Pitfalls: Musculoskeletal, Part 1

Introduction

Good morning.

I'm gonna talk to you in two separate sessions about some pitfalls.

I've decided to narrow it a little bit to the shoulder for this morning.

And then this afternoon we're going to talk about the knee.

But I have to tell you that I was sitting in the back here this morning listening to these two lectures, and I have a great admiration and respect for all of you.

All I can say is wow, that you have to know all of that information and see much more of that on a daily basis.

And I was vaguely remembering some of those words from residency.

Mm-hmm. So it was, it's very impressive to me.

And my heart rate went up every time I heard adenocarcinoma, cancer, and metastases.

So I have great respect again that you do this on a regular basis.

So the next 40 minutes or so, there'll be no reference to cancer, no metastases, no cavitary lesions, nothing like that.

So wanted to sit back and take in as much as we can about this lecture.

It's set up in a way that will allow us to help the clinicians really determine the course of treatment for the patients.

And I've pointed out a few things where I've learned to make better decisions based on some mistakes I've made in the past.

So I too have no relevant financial relationships with commercial interests.

And this is the first of the two talks.

Shoulder Protocols

So I'm gonna start by just reviewing shoulder protocols.

There are many, many ways to design a shoulder protocol, and as all of us are getting busier with practice, and trying to increase throughput, and knowing that we're getting less and less for each scan, but busier and busier with each practice, it's a really good idea to try to streamline and our protocols getting as much information as we can in as little time as possible.

So I've put up here kind of one protocol, one way to do it, but as long as a thought process is the same for whatever you're deciding to set up as your protocol, that's all that really matters.

As long as you have some sort of fat suppressed sequence, that will be important so that you can see things like edema within the musculature or where there's fluid collections in abnormal locations.

You should have a T one weighted image as well that allow you to see a muscle atrophy.

And when we talk a little bit later, when muscles actually disappeared and replaced by fat.

And then for your axial images, when you're looking at the labrum, it's nice to set up, if you wanna do an axial T two weighted image, keep that te a little bit on the shorter side, more in that proton density weighted, and it'll increase the signal to noise and allow you for a wider gray scale to really see a labral abnormalities, particularly if you're not using intraarticular contrast.

So with that thought process in mind, you can come up with a shoulder protocol that's something similar to this where there's fat suppression in all three planes and then a T one weighted image.

And I like the T one weighted images in the coronal plane.

The reason for that is orthopedic surgeons really like to go pretty medial when they're looking for fat, and atrophy of the supraspinatus and the coronal images seem to show that quite well.

Patient Positioning Pitfalls

Now, one of the pitfalls that we can encounter is just on patient positioning.

So we have not really thought much about this.

In fact, the technologists typically put the patient on the table and the scanner in a way that's comfortable for them, so they're not going to move during the exam.

Then we don't get a motion agram.

But sometimes that means that the patient is in internal rotation.

And for the shoulder that can be a problem.

And you can see with what we typically want to see is a patient in neutral position where the bicipital groove is either up at the 12 o'clock position or the one o'clock position with internal rotation, it starts to move a little bit more medial in the joint.

And that presents a problem with the tendon of the supraspinatus.

And let me show you what I'm talking about.

So this is a normal patient contrast in the joint.

You can see the supraspinatus as we go from more posterior to more anterior in position.

So nice low signal sitting on the, or inserting onto the facet.

As we come more anterior, you see the nice low signal blending into the cortex of the fat of the facet.

And what I really want to emphasize is this image right here, which we probably don't really or haven't looked at much in the past.

This is a far anterior image.

Here's the biceps coming up in the bicipital groove, and just lateral to that is the most anterior portion of the supraspinatus.

So let's look at this example.

There's a supraspinatus inserting onto the facet as we move more anterior, it looks pretty normal in appearance as we move anterior still, that's the far anterior portion of the supraspinatus as it inserts.

And you can see that we have a partial tear, a large partial tear of the supraspinatus at its attachment.

Now, this is easily overlooked because we're typically looking at these images to assess the integrity of the supraspinatus tendon.

And in fact, far anterior that is a very high grade partial undersurface tear.

So as patient, obviously this could explain the shoulder symptoms for this individual.

