Tennessee. I'm excited to have our lecturer on today, Dr. Shawn Jorgensen. We're gonna skip through some of these front matter slides and again if anybody has any questions please feel free to look me up participants list up at the top and then or I guess it could be at the bottom of your screen and then find me my name is Sterling Herring I should be up near the top of your screen somewhere. Feel free to shoot me a message and I can pass it along to our presenter otherwise we'll keep everybody video and audio muted and if you have any questions please feel free to reach out. Without further ado we're excited to have Dr. Shawn Jorgensen on the call with us. Thank you very much for joining us Dr. Jorgensen. Am I unmuted here Sterling? You are. Perfect and you got the video and audio everything's good? I have audio you should be able to click the green arrow at the top of your screen and share your screen with us. There we go. Does it look like a PowerPoint presentation? It does looks like a great one. Okay great all right well thanks so much for the intro and thank you everybody for coming to this virtual didactic. We're going to talk about diagnostic ultrasound in the EDX lab. So I work in upstate New York I'm in private practice and my practice focuses on EMG and neuromuscular medicine as well as sports and MST medicine and we do do a lot of diagnostic and therapeutic ultrasound. So this this area is something I've spent a lot of time thinking about, reading about, talking to other people about. Hopefully something you'll find helpful. I do work with residents and students at Albany Medical College and also students at UVM. I have no financial disclosures. I will disclose I'm going to fly through a lot of these slides and not cover a lot of them. I left them there just so you can look at them later if that's helpful. Feel free to email me at this address if you have any questions happy to go over them and so let's let's get rolling. So what we're going to try to do hopefully at the end of this talk rather than really focus on a bunch of numbers and a bunch of specifics that you may by the time you end up implementing any of this may be totally irrelevant. I'm really going to try to instead get you into a good conceptual framework and hopefully come out understanding the current limitations we have in the diagnostic of suspected peripheral nervous system lesions and to know what it is that ultrasound can potentially show us about the peripheral nervous system and then ultimately really understand when and why you want to use ultrasound and when that can help patients in the EDX lab. And I guess the first question in any top any discussion should be why are we talking about it and to me ultrasound has really been the most transformative force I've seen in the field since I began and I really see is it a seismic shift that's going to shake all of the the kind of four pillars of the field that I kind of draw up but we're going to focus on how it affects EMG in the neuromuscular world specifically. But just because it's transforming the field doesn't mean that we should automatically implement it and that's really what we're going to get into. Okay the questions that we need to answer in order for you to come out knowing what I think you need to know is first of all does EDX lab really even need anything? And second of all if it does is ultrasound worth adding? Does that really fill the void if there is one? And if it does have something to add when and where exactly should it be used? So these are the three things that we're going to focus on as we go forward. And one of the things that you're going to encounter is kind of the prevailing attitude I think in a lot of EMG labs. That is that EDX really there's really nothing wrong with it. It's the best test. There's really no competition and you should pretty much do it all the time. And while I love EMG it's the first thing I really became passionate about in the field and I still do and I think it's great. I don't think it's normal for people to get asked if you've been trained at Guantanamo Bay and I get asked this about once a week. So just as kind of a general thing I think that shows that there's something not right. Or have prominent hand surgeons compare what we do to bloodletting. Another sign that perhaps things aren't perfect at a minimum. But having said that there's a reason that a test that came out in 1950 and hasn't gone through any major technological leaps other than digitalization and is painful and a bit expensive is still around. And the reason is it has a lot going for it. Specifically, pardon the pun, it's specificity. Now before I get into that probably a lot of you are thinking wait a minute how can we talk about the specificity of a test that for which there's no true gold standard. And that is a very fair point but I will just kind of table that conversation. Suffice to say some very smart people, some very authoritative people have gotten together over weekends and hotel conference rooms and come together and said that we can do this to some degree. So it's limited but within those limitations EDX seems to be very specific and that's a huge bonus. It's also the test of choice for almost every disorder in the peripheral nervous system. And that is another huge thing that I think sometimes doesn't get appreciated. It can also tell us a lot about severity which in a perfect world would give you perfect guidance and how to treat people and to tell them exactly what the prognosis is. The truth is it's a little more complicated than that but it certainly does help us. And it really tells us things that almost no other test does and it does so without really essentially any risk. So that's the great things about EDX. The not so great things about EDX are primarily the experience. And whether you think it's blood lead in your Guantanamo Bay or whatnot it's certainly not great. It's not pleasant and it is a little on the expensive side and the time-consuming side. It often adds a trip for patients who are waiting to get carpal tunnel surgery or what have you. But the other thing that's underappreciated is the blind spots of EDX. This is a big problem and if you work in an EDX lab a lot this is something that comes up over and over and over again. The sensitivity of EDX for carpal tunnel syndrome is actually pretty good. Problem is carpal tunnel syndrome comes in all the time and so even a low number you're going to get a lot of things that you think may be a false negative. With ulners and cervical radiculopathies those rates are much much higher. Prohibitively high. And I know I don't like when a patient comes to the office with pain in their neck going down the lateral arm form and into their thumb and index finger and I do everything the test has to offer and I tell them that the test is normal and they say okay great what's going on and I said well