Good afternoon. My name is Adam Comer, and welcome to the 2024 AANEM annual meeting. This afternoon, we will be discussing muscle ultrasound, specifically quantitative assessment of muscle ultrasounds and patterns of muscle involvement. We will also have a lot of examples and representative images. I am currently at Indiana University School of Medicine, practice neuromuscular medicine there. And without further ado, we'll get started. I have nothing to disclose. As an overview, we'll talk about normal and abnormal muscle. We'll review the HECMAT rating scale, the difference between the appearance of neurogenic and myopathic muscle. We'll look at muscle thickness and muscle atrophy, discuss quantitative assessment of muscle with grayscale analysis, review relevant cases, patterns of involvement, and look at future directions. So history of muscle ultrasound. Ultrasound of muscle has been available since at least the early 1980s, although I recently have even seen reference to it in the late 60s. There was significant advancement of ultrasound resolution in the 1990s and early 2000s. Neuromuscular ultrasound has developed significantly over the past 20 years, as evidenced by the increasing number of lectures and topics at this meeting discussing the use of neuromuscular ultrasound. It is complementary to the neurological examination and to electrodiagnostic testing. Ultrasound is inexpensive, it's safe, it's portable, and it's easy to use, which makes it a great tool to complement what we already do with electrodiagnostic testing. The parameters with regard to muscle ultrasound, ecogenicity, grayscale analysis, thickness, distribution, and changes over time. Here is an example of the normal appearance of muscle, the elbow flexors. You can see here the topmost layer is skin. There is a thin subcutaneous layer. And then muscle has roughly the same ecogenicity as that subcutaneous tissue in normal muscle. This is actually the biceps here with the brachialis deep to it. Here we can also see, in this particular case, here we can also see, in this particular view, the median nerve in the brachial artery. And one of the nice things about muscle ultrasound is you get this nice wide view. You can see a lot of the muscle all at once with EMG, needle EMG, of course, we're sampling a small amount of muscle at one time. And then we look at different areas to get a more complete picture. In normal appearing muscle, if we look deep enough, we also see this bone signal, which we'll discuss more. And then we essentially anechoic, or it looks dark deep to the muscle. This represents both normal and abnormal muscle. The top image looks similar to what we already saw. And this is showing that the sound waves, the echoes, they penetrate into the muscle and at various points are reflected back towards the surface. Their muscle is said to have a typical starry night appearance. So you have these dark areas intermixed with the brighter appearing connective tissue. In this case, we're looking at a, this is also normal, but here we can see bone. And so the sound waves, they hit the bone and then they are reflected back. And unlike normal appearing muscle, we don't have some that are then propagated deep to the bone. They're all coming back towards the surface and that's what gives this completely dark appearance distal to the muscle or deep to the muscle. And then in our final example on this slide, we see pathological muscle, and in this case, Duchenne muscular dystrophy. And in diseases like this, the normal muscle is replaced by fat and fibrosis. And so what we really have is a hyperechoic appearance. And in this case, the sound waves don't even get deep enough to get to the bone. So we really see no bone deep to the muscle. There is a HECMAT rating scale. This was first published in the 1980s. And this is really a semi-quantitative scale that's used to assess muscle. This is probably what I use most frequently on a day-to-day basis. And so this gradient scale is from one to four. Again, this is the muscle with the subcutaneous layer superficial to it. And this is the normal appearance of muscle. And on the other end of the spectrum, we have grade four where you have no visible bone where the bone signal should be. And then in between those two extremes, you have what is a little bit more subjective, but we try to make as objective as possible. Grade three is where you have clear hyperechogenicity of the muscle, but the bone is somewhat obscured. It doesn't look quite like in normal-appearing muscle. And then grade two, the bone is essentially normal. The bone is, well, go to this. The bone is essentially normal in grade two, but the muscle appears hyperechoic. And so we can use this on a day-to-day basis to describe what we're seeing. Examples of some common muscles here. So on the far left, we have the biceps. Again, in this example, we can kind of just barely see the humerus deep to it. So normal on top and an abnormal muscle appearing below. In the middle column here, B, we have normal and abnormal gastrocnemius. And then on the right side of the screen, we have normal and abnormal tibialis anterior. Here's an example of forearm muscles. And many of us evaluate the pronator teres and the flexor carpi radialis with needle EMG. And this is just showing that as we scan more approximately you can really get a