So just be disciplined to look at the far anterior image identified by seeing the biceps in the bicipital groove and look just lateral to that.

And in fact, it doesn't matter if the patient's in neutral position, internal or external rotation, you'll look for the biceps tendon and lateral to that will be the attachment of the supraspinatus.

And a lot of the origins of the, of full thickness cuff tears begin in this location.

You can see on the oblique sagittal images that the large high grade partial tear is nicely demonstrated.

Types of Impingement

Now, we're used to the clinical diagnosis of impingement and looking for rotator cuff pathology, cuff tears, partial tears that can explain the clinical syndrome of impingement.

But I wanted to point out the two others that are probably less familiar to us, but still can contribute to shoulder pain, subcoracoid impingement, and internal impingement.

Subcoracoid Impingement

Now, subcoracoid impingement occurs when the space between the lesser tuberosity and the acromion process.

The inferior tip is very narrow.

And if you're a radiologist who likes to make measurements, that typically is about four millimeters and it does correspond or can clinically correspond to some anterior shoulder pain.

So be disciplined when you're looking then at the axial images to assess the space between the lesser tuberosity and the inferior tip of the coracoid process.

And you'll see in this example that in fact, the subscapularis, which typically transgresses this space is torn, retracted, and the biceps is out of the groove and dislocated medially.

So that's a very narrow interval for the subscapularis to traverse in the more superior image.

The biceps is out of the groove. It is dislocated medially.

Here's a very attenuated, torn, retracted subscapularis.

And this space here is markedly narrowed.

This is the inferior, most inferior tip of the coracoid process.

Another example here even shows the bone marrow edema of the lesser tuberosity.

Now we do know that bone marrow edema and the lesser tuberosity can also imply that there is subscapularis pathology.

But if you see the bone marrow edema, first assess the subscap to see if it's torn, partially torn, and then assess the interval between the lesser tuberosity and the coracoid process.

Again, you'll see that this is markedly narrowed, and the biceps here is not well visualized in the groove.

The edema is appreciated also on the oblique sagittal images in the region of the subscapularis.

So the measurement to keep in mind is about four millimeters.

Another example here seen on the sagittal T one weighted images, where we typically find that the space is narrowed is in a coracoid process that is more teardrop in configuration or a little bit elongated, such that it can come in contact then with a lesser tuberosity.

So another thing to check to potentially contribute to the patient's shoulder pain.

Internal Impingement

Now, internal impingement has been referred to in the literature also as posterior impingement, but more recently referred to as internal impingement.

And there is a constellation of findings that you can see.

So if you are dictating your case, you're reviewing a case and you see these three things in association, you might want to suggest internal impingement.

These patients usually are throwing athletes or have been throwing athletes in the past.

So the constellation of findings are seen as a result of the patient's abduction external rotation, the motion that one would see with pitching.

For instance, look at the cystic change in the posterior portion of the humerus.

You'll see also that the posterior superior labrum is abnormal in signal intensity or morphology or detached.

And then finally, you can see the undersurface of the infraspinatus, or the posterior aspect of the supraspinatus demonstrates a partial tear.

So the constellation of findings then would suggest internal impingement, and that's important for the clinicians because they actually can do arthroscopically debridement and on follow-up, the cysts will disappear.

It's a pressure phenomenon felt to be due to a pressure phenomenon forcing this synovial fluid into the posterior portion of the humerus.

So another example here, the posterior superior labrum is abnormal, as you can see on the axial images contrast in the joint space.

To make that a little bit more conspicuous observation, the cystic change in the posterior portion of the humerus and the undersurface tear of the infraspinatus, the constellation of findings then suggests posterior impingement or internal impingement.

Labral Mimics and Pathology

Now let's talk about some of the mimics around the labrum and a little bit about the alphabet soup that we hear.

So much about, so contrast in the joint here, just demonstrating normal anatomy of the glenohumeral ligaments, superior glenohumeral ligaments and middle glenohumeral ligament, and the anterior band of the inferior glenohumeral ligament, nicely distended.

And these are easier to see, certainly when there's fluid in the joint space.

On the axial images, the superior glenohumeral ligament is nicely demonstrated.

