0:00

Okay, we've got a 67-year-old man

0:03

with low back and left hip pain

0:05

and a history of a left hip fracture.

0:09

At three Tesla, we've got a sagittal T2 fast spin echo

0:14

without any fat suppression.

0:15

In the middle, we've got a standard anatomy

0:18

T1-weighted image.

0:19

And on the right, an axial standard

0:22

T2 fast spin echo image.

0:24

I haven't put up anything that's extremely water-weighted.

0:27

We might use that, say, to look for fractures.

0:30

Let me blow it up a little bit.

0:32

Or hotspots, or areas of edema that would point

0:35

us in the direction of potential pathology.

0:37

So the history is a little bit amorphous,

0:40

but it localizes somewhat to the left.

0:43

Now, we do have a slip at L4 on L5,

0:46

a very degenerated disc and a very narrow foramen.

0:49

But if I cross-reference that,

0:51

which I'm not going to do right now for interest

0:53

of time, it's on the right side,

0:55

it's on the incorrect side.

0:57

The patient's symptoms are in the left hip,

1:00

and that doesn't look nearly

1:02

as bad as the other side.

1:03

So maybe the left hip pain is from the fracture,

1:07

not from this slippage. So we're too ladling along,

1:11

and some of you might notice that this part

1:13

of the sacrum looks a little strange.

1:16

It's a bit empty.

1:17

There's this globular area of intermediate

1:20

signal intensity.

1:21

We've got roots up high that are flopping about

1:24

and dangling nicely, but no roots here,

1:26

so that's problematic.

1:28

Time to go to the axial projection.

1:30

So let's go back to the axial projection and

1:32

look at where we are.

1:33

We're up high,

1:34

and we're going to scooch up and down.

1:36

And as you do so,

1:38

I would advise you not to ignore the

1:41

atheromatous change in the aorta,

1:43

because sometime you're going to run into 40, 50,

1:46

60% atheromatous change.

1:48

The patient is going to have claudication

1:51

that's vascular in nature,

1:53

or they're going to have thromboembolism

1:54

the cause of their syndrome.

1:55

So do not ignore the atherosclerosis or size of

1:59

the aorta. So as we're toggling down, yeah,

2:02

we've got facet arthropathy,

2:03

but we've got some beautiful, dangling,

2:06

delicate roots. All is well in the land of Oz.

2:10

Or not. Let's pull down the lower axial images,

2:15

which really tell the story.

2:16

I'm going to blow them up a little bigger.

2:19

In fact, a lot bigger.

2:21

And all of a sudden, our dangling,

2:23

delicate roots turn into these lumpy, bumpy,

2:28

irregular objects. In fact,

2:30

it looks like we have a big filum terminale there,

2:33

but we don't. So what's going on?

2:36

Well, this is a post-op,

2:40

but it's also potentially a pre-op, right?

2:42

Meaning this patient's still having symptoms.

2:44

So you're being asked, okay,

2:46

can we do anything about that?

2:48

And this identification Dr.

2:50

Pomeran just made is really important.

2:52

Okay. That nerve root clumping is arachnoiditis.

2:56

So there is a problem, either inflammatory.

3:00

Or something that has caused the nerve roots to

3:03

stick together, and that can be symptomatic,

3:05

meaning you can get back and leg pain from that.

3:09

So if you're contemplating any

3:11

sort of surgical remedy,

3:12

you have to be sure that your problem is compressive

3:14

to begin with. And as you pointed out,

3:16

we already have a couple of discrepancies

3:18

the side of predominant symptoms.

3:20

The patient's already had a decompression, okay?

3:24

Symptoms are on the left,

3:25

and the worst is on the right, right?

3:27

So if there's arachnoiditis,

3:31

that really affects the idea,

3:33

even if there is a compressive component to it,

3:35

as there could be,

3:37

what's the outlook? And the outlook is a lot worse.

3:41

Well, a couple of other comments.

3:43

We've got this sort of globular,

3:45

almost glom-like area of signal change.

3:48

A little bit of it is ossified in signal.

3:52

So while we might be volume averaging

3:55

a little bit from the back,

3:55

we might have a little bit of

3:57

arachnoiditis ossificans.

3:59

But what we do have clearly on the right

4:01

is what I call the empty sac sign.

4:04

So, when you're looking for arachnoiditis,

4:06

this is our dural sac.

4:07

And normally inside you'd have a few delicate

4:10

nerve roots like this. But in this case,

4:12

all the nerve roots are lined up like little

4:16

structures all in a row around the periphery.

4:18

They're out here kind of lumpy and bumpy,

4:21

hugging the edge of the dura.

4:23

And there's nothing in the middle.

4:25

The whole center is empty.

4:27

So that's one sign of arachnoiditis.

4:30

Another sign of arachnoiditis is also present here,

4:35

and that's when you have these pseudomasses.

4:37

So, once again, we've got a sac.

