0:00

So we're delving in now to our identified sites of, uh,

0:04

nerve impingement.

0:06

So again, I've kind of selected a couple of regions

0:08

that you may encounter in practice here.

0:10

Uh, first is a brachial plexus,

0:12

and I'm gonna kind of go through these in the same fashion.

0:15

We'll talk a little bit about the anatomy

0:17

and then the underlying disease process,

0:19

and we'll look at a case.

0:20

So brachial plexus anatomy can be complex.

0:23

Uh, we all remember from, uh, medical school

0:25

and all of our anatomy classes learning the different

0:27

portions of the brachial plexus.

0:29

I think when we get to anatomy, one

0:31

of the things about brachial plexus that's important

0:33

to realize is that you're really trying to identify

0:36

where in the plexus the abnormality is,

0:38

and we can use different anatomic landmarks to help,

0:41

to help us identify those different regions

0:43

of the brachial plexus.

0:45

So this is an abnormal plexus on this, uh,

0:48

stir image in the bottom corner.

0:50

Uh, but it gives you a great layout of kind

0:52

of the different transitions, uh, of the brachial plexus

0:55

as we move from central to distal along the course

0:58

of the upper extremity.

1:00

And now I've chosen to focus on the cords, and that's

1:03

because this is a frequent site

1:04

of nerve impingement in the upper extremity.

1:07

And so remember, our cords are three.

1:09

We have a lateral posterior, and medial

1:11

after those six divisions kind

1:13

of recombine into these three cords.

1:15

And the anatomic region that we are evaluating, uh, is going

1:19

to be just inferior or coddled to the clavicle,

1:22

and we wanna be medial to the pectoralis minor muscle.

1:25

And so those are the kind of general anatomic landmarks

1:28

that we're looking for, uh,

1:29

to identify the region of the cords.

1:31

You'll also note that this is a pretty common space we're

1:34

gonna talk more about, and this is the cost

1:35

of clavicular space.

1:37

Uh, that will come up again and again

1:39

because it's a frequent site of impingement.

1:43

One note and one special thing about thoracic outlet

1:46

syndrome, when you're asked this question in the clinic, um,

1:48

you should think about doing some additional

1:51

sequences on your protocol.

1:52

Uh, so for thoracic outlet syndrome, in addition

1:55

to doing our coronal,

1:56

or I'm sorry, our T one weighted sequences

1:58

and our fluid sensitive sequences,

2:00

we also add a couple of special things.

2:03

The first one is demonstrated here in this, uh,

2:05

lower corner, and that's what the arms in a dynamic

2:09

or kind of an exacerbated position that often brings on

2:14

symptoms in these patient populations.

2:16

Uh, and so this, uh, particular sagittal sequence,

2:19

we have our clavicle anterior

2:21

and our rib kind of along the inferior,

2:23

more posterior aspect of the image here.

2:25

So this is the same sagittal sequence.

2:27

It's a sagittal, uh, proton density

2:30

or a sagittal T two without fat saturation.

2:32

But the arm is in a totally different position

2:35

between these two images.

2:37

The first image, the arms are down to their side,

2:40

so it's a relatively relaxed position for the extremity.

2:43

And the other image, the arm is overhead,

2:45

and that's kind of the stress condition

2:47

of this costa clavicular space.

2:50

And you'll note the, uh, vasculature denoted by this, uh,

2:53

the subclavian vein in blue

2:55

and the subclavian artery in red.

2:56

In this instance, you can see the difference

2:59

In the subclavian vein when the arms are in that relaxed

3:02

or arms down to the side position

3:04

as opposed to the arm overhead.

3:05

That vein is completely collapsed

3:07

and it's collapsed between these osseous stretchers,

3:10

the clavicle and the rib.

3:12

The, the artery can have kind of a variable course, right?

3:14

The vein can as well.

3:16

And so the artery in this instance is away from this CLOs

3:20

clavicular space, and it kind of maintains its normal shape,

3:23

uh, even in the stress condition.

3:26

The other sequence that we routinely perform when evaluating

3:28

for thoracic outlet syndrome is an angiogram.