It wraps around the or parallel, sort of the coracoid process, middle glenohumeral ligament, this low signal structure going from the superior to inferior portion of the joint space.

Occasionally, the anterior band of the inferior glenohumeral ligament can in fact come up and insert onto with the superior labrum onto the superior aspect of the glenoid.

So labral pathology that we can identify, the labrum can be torn, detached.

We can see tears at the labral ligamentous complex and fraying and degeneration.

But before we can make a diagnosis of labral pathology, you want to make sure that you know the normal variance so that we're not over calling pathology in an otherwise normal shoulder.

So we have to be aware of the sublabral recess, the sublabral foramen, and the Buford complex.

Normal Variants: Sublabral Recess, Sublabral Foramen, and Buford Complex

First, the sublabral recess is present in about 70% of shoulders and is best identified on the coronal images.

It most often confuses or mimics a slap tear for us.

So here's a nice demonstration of the sublabral recess.

You see this extra tongue of tissue, and this is due to the fact that the superior labrum is inserting a little bit more medial.

And therefore there's a little bit of opportunity for joint fluid or contrast to ibe with the redundant portion of the labrum between the labrum and the articular cartilage.

Notice that we're anterior to the or at the level of the biceps labral complex, we typically wouldn't call a superior labral tear at the biceps labral complex or anterior to that.

So that is the sub labral recess scene best on the coronal images.

Now slap lesions, a poor term.

And over time we'll probably see much like prints and the symbol and the previously known as symbol will probably have the same categorization for slap lesions over time.

So they don't quite describe well enough what the injury is to the superior labrum.

These are not uncommon injuries, and they're often associated with throwing athletes and most likely due to the pull of the biceps mechanism, many types.

As you know, I think we might be up to 11 different types of superior labral tears, but those are described surgically.

We don't have to be responsible for that as radiologists.

In fact, we're happy to just make the diagnosis of superior labral tears.

If you're diagnosing more than say two or three a month, you're probably over calling superior labral tears.

They're not quite that common where you're seeing them in daily practice.

So here we have the biceps labral complex.

At this point here, we wouldn't necessarily be calling superior labral tear, but we follow that more posterior, and you can see that there is abnormal signal intensity going through the superior labrum to the more posterior slice contrast in the joint here helps to make this diagnosis.

These can be a bit of a challenge making the diagnosis without fluid distension in the joint.

So again, we can see that there is contrast and abnormal signal throughout the superior labrum going all the way posterior to the posterior aspect of the superior labrum.

It's a little bit easier when we have this finding here that of a paralabral cyst.

Obviously that means that the superior labrum in this case is torn, demonstrating nicely the paralabral cyst.

So once you recognize the paralabral cyst, you know that the labrum is torn.

This is a patient that does not have contrast in the joint, but I wanna show you how you can still make the diagnosis of a superior labral tear.

If you look at these posterior images, you can see the abnormal signal going through the superior labrum all the way posterior.

So if you have one or two slices just around that biceps labral complex that demonstrates abnormal signal, not enough to call a superior labral tear, follow that to the most posterior aspect of the joint.

And if you still see that abnormal signal intensity, then you can be much more confident in making the diagnosis of a superior labral tear.

Of course, it helps in this case here, as you can see, a little tiny cyst in the spinal glenoid notch secondary to a small little paralabral cyst.

Now, the sublabral foramen is the detachment of the labrum at the anterior superior glenoid.

So when we're calling or diagnosing anterior labral tears, we have, we can ignore that quadrant at the anterior superior aspect because that's where this normal variant of the sublabral foramen exists.

It's seen in up to a quarter of the shoulders that we look at, and it's a lot easier to see when there's fluid in the joint space.

So here is an example of fluid distension of this joint, and we see this a low signal blob, which we will follow all the way inferiorly.

And this is the detached labrum sitting right next to the middle glenohumeral ligament.

And then finally, more inferiorly that labrum reattaches to the glenoid.

So this is a nice demonstration of the sublabral foramen.

One tip I think that you can use when you're looking at the axial images to determine whether or not you're looking at the foramen or true pathology of an anterior inferior labral tear, is gauge whether or not you're seeing the coracoid on that axial image.