you actually have a radiculopathy. I don't like telling the patient two different things. I don't like writing in a record to referring doctor to totally the opposite things and yet the EDX forces me to do that because of the low sensitivity in many situations. So that's a blind spot. Other blind spots. Localizing severe axonal lesions. We'll give examples of this later on. EDX is not very good at this. It's also not good at saying whether you have a recurrent mononeuropathy after you've had surgery. For example someone who comes in having had a carpal tunnel release 10 years ago who comes in with symptoms of carpal tunnel syndrome. It's actually kind of limited in assessing those people. Similarly people who have a generalized neuropathy say diabetic neuropathy who have a suspected mononeuropathy on top of that. It's limited there too. And then really the biggest blind spot of EMG is etiology. It almost never tells us why something's happening. So EDX isn't perfect. Spoiler alert there. But that does not automatically mean that ultrasound can come in and supplant it or even fill those gaps. That's what we have to establish. But really even that's maybe an unfair standard. What we have to decide is does ultrasound add enough to be worth the inherent downsides of adding another test to a patient coming into the lab. So about six minutes in and we've already answered question number one. Yes the EDX lab does need some things. It's not perfect. But now we have to focus on is ultrasound worth adding. Okay so that's where we're going to go now. Well let's before we even talk about how we should use ultrasound, is it even a legitimate science? And in the interest of time I'm going to kind of bottom line this. It is. It is considered the imaging test of choice when it is accessible, when the thing we want to look at is accessible to ultrasound. It is the test you want imaging wise. And it in and of itself is valid and reliable. In fact if you really want to get into the weeds on this you can pour over this slide. And what you'll find is that it's probably if anything a little more valid than EDX even. But it's valid and reliable. And in terms of accuracy it is certainly within the ballpark of other tests we order for other conditions all the time. So it may not be perfect. It may not be all things to everyone. But it is valid and reliable. Okay well that's good. That's a starting spot but it's not enough. What does it tell us about nerves? That's what we want to get into now. And I'm going to skip over ultrasound basics. I think a lot of you especially people recently trained or in training probably know a lot of this stuff. And I'll just touch on a couple points quickly. This is in general what nerves look like. This is kind of blown up so it looks a little fuzzy. But nerves are hypoechoic. They have a fibular or I'm sorry a fascicular pattern that's kind of chunky compared to a tendon which is more fibular and finer and a little more hypoechoic. This is a nerve on long axis view. Okay so that's just a little bit of basics but you guys probably know most of that. So let's focus on what ultrasound, what sort of abnormalities are we going to see when the nerve is diseased. And these are kind of the main things that people talk about. But I will tell you that these are not very reliable. They're important to know about. They give us some insights into the biology. But they're not very reliable as diagnostic tools. Really this is about enlargement of the nerve. Okay. And here's an example of that. Here's a normal median nerve. Here's a ulnar nerve that is very not normal. And the main thing you're seeing is that is enlarged. It has also got much bigger chunks. It's more fascicular than the normal nerve. It is also, although this is hard to appreciate, it is blacker. It's more hypoechoic. The problem is I turned up the Dane on this. If you look at the background, this is a little lighter than this. So it's a bad example of that. Here is increased power Doppler flow and what turned out to be a nerve mass. So that can be helpful but it's just not one of these things that can help you in every case. I don't have a good example of decreased nerve mobility. Here's some a normal median nerve, someone flexing their tendons. Okay. So that's the sort of abnormalities that are going to manifest on ultrasound when you have a diseased nerve. So now we want to get into, okay, well, when a nerve is diseased, why does it show up as abnormal on ultrasound sometimes? Why does it show up as abnormal on the EDX sometimes? And when are these two related and when are they separate? So here's an example of that. So this is a slide that we could go into for a full half hour easy, but I'll just summarize by saying when you have a thing called axonal conduction block or nodopathy in the nerve, that will manifest on your EDX study as conduction block or sometimes conduction slowing. When you have a true loss of myelin and remyelination, you'll get conduction slowing, temporal dispersion, or conduction block, or sometimes a combination. And if you have death in either the axon or the soma of the nerve, you'll get this pattern called axon loss, and you can also have conduction slowing if it's significant. All right. So that's kind of the very Cliff Notes version of comparing what's going on in the health of the nerve and what the EDX patterns are. So let's shift to health of the nerve and health of the nerve and what you're going to see on ultrasound. And like we said, this is mainly about the nerve size. So there are certain things that pretty consistently lead to a significant increase in nerve size. And here's what they are. Axonal focal mononeuropathies, like an ulnar neuropathy, like a fibular neuropathy. If they're axonal, they'll tend to make the nerve larger. Inflammatory nerve edema will do this as well. And then demyelination with the caveat that this, it enlarges when there's prominent remyelination. And you see that primarily in CIDP and CMT and some other disorders. And here's an example of this. If you, if this is a normal axon, a myelinated axon, here's one just slightly blown up, but not blown up that much. You can appreciate this one has a lot of redundant myelination. And you look at how much bigger these are than this. So you can imagine if this is going on in most of the neurons within a nerve, it's going to make that nerve much bigger. So that's probably why that is. Other conditions will cause really no significant change or a minimal change in the nerve size. And these are axonal generalized neuropathies, like diabetic neuropathy to some degree, or some chemotherapy related neuropathies. Interestingly, you will see enlargement in a generalized axonal neuropathy at entrapment sites. Why? We don't know. And this often happens in patients who have no symptoms. So for example, the median nerve will be enlarged in someone with diabetic