0:00

My partner and I are going to attack

0:02

this master level case.

0:04

It's a 54-year-old woman

0:07

who presents with back pain.

0:10

That's not particularly helpful.

0:12

I'm showing you some images from 2014.

0:16

We've got a sagittal water-weighted fast spin-echo T2,

0:19

a sagittal T1 non-contrast,

0:22

and an axial T2 fast spin-echo.

0:25

And we're going to scroll for a minute

0:26

in the sagittal projection,

0:28

and the findings aren't that impressive.

0:32

The cord itself has normal signal

0:35

intensity intrinsically,

0:37

and there's some heterogeneous signal posteriorly in

0:40

the thecal sac, which can be any one of a number of things,

0:43

but is most commonly related to pulsation.

0:47

Now,

0:47

we'll see later on that when you look at pulsation

0:50

in the cross-sectional view, in the axial view,

0:53

it's very black, it's very big, it's not punctate.

0:57

And that's going to be an important differential

0:59

diagnosis in this case.

1:00

But there is a finding on the T1 sagittal.

1:03

And Dr. Lasar, what do you think that is?

1:06

I'll make it a little brighter while you're talking.

1:08

So essentially, looking from the T2 to the T1,

1:12

you would first attribute that abnormal signal

1:14

to artifact, like Dr. Pomerance just stated.

1:17

But then looking at the T1 sequence,

1:19

you see these serpiginous lines coursing through

1:23

the posterior aspect of the spinal canal.

1:26

Yeah. Right there. They look like hairs, don't they?

1:28

In which yeah, they shouldn't be there.

1:30

That would not be associated with pulsation artifact.

1:33

Yeah. So let's go over to the axial T1,

1:37

and I'll turn my pen off for a minute,

1:39

and let's start scrolling,

1:40

because you really have to tease this case out.

1:42

So as you scroll, you say to yourself, okay, well,

1:45

these two little dots right here, they're paired,

1:48

so they're probably going to be nerve roots.

1:50

Now let's scroll and see if they find their way home.

1:53

Yes, they do.

1:54

And a lot of these linear structures find their

1:56

way back to the cord.

1:59

But do they all?

2:01

And the answer is no.

2:03

Like, for instance, how about these two?

2:06

They're kind of floating out there all by themselves,

2:09

and they don't really go anywhere.

2:11

At least they don't go back to the cord.

2:13

And you don't have a matching pair on the other side.

2:14

And you don't have a matching pair on the other side.

2:17

And they're too peripheral. The body is symmetric.

2:20

You're right. And they're too peripheral.

2:21

All great points.

2:23

So we've got to be worried about something that

2:25

is occurring in the intradural space,

2:28

which is where this entity occurs.

2:31

So now what I'd like to do is I'd like to go

2:33

backwards, and we'll go backwards in time.

2:37

Let's go to 2011. Let me take off my 2014 exam,

2:45

and let's pull up our 2011 exam.

2:48

And it is dramatic. Impressive.

2:52

Very impressive. Yeah, let's blow it up.

2:54

We'll make it a little brighter and a little bigger,

2:57

and we've got a lot.

3:00

Lot of dots.

3:01

A lot of dots. Now,

3:03

this is a non-contrast

3:05

sagittal T1-weighted image.

3:08

Let's grab the axial water-weighted image.

3:12

I'm going to blow that up to make

3:13

it a little easier to see.

3:16

And

3:18

now what do we think?

3:20

I believe we also have a lumbar, too,

3:22

which will show

3:24

you. I'll pull that up in 1 second.

3:26

So what do we think is going on now?

3:29

So,

3:30

looking back in time at these images,

3:33

way too many serpigenous structures.

3:36

And the first thing,

3:37

it's almost a classic picture for

3:40

a

3:43

spinal dural AVF. Yeah, spinal dural AVF.

3:46

And there's kind of four types of spinal vascular

3:50

anomalies, which we'll discuss,

3:52

but the most common is the Anson Spetzler type one.

3:56

And with one feeder, it's a one A,

3:59

with multiple feeders, it's a one B.

4:02

But one of the important take-home points is that

4:07

these things are dark. They're not black,

4:09

but they're dark.

4:10

They're not as black as pure pulsation,

4:14

and they're much more delicate,

4:15

and they're a lot smaller because

4:18

that's a common source of confusion.

4:20

For instance, in this axial projection,

4:23

you're seeing both pulsation right

4:26

here around the periphery,

4:27

but you're also seeing these very ill

4:29

defined small little dots. Now,

4:31

why don't they show up as punctate

4:34

as they do over here?

