tethering.
This is a very thick echogenic filum terminale.
This is a patient who has anal atresia imperforate anus.
All of those children get scanned as a screen
for an occult tethered spinal cord,
more don't have a tethered cord than do,
however, the incidence
of tethered cord is much higher than in
the general population.
So they should all be evaluated at some point.
This is in this static image. This is it in short axis.
And there's the thick echogenic filum terminale,
which really normally should be no more than one or two millimeters.
This is much thicker than that.
And again, with the conus position, you know
that this is a tethered cord.
So at some point, this will have to be released.
It's not necessarily an emergency right
at the moment to be done.
They'll do the some of the
rectal work first,
but at some point, that's gonna have to be addressed.

Oscillations in Tethered Cord

Another feature besides the abnormal position is,
you notice that the damped caudal oscillations.
So in this picture, which I've shown, an
and basically a cine loop on the top, what we would do,
it's also shown on an M mode,
which is popular in Europe.
You can actually see right through where the line is.
It's just showing you that portion of the image
and how much motion is occurring.
And notice how this, in short axis, notice
how it's bouncing up and down.
This bouncing is a normal feature, oscillation.
But a couple of things. One is that you
might not see such brisk oscillation, and the very, very young infants
and neonates, I don't know why that is.
I think usually by about six weeks you see it.
The other thing is you may see oscillation still present,
although the cord is tethered,
and it could just be that it hasn't been pulled taut yet.
And eventually it will become damped.
Or what you'll see is that as you get closer, more caudally
to the place of tethering, that the oscillations will become less,
and they'll become damped.
You may go up a little higher away from the tethering,
maybe in the low thoracic level or whatever,
and you may see almost normal oscillation.
And you can see that you're kind of high here.
'cause actually seeing the child's lungs over here
as he's breathing, you might notice that.

Determining Conus Tip Level

Okay, so basically the conus tip low, yes
or no, we have to determine that,
you wanna see it in two views.
Well, how do you determine where the vertebral level
and there are some landmarks.
You can just palpate the lowest rib I've found
and then just kind of go across horizontally from there.
And that's often around L two.
If you're scanning the child, you may just know
by you're scanning that you're in the high lumbar canal.
So actually assigning a number might not be that critical.
You can use the lumbosacral junction,
which we've shown in a few examples already.
Identifying that very much like a lateral radiograph,
the caudal end of the thecal sac, I've shown you,
and I'll show you in a moment how that really fits in,
as a landmark.
And again, if you're actually doing the scanning,
you can just look at the patient's back
and have a sense of where it is.
People have asked me,
do you ever just put a marker on take a radiograph?
Very rarely. I did do it for a study some years ago.
But clinically, it's rarely necessary.
But if you do, make sure that you know exactly where the tip
of the conus is in both long axis
and short axis, put a mark on the skin, then put the marker
and take your radiograph.
You have to be very precise about it.

Landmarks for Vertebral Levels

Alright, you can look at the lowest rib,
and then you have to go out laterally over the kidney,
find the lowest rib, which you can see there
with the shadowing and the left side of the picture.
And then stay there, and then just come towards the midline.
And then you can assign that as T 12.
Now, T 12 is in quotes
because not everybody has 12 sets of ribs.
It could be actually T 11,
or it could actually be like a T 13.
So again, it gives you an approximation
and you can check one side and the other side, right
and left lumbosacral junction, you can look at that
and notice how the orientation
of the vertebra changed from being horizontal again,
to like ascending towards the transducer, like an escalator,
so that you could call that L five.
And that S one,
you could count backward from the sacrum.
Of course, that's assuming you have five sacral elements.
Now, the end of the thecal sac is an interesting one.
The spinal canal goes all the way down
to the end of the sacrum.
But the actual CSF,
the cerebral spinal fluid in the thecal sac
usually ends at about S two.
And that's been known for years from myelography.
And I think it's a fairly reliable sign.
So you've heard a couple of ways to do it.
And the only thing I can tell you is that if you've
assigned a vertebral level, looked at it
with all these different ways,
and you keep getting the same
assignment like L one
or L two, it's probably right if multiple methods are giving
you the same number, if you're getting some variation.
Well, again, there could be some anatomical variance,
as I said, for instance, the number
of ribs that the child has.
And if you're in a tough spot
and it's necessary, you can always put the marker on.
But I found that is rarely needed.
And if you do, make sure you put it exactly on the conus tip
as noted in both views.