neuropathy, even though they don't have symptoms of carpal tunnel syndrome. You also will not see usually a major change in size in a demyelinated neuropathy, which does not have prominent remyelination, such as a diabetic neuropathy and some other entrapment neuropathies. And then you'll actually see a decrease in nerve size in ALS and some severe entrapment neuropathies. And this actually ends up becoming a big problem for ultrasound, as we'll go into in a couple minutes. So just to summarize what we went through, because I know that's a lot of biology and you're probably not really looking to learn a lot of histology at this point, but just to bottom line it, you get usually significant enlargement in nerves on ultrasound with axonal focal mononeuropathies, demyelination with prominent remyelination, and inflammatory nerve edema. You get minimal or no enlargement with axonal generalized neuropathies or demyelination without prominent remyelination. Now if you look hard, you're probably going to find a zillion counterexamples to this. This is trying to really draw out trends, okay? All right, so we talked about EDX patterns you see with certain nerve pathology and ultrasound patterns you see with certain nerve pathology. Let's see how do the EDX and ultrasound correlate with each other, and how do they compare? Well, first of all, let's look at sensitivity. Which one's more sensitive? It turns out EDX is more sensitive. Why? Again, there's limitations in determining how sensitive or specific something is if there's no gold standard to compare it to, but within those methodological limitations, most authorities acknowledge that EDX is a fair bit more sensitive. In fact, it's often used as the gold standard. And this is a good example. This is a patient. I'm looking at their ulnar nerve. This is under the FCU and the proximal forearm. The ulnar nerve really doesn't look very big, but here's what the nerve conductions look like in this patient, and you can see we got a major problem with the stimulation above the elbow with a significant widening of the duration, a drop in amplitude, and a drop in conduction velocity. So this has got some temporal dispersion and probably some conduction block on top of that, yes, and some significant conduction slowing. So this is a pretty unhealthy nerve, but the ultrasound looked great. So why is the EDX more sensitive in these cases? And the answer is I don't know for sure, and I'm not sure it's known by anybody, but it's reasonable to speculate that if you have an entrapment neuropathy that has demyelination but does not have prominent remyelination, or if you have axonal conduction block slash nodeopathy, these don't generally cause the nerve to become enlarged. So they'll give you EMG abnormalities. They'll give you symptoms, but the nerve will look good on ultrasound, and this would make the EDX more sensitive in that case. All right, how about specificity? Well, the EDX, as it turns out, is thought by most to be more specific, again, within those limitations, but it's actually probably the EDX advantage on specificity is even greater than sensitivity. Why? Well, again, I don't know for sure, and I don't know that it's known, but it may be that nerve enlargement is just fairly nonspecific. In the example we talked about where patients with diabetic neuropathy have enlarged median nerves at the wrist, even when they have no symptoms, for some reason this just happens, and that's the problem. You don't know in a given patient, is that because they don't have a real problem there? Is that just one of these things that happens? It decreases the specificity of the test, and that really does hurt the utility of the test. It doesn't make it useless, but it does hurt its utility. This is going to be a recurring slide. I think it's very important when you're bringing ultrasound in to be skeptical and to be a smart consumer of the information you're being given. What we don't want to create is a generation of physiatrists that are like some of our spine surgery colleagues, that all they do is run around chasing test findings without correlating them to the patient and without knowing how nonspecific those findings are. So the picture does not equal the diagnosis, not automatically anyway. You have to be very aware of that, so you're going to see that slide again and again. So it sounds like at this point it probably sounds like ultrasound has really nothing to offer, and that is not the case either. In fact, strangely, while EDX is more sensitive than ultrasound most of the time, sometimes ultrasound is more sensitive than EDX. How does that make sense? Well, we know this, for example, with tarpal tunnel syndrome. We see this a fair bit, and I'm actually going to get back to this slide a little later. But there's many cases where the EDX is normal and the ultrasound is positive, and we think the ultrasound is right. So how could that be? I'm sure I don't know, and it may not be known, but I could speculate that based on what we already reviewed, if you have a lesion that is a constant entrapment where there's damage and healing and damage and healing, and it's a kind of you're almost on a treadmill, and it's rapid and constant axonal regrowth reintervating the damage from the axonopathy, this is a known blind spot of EMG and nerve conduction studies. And yet axonal focal mononeuropathies are something that cause your nerve to enlarge. So I suspect in many of these cases in tarpal tunnel syndrome, this is exactly what's going on. But it's hard to prove, and I've not seen any literature to this effect, but it's possible. Okay, well, why can EDX show severity better than ultrasound? This to me, actually, there's two big reasons for this, and they both make a lot of sense to me. The first reason is that EDX, as we just reviewed, shows you a bunch of different patterns, conduction block, conduction slowing, temporal dispersion, axon loss, and these all have different implications in terms of the nerve pathology, where ultrasound really just shows us one thing. I mean, it shows us other things, but they're not really that robust diagnostically. And even that one trick pony, that one trick is a little nonspecific. And I like to think of this as, you know, you have the many moods of the cat, right? And I liken this to EMG and nerve conduction studies. It has many moods, conduction slowing, block, temporal dispersion, axon loss. It has many responses to nerve pathology, where the other side of the coin is the dog that typically has about the same response to all of its different emotions. And I sort of liken this to ultrasound. It's really got enlargement, and that's kind of the one face it has. So I think that's one reason is there's much more nuance to the things that you can see on EDX. The other reason is, and this is a huge problem, I think, we know in some cases that as nerves get more