clear sense of the location of both the pronator teres and as you look more distally, the flexor carpi radialis, which is this here. So we talked about the abnormal appearance of muscle and muscle disorders, but there are also some patterns that we see with neurogenic denervation. This example from a patient with spinal muscular atrophy is showing this so-called moth-eaten appearance. And with this, we see some areas of hypertrophic fibers, as well as areas of atrophic fibers that look more like the disease muscle we saw in previous slides. So you have this non-homogenous, inhomogenous appearance of muscle that would be more typical of a nerve disorder. With very longstanding diseases of both nerve or muscle, it can become more difficult to really distinguish between a neurogenic or a myopathic process. Here's another example of a patient with a severe radiculopathy and again, some inhomogenous appearance to this muscle. So there's also quantitative muscle ultrasound. And so we can do this with a couple of different methods. We can look at muscle thickness and we can also look at quantitative grayscale analysis. Really with these techniques, consistency is key. And the limitations to grayscale analysis in particular are the need to create reference values for each lab and really each individual machine. We also have to keep all of the parameters constant and they have to be constant for every muscle that you're evaluating compared with the way the reference values are generated. So these would include the machine itself, the transducer, position depth, frequency gain, and dynamic range. Muscle thickness, which is just a measurement, is relatively less subject to these parameters. And here's an example of muscle thickness and reference values based on age, gender, other demographics have been published. But again, it's important to measure in the exact same way that those reference values were generated. You can change muscle thickness by changing the amount of pressure on the transducer. So this is just an example I made quickly, but you can clearly see you would get different values for this muscle depending on how hard you push. So that is, again, something that has to be maintained constant with the way the reference values are generated, usually with a minimal amount of pressure on the transducer. Quantitative grayscale analysis is a technique which involves looking at the gray values between zero and 255. And so a region of interest is selected, and then this is analyzed using an imaging software. You can see on the left, this is normal muscle, and just looking at the histogram that is generated, it's shifted to the left relative to the abnormal muscle, which is shifted to the right. And so to generate these histograms, you actually have to take the images off of the ultrasound machine, look at them on a standalone computer to get these numerical values. To date, most ultrasound machines don't have this integrated into the existing software. You can use a variety of imaging software, one of which is this ImageJ, which was created by the NIH and is open source and free. So we do get numerical values with this technique. We get a mean and a standard deviation. And the images on this slide are meant to reflect what would occur if you change the gain. So if you change the gain, we've kept a constant nine megahertz for the frequency, but as we increase, the gain right here is 42, is where we start out, and then we increase to 50, 60, 70, 80. I think it's apparent that the image itself is changing. It looks brighter. And then you can see that this curve is then shifted to the right, and you can make a normal appearing muscle look like it is diseased. And the numerical value that started at 10 ends up at 133. So again, it is important to keep all of these parameters constant. Because of this sort of conundrum, we can't just take values that are published in the literature and use them on our own devices. It really takes some additional work to create them at your own institution. Folks have looked at trying to compare different ultrasound machines and change the settings so that we get roughly equivalent images. And there's some success in doing that, but it's really a significant challenge. This group looked at coming up with their own phantom, which is something you can scan, and then use to compare between two different devices. And then they had to come up with a formula using this phantom to take their reference values from one machine and then be able to use them on a different machine. But they were successful in doing so. In addition to looking at quantitative assessment of muscle, we can also look at the distribution of abnormal muscle, just the way we would with our clinical examination as well as MRI. And in my experience, when I'm looking at muscle with ultrasound, sometimes I will find a relatively weak muscle and the muscle looks less abnormal than I would expect on ultrasound, but I've also seen the opposite where the muscle looks disproportionately abnormal when my exam was closer to normal. So I think really putting that all together can help you get a sense of maybe what the underlying disease process is. And so this paper looked at the different distribution of findings on MRI and how they correspond with different dystrophies. Additionally, we can look at changes in muscle