Normal Level of the Conus Tip

What is the normal level of the conus tip?
Well, this is a study I had done using ultrasound
and then correlating with radiographs was the child was
going to get anyway,
so we didn't do any extra x-rays on that.
But interestingly, really most of them seem
to be L one or L two.
Occasionally.
Here's one that extended down
to L three, but you can see it here.
And even we went out over a number of years
and pretty much the average is about the same.
Basically, I
don't just worry about people ask me, well,
aren't you concerned because the vertebral the tip of the conus is at L three, and is that a tethered cord?
Well, another thing though is
that something has to be tethering it.
In my experience, most spinal cords
that are tethered are obviously low.
I mean, they're down by the lumbosacral junction like you
saw on that child early with imperforate anus.
Usually it's not that subtle.
And the second thing is you have to find something
that's tethering the cord.
And I think keeping that in mind will help you from
going astray on this.
So basically, if you have a spinal cord tip
of the conus, it's maybe marginally whether it's low,
but everything else is normal.
Is that tethered? Well, it may not be, especially
around L three or so can be normal.
And if it's tethered, there should be a reason
for the tethering, and you should be able to see that.
So you have to put it all in context.
And again, in this case that you saw, not only is
that conus tip low down by the lumbosacral junction,
but there's a reason for it with a thick filum
terminale another method that
that you can use
to corroborate with the other ones.
And this was suggested to me by one
of my colleagues, Dr.
Larry Kim, is to use the origin of the psoas.
Now the psoas muscle originates all along the lumbar
vertebrae, as you see, but the top of it is that L one,
it's been designated as so in anatomy books.
But we did a study using patients
who are having basically total spine MRs.
And to see if it really held up clinically.
'cause sometimes pictures,
anatomy books may really just be based on one
or two corpses from years ago.
But it ends up that it does hold up.
And so it's another sign that could be used.
Now, this isn't a plane that you're not gonna really use
for the spinal canal sonography,
but you can see the top of the psoas here.
You see, this is actually a renal shot,
and that should be L one.
But you can see it actually in the way that we will image for the spinal canal.
Notice this, psoas is here,
and this would be the spinal canal here.
So if you flip this picture upside down, this is
where we're gonna be seeing here.
So here's this case, is the right kidney, the left kidney,
the psoas, this is the spinal canal.
These are roots of the cauda equina.
So what I do is I find a picture
where the psoas is quite obvious,
and then I just march superiorly towards the head
until you just barely see it.
And then notice what's going on in the spinal canal,
and then call that L one,
and then just come back down from there
and you can see where you are.
So it's another way that can help the older child.

Techniques for Older Children

Now, olders in quotes,
because some radiologists consider once you reach six, seven months
of age, there's really no place for ultrasound anymore.
You can't do it. That's not the case.
I've done spinal canal ultrasound and
children that are several years of age.
But the older they are, the bigger they are, the
more limited your scanning will become.
And that's
what we're gonna discuss in a minute.
And then, and really, as we've said
before, you really have to get the child flexed to see it.
So I'm gonna talk a little bit about, it's really a
size limit, more than an age limit,
but usually they go together, techniques
for the older child is really just an accentuation situation we
talked about already, but
we'll discuss that a little bit more.

Who Orders Ultrasound for Older Children?

Who orders an ultrasound for older children?
Well, in my situation, most of the time
these are ordered by clinicians such as pediatric urologists.
So here's a very common scenario.
The child is having some urological issues,
maybe related to the bladder.
They're not really suspicious
that there's a tethered cord,
but they would really like to know,
they would be reassured knowing
that the conus level is normal.
And that's really their only question.
They don't wanna put the child through an MRI.
Very often if the child can cooperate enough,
and you'll see in pictures if I can get flexed enough,
I can identify where the tip of the conus is,
and I'd probably be able to identify whether
or not the spinal cord is oscillating,
but basically the conus tip.
And if it's stone cold normal,
and the high up in the lumbar canal,
that might be enough information for the urologist.
And I put in the report
that if you need any information other than that,
then you have to do an MR.
Notice that in ultrasound,
our spatial resolution is quite good
because you can do measurements
that you're in the tenth of a millimeter range,
which if you wanna sound impressive, instead
of calling it tenth of a millimeter,
call it a hundred microns.
That sounds pretty impressive.
But there's no question that if you can get
to the structure with the ultrasound that
the spatial resolution is very, very good.
So as the child gets old
and larger, the visualization is very, very limited.
I found the technique that can help is
to go off the midline a little bit,
through the interlaminar area
and then kind of angle in towards the canal.
And show you a little bit about
that, how we do it.