diseased, they initially get bigger, then smaller. Where EDX findings, you know, if you have a progressive nerve disorder and the amplitude is low, as it progresses, it's just going to keep getting lower. You know, this would be a good graph of EMG abnormalities and nerve severity. If ultrasound looked like this, it would be very simple. If you had nerve size here, and you had, and it was getting bigger, and it was getting bigger, and then you had nerve severity here getting worse, and then you said, okay, the nerve is, say, 10 millimeters square. You would know through this sort of relationship that the nerve is a certain severity, let's say moderate in this case. But this is not the relationship, at least in some cases. It appears to be more complex. It appears to be more like this. And so the problem is, if a patient comes in with a 10-millimeter squared cross-sectional area of the nerve, you don't know if they're on the front side of this curve, and the damage is mild, versus they're on the backside, and the damage is actually severe. So that's a huge limitation potentially for ultrasound. So overall, in terms of utility of the ultrasound and assessing nerve pathology, what does it actually have to offer? And I think if you boil it down, this is what you can safely say. It offers a different scientifically legitimate way of looking at nerves. One that can see some things that EMG is blind to, but is also blind to some of the things that the EMG sees. And one that is in some ways better than EDX, but in some ways, and perhaps more ways, worse. But different. Different but legit, I think, is fair. But again, the picture does not equal the diagnosis, and we're going to go through some examples of that. Now, you don't have to take my word for it, fortunately. The AANEM, which for people who are new to the field, this is a group of physiatrists and neurologists that were organized around the common interest of EDX, as well as neuromuscular medicine, and more recently, ultrasound. And this group, eight years ago, actually took on the job of coming up with a consensus statement about ultrasound for carpal tunnel syndrome. Now, again, these are people whose primary career interest in research and training has been in EMG. You might expect them to be a little skeptical and to be downplaying the role of ultrasound, but it was actually sort of the opposite. They came out and gave it a level A evidence for diagnosis of carpal tunnel syndrome. So, a very legitimate, authoritative body came out and says, you can use ultrasound for diagnosing neuromuscular problems. So, this answer is actually pretty easy, too. And hopefully, we've gone through some of the reasons why. You don't just have to take it on faith, but you could. All right. So, we've accomplished two things. Now, we're going to go on and talk about the other two. So, we've accomplished two things. Now, we're going to go on, and this, I think, is the harder part, is saying, okay, fine. EDX has limitations. Okay, fine. Ultrasound is valid and can give us some things that EDX can't. Great. Where do we plug it in? And that's the challenge. But I first want to caution us because one of the easy answers would be, oh, well, let's just do it on everybody. And, in fact, that's what they're doing at many academic centers. They may be even where you're training. This is a patient I had that was kind of a cautionary tale of why we don't do that or shouldn't do that. The patient who had it, a kind of ambiguous clinical presentation, could be carpal tunnel syndrome. Exam didn't support it at all. I'll fly through the EDX. This isn't the point of the lecture, but I applied the most sensitive tests for carpal tunnel syndrome and could not find any on either side. I went out and did an ultrasound. I suspect that this was a false negative. And, in fact, the median nerve was not terrible but was a little enlarged. That's above a lot of upper limits in normal. And when you calculate a risk-forum ratio, which is a way I like to do it, it's a more accurate way of distinguishing normal from abnormal, he was well, this patient was well in the abnormal range. So here's the problem. We don't know if the patient has carpal tunnel syndrome with a kind of ambivalent history and physical and a falsely negative EMG but a truly positive ultrasound versus they don't have carpal tunnel syndrome, the EMG was correct, and the ultrasound is a false positive. We don't know this. Except in this case, we might because this person failed conservative measures, went on against my advice to consult a surgeon, had surgery, and is now worse. I don't know that that ultrasound was wrong. It's possible they just had unsuccessful surgery, but I'm very concerned that I might have helped that person end up in the wrong place by throwing another test in. The picture does not equal the diagnosis. This is the big hurdle we have to get over. We have to make sure the ultrasound is going to provide enough information to overcome the inevitable false positives it's going to cause. It's going to cause some. If we use it, we will get some. But hopefully the benefit will outweigh those. And so speaking of that do ultrasound on everybody approach, one of the thought leaders in this field down in Wake Forest did a trial where basically they do ultrasound on everybody that comes to the EDX lab. It's part of their training. And what he did, though, is he randomized people to one or two groups. One of the groups had the reports of the ultrasound sent to the referring doc. The other group did not. And then he measured the outcomes afterwards. And he had many outcome measures, but there was one main outcome measure. And in that one, I'll bottom line this, they did not reach statistical significance. And they interpreted this in a very optimistic way. But basically this was negative. They showed that you did not improve patients' outcomes by doing ultrasound on everybody. And I'm sure in part that's because they incurred some false positives. So indiscriminately using ultrasound on everybody does not improve outcomes and adds expense and time, et cetera. And remember, false positives, like that case I showed you, in the environment we're working in where many of these things turn into surgery, a false positive, a little math here, false positives equal unnecessary surgery. Unnecessary surgery equals bad outcomes. And therefore, by the transitive property, false positives equal bad outcomes. So we have to be very careful about false positives. But that does not mean that ultrasound can't be used. It's just that it has to be used with a little more precision. Okay, so fine. Where are we going to use it? Well, first of all, you can use it therapeutically. We do this a lot in our lab with injections and aspirations and whatnot. That's not what we're talking about today. But clearly that is a use. Diagnostically, you can use it to enhance nerve