4:35

And the answer is a combination of pulsation

4:38

and spatial resolution. Most of the time,

4:41

you will actually see the little dots very well

4:45

circumscribed in the axial projection as well.

4:47

What's very startling is the paucity of findings on

4:51

the T1 at the time of the initial diagnosis.

4:54

Now, when I see these ben,

4:56

most of the time I'm the fifth person to see them.

4:59

It's been missed four times.

5:01

And the reason it's been missed is people

5:04

don't get very small fields of view,

5:07

very high resolution to see these tiny little things,

5:10

or maybe they're a little more subtle,

5:12

and people write them off to pulsation,

5:15

which is an extremely common phenomenon.

5:18

Now, this is a woman, and I brought that up earlier.

5:22

Dural AVFs are more common in men.

5:25

They do present with back pain,

5:27

but the typical history is lower motor neuron

5:32

symptoms, an ascending weakness that is very gradual,

5:37

and eventually they develop a sensory level.

5:41

So it's kind of a progressive thing.

5:43

They develop bowel and bladder dysfunction.

5:45

They develop impotence.

5:47

And once those things happen over a period of time,

5:50

they're irreversible.

5:51

So if you don't catch this early,

5:53

it is a total disaster.

5:55

And you can contrast that with the true AVM.

6:00

Because in a true AVM,

6:02

it's usually a more catastrophic thing.

6:04

They present with an acute bleed.

6:06

These people usually don't bleed.

6:08

They don't even usually present with

6:09

a subarachnoid hemorrhage.

6:11

It's just this sort of ascending gliotic event.

6:15

And why do they get this high signal in the cord?

6:20

Why do you think that happens?

6:22

Typically what happens is there's a couple

6:24

of things that could happen.

6:25

One is it leads to abnormal arterial venous flow.

6:30

And so you get dilated venous structures

6:35

and you get venous congestion, right?

6:37

Because an AVM, in an AVM,

6:41

you got a venous side and you got an arterial side,

6:45

which will make red.

6:47

At least we'll try and make it red.

6:48

Here we go. And then you get in between,

6:52

you get a tangle like this.

6:55

So there's kind of an intermediary.

6:58

There's an intermediary right here,

7:01

and that's why AVMs bleed.

7:03

You get this kind of REIT in between the arterial and

7:07

the venous side. And this can occur intramedullary,

7:11

whereas an AVF does not occur intramedullary.

7:15

An AVF occurs intradural.

7:18

There is a subtype that occurs extradural,

7:20

but that's much rarer. The type one and the type two,

7:24

the dural AVF and the AVM are the two most

7:28

common types. So what about an AVF?

7:31

What does that look like?

7:32

Well, that's a bit different.

7:34

That's a direct fistulous connection.

7:37

So it's properly named. So if you look at, say,

7:40

a small arterial,

7:46

it goes directly into the arterial

7:48

side without the REIT in between.

7:51

So because of this open communication system,

7:58

the flow overcomes the venous side and the venous side

8:03

becomes congested. And if you get congestion,

8:06

what do you get? Increased pressure.

8:08

You get increased pressure. Now what happens,

8:11

you start to compromise this side of the inflow.

8:14

So basically what's happening is you're getting venous

8:17

congestion that produces progressive

8:20

ischemia over time.

8:22

And that ischemia goes up and up and up and

8:25

progressively ascends over time in a man.

8:30

So that's the typical history.

8:32

Now, sometimes what can happen is this can thrombose.

8:37

And if that thrombosis,

8:39

now you get the unusual to rare situation where they

8:43

have something called subacute necrotizing

8:45

encephalopathy or myelopathy. Sorry.

8:49

And that has an interesting French name.

8:51

Can you pronounce it? I cannot, actually.

8:53

I think it's called foie allah Juanine Syndrome.

8:57

So that's a more acute.

8:59

Onset phenomenon in something

9:02

that is more slower paced.

9:06

So what other comments do you think are relevant to

9:08

make in this case? And while you're doing that,

9:10

I'm going to pull up the lumbar.

9:13

Any other thoughts? So the next thought is,

9:16

is the cord okay? And I think Dr.

9:19

Pomeranz has alluded to the fact that the cord

9:21

signal intensity is fine. But in reporting,

9:24

the next step that I would take if I'm looking at

9:27

a case like this is to make sure that there's

9:29

no abnormal signal within the spinal cord.

9:31

How emergent is this case?

9:33

To get to treatment, to kind of

9:37

fix the abnormal vasculature?

9:41

One other thing that's important,

9:43

if you can figure it out, is to try and figure

9:46

out where the connection is.

9:50

Now,

9:51

these are caused by radicular intersegmental vessels,

9:55

so they occur, the fistulous communication

9:58

actually occurs out here.