Scanning Techniques for Older Children

So here's a radiograph on an older child,
and you can see I'm off the midline a little bit
because the spinous processes are a little bit
too difficult to get through.
But if you go over by the lamina
and you kind of angle in,
you can perhaps see in there a bit.
This is, I got this idea from years ago doing myelography in
patients that had a lot of midline scar,
and to get the needle into the spinal canal, you had
to come off center a little bit
and then kind of angle in from the side.
So I'm really just doing the same thing.
And sometimes it helps, but again, what's most critical is
that you get adequate flexion.
So here's a girl, she's five years old, she's thin.
You can see her spinous processes back here,
and we can actually see her canal pretty well,
but she really has to cooperate and be flexed for it.
And I'm just showing the how we're kind
of off the midline and angling in,
it's probably dramatized a little bit more just
so you can see it, but you can see what we're doing.
And this is from a top down look on the bottom,
you know, her head is up here,
and then you can see how we're coming in from the side
and doing that matching the, that's not her radiograph,
but matching the radiograph.
Now this is an old scan.
This is probably from the early 1990s perhaps.
And this is an 8-year-old,
and this is a longitudinal image.
And you can see though, it's kind of crude,
but this is actually dorsal
and ventral portions of the spinal cord.
This is the back of the vertebral body.
This is the like the dorsal dura
area, lot of shadowing.
This is from a spinous process,
which is quite ossified, big shadow.
And you can look at one level, and then you come down
and you don't see any more cord, you just see roots
of the cauda equina.
So you can infer that the tip of the conus is right here.
And we'll come back to the
images like that in a moment.
Similarly with the transverse,
and again, we've exaggerated it some just so you can see
what we're doing, but we're kind
of off the midline, angling in.
Sometimes this trick can help you,
but again, the most important thing is flexion.
Now, here's a child a little bit later,
vintage ultrasound,
but still relatively older.
And this child is nine years old, weight 65 pounds.
They really just wanna know where the conus was.
This is coming from the midline, the canal.
They're not really seeing a whole lot in there.
But when we come in from the side
and this short axis view, angling from the left,
then angling from the right,
you can actually see the cauda equina quite nicely.
And then you can scan up and down towards the head towards the feet.
And you can find the cord
and see where the cord ends
and where you just get cauda equina.
Now. And this sequence where we're gonna keep repeating here
is a long axis.
The head is toward your left,
and at the beginning of it, we're seeing spinal cord.
Then we're seeing tapered,
there's three segments, three levels we're seeing.
Then we're gonna see tapered conus medullaris,
and then we're just gonna see a hair-like roots
of the cauda equina.
So when we get back, and I'm
and I'll just call out to you where we are.
So here we go. There's here comes spinal cord conus and cauda equina.
It goes kind of fast. I'll have to do it again.
So here we go. And spinal
cord conus, roots of the cauda equina,
once more cord conus roots.
So you really, even though this child is at this age,
you can really identify where the tip of the conus is.
Now this is the same thing in short
axis, again, at three levels.
So like pictures we've seen
before, you're gonna see the hypoechoic cord in the middle.
Then you're gonna see the cord being smaller, which is the
conus medullaris going towards the tip.
And then you're just gonna see fuzzy roots
of the cauda equina.
So in a moment, when I get in phase over here,
I'll call it out to you again,
cord conus roots.
Here comes again, cord conus roots once more, cord
conus roots.

Reporting

Now, how do we word it? The reports?
Well, here's a report
where you gotta be a little bit careful.
Now, this is a common finding.
I mean, again, I'm not really discussing a lot
of the findings and pathology in this talk, but
you'll identify this extended field of view image.
And here's the conus medullaris.
There's a little bit of separation actually here,
the central echo complex.
So there may be a tiny bit of fluid within the central canal down here, which is a quite common finding,
especially in neonates, roots
of the cauda equina hairy here.
We're well away from the lumbosacral junction.
We're in the upper lumbar canal, so that's not an issue.
You can see you're going from lumbosacral here,
but what's this hypoechoic thing,
like right smack in the middle here, just inferior
to the tip of the conus.
We see these all the time.
Now, in fact,
I think we more often see them than don't see them.
And it's really just the product of
the higher resolution and the better machines
and transducers that we have available.
We call it a filum cyst.
Now here's another case
and we'll come back to that in a minute.
But here's another case that has one also.
But this case is a little bit different.
And look at it for a minute
and see some of the things we've talked about already.
So here's the conus medullaris, but look at where it is.
The other one was high up in the lumbar canal.
This one is down by the lumbosacral junction.
So this is a tethered cord,
and there's the filum terminale.
And here's this cyst, like within the filum terminale.
But this one actually has an issue
because this has a filum cyst,
but in association with a tethered cord in this case.
So that's the difference in these two conus levels.
Different. And another feature that's a little different,
but we're not gonna go into a big discussion of it, is
that this one, actually the thecal sac
actually goes quite far into the sacral canal.
And we see this once in a while, right there.
See, it should have been ending about here,
but it keeps going down.
Sometimes these are referred to
as intraspinal meningeal sacs.
Occasionally we see it. But when we're discussing the
the fact of the little filum cyst
where everything else is stone cold normal, some
of my colleagues don't even mention it
because we see it so often.
I will put it in the report because we are seeing it.
But you gotta make sure that it doesn't get a clinician
unduly excited.
And very often what I'll just say, it's
a normal variant or common finding that alone
in absence of anything else
has no known clinical significance.