conduction studies, which we actually do a reasonable amount for the lateral femicutaneous nerve and also the ulnar nerve after surgery. And here's an example of the lateral femicutaneous nerve. And tracking this down and then doing your nerve conduction studies where you've confirmed it to be has helped us. You can also use it to guide needle EMG into difficult muscles. These first two we do a fair bit, and it has definitely helped us. But how about the actual ultrasound itself, not enhancing something else but being used in its own right? Well, one of the places this has been used is in diffuse neuromuscular disorders, which may be not what your lab sees as much of, but it has been used quite a bit. And this is one of the main thought leaders in this area. And just to summarize it, there's a lot of different findings you'll see in different neuropathies. It is largely investigational at this point, although there are some uses that you could probably incorporate right now. It's mostly investigation for neuropathies. For myopathies, actually, and this is one of the areas where I think you'll see ultrasound really get a good foothold, is in the assessment of neuromuscular diseases in newborns and infants. And it's very good at this. Similarly, in motor neuron disease, distinguishing SMA from muscular dystrophy or central causes of weakness, it's actually quite good at. And if you think about it, these are the patients that you're really least able to do EMG on. So between ultrasound and genetic testing, EMG is really going to lose a place here, which is for the better. But in motor neuron disease, it's not just restricted to the pediatric world. In adults, it's actually very helpful for fasciculations. Ultrasound has been shown to be better at detecting fasciculations than either exam or needle EMG. It also, interestingly, can be used to track the size of a nerve, which in the ulnar, but not the median for some reason, declines pretty predictably in size as the disease progresses. And this actually is thought to be something that can be used as a biomarker for both clinical trials and maybe even clinically, a painless, noninvasive biomarker. So just to summarize the ultrasound used for diffuse neuromuscular disorders, it's not widely used, though it has already been shown to be of significant benefit in certain places. And no doubt this is a fair statement for ultrasound and the EMG lab in general. Ultrasound is going to have more and more of a place as time goes on. Okay, so let's move on from that. Let's talk about ultrasound abnormalities for focal mononeuropathies, which is, I think, where most of us are interested in most of the time where we're going to use it. It's certainly where we use it the most. And, of course, we'll focus in on triple tunnel syndrome, which we all know about. Here's what a typical median nerve at the wrist looks like. Here's the flexor tendons, the FCR. And here's the median nerve in the forearm with the superficial and deep layer above and below it, respectively. This is kind of a list I put together of the things that we – basically the ways we would judge whether a test is useful or not in our EDX lab is its ability to do these things. And so we have to decide. We know that EMG has some limitations, but it has a lot of strengths. We know ultrasound is legitimate, so which of these should we do in a patient presenting with suspected triple tunnel syndrome? So I think the way to do that is to judge it according to these criteria. In terms of the accuracy, triple tunnel syndrome, EDX is thought to be more sensitive and specific. It's also much better at assessing deaths number 2, 3, and 4. If someone who comes in with hand numbness isn't found to have triple tunnel syndrome, at least in my lab – and this is not a scientific – this is something I derive scientifically – but these are the other things that typically will cause those symptoms. And of all of the five of those, the EMG is not just good. It's the test of choice for all of them except one. That's a huge benefit of EDX over ultrasound. It's also better at assessing severity, and I throw this slide in. I won't get into it in great detail, but in a simple world, you'd think that knowing the severity of a lesion tells you exactly how to treat it. The truth is that's not really true. It's a start, but it's not quite enough, and we don't really have a lot of data guiding us. But certainly, whatever test is better at telling us severity will probably be the better test at telling us what's going to happen to that patient and how we should have that patient treated. So when you very non-quantitatively stack these factors up, what we find in terms of what we are trying to draw out of the test, the EDX has a bunch of advantages in terms of the accuracy, in terms of the ability to rule out mimickers, and in terms of assessing severity is much better. However, from what the patient gets from the test, the ultrasound is quite a bit better in terms of being much more tolerable and a little cheaper and a little faster. So boiling all that down and coming up to one of the main questions that we have to answer for the role of ultrasound in the EDX lab, which should be the first test to use for suspected carpal tunnel syndrome? And the answer, I think, is for almost everyone it should be EDX because of its better accuracy, because of its better ability to rule out likely mimickers, and because of its superior ability to assess severity. Now, I do think ultrasound should be used first in some patients. Sometimes patients are referred to my lab, and I'm sure yours, for rule out carpal tunnel syndrome, their symptom is wrist pain. Well, to me, wrist pain without numbness and tingling almost never turns out to be carpal tunnel syndrome, but it does turn out to be a ganglion cyst in the wrist or a flexor tendinopathy or what have you. So to me, it makes more sense to start with ultrasound in these patients. The other group is people who are intolerant of EDX, and I just had a colleague of mine's mother-in-law, who is coming on her 95th birthday, come into the office the other day, and I went into great depth and told them all the pros and cons of doing the EDX versus the ultrasound, and said you won't know the severity, you won't be able to rule out other things, blah, blah, blah, and they said just do the ultrasound, and I thought that was reasonable. So there is certainly a place for a test that gives less information but at much less of a cost to the patient. Now using it as a screen, this is a very complicated, controversial question. There's a lot of people both within our field who are calling for ultrasound to be used as a screen for carpal tunnel syndrome, and outside of our field, real leaders in the neuromuscular world who are calling for this. I will tell you that if you get into it in great depth, it's very messy, but I don't know that