10:00

It occurs out to the side,

10:02

not within the spinal canal,

10:04

where it occurs along the dural sheath.

10:06

So that's a common misconception.

10:08

And usually, you're going to find it

10:10

anywhere from T5 to L3,

10:13

although the connections have been described as high

10:15

as the vertebral artery and as low as the upper

10:19

portion of the internal iliac vein.

10:21

So there's quite a bit of distance

10:25

for you to be searching for this connection.

10:28

And you may have to use a conventional spinal

10:31

angiogram to find that connection.

10:33

Some people use spinal CTA.

10:36

Some people have even used dynamic spinal MRA.

10:40

When you're looking at these things,

10:41

you want to try and dial into the location of the

10:44

fistula, want to see what type of shunt it is.

10:47

This is an AVF Anson Spetzler type 1.

10:52

You want to assess the angio architecture.

10:54

If it's an AVM, do they have aneurysms?

10:58

What space is it in?

10:59

Usually, these are intradural. The true AVMs.

11:03

This is an AVF. True AVMs are frequently intramedullary.

11:07

And then, as you said,

11:08

you alluded to this quite properly.

11:10

What are the imaging features?

11:12

In other words, what's going on with that cord?

11:14

If that cord is looking pristine,

11:16

you can save the patient.

11:18

But if you've got gliosis or swelling or edema

11:21

going all the way up and down the cord ODS,

11:23

are you're not going to be able to help the patient

11:26

a lot? And then where are they clinically?

11:29

Are they already paralyzed?

11:31

Do they already have impotence?

11:32

Do they already have bowel or bladder dysfunction?

11:34

If they do,

11:35

probably game over.

11:38

What do you think the role of contrast

11:40

is in a case like this?

11:42

The role of contrast would be to essentially

11:44

assess the spinal cord.

11:47

Is the spinal cord integrity maintained?

11:51

Suffice it to say,

11:53

is there enhancement within the spinal cord?

11:55

Which would be an early finding of venous.

11:59

Congestion or essentially ischemia

12:02

within the spinal cord. Yeah,

12:04

and I think your point is well taken

12:07

and the kind of enhancement that you're used to

12:11

seeing isn't what happens in a Dural AVF.

12:15

We're all used to seeing this

12:16

focal intense enhancement,

12:18

but I would describe it more as sort of almost like a

12:21

film, like you're looking through a pane of glass,

12:24

just very subtly shaded glass.

12:26

And I've got the Sagittal contrast-enhanced T1 in

12:32

the lumbar region. And if you look very carefully,

12:34

it's gray, it's gray, it's gray, it's gray.

12:37

And then it's not so gray.

12:39

It's a little bit filmy right here.

12:41

It's a little bit of ill-defined enhancement.

12:44

And commensurate with your observation earlier,

12:47

you have these little hairs on the surface right

12:50

there, which is part of the Dural AVF.

12:54

So this is a really important case because,

12:57

first of all,

12:58

it's easily missed because it's a woman and

13:00

you don't think about it in a woman.

13:02

Second,

13:03

it's a really important case because

13:04

we're early enough in the game.

13:06

We do have some venous congestion here,

13:09

but the cord signal is for the most part preserved.

13:12

So we could really do some good by

13:15

making an early diagnosis here.

13:17

And this patient referred for spinal angiography and

13:21

subsequently treated, and that's why in 2014,

13:25

we could barely see the Dural AVF.

13:28

Look how long it took, though.

13:30

We went from 2011 to 2014.

13:34

My guess is there were multiple intervening MRIs at

13:37

other institutions before they came up with the answer

13:40

and then did the angiogram and then did the therapy,

13:43

probably with Embolization. Any other thoughts?

13:46

Any other closing remarks on this case

13:48

before we turn away from it?

13:50

The only one thing like you alluded to already would

13:53

be looking for signs of subarachnoid hemorrhage.

13:55

Typically, it is rare,

13:56

I think it's like 35% of the time that

13:59

it can happen in a case like this.

14:01

But that would be another tip-off, I think.

14:04

And one other vascular entity would be a cavernoma.

14:09

Those are localized.

14:11

You should never confuse a cavernoma with a Dural AVF.

14:16

It's usually a round lesion, by the way.

14:19

They don't calcify in the spine

14:21

like they do in the brain.

14:22

They do bleed in the spine much more frequently,

14:26

about 1% per year,

14:28

as opposed to what they will do in the brain.

14:31

And they're frequently associated with a DVA.

14:34

So don't get mixed up

14:36

with a cavernoma in the spine with this entity.

14:40

This is a critical entity, and we're going

14:41

to show you some more of them.