Sonography of Abnormalities of the Wrist and Hand - SD

Sonography of Abnormalities of the Hand and Wrist

In this lecture I'm going to discuss sonography of abnormalities of the hand and wrist.

The topics that we're going to cover are listed here, carpal tunnel syndrome, tendon injury, ligament injury masses and foreign bodies.

Scanning the Carpal Tunnel

When scanning the carpal tunnel, the transducer is placed over the volar aspect of the wrist, placed in a transverse plane and swept approximately and distally over the volar crease of the wrist.

We get an image that looks like this in the transverse plane and I put the corresponding axial Mr image just for landmarks.

You can see here your bony landmark is the hook of the hamate on the ulnar side.

On the radial side you have the hook of the trapezium.

You have the flexor aum with the contents of the carpal tunnel between the flexor retina aum and the osseous structures of the wrist.

That corresponds to what we see on the transverse ultrasound image with the echogenic cortex of the hook of the trapezium, the thin fibrillar appearance of the flexor rein aum and the echogenic cortex of the hook of the hammit.

The contents of the carpal tunnel are within.

You see the echogenic, flexor tendons, the slightly less echogenic fibrillar appearance of the median nerve.

And then outside the flexor reticulum, we have the ulnar artery in ion's canal with the ulnar veins and ulnar nerve.

Carpal Tunnel Syndrome

Carpal tunnel syndrome is a syndrome of paresthesias in the hand due to compression of the median nerve with the carpal tunnel.

There are numerous causes, but you should be aware that probably over 90%, actually closer to 95% of cases are actually idiopathic just due to overuse.

When people do have specific reasons or causes of carpal tunnel, they can be due to congenital abnormalities such as an anomalous muscle insinuating itself into the carpal tunnel or acquired abnormalities such as Tino synovitis In someone with rheumatoid arthritis, the presence of masses such as ganglion, cyst lipomas or vascular masses, patients with amyloid may get deposition of the material within the carpal tunnel and patients who've had previous wrist fractures or dislocations may have osseous deformity that crowds the carpal tunnel.

Ultrasound Criteria for Carpal Tunnel Syndrome

The ultrasound criteria for carpal tunnel syndrome are flattening of the median nerve distally, swelling of the median nerve proximally and increased bowing of the flexor ulu.

The problem with these criteria is that they were only present in 7% of 68 symptomatic patients in this one series showing that these criteria or findings may not always be present in patients with clinical carpal tunnel syndrome.

What we're looking at on this longitudinal view of the median nerve is distal compression and proximal swelling.

You should be aware also that there are sometimes, normal variations in the median nerve.

In this particular case it's bifid.

And what you would do then when you're trying to determine if it's swollen, is actually measure both components and add them together.

Threshold for Median Nerve Swelling

When we're trying to diagnose carpal tunnel syndrome and we're using the median nerve swelling as our criterion, the question in the literature becomes what number should we use as our threshold for swelling?

And there have been several studies written in the literature using different numbers.

This one by Dewey Lee using 15 millimeters as his threshold found excellent sensitivity and specificity for ultrasound.

However, a study several years later looking at several different values for median nerve swelling found that if they used a low number as their threshold for swelling, they had excellent sensitivity because they were capturing all the cases of carpal tunnel, but they had very poor specificity because they were also including cases of normal.

And if they went up to higher thresholds of swelling, their specificity went up 'cause they were excluding normal cases, but their sensitivity went down because they were missing cases.

And if you plot that on a receiver operating curve, it looks like this showing that it depends where you want to be on the curve.

Do you wanna be more sensitive or more specific using their numbers?

They found that probably about 10 millimeters of swelling is optimal, giving you probably somewhere between 75 to 80% sensitivity and specificity for determining carpal tunnel syndrome.

Tendon Injuries

Moving on to the tendons, there is a spectrum of abnormalities of tendons such as tenosynovitis, which will be seen sonographic as a hypoechoic rim, partial tearing of the tendon, which will manifest as thickening or thinning depending on how extensive the tear is.

The tendon may be ruptured with discontinuity, with or without retraction.

And then there's trigger finger, which is a flexion deformity.

The tendon may be thickened or irregular.

There may be cyst or synovial thickening accounting for the trapping of the tendon within the tendon sheath.

So here on this transverse view of the flexor tendon, we can actually see this hypoechoic rim around it that represents fluid in the flexor tendon sheath.

Here on a transverse MR image of the wrist, we can see high signal intensity in the sheath around the flexor carpi narrows tendon.