ultrasound should automatically be used for that. In fact, I would say it should not. So in general, most patients, we should probably use EMG first, at least with all the data we have right now. Okay, fine, but ultrasound has uses. Are there times that we should add it on to someone who's already had EDX? Now we know from earlier that we shouldn't do this on everybody because that does not improve outcomes, and it definitely exposes patients to the possibility of false positives, like my unfortunate patient. Very glad surgery didn't do better. So when are the smart times to add ultrasound to EDX? Well, one example we talked about briefly before was a suspected false negative. When you look at the studies that have been done on this, and there are several now, this is not one study, the yield on this is very high. They probably range about 50%, but a lot of the more recent ones are much higher, and I have to say in my lab it's probably more like 75% of these patients. This is someone who comes in, they have a story that's very suspicious of carpal tunnel syndrome. Maybe their exam supports it, but their EDX is negative. When you do the ultrasound on these patients, I'd say probably at least three-quarters in my lab, and the literature supports this, will have an enlarged median nerve. Now again, we don't know. Maybe that's a false positive and their EMG was correct, but I would say for every one of those patients I described to you earlier, there's probably at least 20 that respond to treatment for carpal tunnel syndrome. So that's one use. Another use is postoperative. Now this I'm going to tell you, this is where we have to worry about a picture being equated to a diagnosis, and there's this shiny object phenomenon going on here. So the vaunted notch sign that you're going to hear people talk about, this is why we need to do ultrasound in patients who've had carpal tunnel surgery but they're still having symptoms. We've got to look for a notch time and indeed I have found the notch time. Here's an example. If this is proximal in the nerve, this is a long axis view. We go a little further down, it certainly gets narrower and somewhere around here is where our notch is. Here's a better example where it gets even narrower and if you look at the cross-sectional areas or the short axis views here, look at the the AP diameter of the nerve here versus here. Much different. And here's an even better example. If you follow this median nerve right here, we're going proximal to distal toward the carpal tunnel. Look how small this gets. It almost disappears before it reappears down here. So we have some great, I have great examples of the notch sign. It's definitely a thing. Here's the problem. I see notch signs in people who have carpal tunnel syndrome and who have never had surgery. I have notch signs in patients who have had carpal tunnel surgery but are coming in for wrist pain and we find a ganglion cyst and oh by the way, they have a notch sign. So what exactly does this mean? We don't know. And this is an example where the picture gets equated with the diagnosis. We have to be more critical thinkers than that, I think. How about for people that we've done our EMG, they have carpal tunnel syndrome, should we screen them for an underlying cause? Because as we said, EMG is terrible at this, where ultrasound has a lot of promise. Well, if you ask the AANEM experts, and you should, they will tell you that there's level B evidence for this. And I don't disagree. This is no doubt true. In fact, it'd be hard for me to disagree because this is my own wrist and if you put this under ultrasound, or I'm sorry, doppler, you see a lot of flow here because I have a gigantic persistent median artery on both sides, actually. Here's someone who had a ganglion cyst and if you look at the articles that they reviewed, there's quite a bit of people who have a finding, like a bifid median nerve or persistent median artery or ganglion cyst or a couple other random things. The question I have is, I came to this, I came with this information, all excited to my surgeon, they said, I don't care. I'm going to do the same thing on them no matter what. Now maybe that's bad medicine, maybe I should be trying to teach them, but I guess the point about the persistent median artery and the bifid median nerve is that you have to know that it's going to change the treatment for your patient and their environment. The ganglion cyst thing I find a little more troubling because just because you have a ganglion cyst, who says that changes the way you treat things? Who says they're related at all? Association does not imply causation and even if we were able to prove that there was causal related, that does not mean that treating that, that we would change the way we're going to treat it. Maybe we would just do a carpal tunnel release on everybody anyway. Or even if it's going to change the way we treat it, that doesn't mean that that improves outcomes and improves outcomes in a cost-effective way. Really, in order to justify doing the test, we have to know that there's at least a reasonable expectation that this finding is going to lead the patient to a better place in a reasonably cost-effective way and we don't know any of that right now. So I would just have you be a little cautious about that. Okay, can't say it enough times. Okay, so that's carpal tunnel syndrome and that's really the majority of what we talk about, but ulnar neuropathies is also a big area. It's the second most common focal mononeuropathy. So let's go through and kind of apply the same standards to ultrasound and edx and decide which of these should come first. Without getting into a lot of detail, again, the sensitivity actually of edx for ulnar neuropathies is terrible. It's very low. Unfortunately, so is ultrasound. Ultrasound is actually a little better at assessing severity, or I should say there's more data supporting its ability to assess severity in ulnar neuropathies than in carpal tunnel syndrome. I would say the advantage for edx in assessing likely mimickers is actually more of a factor than it is for carpal tunnel syndrome because I consider c8 radiculopathies a lot more of a problem than c6 radiculopathies, which are more likely to mimic the carpal tunnel syndrome, and I also consider lower trunk plexopathy is much more of a problem than an upper trunk plexopathy because they're more likely to be cancer. So it's ruling out much more important things in my opinion. But overall, I believe the same answers apply. Edx should be the first line test because it's more accurate, because it rules out likely mimickers better, and it is better assessing severity. Though I still would argue that some patients should have ultrasound first, particularly if they're referred for elbow pain because most patients with an ulnar neuropathy don't have elbow pain and most people with elbow pain don't