If you're inferior to the level of the coracoid, then that becomes pathologic superior.

And at the level of the coracoid, we're talking about detached labrum from a the sublabral foramen.

Now how about this case? We have a nice low signal round structure contrast to standing the joint.

We can see that going all the way inferior in the joint space, and it's sitting anterior to the glenoid.

And this is the Buford complex.

So that's, that was a very thick middle glenohumeral ligament.

There's absence of the superior labrum with this entity.

The middle Glen Humal ligament is cord like and probably is compensator thickened from the absent anterior labrum.

And it's seen at about 3% of shoulders.

Another example. So starting at the apex of the joint, we have this real round or low signal structure that as we follow all the way inferior represents the middle glenohumeral ligament, you can see that there is no anterior labrum here.

This is the articular cartilage and the glenoid surface.

Bankart Injuries

So now we can look at true labral pathology with those normal variants as our own observations.

So let's first talk about bankart injuries.

A true detachment of the labrum.

If you see a hill sax lesion, as we've demonstrated here, so impaction at the posterior superior humerus, remember you're looking at the top three slices, three axial images through the shoulder to determine whether or not there is a hill sax lesion.

If you identify a hill sax lesion, then you know the patient has had a bankart injury.

The reverse is not true.

You can certainly have a bankart injury without seeing a hillsack lesion, but the presence of a hillsack lesion tells you that that was a severe enough dislocation to cause impaction, and that labrum is going to be abnormal.

So be very critical of the appearance of that anterior inferior labrum.

When you see this deformity at the apex and posterior humerus, now you don't necessarily see, particularly if you're looking in the more chronic situation, you may not see the bone marrow edema, but if you still see presence of the hill sax deformity, again, look very closely, you might even be looking at a chronic bankart injury.

So when we get to the more inferior portion of the axial images, we can see that the labrum is peeled away.

It's torn from the underlying glenoid.

It's actually turned so that the configuration of the labrum is abnormal.

There's no normal low signal triangle sitting on the anterior inferior glenoid to compare that to the low signal of the posterior labrum.

So this is all the articular cartilage.

This is the cortex of the corner of the glenoid, and the labrum is detached and turned on itself, leaving this kind of horseshoe configuration.

So a bankart injury with a hill saxon, someone who has suffered a relatively recent anterior shoulder dislocation.

Another example here, where we have a little bit of contrast in the joint space, nice posterior labrum, nice low signal triangle.

If you were looking at this case, and particularly after you were looking at one of those cavitary lesions in a chest ct, and this is the next case that you're looking at, I think it's pretty easy to overlook the fact that there is a bankart injury here.

So be very critical of the fact that we have abnormal appearance to the anterior inferior labrum.

This is low in signal, but this should be sitting directly on the glenoid.

And there's intervening intermediate signal between the labrum and the underlying glenoid.

So this is more of a an appearance to a chronic bankart.

I think, again, as you're looking through many cases, this can be something that might be harder to pick up, but you have to be very critical of the appearance of this very redundant looking anterior labrum, intervening signal intensity, and then the underlying glenoid.

Osseous Bankart Lesions

Now the rumor has it that MR is not as good as identifying osseous bankart lesions as CT is.

And many patients after they've had an Mr. May go on to a ct, or the surgeon may just preferentially want to do a CT to assess the degree of bony injury.

This is a very important thing for the orthopedic surgeons to know what the degree of glenoid is that has been injured, removed, fractured.

It's important because in about the magic number for us it's about 25 to 30% of the glenoid.

So if you're looking at the glenoid as a clock face, about a third of that glenoid, if it's injured, becomes more problematic for the patient with recurrent dislocations, and the orthopedic surgeon is going to want to fix that.

And so typically there might even be a staged procedure to fix the osseous component and then the labral component of the injury.

And these are much more invasive surgical procedures.

So we wanna be able to assess this with MR with things that help us, like bone marrow edema.

As we can see the inferior portion of the glenoid is taken off.

And on the sagittal image, we get an idea of how much of that glenoid is missing.

So in this case, it's about 25%.

If we were to envision this as a circular clock face, we're missing between say, four and a six o'clock.

And that's the osseous piece that has been pulled off.

