0:00

Finally the ulnar nerve in the wrist, a little bit more

0:03

of a superficial course,

0:05

and it ovates the rest of the hand muscles.

0:07

So you have your hypo thenar muscles, your, uh,

0:09

intrinsic hand muscles, all innervated by the ulnar nerve

0:14

and ulnar nerve entrapment, also known as GI canal syndrome.

0:17

Because of the space through which it travels, uh,

0:20

this is one that can be injured either proximal

0:23

to the bifurcation or distal,

0:24

and you'll get varying symptomatology based on the level of,

0:28

um, entrapment.

0:29

In this instance, you can have a space occupying lesions.

0:33

Ganglion cyst very being very common about the wrist are a

0:36

frequent cause of ulnar nerve entrapment.

0:39

And the clinical features similar to cubital tunnel,

0:41

you kind of get that distribution of findings in the small

0:44

as well as in the ulnar aspect of that long

0:47

or of the ring finger.

0:49

You can get both motor and sensory.

0:51

Again, just kind of depending on the site of entrapment.

0:55

So here's a case of 28-year-old man.

0:58

He'd actually had quite a bit of wrist pain that was ongoing

1:01

for a while, and he had this fifth finger numbness that was,

1:03

um, very, uh, bothersome to him.

1:06

And it was quite the clinical conundrum

1:08

because it was present bilaterally.

1:10

So he had been worked up for quite a few things

1:12

before he made it to imaging.

1:14

Uh, they thought something potentially systemic was going on

1:17

and causing an issue with his peripheral nerves.

1:20

When we did imaging, uh, the answer became pretty apparent.

1:23

Uh, so this is kind of a fuller

1:25

because it's not something

1:26

that really jumps outta the screen,

1:28

but you really have to understand your anatomy

1:30

of this region to identify

1:31

that something here isn't supposed to be here,

1:33

and that's this muscle belly.

1:35

So we've identified the flexor carp by ulnar,

1:37

which should really be the most superficial aspect

1:40

of that guidance canal.

1:41

Um, but in this instance we have another muscle belly,

1:44

and this was an accessory hypo thenar muscle.

1:47

It runs just superficial to that ulnar nerve

1:49

and was causing some entrapment present bilaterally.

1:52

Uh, so this patient actually did pretty well

1:54

with some surgical resection of that abnormal muscle,

1:59

and that was our whirlwind tour of entrapment.

2:01

So, uh, just keep in mind there are lots

2:03

of other entrapment syndromes that you may encounter,

2:06

but taking kind of that stepwise approach,

2:08

getting the clinical information that's available out there,

2:11

uh, and then really starting

2:13

with those secondary imaging findings, looking for

2:16

that muscle edema, identifying the pattern of atrophy

2:19

and then saying, okay, this is a radial nerve distribution.

2:22

Going back to the course of that radial nerve, uh,

2:24

to see if you can find a primary abnormality.

2:27

And then lastly, looking for those causes

2:29

of potential entrapment.

2:31

So is there extrinsic compression?

2:33

Is there an anomalous muscle, et cetera?

2:35

Uh, just keeping in mind that cm of these are more common.

2:38

You'll, you'll certainly encounter thoracic outlet syndrome

2:41

cases, um, with the frequency of paralabral cysts.

2:44

You'll probably encounter a derivation process about the

2:47

shoulder, uh, for, uh, cases, certainly less frequent.

2:51

But make sure you're evaluating those nerves when you're

2:53

reading those elbow MRIs.

2:55

It gives you a great internal control

2:57

of normal and what the nerves

2:58

Should look like. Uh,

2:59

also gives you a great kind

3:01

of anatomic review in each of those cases.

3:04

And finally, the wrist, uh,

3:05

entrapment syndromes we don't frequently image.

3:08

Remember, there's a few pitfalls when you're facing carpal

3:10

tunnel cases in the median nerve itself.

3:13

Um, and look out for weird stuff that can involve

3:15

that guy's canal, including some accessory musculature

3:18

as we saw in that last case.

3:20

So thanks everyone for joining this whirlwind tour.

3:24

Uh, it's been a real pleasure kind of going over some

3:26

of these upper extremity entrapment syndromes.

3:29

Um, and I hope that we, uh, can enjoy some more cases.

3:32

Thanks so much.