have an ulnar neuropathy. That's not a good reason for doing an EMG in most patients, so doing ultrasound on them makes sense. And those that are intolerant of edx, another good reason, and then you get into the whole issue of screening, which we won't get into. All right, so again, people, someone comes to the lab, suspected ulnar neuropathy, makes sense to do edx first for the bulk of people. But when should we add on ultrasound? Suspected false negatives. Does this apply? Well, in some ways more so because the sensitivity for edx for ulnar neuropathies is much lower than it is for carpal tunnel syndrome, so the need is much greater. And I can tell you, you will certainly see cases if you do this where you find the answer by doing the ultrasound, like this patient who had ulnar neuropathy symptoms, normal edx, but if you look at this nerve, the upper limit of normal is 0.07. This is 0.30. It's over triple, or I should say over quadruple the upper limit of normal. So it was very useful in this case, and I will tell you I use it clinically for that all the time, but there's not a lot of literature supporting it. Now absence of evidence is not evidence of absence. Just because we don't have literature doesn't mean it's not true, and I suspect in time this will be proven to be true. And in the meantime, I think the benefit outweighs the risk, so I do it, but I don't have a lot of literature to support me on that. How about something we didn't run into with carpal tunnel syndrome, which is these axonal non-localizable lesions? There's actually quite a bit of literature on this. What the heck is that? Well, you've probably seen this. This is a patient who has a totally fried ulnar nerve, and because we can hardly get any responses, the numbers that we are getting out here are garbage. These conduction velocities mean nothing. These amplitudes mean nothing. You really can't realistically get any conduction slowing or block through your nerve conduction studies, and that's how we tell whether this lesion is at the wrist or the elbow or the plexus. The other way we can do it is with needle EMG, but because of selective sparing, this isn't often an effective way to do it, and I don't like committing people to surgery based on the needle EMG. I don't think it's reliable enough, and this is fortunately somewhere where ultrasound has really stepped up to fill the void. So here's the ulnar nerve looking relatively normal, six centimeters proximal to the line connecting the medial epitondyle and electron. Here's the same nerve two centimeters from that line. Huge, black, all one-facetal, with maybe even a little calcification, and much, much bigger than it was. So here's an example where the ultrasound really showed you where that problem is and had you, you can send that person to surgery confidently, knowing that the problem really isn't at the wrist. So that's a very useful place. How about after surgery? I'm going to show you this video twice. We're looking in the forearm and we're moving toward the elbow. Here's the flexor carpi ulnaris. Here's the ulnar nerve getting bigger as we go, and what you'll notice is that it splits the two heads of the FCU because this person's had a transposition. That's the first thing you see. The second thing you see is that this nerve is grossly abnormal. So no doubt this person's symptoms were in part due to an ulnar neuropathy, but again I want you to just appreciate this, this nerve splitting. Rather than sneaking underneath, it splits these two heads of the FCU, which I just think is very cool. And so studies have shown that it is useful to diagnose problems post-operatively. Now one of the big things you'll see is using this to look at dislocation versus subluxation of the ulnar nerve. This to me is another shiny object. It's very cool. Here's a person who dislocates not only their ulnar nerve but subluxes their medial triceps. Very cool, and people who are trying to pitch ultrasound to you will often give you this as an example. And here's an example of someone just in our lab. When you fully flex the elbow, the ulnar nerve sits right on top of the medial epicondyle, but with it only partially flexed, it sits right back in here. But the picture does not equal the diagnosis. The data, if you look at it, you don't just cherry pick one study. Some studies say people with ulnar neuropathies have more subluxation. Some studies say people with ulnar neuropathies have less. And what I've seen is the best analysis of this says people with mild ulnar neuropathies sublux more, but with severe ulnar neuropathies sublux less. And that dislocation probably is protected. Boil it all down, it's a mess. This probably isn't a good reason to look at ultrasound. How about looking for an underlying cause? Here's a video of a person with ulnar symptoms, but a normal edx study, strangely, and has this woe going on. This turned out to be, we did an ultrasound or we did an MRI on this, which was just said a mass, and the neurosurgeon said it wasn't worth doing a biopsy, so we think this is a cystic schwannoma. Here's a patient with an anchoneous epitrochlearis, which is an anomalous muscle that a certain percentage of us have. Here's another example sitting near the medial triceps. So sometimes you'll find an underlying cause. I'm just going to buzz through these next two quick, but fibular neuropathy, this is actually a good reason to do ultrasound. Here's a fibular nerve on long axis, here it is on short. It's pretty good at looking for suspected false negatives. It's pretty good at looking at non-localizable axonal lesions, just like the ulnar nerve. But the main reason to do ultrasound and fibular neuropathies is anybody you confirm has a fibular neuropathy, if you do their ultrasound, at least one, about one in five is going to have something that you'll want to know about, usually an intraneural cyst. Here's an example from our lab. Here's another that we drained, and this is absolutely the cause of those fibular neuropathies, and it will change your treatment, and that treatment will change the patient's outcomes. So this is a very good reason to look and use ultrasound in the EDX lab. Tarsal tunnel syndrome, there's not quite as much data, but it is also good at assessing for tarsal tunnel syndrome compared to EDX. And similarly, it finds a lot of potential, potential underlying causes, but it's not clear if these are really the underlying cause or just a totally unrelated incidental illness. So, and just a word on plexopathies, it's very good at neuralgic amyotrophy. I'm going to show you an example of that in a moment. But let's just take all focal mononeuropathies. If you have to come out of this with one kind of general algorithm, this is the one you should probably take with you. The first test for most patients in the EDX lab should be EDX for focal mononeuropathies, because it's more accurate, because