So that helps the surgeons to determine what kind of intervention is going to need to be to take place to fix repair this patient's shoulder so that recurrent dislocations are not a problem, and we can recognize that as radiologists and I think maybe even prevent the patient from having to go on to get a ct.

But it's a very important piece of information that they can use for a surgical repair.

ALPSA Lesions

Now let's talk a little bit about some of the interesting acronyms that we see around the shoulder these or the anterior labral periosteal sleeve avulsion.

It's similar mechanism to a bankart injury, and the what we see in the case of an alpsa lesion is that the periosteum is still intact.

So in this example, the periosteum is still attached, but you see all of this intermediate signal intensity surrounding the labrum.

So that's the labrum either turned on itself and injured, or this could be in fact the same appearance as a chronic bankart that has some synovitis about it or fibrosis if it's been more longstanding.

So it can be very difficult to distinguish an alpsa lesion from a chronic bankart injury.

The most important thing is being able to recognize it.

So there is contrast in the joint here to make this distension the distention of the joint a little bit easier to see this entity.

Usually the labrum is medially displaced and internally rotated.

And because we can overlook this, especially if there isn't a fluid distension in the joint, and when the surgeons look arthroscopically, they may see a lot of fibrosis and it may in fact simulate a normal appearing anterior inferior labrum, and the patients can still seemingly be unstable.

So another example, again, this joint is distended, and we can see that the anterior labrum has some contrast in vibing between the glenoid and the labrum, but it is still attached to the glenoid.

And then the adjacent image shows that there's still a periosteal sleeve attached, but the labrum itself is detached from the underlying glenoid.

So a nice demonstration of an alpsa lesion or a chronic bankart only way you can really tell is clinical history to know how long ago that patient may have dislocated Another example here where we can see that the labrum is attached by a small periosteal sleeve.

The chronicity of this would be determined if whether or not you saw a bone contusion with the hill sac lesion, or if you were lucky enough to have some clinical history as to know when the patient ultimately dislocated.

So just keep in mind that it's not so crucial to recognize and term it an alpsa lesion, but instead to recognize that the labrum may still be attached surrounded by some synovitis.

And the reason that's important is, again, it can be overlooked or the patient may not go on to surgery when surgery is indicated or overlooked at surgery.

So be mindful of this appearance.

And there again, we have evidence of the hill sac lesion, the bone contusion, suggesting this is a little bit more acute and likely an alpsa lesion.

GLAD Lesions

Now the GLAD lesion or glenoid labral articular defect is superficial at the anterior inferior labral tear and said to not be lead to the instability itself.

So the cartilage lesion doesn't contribute to the instability, but it's a defect that's associated right adjacent to the labral tear.

So you want to, once you recognize the labral tear, pay close attention to the appearance of the articular cartilage.

So that means that you have to have a sequence that will allow you to distinguish fluid signal from articular cartilage.

And you also want to have signal intensity that will allow you to distinguish labrum from underlying articular cartilage.

And that gets back to setting your te.

If your te is too high, then the cortex of the bone and the articular cartilage are similar in signal intensity, which coincidentally would be the same signal intensity as the labrum.

So once you drop that te, the articular cartilage becomes a different signal intensity distinguishing it from the cortical bone and the signal intensity of the labrum.

So you'll be able to make these diagnoses a little bit more easily.

It's contrast in the joint shows the articular defect right adjacent to the anterior inferior labral tear.

So important to point out to the orthopedic surgeon that there is an articular cartilage defect, so they can address that surgically.

HAGL Lesions

Now, the haal lesion or hagel lesion, humeral avulsion of the glenohumeral ligament is a result of an anterior shoulder dislocation.

So there may be some other sequelae that you can appreciate on the mr that would suggest an anterior shoulder dislocation.

This particular entity is often seen or more often seen in slightly older patients, and it also is often associated with a biceps dislocation because of a subscapularis tear.

So the normal appearance then of the anterior bundle of the inferior glenohumeral ligament is this nice U-shaped low signal configuration attaching to the humerus.

So the humeral avulsion basically would mean then that this is the portion that tears.

So instead of necessarily seeing the bankart injury, we'll see then a tear of the capsule as it attaches to the humerus.