The tendon itself looks fine, but with mr, we can't tell if this high signal intensity represents bland fluid or actually inflamed thickened synovium.

When you do the corresponding transverse ultrasound image, we again see the tendon, but now with power doppler, we see that there's actually hyperemia within this thickened inflamed tendon sheath.

And so all of this abnormal signal on the MR is in fact thickened inflamed synovium.

Tenosynovitis in Rheumatoid Arthritis

Here's a patient with rheumatoid arthritis.

Here's the transverse fat suppressed T two weighted MR image.

You can see the high signal intensity surrounding the extensor tendons.

There's a similar process going on in the around the flexor tendons in the carpal tunnel.

This is the corresponding sagittal fat suppressed T two eight MR image showing what is either going to be fluid or thickening of the synovium around the extensor tendons.

Here's the corresponding transverse ultrasound image.

You see the tendons within this, hypo coic, fluid.

When you put power doppler on, you see that in fact there is no thickening of the synovial, more hyperemia.

And so this is all actually just bland effusion.

De Quervain's Tenosynovitis

In this patient with que veins teno synovitis, we see the tendons of the first extensor compartment, which are the abductor lysis longus and the extensor lysis brevis.

You can see that they're thickened, they're mildly irregular in their contour, but more importantly, notice the marked thickening and irregularity of the tendon sheath.

Que veins is a stenosis teno synovitis.

You get thickening inflammation and irregularity of the tendon sheath.

We see that here in the long axis view and the short axis view.

You can see the thickening of the, tendon sheath power doppler, however, shows at this point no hyperemia in this particular case, the tendons can become degenerated and partially torn or completely ruptured.

Tendon Degeneration and Rupture

In this particular case, we have marked swelling of the flexor carpi naris tendon.

Here on the fat suppressed T two Mr image, you see the high signal intensity within it representing extensive mucinous degeneration.

Here's the corresponding coronal, T two edit sequence showing this fusiform swelling of this particular portion of the tendon.

Here's the corresponding short axis ultrasound image.

This is the tendon here with this marked swelling and hypoechoic area within it.

And then here's the corresponding long axis view.

This whole area from here to here is the tendon.

You can see that it's fuss are formerly thickened with this one particular area corresponding to the mucinous degeneration that we see here on the MR image.

And then of course lastly, tendons may frankly rupture.

This is a patient who ruptured one of the flexor tendons.

You can see here on the sagittal fat suppressed T two weighted MR image.

This is the metacarpal head.

This is the base of the proximal phx.

You see this torn retracted tendon, which is balled up on itself with surrounding edema.

And here on the corresponding long axis ultrasound image, I've tweaked the image a little bit, so I wind up with another tendon just next to it.

But here you can see this torn retracted, tendon edge with some fluid around it.

Here's the corresponding transverse, MR image.

We see the normal flexor tendons of the adjacent fingers.

And then in this affected finger, all we have is high signal intensity fluid filling the gap.

And here in the corresponding short axis ultrasound image, this is the echogenic cortex of the felan with nothing sitting here in the tendon sheath because the tendon has retracted out of the plane,

Tendon Pulley Injury

the tendon pulley may be affected by injury.

Typically, the injury occurs in rock climbers or people who do a lot of clenched, finger type of activities.

There are two types of pulleys in the fingers.

There are so-called annular pulleys, of which there are five running from the metacarpal head to the distal pharynx.

And then there are three cruciate pulleys.

The purpose of the pulleys is to provide mechanical advantage to the tendons so that when you go to flex your finger, the pulleys keep the, tendon against the phalanges and the joints giving mechanical advantage to them.

When the tendon pulleys are injured, they may be thickened if partially torn, and if they're ruptured, what will happen is the tendon will boast string outward when the finger is flexed.

So the boast stringing of the tendon is a secondary sign of pulley rupture.

And using these signs, ultrasound has been shown to have 98% sensitivity and 100% specificity for pulley injury.

Here is an example of boast stringing.

This is the flexor tendon.

The asterisk denote the space between the deep surface of the tendon and the echogenic surface of the phalanx.

And so what happens is when the patient tries to flex while you're scanning their finger, this tendon will bow outward away from the cortex.

And if you're not sure that that's real or not, look at an unaffected finger and ask the patient to flex, and you'll see that the tendon stays against the cortex of the phx.

Notice also in this particular case, there is edema within the tendon sheath

In this picture taken from the literature, what the authors are showing us is that the tendon here is against the echogenic cortex of the phx compared to a patient with bow stringing in which the tendon is displaced away from the cortex.