over time. So in this instance, they divide a muscle ultrasound sum score and they were actually able to see the changes of facial scapulohumeral dystrophy over I believe it was about a year, which of course would serve as a nice biomarker for a future therapy trial. And this is being looked at in other disease states, other dystrophies as well. And some cases. So case one is that of a 53-year-old who presents with gait instability, knee buckling and quadriceps weakness as well as atrophy. This individual noted or had marked weakness of the distal finger flexors, but attributed this to arthritis and getting older. And ultrasound has been used to look at the proximal forearm muscles. And on the left, normal appearing muscle, you can see the flexor carpi ulnaris with the ulnar nerve deep to it. And then the flexor muscles adjacent to the FCU. And then in the case of inclusion body myositis, the FCU is often relatively spared, but the deep finger flexors appear atrophic and hyperechoic. So this ultrasound finding is often seen with IBM. In this case, we had a person with left foot drop after a motor vehicle collision and severe knee injury requiring multiple repairs. And this individual had limited ankle dorsiflexion and eversion. The referring physician suspected peroneal neuropathy with the fibular head and had ordered an MRI of the knee, but the interpreting radiologist hadn't identified any pathology that would explain this. On EMG, we did see abnormality of the tibialis anterior and the peroneus longus, the gastrocnemius appeared normal. This is showing the anterior foreleg muscles, including the tibialis anterior. These all appear bright and abnormal, relatively atrophic, juxtaposed against the gastrocnemius and posterior compartment muscles that then appeared normal. So looking more approximately at the sciatic nerve in the peroneal and tibial nerves, we see here the peroneal nerve appears as a large hypoechoic, round hypoechoic structure with a greatly increased cross-sectional area of 68 millimeters squared. And then so looking back at the MRI that had been done, we can see the fibular nerve, which usually is significantly smaller than the tibial nerve and in this instance appeared about two to three times larger than the tibial nerve. So we thought this was a neuroma in continuity from the previous trauma at this location. Next we have a 29-year-old female who presents with four months of continuous muscle movements and stiffness in both lower limbs. The EMG appears chaotic with abundant myokymic discharges. And so this patient was treated between 2019 and 2020 with IVIG. Here on the left is the initial study, which shows these very frequent sort of torsional movements throughout the muscle. And on the right, I don't actually have a video to show here because there were no movements a year later with the treatment of IVIG. And then this is showing the quadriceps. And again, similar findings a year later. It's just an occasional abnormal movement. And so this patient had Isaac syndrome and continued to respond well to IVIG. And then this individual is a 68-year-old who presents with a spastic dysarthria. And I like to look at the tongue with ultrasound. It's nice because you can see multiple muscles all at once. And we have these very brief torsional movements. This is the anterior belly of digastric. Tongue muscles down here. And the nice part about this is we're really seeing muscles that have different peripheral nerve innervation. So the anterior belly of digastric is 5'3", cranial nerve 5'3". Genial hyoid, C1, by the 12th nerve. Genial glossus, which is innervated by the hypoglossal nerve as well. So this individual with a spastic dysarthria, in this case, really suggested bulbar onset Lou Gehrig's disease. And then we have a 39-year-old male with a history of trauma while riding a bicycle. This patient subsequently noticed right-sided scapular winging and shoulder instability. There had been very little improvement in shoulder stability in recent weeks. This patient had a previous EMG at another institution. In this case, we looked at the serratus anterior, and there were some fibrillations and positive waves as well as some more chronic findings. And on the left here, we see the left unaffected side with normal appearance of the serratus anterior. And then here we can see on the right side, it's a little bit subtle, but the bone is not quite as clear here compared to that on the left side and there is a mild degree of atrophy here and a mild degree of hyperechogenicity. And this corresponded with the EMG findings. It also was helpful in looking at the muscle initially with ultrasound and then making sure that we were in the correct location prior to the needle EMG. So here's another example of that with this nice paper that has a protocol on how to evaluate scapular winging. Again, the latissimus dorsi is superficial to the serratus anterior here within the ribs appearing here and pleura deep to it. And then finally, just a brief word on future direction of muscle ultrasound. So in this paper, this group looked at deep learning techniques. Of course, we see a lot about artificial intelligence now in the media. And one of the many factors that we have to keep fairly constant is how are we selecting this region of interest when we do quantitative muscle ultrasound? And so what