0:01

This was a 28 year old man.

0:03

He actually had bilateral wrist pain and he had some numbness in his small

0:07

finger. He was otherwise healthy.

0:13

So this is an m r i of the wrist. In this particular instance,

0:16

we'll scroll through these images a couple of times.

0:20

Our sagittal sequence, tough to see, uh,

0:24

get your bearings here in space,

0:26

but hopefully catch a couple images of those nerves here.

0:33

All right, one more time through that axial sequence.

0:35

I think this is probably the most helpful sequence.

0:38

Can I go from the distal aspect of that forearm through the wrist moving

0:42

distally towards the hand.

0:47

All right. And for case question number nine,

0:52

what is the most common cause of guy canal syndrome?

0:56

Is this hypoth or hammer hook of hamate fracture,

1:00

ganglion cyst, or repetitive injury?

1:06

All right, common things being common. Very good ganglion cyst.

1:09

So we often see ganglion cyst about the wrist, um,

1:13

and they can impinge upon our nerves. So, um, s space,

1:18

occupying lesions, tumors,

1:19

other things are by and far more common than kind of a traumatic injury. Uh,

1:24

patients in these, uh,

1:25

in this scenario present with motor or sensory weakness and the,

1:29

the bifurcation, um, of the nerve at this level. Um, part of it is sensory,

1:33

part of it is motor.

1:34

So just depending on how proximal or distal the impingement is,

1:38

will kind of determine how the clinical presentation is. Uh, they have the,

1:42

the typical ulnar nerve distribution with the, um,

1:46

ulnar aspect of that ring finger and the small finger.

1:49

And even though not present in this case,

1:51

you can see the denervation of the intrinsic hand musculature, um, or,

1:55

or of the hypoth muscles. So let's go back to this case.

1:58

This was a pretty uncommon cause of ulnar nerve impingement and that is the

2:03

presence of an anomalous muscle. So we should have one muscle out here.

2:08

This is gonna be our E C U extensor carpal nerve, or I'm sorry,

2:13

F C U flexor carpal nerve. We shouldn't have a second muscle,

2:17

so we have another muscle belly.

2:19

It's just deep to our normal tendon and immediately superficial to our ulnar

2:23

nerve branch in this case.

2:26

And so this was thought to be an accessory hypothenar muscle running just

2:29

between the F C U and the ulnar nerve. Uh,

2:32

you can kind of see the corresponding abnormality of the nerve on the sagittal

2:36

here. It's a little bit hyperintense, but pretty hard to, uh,

2:40

pretty hard to point to any one area and say that that is profoundly

2:44

hyperintense. Um, interestingly enough,

2:47

this is a contralateral wrist in the same patient.

2:50

He had the same thing on the other side,

2:52

so his symptoms were worse one side than the other.

2:54

But this was just thought to be some sort of anomalous developmental thing that

2:58

was present in him, um, and present bilaterally.

3:01

Thought to be accounting for his symptomatology.