3:31

We do these all concurrently at the same time,

3:33

and we do those angiographic sequences with the arms, uh,

3:37

ab abducted down to the side as well as the arms overhead.

3:40

So again, in kind of a relaxed, in a more stressed position,

3:43

we do these, uh, nice 3D maximum intensity reconstructions

3:47

to get a great idea of the normal course of the vasculature.

3:52

So thoracic outlet syndrome, something we've probably,

3:55

you know, encountered at one point

3:57

or another in our, uh, training.

3:58

It's something that we image for, um,

4:00

probably most frequently of all

4:02

of the nerve entrapments in the upper extremity.

4:04

Doesn't make it the most common,

4:05

but it's one that we image for, uh, frequently.

4:08

So remember that this is a compression phenomenon

4:11

and it can happen at different sites.

4:12

So the caoc clavicular space most common,

4:15

but we can see compression in the intra scale triangle

4:18

as well as the rectal pectoral minor space.

4:21

And there are kind of two distinct clinical presentations

4:24

of thoracic outlet.

4:25

You can have a purely vascular compression,

4:28

and that's the more classic kind of pain alteration of,

4:32

of skin temperature and color.

4:34

Or you can have a neurogenic, uh,

4:36

those ones are a little bit less common

4:38

and those patients present usually with atrophy.

4:41

Uh, they can have some sensory loss,

4:43

but it's usually not a painful phenomenon.

4:45

You can also get features of both,

4:46

which makes it very confusing.

4:48

Uh, but remember we're looking at those as kind of distinct,

4:52

uh, structures and distinct disease processes.

4:55

One thing to note about the vasculature is that some degree

4:59

of venous narrowing can be normal, right?

5:01

There's, it's a physiologic, it's a dynamic space.

5:04

And so you can have physiologic narrowing of the vein.

5:06

Our general rule of thumb is that when it gets

5:08

to be more than about 50% of the caliber of the vein, uh,

5:12

then it's considered abnormal.

5:14

Any narrowing of the artery should be considered abnormal.

5:17

So just a nice, uh, uh, arterial image.

5:20

Uh, example here you can see there's this arterial phase.

5:23

We have some venous filling as well,

5:26

but that first branch of the aorta

5:27

and then branching the subclavian artery, we can see

5:30

that focal mass effect.

5:31

It is in the region of the costal clavicular space.

5:34

We can see that the arms are overhead.

5:36

Uh, and this would be an abnormal finding in this instance

5:38

concerning for thoracic outlet syndrome.

5:42

All right, so let's move on to an unknown case.

5:44

So this is a 30 5-year-old woman.

5:46

Uh, she has numbness and tingling.

5:48

The clinical concern was thoracic outlet syndrome.

5:51

It was exacerbated with those overhead activities.

5:54

So we have those two sagal sequences lined up side by side

5:58

with the arms neutral

5:59

and the arms overhead in this instance, as well

6:02

as some selected radiographic and post contrast imaging.

6:06

So in our first two sequences, you'll note, uh,

6:09

that there's some abnormality here,

6:11

and it's an anatomic abnormality

6:13

that I think is better appreciated.

6:14

On the radiograph, uh, we can see

6:17

that there's an abnormal fusion of

6:18

that first and second rib.

6:20

So that costa clavicular space is already narrowed even

6:23

before we have the patient lift up their arms.

6:25

And we're really looking for the fat in this region.

6:27

We can see our vein or artery

6:29

and kind of our surrounding brachial plexus structures, uh,

6:32

specifically our brachial plexus cords.

6:35

And I know when we put the arm up,

6:37

that space narrows pretty drastically, right?

6:39

We can see some mild mass effect.

6:41

On the vein, we can see we were starting to lose all

6:43

of the fat in this region,

6:45

and that's concerning for impingement on those

6:47

brachial plexus structures.

6:49

And finally, this is a mixed case.

6:51

We have arterial abnormality as well.

6:54

I think probably best evaluated on

6:55

the post contrast sequence.

6:56

You can see that there's this central hypo intensity

6:59

or a filling defect, uh,

7:01

with surrounding contrast in that vasculature.

7:03

And unfortunately, the person had a large clot in

7:06

that subclavian artery.