they sought to do was to see if these deep learning techniques could automatically select this region of interest in the same way that someone with years of experience would. And this is showing you what the computer is sort of seeing, so to speak. It is selecting this region of interest. These are each sort of different steps in the process. And then finally, in yellow here is really the area that was finally selected and can then be looked at to get that quantitative information about this muscle. The nice thing about this work was that they published all of this. So they published their examples of the ultrasound they had done on these muscles. So there are examples, thousands actually, of both normal and abnormal-appearing muscle. And then they also published their computer code so that this can be replicated and that other groups can use it in their work as well. There are some other techniques that can also be used to look at muscle ultrasound. There's a technique called texture analysis, which can be used to try to distinguish one disease from another. In this case, they looked at mitonic dystrophy, inclusion body myositis, and then polymyositis and dermatomyositis. And they had some success in distinguishing these different conditions based on the overall appearance, the way the AI could identify the appearance of the muscle. And then using similar techniques, they've looked at identifying neurogenic versus myopathic-appearing muscle with some success there as well. So in conclusion, muscle ultrasound we really find is a great complement to electrodiagnostic testing and to nerve ultrasound. Consistency is really important for the quantitative techniques. And this may become more widespread with improvements in ultrasound software and as these techniques are integrated into the equipment that we're using on a daily basis. So I think we'll actually do questions at the end. And now I'll ask Dr. James Meiling to talk. He attended Texas College of Osteopathic Medicine and did his residency in physical medicine and rehabilitation at Mayo Clinic. He did his fellowship in neuromuscular medicine at Wake Forest University. And he's currently faculty at the Mayo Clinic in Rochester, Minnesota. All right, so I get the pleasure of doing the second part of the presentation today. Thank you, Adam, for everything you've shared in the first part and giving us a good introduction to muscle and to what we should expect to see with ultrasound and also a lot of the terminology. So I don't have to go over that. So thank you very much. So I don't have any financial disclosures to begin off. And my goal today is to kind of show how you can use ultrasound within the EMG lab. And that it's just this really good tool that is an adjunct to your electrodiagnostic exam. It doesn't replace it. But if you use both of them together, they can be quite complementary. And so I'm gonna do that today by using kind of this case-based approach to learning. I've got a lot of cases we'll go through. We'll see what we get to in this. I will say in the first part here is that that Adam shared a couple of cases at the beginning that may look similar or may present differently. But I think with ultrasound, it's really important to remember that repetition is key. And so as you're doing ultrasound and you're seeing these cases again and again, that's when it starts really sticking in your mind, this is what it should look like or this is what it should not look like. And so we'll kind of go through these. So the first case I have is this 75, or sorry, 74-year-old guy who came in with reported weakness of his right hand. And that was it. He didn't say it was anywhere else, just the right hand. Notice that it would kind of come on over several months. It was pretty gradual, had difficulty with gripping and lifting. And then I asked him to stand up, and he really couldn't unless he really struggled to push off of his armrest to get up there in the first place. Got a little bit of tingling in the hand and then tingling in both of his feet as well. I'm just gonna give significant portions of his exam. So for him, he did have some finger flexion weakness, worse on the right side than the left, as well as weakness with his knee extension, as well as ankle dorsiflexion as well, kind of asymmetric, right worse than left side. And again, was not able to stand from a seated position without using the armrest. He was intact to light touch sensation. He was kind of hyporeflexic throughout, and there were no upper motor neuron signs in his examination. There's a lot of words on here, but basically I will just say that the nerve conduction studies showed some findings, but they weren't that bad. The needle electromyography did show this mixture of motor unit potentials. You have some more early recruitment of these short duration, low amplitude motor unit potentials mixed into these kind of reduced recruitment of long duration, high amplitude motor unit potentials, and sometimes within the same muscle, which for a lot of us who do EMG, a little sirens or bells should be going off in your mind when you see that. Now, I added in some ultrasound on this guy, and this picture may look a little familiar. This image is, if you were thinking, oh, this could be inclusion body myositis, this should be the image you go to right away. So you have the