0:01

Here talking about nerves.

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So, uh, nerves are certainly something

0:04

that can be pretty intimidating, especially

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because we're not imaging them often,

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but they're always present in all

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of those joints that we image.

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So I hope to give you kind of a broad overview of some

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of the things I look for when evaluating these nerve cases.

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So today I'm just gonna touch on a few ways

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to approach a nerve case.

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Uh, specifically we'll look at the protocol

0:25

and how those different sequences can be useful, uh,

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when you're doing those evaluations.

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And then I'm gonna talk about a general approach.

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And, um, when you're looking at these nerve cases,

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the approach is a little bit different when we're looking at

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injury cases or tumor cases.

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And finally we'll get into some

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specific entrapment syndromes.

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So this is certainly not an all-inclusive list.

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If you think about the length of the nerve all the way, uh,

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from the root, uh, as it exits the spinal canal to,

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you know, the tip of your finger, there's a lot

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of different sites that the nerves can be entrapped.

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Some of them are more frequently, uh,

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frequently encountered than others.

1:00

And so those are some of the cases I chose to show today.

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Uh, and just a fair warning, uh, some

1:06

of these cases have great, uh, imaging examples

1:09

of the pattern of muscle denervation.

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Uh, but they may not be true entrapment cases.

1:14

When we say entrapment, we're really talking about

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mass effect or extrinsic compression on the nerve.

1:20

Uh, the cause of the extrinsic compression can be varied.

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Um, but just remember that any nerve abnormality,

1:26

whether it's traumatic

1:27

or a tumor, can give you kind

1:29

of a similar secondary findings in the muscle.

1:31

And we'll talk more about that.

1:33

So when we're looking at cases, I broke these down

1:35

by general anatomic region, and that's

1:38

because that's usually how we image these cases.

1:41

Uh, the surgeon or clinician will have a general idea of

1:44

where the nerve abnormality is occurring,

1:46

and we'll get dedicated imaging of

1:48

that joint or of that region.

1:50

So they're broken down by

1:51

entrapment syndromes about the shoulder.

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And then we'll look more specifically about some entrapment,

1:56

uh, syndromes of the elbow.

1:58

And finally talking about a few

1:59

entrapment syndromes of the wrist.

2:03

So first we'll talk about protocol.

2:05

So, um, the T one weighted sequences

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and nerve imaging are very important, and that's

2:09

because these really give you a great idea

2:12

of the normal anatomy.

2:14

So all of our nerves have this great, uh,

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T one hyperintense REM of fat.

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This perineural fat is one

2:20

of the normal features of our nerves.

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And so identifying this region

2:23

of fat really helps you follow the course of the nerve.

2:27

Uh, we use a lot of axial sequences

2:29

because you can kind of see the nerve in continuity,

2:31

get a sense of its normal caliber

2:33

as you're evaluating these cases.

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So the T one weighted sequences are also great

2:38

for muscle abnormality.

2:39

We'll talk more about the sequence of muscle injury

2:42

and how those, uh, imaging findings change over time.

2:45

Early on, those T one weighted, uh, muscle

2:48

findings may be normal,

2:50

but as that muscle denervation progresses,

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we'll often see fatty infiltration

2:54

and atrophy of the muscles,

2:56

which becomes much more apparent on our T one weighted

2:58

Sequences.

3:00

We, of course, do fluid sensitive sequences,

3:02

and that's mostly to identify signal abnormality within the

3:05

nerve or signal abnormality within the muscles.

3:08

We do a mix of T two, uh, stir

3:11

and proton density sequences, all with fat suppression.

3:15

Uh, the proton density sequences are great for

3:17

that high spatial resolution.

3:19

So these are small structures,

3:21

so those are very useful in identifying the

3:23

morphology of the nerve.

3:25

Your stir sequences are certainly going

3:26

to be more sensitive when you're trying to identify edema.

3:30

And so kind of depending on what you think, uh,

3:33

the more likely processes you can tailor some of these s

3:36

we do long access imaging as well.

3:38

So we do sagittal and coronal sequences.

3:41

Oftentimes we'll trade the axial proton density, uh,

3:45

and the long axis, uh, stir

3:47

or T two with fat saturation sequences.

3:50

And finally, post contrast imaging.

3:52

This is not a requirement in all nerve cases.

3:54

There's a couple of instances where it is very helpful.

3:58

So anytime you have tumor

3:59

or infection, which is not really the focus of this talk,

4:02

uh, but when you encounter those in the clinic where

4:04

that is the specific clinical question, uh,

4:07

contrast gadolinium based agents are, are a must.

4:09

Uh, they really help you define the extent

4:12

of those abnormalities, um,

4:14

and can help you characterize tumors for certain.

4:17

Uh, there are sometimes abnormalities

4:19

of the nerve signal post contrast in cases of injury.

4:22

So similar to the brain,

4:24

our nerves have a blood nerve barrier,

4:26

and when that's disrupted,

4:27

you can get abnormal enhancement of these nerves.

4:29

So, uh, don't be surprised when you do have nerve

4:32

abnormality to see some enhancement.

4:34

But oftentimes the non-contrast sequences are adequate

4:37

for identifying, uh, those abnormalities.