Ligament Injuries

Sonography has been used to look at the intrinsic ligaments of the wrist, namely the scapholunate and lunar triquetral ligaments.

And these are seen as thin hyper coic fibrillar bands.

The s scfo lunate ligament was seen in the dorsal aspect of the wrist in 78% of normals in one study, whereas the volar aspect of the ligament was visible in only 16% of normals in this study published several years ago.

It's the dorsal aspect that is mechanically most important and therefore it's good that that's the one that we are usually able to see because that's the one we want to evaluate clinically.

What the normal looks like is depicted in these images.

The image on the left is a transverse, MR image showing the low signal intensity, band of the scapholunate ligament.

And here's the corresponding transverse or short axis ultrasound image showing the echogenic fibrillar appearance of the dorsal aspect of the scapholunate ligament.

We have the echogenic cortex of the scaphoid, the echogenic cortex of the lunate, and here's this fibrillary appearance of the intact dorsal aspect of the scapholunate ligament

In this particular patient. There's rupture of that ligament.

So here's the scaphoid, here's the lunate.

All we see is this heterogeneous echogenic swelling between them.

There's no fibrillary structure to suggest that the ligament is intact.

If you're not sure, you look at the patient's contralateral side.

And here's the lunate. Here's the scaphoid.

This structure here from here to here and running this way is the fibrillary appearance of the normal intact scapholunate ligament.

In this patient, the lunar triquetral ligament is ruptured, similar in appearance to the scapholunate tear.

We've lost the normal appearance of the ligament.

It's replaced by this heterogeneous ill-defined edema and hemorrhage.

And again, if you're not sure, you look at the patient's contralateral side and here we see the echogenic fibrillary appearance of an intact lunar triquetral ligament.

Ulnar Collateral Ligament of the Thumb

The ulnar collateral ligament of the thumb can also be injured.

We call that gamekeeper's or skiers thumb.

This is what this injury looks like here in the slide on the left we have a coronal T two edit Mr image showing the torn ligament with interposed fluid between the torn ligament edge and the bony attachment site.

This is what the corresponding ultrasound image looks like.

This is the echogenic cortex of the proximal phx, the echogenic cortex of the first metacarpal head.

And here we have the ligament coming up.

It's detached right here with this hypoechoic edema interposed between the torn ligament edge and the expected bony attachment site.

Corresponding to what we're seeing here on the MR image.

Here in another patient we have the coronal T two added MR image.

This is the torn ligament right here.

Again, this is what it looks like on the corresponding ultrasound image echogenic cortex of the base of the, proximal phx, the echogenic cortex of the first metacarpal head corresponding to what we're seeing here and here.

And then here is this disrupted ligament.

And again, if you're not sure, you compare it to the patient's contralateral side and this is what the normal ligament should look like.

Stener Lesion

A stents lesion is a torn ulnar collateral ligament that has now been displaced superficial to the adductor apo neurosis.

And the reason this is important is because in a non-displaced tear of the ulnar collateral ligament, just a plain old gamekeeper's or skier's thumb, the surgeons will merely splint or cast the thumb and that ligament will scar back into place.

However, in a entner lesion in which the ulnar collateral ligament is displaced superficial to the adductor apo neurosis, it now cannot scar back in place on the bone.

And that becomes a surgical lesion.

So the surgeons want to know if the ulnar collateral ligament is displaced or not.

And what we're looking for is the displaced ligament on either MR or ultrasound.

And so here on a coronal T two weighted MR image, we see the adductor apo neurosis here and this displaced balled up, retracted, torn, ulnar collateral ligament giving the so-called yo-yo on a string sign.

And we can see the same thing with ultrasound.

This is the corresponding long axis ultrasound.

Again, this is the cortex of the proximal phx, the cortex of the metacarpal head.

Here we're seeing some of the adductor apo neurosis, and then we see this balled up retracted ulnar collateral ligament, which is displaced superficial to the adductor a neurosis.

And for confirmation, we look at the patient's contralateral side and here is the normal ligament with a normal adductor apo neurosis overlying it.

Ultrasound has been shown to have 82% to 92% accuracy, which makes it quite good for evaluating these lesions.

Certainly you can go ahead and do this as a screening test, reserving MR for cases that are equivocal.

Masses

Masses are very well depicted with ultrasound and certainly when we're talking about hand and wrist, evaluation of palpable masses is a common indication for sonography.

Ganglion cysts are probably the most common masses that we're going to evaluate.