FCU muscle right here. You're getting a little bit of a tendon as well, but you have the FCU muscle right here. And then you have the FDP underneath. And you'll see how the FDP, it doesn't quite look like that FCU. There are parts of it that do, maybe this part up here, but other parts are quite bright or what we call hyperechoic. And then it should be bulkier than this, and it just looks like there's just not as much to it as that FCU. And if you look on the other arm, it was very similar. The FCU, you can see, stands out just as kind of this oval right there that looks pretty good. But the muscle right underneath, you can see, is hyperechoic. We can call this atrophied. And just that normal muscle architecture that you'd expect to see, that starry night pattern, is just gone. And so, I didn't include all the images, but his right FDP, his right FPL, and his left vastus lateralis all showed this hyperechoic, atrophic changes. Going back to the HETMAC scoring that Dr. Comer mentioned, it was maybe a grade two is what we said at the time. But then if you look at his FCU muscle and his biceps, they looked pretty okay in comparison. And so, ultimately, for this study, we called it an abnormal study. There was EMG and sonographic evidence that showed this active, chronic, diffuse, mixed neurogenic process. Ultimately, what we're describing here is inclusion body myositis in this patient. Other things that we checked around the same time, because we don't just do EMGs, we also wanna make sure that we confirm with labs and other things for these patients. So, we had CKs that were elevated, and we also had a five prime antibody that was positive as well. So, you'll notice on my slides, I have this little key up here. That's on purpose. These are key things I want you to remember from this presentation. So, if you see that, just stick that one in your mind if you can. But the FDP, this view that we have here, is the view you want. So, what you'll do is, from an ultrasound perspective, is you'll go about, yeah, you'll probably go about two thirds of the way up the arm and the upper third of the forearm, more on the medial side of the arm, right around where the ulnar nerve is. You wanna be in a short axis, or a transverse view, to be able to give you the cross sections of both those muscles. And in that view, you'll see that FCU looks pretty normal, but in FTP, you're expecting this hyper-echoic, atrophic changes to it. And they've shown in studies that FTP is gonna be the most discriminative muscle, actually, under ultrasound. So, that's why it's a key one to look at here. Showing normal versus unhealthy, you can see that on the right side here, the hyper-echogenicity compared to this side, you can see how there's a little more bulk on the healthy muscle, as opposed to the unhealthy one here. And so, knowing what normal, knowing what abnormal looks like, and being able to say, that's abnormal when you see it, is gonna be pretty key. Pun intended. As well, flexor pollicis longus, another muscle you can look at here. It's right here. There's not a whole lot to it when it's not healthy. And so, you wanna go about half the way up the forearm on this one, again, in a short axis view, so you get kind of that cross section of the muscle here. And it's gonna show similar findings to the FTP. It's gonna be bright, it's gonna be atrophic. As opposed to, and this is an oblique picture, sorry about that, but as opposed to here, you can just tell that the echogenicity is a lot more normal, and as expected, in a healthy individual. So, the second case, this is a 45-year-old female with proximal muscle weakness. This was gradual onset, but it was about over three months. And she noticed that she could not lift her arms over her head, nor could she stand from a seated position either. Kind of a running thing with these patients that we've seen. But they were having, or she was having cramping, and she was also having tingling in both of her hands. Other past medical history for her that was pretty important was she, even as a 45-year-old, had already had one heart attack and had coronary artery disease, and was on atorvastatin 80 milligrams daily. She had hyperlipidemia, she had hypertension. She was also morbidly obese. But this patient, when trying to check her strength, is pretty consistent with this proximal weakness in both the arms and legs, as well as some neck flexion weakness. But her sensation was intact. She was a little hyporeflexive throughout her lower limbs. Her upper limbs were okay, and then no upper motor neuron signs. In this study, we showed, and we saw a little bit of abnormalities in the right ulnar nerve, but the more pressing things on this one as well was the needle electromyography, which showed that she had fibrillation potentials, a lot of CRDs, and this early recruitment of these polyphasic, short-duration, low-amplitude motor impotentials, which scream muscle or myopathy in my mind. And these were worse in the arm than in the leg. Her thoracic paraspinals also showed these things. So for her, if you look at her right arm around the bicep, this is sub-Q tissue, this is bicep, and this is brachialis down here. That's why I have the labeled picture on the side here. But you can see how her biceps doesn't quite have that same echogenicity as the sub-Q tissue, as Dr. Comer was talking