Webinar and Live Scanning Questions

[Diane]

Hi Steve!
I have some questions on the webinar:
1) I too have noticed the characteristic ganglions that wraps around the radial artery. I’m still a bit confused. Do these ganglions arise from the FCR tendon sheath strictly or does it come from the radiocarpal joint space or does it arise from the intrinsic ligaments of the proximal carpal row?

2) In a normal patient when the median nerve enters the proximal carpal tunnel, do you expect to see a SLIGHT compression because it is where it gets naturally compressed? Or do you expect it to be one size all the way through? Sometimes when I’m scanning the median nerve in long, I see a slight compression but am not sure whether it is a true step sign.

3) When performing a dynamic assessment of the A1 pulley, do you only move the finger at the PIPJ or do you require to bend at the MTPJ?

4) At the STTJ, are you more concerned about the any bony irregularity of the scaphoid and the trapezium rather than the trapezoid? It’s just that the trapezoid wasn’t stressed that much in the live scanning. I’ve attached a picture for reference, where the FCR inserts onto the 2nd MCbase, is that bony structure to the left of the MCbase the trapezoid? Would you look for bony irregularity there too? Or is it more of a benign bone?

5) In your ultrasound reports, do you include the nerve flattening ratio and WFR or do you just generally give the cross sectional area measurement?

Thanks again 🙂

[Stephen Bird]

Good questions as always,

1: These ganglions may arise from any of the sources you have suggested. They can be from FCR sheath. They can be from the radio-carpal solar ligament complex (these are most common in my experience). They can arise from the proximal row intrinsic ligament complex. It may be impossible to be absolutely sure on ultrasound and MRI may help to clarify if it is important.

2: Yes I always see a slight flattening as the median nerve goes under the transverse carpal ligament (TCL) at the level of the distal lunate / capitate. I think it is normal for the nerve to look slightly wavy approaching the TCL and then look a little more “ironed” when it goes under it.
This does not indicate a step sign in my view. For a positive finding I need fascicle oedema proximal to the TCL with an abnormal cross sectional area and abnormal WFR. Then you see real compression and an obvious step sign. The presence of a normal cross sectional area and WFR indicate a normal examination for me.

3: I lock the PIP and flex the DIP only as this moves just the PFD tendon. Then I flex the MCP and DIP together to watch them both slide.

Sometimes it is the FDP that gets stuck and I will share a case of this with you soon. Mostly it is common for the FDS to get stuck or both together.

4: I look at the scaphoid and trapezium as I don’t get such a good look at the trapezoid. Looking at the scaphoid and trapezium is fine for seeing the arthritis.
I can’t see the image you posted. You may need to re-upload it.

5: I put the cross sectional area and the WFR on my worksheet as well as the myriad of other observations I make in general assessment of the nerve, the tunnel , the articulations and the thenar muscle bellies.

Steve

[Diane]

I have reuploaded the ?trapezoid image below, hopefully it works this time. Thanks for the detailed answers as always!

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[Stephen Bird]

That is a really perfect ultrasound image and it is technically difficult to obtain,

You have worked out the secret of heel toeing the transducer firmly into the palm of the hand to show that distal FCR insertion to the base of the 2nd M/C

Yes indeed I agree with your bony annotations and if you see bony change in the trapezoid on this image it helps to make the diagnosis of STT arthritis.

In clinical practice for me the scaphoid and the trapezium are far easier to assess than the trapezoid and hence I tend to make the diagnosis of STT arthritis on these 2 bones.

But you will certainly see it on the trapezoid as well if you get a great leek like you have achieved.

Remember always to review the plain radiographs as well before starting the ultrasound as the answer is often on these beautiful old fashioned images.

I do love a plain radiograph!

Steve.

[Jonathan Wride]

Hi Steve,

Have you any good resources tips on best injection approach for the ECU?

Also with De Quervains and injections do you find better results if you specifically inject under the thickened retinaculum or are happy to just infiltrate into the sheaths slightly distal and let the steroid work its way around? In my experience injecting under the retinaculum is a lot more uncomfortable for patient and not sure if increases efficacy.

Finally just a quick one on CTS. I had a patient yesterday who clinically had every positive test for CTS (phalans, Tinnels, Nocturnal pain and numbness with a repetitive strain mechanism working as a chef) but the median nerve quite frankly looked normal (maybe a bit excessively flattened but only 8mm2 cross section). Symptoms only present for 6 weeks. My question is in these obvious clinical presentations that are relatively acute would you not expect to see much sonographic evidence?

thanks 🙂 love this forum by the way, really great work on the website and resources.

Cheers.

[Stephen Bird]

I think just distal to the retinaculum is best as there is a nice potential space in the synovial sheath to access.
If you inject right under the retinaculum it is very tight.
We scanning the short axis so we can see the liquid flow into both tendon sheaths (APL / EPB). If we see it is only going into one sheath you are dealing with a patient with seperate sheaths and we advance the needle into the second sheath and fill that as well.
It is worth identifying the superficial branch of the radial nerve so you don’t damage it. It is always close to the injection site.
I have had some radiologists inject the whole volume into the tendon sheath which I think is great and others will reserve a small volume and inject it outside the sheath over the retinaculum which I also think is fine.

As for CTS there is certainly patients where the clinical presentation is classic and the ultrasound is negative. I see this in acute settings and also chronic settings and also during pregnancy. I am never surprised by this as the ultrasound can not assess the nerve function so the nerve can look anatomically normal , however it is either under or over active with its function leading to the symptoms .

Remember :

“Treat the patient, not the imaging”

Steve

[Jonathan Wride]

perfect, thanks.

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