So in this case here we see evidence of a dislocation by the large hill sax lesion posteriorly, but we can see that the normal JS shaped or u-shaped configuration of the anterior inferior glenohumeral ligament is torn away.

The secret to this diagnosis is in addition to recognizing the lack of the U-shape, look at the fluid that's going to descend along the proximal humerus.

The only way that that can get there, particularly in a non-contrast study, is if the capsule is torn and the joint fluid is leaking out along the humerus, you wanna be able to make that diagnosis and help the clinicians.

They don't necessarily repair that portion of the glenohumeral ligament, but they will protect it.

And obviously this will lead to recurrent instability, if not appropriately addressed.

And we have the first ability to make that diagnosis and help to dictate the kind of treatment that the patient is going to receive because we see it better than they will see it either clinically or certainly at arthroscopy.

So that's an important point for us to recognize is we can help to determine the course of action for that patient.

Another example here where you can see the abnormal signal intensity going along the humerus and the abnormal configuration to the anterior inferior glenohumeral ligament.

This is a guard for a college basketball team who had an event where he ran into a player and in the post position and felt his shoulder sublux posteriorly.

And you can see that he has a soft tissue injury posteriorly.

The posterior band of the inferior glenohumeral ligament, again, is torn and retracted.

There is redundancy of the contrast that's put into the joint space here.

The labrum itself is intact, but they decided to treat this non-surgically.

This is very useful information for them to see that the labrum itself was not torn just the soft tissue structures of the glenohumeral ligament.

So this allowed him to be protected, rest from basketball for a little bit until his shoulder improved.

So very useful information for the referring clinicians.

Reverse HAGL and Posterior Labral Tears

So a reverse hagel or posterior hagel deformity.

Posterior labral tears obviously important also to recognize, we don't see them nearly as often as the anterior labral tears or bankart injuries.

Again, recognizing the reverse hill sax lesion, you wanna spend some time looking then at the posterior labrum to make that diagnosis.

So we can see the reverse hill sax lesion and the posterior labral tear.

See the labrum hanging off of the glenoid detached from the glenoid with some signal intensity between the glenoid and the overlying labrum Contrast in the joint in this patient makes this diagnosis a little bit easier to see with a contrast in vibing between the labrum and the underlying glenoid, and even the early formation perhaps of a per labral cyst from this detached labrum.

In this example, we can see the reverse hill sacks quite nicely with the associated bone marrow edema.

So again, if you are able to put contrast in the joint, these diagnoses are a whole lot easier to see, or at least you have more confidence in making the diagnosis.

But once you see the presence of the paralabral cysts, it's a slam dunk that you know that you're dealing with a labral tear or labral detachment.

The other reason to recognize the cyst is that they can propagate you along the course and path of least resistance into the spinal glenoid notch leading to suprascapular nerve entrapment.

These are mostly due to ganglion cysts or varices that can live within the spinal glenoid notch and cause mass effect on the suprascapular nerve.

The ganglion are associated with labral tears.

If longstanding can lead to atrophy of the infraspinatus, atrophy of the supraspinatus is less common.

The reason these are seen or supposed that these are seen almost exclusively in men is due to the fact that many of these individuals are weightlifters and in bench pressing.

When your shoulder becomes then a weightbearing joint, particularly an extension, and the force of the weight is now translated to the posterior aspect of the joint space that ultimately leads to weakening of the labrum.

And particularly if there is any underlying glenoid dysplasia, that labrum is already predisposed to tears or detachments.

And so it can lead to the development then of these spinal glenoid notch cysts and mass effect on the suprascapular nerve percutaneous drainage or treatment surgically with ligation.

And addressing the labral tear is the definitive treatment.

So here is a nice example of this large cyst as fluid collection living in the region of the spinal glenoid notch.

So the distinction between the spinal glenoid notch and the suprascapular notch is just that the spinal glenoid notch is the posterior extension of the suprascapular notch.

So you want to be very clear in your dictation because suprascapular notch is going to suggest to the orthopedic surgeon or the arthroscopist that they're going to require an anterior approach to decompress that cyst, whereas the spinal glenoid notch is the posterior extension of that.

