0:01

So this was a 68 year old man. He had a,

0:04

a really interesting clinical history in that he had a penetrating injury, um,

0:08

from a box cutter. So something he was using to open some boxes at work, uh,

0:13

caught him in the arm and he had some resultant weakness and pain, uh,

0:17

in his upper extremity. So I have, uh,

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axial sequences here. I'm gonna scroll through those a few times.

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All right, and another plane. These are actually, uh, coronal,

0:33

post contrast and an axial post contrast

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and from distal in that forearm proximal. One more time through.

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All right. And for our polling question number three,

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neuroma and continuity is seen in the setting of complete nerve transect.

0:57

True or false? Can you use those test taking skills here? Hopefully guide your,

1:02

uh, answer a little bit. All right. And hopely,

1:06

everybody's had a chance to answer this one. Uh,

1:09

just generally with any true or false questions, they are false. And this is,

1:13

uh, the case, uh, here. Neuroma in continuity is, uh,

1:17

often seen in cases of partial nerve transections.

1:20

So let's talk a little bit more about that. Uh, just in general,

1:23

when evaluating some of these nerve injuries, there's obviously severity. Uh,

1:28

there's a couple of classifications. Uh, both of them are fairly old,

1:32

but they have kind of the same, they cover the same concepts.

1:35

Is this just a stretch injury?

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Meaning are all of the nerve elements intact or is there partial disruption?

1:41

And the reason I broke this down this way is because the neuropraxia and ESIS

1:46

are predominantly treated conservatively and don't require surgery.

1:51

So people will recover nerve function, uh,

1:53

on some of these low grade injuries versus having a more severe injury,

1:57

a type four, type five or neuro emesis injury.

2:00

And the difference is that there is some disruption of the nerve elements in

2:05

these type four or type five injuries. Now,

2:08

the type four injuries result in neuroma and continuity and type five injuries

2:12

have complete transection. So we've seen a case of both.

2:15

Now we'll go back to this prior case, which is a neuroma and continuity. Um,

2:21

and the distinction between the three and the four is that the nerve can have

2:25

some abnormal signal in a type three injury, but, and it will be continuous,

2:29

but it shouldn't be enlarged.

2:31

So anytime you have this change in caliber or enlargement of the nerve,

2:35

you should be thinking it's a partial disruption of the neural elements,

2:39

maybe an aroma in continuity. And if you have discontinuity,

2:42

that is considered a type five injury. All right,

2:45

so if we go back to our case here, uh,

2:49

starting with those short axis sequences, uh, hopefully you were able to see,

2:53

uh, this kind of leading, uh,

2:55

linear signal abnormality from the skin through the muscles. And if you,

2:58

you didn't, there is isolated muscle abnormality.

3:01

Tough to see in this case cuz of the really bad fat saturation. Um,

3:05

but deep there is the brachialis muscle muscle of the upper arm.

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And as we go along the course of the brachialis,

3:11

we can see that adjacent radial nerve and it's enlarged and it's increased in

3:16

signal. And so we can see that it's still contiguous.

3:20

We go from this slice of nerve,

3:22

we can see that there's still nerve elements there, but they are abnormal.

3:25

There may be even a rind of hypo intensity, which may suggest some, um,

3:30

some scar formation or perineural fibrosis. And we can see that,

3:35

uh, here on this T1 sequence as well.

3:37

We start to lose some of that normal perineural fat. Uh,

3:40

at the site where the nerve is injured,

3:42

it's immediately adjacent to this linear signal abnormality,

3:45

right where this patient had this penetrating injury.

3:48

And on post contrast sequences, remember that those neuromas enhance.

3:51

So we have a little focus or little blush of enhancement here, uh,

3:55

involving that radial nerve. Uh,

3:57

this is why we don't show these nerve cases with the kind of the coronal or long

4:01

axis imaging cuz you really only get that abnormality on a few slices.

4:05

And the corresponding, uh, post contrast T1 signal,

4:07

we can see again that focal enlargement consistent with a neuroma and continuity

4:12

or type four injury.