about earlier. They should be similar, maybe, but it's quite a bit brighter here. And you can see on the left arm, also quite a bit brighter, and dare I say, a little bit worse thickness-wise on that arm as well. Now we also looked at her legs. This is her vastus lateralis, and then her vastus lateralis on the other leg as well. And you can see again the hyperechogenicity that we see there. And so ultimately, with ultrasound, both her biceps muscles, both her vastus lateralis muscles were hyperechoic and atrophic. But then, I didn't show the picture of the TA, but the TA, when we looked at it, was pretty normal-looking, it was pretty okay. And so in this patient, we had EMG and ultrasound evidence of a chronic diffuse myopathic process, which was more in the proximal upper and lower limbs, had fibrillation potentials present, and so more akin to maybe an inflammatory myopathy. And it's cheating a little bit, because I already knew the antibody had come back too, but she also had a positive HMGCR antibody. She had had CKs that were in the six to 8,000 range, and once she was on prednisone, it actually went down to CK of 125 after about two months or three months. She did have a muscle biopsy as well, which also showed a necrotizing myopathy. One thing that's nice there is that ultrasound, we were able to look at both biceps muscles, but we didn't have to stick a needle on both of them to be able to tell that something was going on. We stuck a needle on one of them, we were able to see, oh, there is some changes that are more myopathic. But then in the ultrasound, we could analyze the other one without destroying the integrity of it, so then it made it a good muscle that we could still biopsy and then get a good result. So in inflammatory or hereditary muscle diseases, again, we'll kind of expect this more atrophic and hyper-echoic appearance to the muscle. And generally, you want to scan the weakest muscle that you can find for optimal findings, and ultrasound can help guide muscle biopsy site. Again, key point here. And so looking again at a healthy versus an unhealthy muscle, so you can see how a healthy bicep should have that starry sky, starry night appearance, and more hypo-echoic with just these streaks of white as opposed to this kind of embedded white throughout. So the next couple cases I have, I'm gonna call quick-fire cases, because I'm not gonna give you a whole history, I'm just gonna kind of go into images here. So the first one, this is a very common view if you do ultrasound in the EMG lab. We were looking at the median nerve at the wrist. And in fact, we were looking at it for carpal tunnel. That was the whole goal here. But while we were looking at that, there's the median nerve there, circled. We figured, what the heck is this? Something's sitting on top of the median nerve. And so we decided to follow it up. And so we scanned proximally, and you can see that it gets bigger as you go up. I'll show it again. Yeah, it's palmaris longus. In fact, it's the palmaris longus that has a muscle body that kind of continues a lot further than it should have. We call it a hypertrophic palmaris longus muscle, because if we kept scanning for this individual, the muscle just went all the way up. There was no tendon at the top, and it wasn't reversed in this case. It was just muscle all the way up. And as you can see on this longitudinal image, it's just muscle all the way up. And as you can see on this longitudinal view, you can see this muscle go all the way down and then attach right into that fascial layer, that transverse carpal ligament area in the median nerve right underneath. And so very, very, very short tendon. Maybe, maybe a little bit. So, case 3.2, just building off of that, again, scanning someone's median nerve and thinking, okay, we're looking for carpal tunnel and we see something else on top of this. And so in this one, when we started scanning it up, you can see there's a muscle body, but as we go up higher, it gets a little smaller, and we keep going up higher and eventually it becomes kind of tendinous when we get up to the top. Can we dim the lights? I don't have the power to dim the lights. I wish I did, I'm sorry. He's going to go check and see if we can dim the lights. And so in this one, it showed more of a reversed palmaris longus. So you had the muscle body that was more distal, whereas you had the tendon that kind of went up further at that point. So there's lots of different variations that can happen with the palmaris longus muscle, or really a lot of muscles. You can have these congenital muscle anomalies. So for palmaris longus, it can be present. It can be completely absent. You can have digastric ones. You can have duplicated, where you actually have two muscle bodies and two tendons. You can have one, like the case 3.1, that was more muscle body throughout the entirety of the thing. Or you can have things flipped from what it normally should be like. Case four, so this is the ulnar nerve right here, right about where we're going to be at the true cubital tunnel. And we see the FCU, or part of the FCU. And then you see this tiny little muscle right there. That is the other FCU head. Normally, FCU should be this big muscle right around there. And then as you go a little more proximal, it may continue to look like that. It may go into more of this kidney