it does a better job at ruling out likely important mimickers, and because it's better at assessing severity and giving you a way to guide treatment and prognosis. Patients with a likely MST problem, pain without numbness or tingling, or who are intolerant of EDX, makes sense to do ultrasound first on them. And for those who get that EDX, when do you add on the ultrasound? Suspected false negatives, axonal non-localizable lesions, trauma including fractures is actually a very high yield time to add it on. We didn't have time to get into that. And then in select cases, screening for underlying causes. So we've covered a lot, but the one thing I didn't cover is the main reason that I think you should do ultrasound in the EDX lab is because it's very cool. Here's a patient who came in, suspected radial neuropathy, they didn't want an EDX study, and I found the radial nerve was kinked and tethered to this hyperechoic thing here, which on x-ray looked like this, and after surgery looked like this. This craziness. How about someone who I thought had dacra veins, instead they had a gigantic ganglion cyst over the tendon. Well here's some slides from a study that I just find mind-boggling on neurologic amyotrophy, where the nerves are literally torced, and the ultrasound gives you a hint of that. So EDX has many strengths, but some weaknesses in evaluating the peripheral nervous system. Ultrasound for nerves is scientifically valid, reliable, and legitimate, and they have overlapping sometimes, sometimes not overlapping information they give you about the nerves. EDX is probably the best first test, except for a select few, and ultrasound should not be added to everyone, but judiciously in certain high-yield situations, and the role of ultrasound is probably only going to expand, but ultimately it shouldn't be viewed as a fight. These three modalities can work together and make beautiful music, and I think they should, and I hope that helps. Thanks a lot. I'll stick around for questions. Thank you very much. It sounds like this is a very complicated, but like you said, kind of use them appropriately, and I think it can work together. I think it sounds to me like, based on what you're telling us, that where you get in trouble is when you rely entirely on one or the other, or say this is the way to go and not the other. Yeah, or if you do both all the time, as I said, I think that's why those studies did not show success, is because the false positives is something we don't think about a lot, but it's a real problem. Or if you randomize who you refer back to the recurring physician, right? Right, exactly. A couple of questions. One was, there was a reference to an article by Robinson that talks about stratifying severity of carpal tunnel in EDX. Do you happen to know what that reference was? Yeah, well, it's in the references. He probably has a couple, but it was from 2013, and what it was is a muscle and nerve, and it was actually a point counterpoint, and he was the counterpoint. So I should, in full disclosure, say that somebody was arguing before him that you should use severity, and I'm not even necessarily taking a position on that, but he makes an excellent point that just saying someone has severe carpal tunnel syndrome, for example, does not tell you what to do with that patient. If you think about this for a minute, and again, I would have gone into this in more depth, but it takes a little while. If we thought that way, then we'd say, wow, surgery never works because I send everybody who has severe carpal tunnel syndrome to surgery, and they all do poorly. Oh, surgery must be terrible. Well, that's really the wrong way to think about it. What you want, and we really don't have as much data on this as we would like, is to say, okay, for a person with this degree of carpal tunnel syndrome, if we send them to surgery, this is what happens to them versus we send them to surgery or to something else, this is what happens to them, and you'd think we'd have all that data, but we don't have that much, and that's the point he's making, and we would want that same analysis for every grouping, and another point that's very interesting and I didn't, again, get into is when you look at the outcome studies based on our typical mild, moderate, severe, they generally cannot predict the outcomes of surgery. The hand surgeons are all over this, and the skeptical ones will use this as a reason to not refer for EMG, but Larry Robinson and company have one scale, and then Jeremy Bland out in England has another one that go into about six or seven categories, and those do, but I guess the short thing to take away from that is we all go confidently and say, oh, our mild, moderate, severe, this tells us everything we need to know. Not really. It's unfortunately quite a bit more layered than that. Okay, that's helpful. Another question was if you were to use ultrasound, is that something you would do in the same visit as your EDX, or is that something you'd bring somebody back for? Yeah, well, this is, and this is the whole implementation end of it. We, so in my lab, and, you know, we're in private practice, one of the great things is that we can just make things happen if we decide to, you know. It's much easier to do that than in a large institution, so we have built in the capacity to add on ultrasound on anybody who needs it, and the only times we bring people back is when they need authorization, so we almost always do it right then. You might have to add it on later on. Patients hate that, of course, and you're always balancing the utility, and, you know, try not to completely blow up your schedule, but, and if you don't have any help in the lab, adding on an ultrasound is not a small thing. If you have help, it's manageable, so I think that answer completely depends on your context, but we add them on on the same day if their insurance allows it. Okay, all right. Thank you very much. I appreciate it. I think we're out of time, but if people have further questions, can they reach out to you at that email address there? Yes. Perfect. All right. Thank you so much. We appreciate you joining us today. For everybody else that joined us today, if you missed part of this lecture, or if you have colleagues that weren't able to watch, that website, physiatry.org slash webinars, is where you're going to find a recording of this, and again, that will be hosted through the end of this calendar year, at least. If you have any questions related to this lecture, please reach out to Dr. Jorgensen directly at his email address there, or you can hit, you can reach out to me or AAP on Twitter. Those are our handles there. Again, thank you very much for joining us. We appreciate you spending time with us today.

ultrasound

peripheral neuropathies

carpal tunnel syndrome

ulnar neuropathies

accuracy

sensitivity

specificity

electromyography

EDX