Case Example: Prenatal to Postnatal Finding

Showing it, basically getting good pictures.
This is a case I'm gonna show you now
and kind of the message is just like
maybe all roads don't lead to Rome.
All ultrasound studies don't lead to MR many
of you have probably heard the thing.
Well, we're just gonna get an MR anyhow.
Or the ultrasound is just the prelude to MR.
Let's get the real study. The MRI.
Well, it's not always that case.
And as some of you that are heard messages from the AIUM,
the American Institute of Ultrasound in Medicine, their
theme last year was about sonography first.
And I think this is a good example of that.
And you'll see what happened.
It really wasn't a pushing on our part, it was acceptance
of the images by the clinician that was kind of striking.
So this is an example of a prenatal to postnatal finding.
So this child, and this is the history typed in
by the sonographer child had been seen,
they wanted an ultrasound done
to follow up on a prenatal finding.
This is just the fetal bladder, the child's head,
the bottom of the screen, the rump is towards the top
of the screen and that's the fluid filled white
fetal bladder.
But then there's another white thing down there also.
And it was just anterior to the
to the sacrum area right there.
And they thought there's some kind of a cyst coming off.
Child is born, this is a radiograph, which is unremarkable.
I do like to get radiographs.
I like to see what's going on with the vertebra.
If there's anything
that we're seeing with that can be helpful.
This was they're looking at kidneys
and bladder, et cetera.
There's the bladder. There's the very prominent
but normal uterus
that you see in a newborn girl from the stimulation
from the mother's hormones.
And here's the low lumbar, the lumbosacral junction.
This is the sacrum
and the areas you're showing you like really inferior
to the coccyx, which is down here.
There's this hypoechoic thing
with some low level echoes within it.
And that's the thing that was seen in utero.
Fine,
you can do some measurements on it and you can see it.
And we're showing it in long axis and short axis.
So an MR was ordered,
and then one of my colleagues asked me, well, you know,
should we protocol it as a spine study
or protocol it as a pelvis study?
So we decided, why don't we do an ultrasound
and look at it more carefully.
'cause the other images
that I showed really weren't done for the mass.
They were really done for the kidneys and bladder.
And let's really take a look at it
to help us determine what's the best study to get.
And that's why we did the ultrasound.
So let's come in from the back
and maybe we won't even need the MR
and at least what we'll do is we'll prescribe a better protocol
'cause we know what we're dealing with.
So we did go up and take a look and
make sure that the cord wasn't tethered
as they sometimes can be with presacral masses
and cysts, cord not tethered.
Nice. Short axis of the conus medullaris.
See the hypoechoic center echogenic roots of the cauda equina,
as you've seen other examples coming down the lumbar
canal, we're still lumbar.
These are just roots of the cauda equina.
Everything looks normal getting down by the sacrum.
Thecal sac is ending at about S two.
Everything looks fine so far.
Now we're getting into hypoechoic coccyx and bingo.
Here's the coccyx here.
And here's our thing that we're seeing,
has some low level echoes within it.
And basically notice that it really doesn't go cephalad
to about S five.
It has some areas that are anechoic areas
with low level echoes and short axis.
It's a little eccentric. This is the hypoechoic coccyx.
It's a little off to the side, a little bit,
not exactly midline.
And we look to color and power Doppler.
And basically there's very minimal internal vascularity,
a little bit of vascularity around it.
And actually, I had the surgeon come down
to take a look at it, and basically he looked at it
and he said, okay, that's enough.
I can work with that. And he really made the decision not
to proceed, and he canceled the MR.
And I think the lesson of this is,
I think the pictures were very good
and we took them with a lot of care.
And then the way that they're presented,
which I think is important,
because it's the clinicians that ultimately really have
to accept the images and
decide that they can work with them.
It gives them a mental picture of
what they're gonna encounter in the OR.
Surgeon was very happy with them.
And basically we went from there.
So I like to show this case as an example of how important it's to really get good images.
This was removed. It was a mature teratoma.
Everything went well.
So really the points of that case are noted here.
And as we've discussed, clarity of images
and orientation are critical.

Ultrasound to Clarify MR Findings

Now, occasionally, I'm not gonna go into this,
but sometimes I actually am asked to do an ultrasound
to clarify MR findings.
Most of the time it's from the neurosurgeons.
Perhaps there's something that's complex,
but they have a very specific question for me.
And I approach that and after reviewing the MR.
And sometimes it
can be very, very helpful for them.
So sometimes it goes in this direction that
again, that ultrasound is needed to help clarify something
that's questionable on the MR study
or they need some more information.

Summary

So basically in summary, how do I do it?
And you can see carefully and technique is just critical.
And the major technical point
that we've been talking about is flexion
and the ways to achieve it.
And thank you very much.