4:40

We'll make our sac just to be consistent,

4:42

we'll make it orange. And then inside the sac,

4:45

we've got structures that look kind of like this.

4:48

Whoops didn't get the right color on there?

4:50

Here we go. So it looks kind of like this.

4:54

So the pseudomass sign.

4:56

Then we've also got something called the dural

4:59

thickening sign, which this patient also has.

5:01

I mean, it's all here: dogs and cats living together,

5:04

ten days of darkness, the plague, mass hysteria.

5:07

It's all in this case.

5:09

Look at this sac. Check it out.

5:11

Down low, we'll make our sac green this time,

5:14

but look at the edge of the sac, it's too thick.

5:17

So we've got a third sign of arachnoiditis,

5:21

and finally a fourth sign of arachnoiditis,

5:24

which we sort of have here when you get up

5:26

higher is the pseudochord sign.

5:29

Now,

5:30

we have a better example of this,

5:31

but in this situation, you have a sac,

5:35

and then inside it,

5:36

all the nerve roots have just glued together right

5:39

in the middle and produced something

5:40

that looks like a cord or a CONUS.

5:43

So virtually every single sign of arachnoiditis

5:46

is present, in this case,

5:48

most likely occurring postoperatively.

5:51

So what are some other possibilities for

5:54

arachnoiditis, etiologically?

5:58

Well, surgery as. Mentioned,

6:00

but there are other possibilities.

6:01

For example, trauma.

6:03

Let's say somebody had a hemorrhage, all right?

6:05

So anything that gives you an inflammatory problem

6:08

inside the sac has that potential.

6:11

Now, you also will see it with very severe stenosis.

6:15

And you see you don't know that because you see the

6:18

cauda equina all squeezed because of severe stenosis.

6:21

You decompress and the sac opens up,

6:24

but the roots stay all clumped together

6:26

and you're in trouble there.

6:27

Those people do not do very well and it's very hard

6:30

to say beforehand what that's going to be like

6:33

because you don't know if it's from Extrinsic

6:35

Compression or Arachnoiditis.

6:37

So I would say those are the two most common causes.

6:40

There are other things out there.

6:42

There are injections.

6:43

We used to use contrast agents in the spine that

6:46

were shown to be taken off the market for causing

6:48

arachnoiditis. There are some infections,

6:51

inflammatory causes.

6:53

Let me ask you a question because this comes up for

6:54

me all the time. You've got severe stenosis,

6:57

let's say, at this level.

6:58

And then the nerve roots,

6:59

I'm going to make my line a lot thinner.

7:01

And then the nerve roots kind of get pushed up and

7:05

they get very squiggly and wiggly right

7:07

above the area of stenosis.

7:09

And there are times when I'm not sure if those roots

7:12

are just kind of pushed up or whether they're

7:15

pushed up and they're adherent.

7:16

Is there any way to tell or is it

7:19

a surgical diagnosis only? Well,

7:21

you will get that sort of corkscrewing thing

7:24

is some terminology that I've read.

7:26

But usually you'll be able to see that even though

7:29

if the roots kind of are a little redundant on

7:31

themselves, there will be CSF between them.

7:34

Okay?

7:34

Whereas this pseudomass where there's nothing there

7:38

except the mass of something that is a little more

7:41

worrisome. And if there's severe stenosis,

7:44

if there's severe stenosis and the

7:47

patient is really symptomatic,

7:49

you are probably going to give that a try.

7:53

Another thing would be what is their response,

7:56

for example, to epidural steroid injections?

7:58

And I think that extrinsic compression is going

8:02

to respond better than arachnoiditis will be.

8:05

So if they respond to an epidural steroid and they

8:07

have that history, that activity history,

8:09

whereas I think arachnoiditis is not going to

8:12

have that classic stenosis activity history,

8:16

it's going to be more constant pain,

8:19

not activity related, not posture related as much.

8:22

I mean, they can overlap to some degree,

8:24

but on a historical basis,

8:25

you can also probably help yourself a little bit.

8:27

So three things then.

8:29

The three things are confluence.

8:32

You don't see any CSF in between these little

8:35

squiggly lines. That would be one.

8:38

The second one would be response perhaps to steroid

8:43

injection and the third one would be

8:46

positional or symptom-related.

8:48

Arachnoiditis is there all the time,

8:50

whereas stenosis,

8:52

they can get some relief in one position or other.

8:55

And I think that's really important because this

8:57

comes up all the time and I'm going to show a case.

9:00

Very similar to this,

9:01

where we have the nerve roots kind of clumped above

9:06

the area of stenosis, and this comes up.

9:08

So in summary, then arachnoiditis,

9:11

we've got all the major signs of arachnoiditis.

9:14

We've got a pseudochord sign,

9:16

we have mass-like lesions inside as a sign,

9:19

we've got thickening of the dural sac as a sign,

9:22

and we've got an empty sac sign,

9:24

all indicative of arachnoiditis.