And then the arthroscopist will want to put the portal in posteriorly to decompress that cyst.

So even though it's essentially the same space, you're talking about anterior or posterior in the shoulder, which has some implications for intervention.

So this cyst is sitting in the spinal glenoid notch, and you can see that it's causing edema of the infraspinatus as we look a little bit more superior in the joint.

You can in fact actually see where this is emanating from the joint through the labrum into the spinal glenoid notch causing mass effect on the suprascapular nerve, which is now innervating just the infraspinatus.

Parsonage-Turner Syndrome

Now what about this example Here we have abnormal signal intensity extending through the supraspinatus muscle belly and even a small portion of the infraspinatus muscle belly.

We don't see any mass effect in the region of the suprascapular notch spinal glenoid notch.

And this entity is parsonage turner.

Very important for us to recognize this entity, so that these patients don't undergo exploratory arthroscopy because this can mimic rotator cuff pathology.

It's an unknown etiology, but the patients have a fairly predictable clinical history, sudden onset of severe pain followed by weakness and ultimately atrophy of the muscle bellies.

It's a self-limited course, and the suprascapular nerve seems to be the most often involved with this brachial neuritis.

So if you have the opportunity to talk to either the clinician or the patient, this history is very classic, sudden onset of pain followed by profound weakness.

It's been suggested that a viral illness predates or disposes to this or anti seeds the development of a brachial neuritis.

Similarly, vaccinations in a quarter of the patients who have this complaint of parsonage turner have received flu shots.

And then finally, patients often can wake up from surgery and complain of this profound pain and of weakness.

And it's been thought that either anesthesia or incorrect placement of the patient at surgery leads to the development of parsonage turner.

However, we can identify this quite readily on Mr, particularly with the fat suppressed techniques looking for abnormal signal intensity throughout the muscle bellies.

And most often it's the supraspinatus and or infraspinatus that are involved with parsonage turner.

About a third of the cases can in fact be bilateral and usually can recover within a year or two years.

Some unfortunately may go on to chronic symptoms and complete atrophy of the muscle bellies that are involved.

So in this case, we see that there is atrophy of the supraspinatus muscle belly.

It's paralleling the floor, therefore we know that we're still in supraspinatus.

Remember that infraspinatus runs obliquely and we're not far enough posterior to recognize the infraspinatus.

So there is abnormal signal intensity and the development of atrophy in this patient with parsonage turner.

So you can see the involvement of supraspinatus as well as infraspinatus with this entity.

Quadrilateral Space Syndrome

And what about this case here?

This is a demonstration of why it's important to have T one weighted images as well in your protocol.

On the oblique sagittal images with all of the with the fat suppression, the musculature when you examine it looks pretty normal.

But because of the fat suppression, we've overlooked the fact that the teres minor is in fact not there.

Where is the teres minor?

And this is quadrilateral space syndrome.

These patients have shoulder pain that mimics rotator cuff pathology and it's secondary to axillary nerve compression, usually fibro spans.

And typically we don't see the reason for the development of quadrilateral space or the reasons for atrophy of the teres.

Only occasionally might you see a cyst in the region of the quadrilateral space that can have mass effect on the axillary nerve contributing to quadrilateral space syndrome.

But again, these patients can present like rotator cuff symptoms, important for us to recognize and remember to have a T one weighted image.

So in your search pattern, you can recognize those muscles that suffer atrophy.

To remind you, the quadrilateral space is comprised of the teres minor, the teres major, this space here, the triceps and then the humerus itself where the axillary nerve and a small recurrent humeral artery eman from this space in the old days before Mr.

Predating Mr.

This would be diagnosed with angiography and the patient would be put in provocative maneuvers to see if flow was disrupted in that humeral circumflex artery.

So another example, oblique sagittal T one weighted images.

There's absence of the teres minor here where we can implicate quadrilateral space as a reason for the atrophy.

Conclusion

So in conclusion, there are many entities that can mimic rotator cuff or labral pathology, which I've tried to present to you today.

So we can be more accurate in our diagnosis and awareness of these entities can increase our accuracy as well as avoid unnecessary surgery, as well as help the clinicians with surgical planning.

Thank you for your attention.