They can either be palpable masses or occult merely presenting as pain but without a actual palpable abnormality.

But other masses are present around the hand and wrists such as giant cell, tumor of tendon sheath, lipomas and vascular abnormalities.

This is two different patients.

We have one patient on top and a second patient on the bottom showing the typical appearance of a ganglion cyst.

They're typically as would be expected from a cyst in any portion of the body.

Hypoechoic basically a thin, almost imperceptible wall.

You see posterior acoustic enhancement.

And here in this, short axis, you see very nicely this hypoechoic, ganglion cyst interposed between the flexor tendons in the third web space.

Occult Ganglion Cyst

In this patient with wrist pain, there was no palpable abnormality, but there is what we call an occult ganglion cyst.

Here on the image on top we have a sagittal fat suppressed T two 80 MR image showing this high signal intensity homogeneous mass sitting on the dorsal aspect of the lunate.

Just at the lunar capitate articulation, these occult cysts typically arise from the intrinsic ligaments of the wrist.

And here on the corresponding long axis ultrasound image, we see the radius, the lunate, the capitate.

We see the overlying extensor tendons.

And here is this hypoechoic ganglion cyst in this patient who has a giant cell tumor of tendon sheath.

The long axis sonographic image shows a fusiform echogenic mass, thus distinguishing it from a ganglion cyst.

Since the tumor arises from the tendon sheath, it will be adjacent to the tendon, but the tendon itself will be normal in appearance.

Lipomas

Lipomas can have a very variable appearance on ultrasound.

There is no characteristic, appearance.

They can be both hypoechoic as we see here in the slide on the top of this image, or hyper coic as we see here on the bottom image in the thenar musculature.

And you can see that it's actually as echogenic, if not more echogenic than, the adjacent thenar musculature.

And so you must be aware that lipoma can have a very variable appearance.

It does not have a typical characteristic echogenicity.

Vascular Masses

This is a patient who had a vascular mass.

The patient came for an MR originally because they had this doey palpable area in the region of their carpal tunnel.

And here on the axial Mr images, we see flexor tendons, but there's something interposed in between them.

And on the T two edit sequence, that's something becomes bright.

The nature of this abnormality is better seen on the sagittal image where it looks like there is lumen within this suggesting it's a vascular mass.

Ultrasound is very nice for confirming this.

We brought the patient to ultrasound after the, MR examination here on the short axis image.

Looking in the carpal tunnel, we see the echogenic flexor tendons, but then we see these hypoechoic serpiginous looking type of structures on a long axis in the superficial tissues, superficial to the carpal tunnel.

We see similar looking serpiginous, abnormalities.

And when we put on the power doppler, we see that there's marked signal and flow within them indicating that these are all in fact serpiginous vessels from a vascular malformation.

Foreign Bodies

Lastly, foreign body is another common indication for evaluating the hand and wrist, particularly around the fingers and the palm of the hand.

Foreign bodies are going to be hyper or coic.

They're usually linear.

So even if it's in a jagged, irregular piece of, glass, the fact is that as you're scanning it, you will typically see at some point a linear, surface and they may or may not shadow.

Typically metal ceramic, glass will shadow wood such as splinters or thorns may or may not shadow.

And the reason for that is they ibe, fluid from the surrounding, soft tissue.

If it was a very moist piece of wood to begin with, it will have fluid within it and it may not shadow for that reason.

This was a patient who came to me, complaining of about two months of swelling over the dorsum of her third finger and the knuckle area.

And we did the MR to rule out, infection and teno synovitis.

And here on the fat suppressed transverse T two weighted MR image, all we see is this edema involving the dorsal subcutaneous tissue of the area of the metacarpal head.

We brought the patient to ultrasound to investigate this further.

And as I'm scanning, I was chatting with the patient.

I said, when did this begin?

She said, about two months ago I was working in the garden.

Well, that automatically tipped me off to the fact that there should be a foreign body in here.

And sure enough, as I'm scanning, I see this linear echogenic structure.

Notice that it doesn't have any shadowing, but it does have a, hypo coac halo, which is typical for foreign bodies.

They incite an emus granulation type response.

So what you're looking for is a linear echogenic foreign body with a surrounding hypoechoic halo.

This turned out to be a rose thorn that was retrieved surgically, and the patient went on to do very well.

Conclusion

So in conclusions, sonography is excellent for the evaluation of tendons and ligaments, masses and foreign bodies.

I think it's role in the evaluation of carpal tunnel syndrome is still uncertain until we determine what the best criteria are for determining carpal tunnel.

Thank.