bean type shape, or may even split into two distinct heads that you can see. On this one, you just didn't really have much of that other portion there. And so in this individual, we were able to diagnose flexor carpi ulnaris head agenesis, which ultimately was not causing anything for them. But as we looked at the ulnar nerve going up, it was just something we found along the way, just incidentally. But the FCU muscle can be digastric. You can have two heads, two tendons going down. You can have agenesis of a head, or it can look normal. But there's lots of variations to muscles. And the more you scan, the more you realize that everybody's a little different. So in this case, again, we're looking at median nerve. And the median nerve is over here in this direction. And this is a video. I'm scanning down the arm. Median nerve is over here. Ulnar nerve is going to come into view here. And there's this black muscle body that comes over the top of the ulnar nerve there. I'll do that again. So watch as the ulnar nerve and the ulnar artery come into view. And you have this black muscle body that comes over the top. And so this is another anomaly, but actually quite a common one, called the accessory abductor digiti minimi, or accessory abductor digiti minimi brevis. But it's a muscle that just goes over the ulnar nerve as it's going down by the pisiform and then attaches on to the actual abductor digiti minimi. And so it's the most common accessory muscle in the wrist. In fact, about a quarter of the population actually has it. I think I have it on one of my wrists just as I was scanning for fun. But you can find that muscle going over the ulnar nerve. And usually, it's just this incidental finding. It doesn't really cause a whole lot for people. But if it's ever hypertrophic, if you ever see swelling of the ulnar nerve around that area, maybe it's causing an entrapment syndrome. Or maybe it's actually doing something and not just incidental for this individual. And I think that's kind of a key with a lot of these congenital muscle abnormalities is that you can have variations of normal muscle. You can have absence of normal muscle. Or you can have addition of muscles that normally aren't there. And most of the time, it's just asymptomatic, incidental, not a whole lot to worry about. Except in the cases where it acts kind of like a mass effect, and if it's pinching on a nerve or causing an entrapment. And then you can have these unusual nerve entrapments or symptoms. Then it might become more clinically relevant for these individuals. Key point. Case number six. So this was an individual, a 66-year-old male, who reported weakness in his left shoulder. And so he was previously in the military. He'd been parachuting for years. He had a parachuting injury 46 years prior. But he's had shoulder issues ever since this injury. And for him, he had difficulty with reaching in front of himself or overhead. And things have kind of been unchanged since the initial injury 46 years ago when he was 20. And so interesting enough is we're examining this individual. If you put his left arm kind of to that 90-degree angle and then test external rotation, it was about a 4 out of 5. If you put it at its side, about a 5 minus out of 5. So a lot stronger here as opposed to lifting it up. The remainder of the left upper limb was normal, though. And his sensation was normal. His reflexes were fine. There were no upper motor neuron signs. So it's really this one little finding that we could find prior to his exam. He had had an MRI done, which was kind of interesting. It showed prominent asymmetric atrophy of the left teres minor muscle. And that was it. Otherwise, things looked pretty darn good for a 66-year-old guy. So we kind of get to this dilemma. So there's a couple different muscles that externally rotate the arm. You've got the infraspinatus. And you've got the teres minor. These two muscles sit right next to one another. And the infraspinatus is the suprascapular nerve. And the teres minor is the axillary nerve. So the dilemma is that once they sit right next to each other and have identical actions, how do you know which one of them you're in? Especially if there's an atrophic muscle, it's going to be hard to find anyway. But even if it's smaller, how are you going to know you're in that muscle in particular? My answer and a lot of other people's answers to this are ultrasound-guided EMG needle placement. And so when you're not quite sure that you are where you are, put down an ultrasound and then stick the needle in. You can see the needle right there. And then you can proceed with the rest of your EMG. So that's what we did. We took a look at his deltoid and his teres minor. And in this view, where you get a little bit of the deltoid that's overlying it still, you can see the definite difference between the two muscles, the teres minor being underneath. You could see it was hyperechoic and atrophic. We did compare side to side. And the other side looked fine. And then I have varied how I do this muscle, because I end up testing this muscle quite a bit for people now. But you can either do it with them side-lying and have the affected shoulder up, or you can have them sitting up. But ultimately, I like to get this more long-axis view of the teres minor muscle. And then I use the transducer. I put the transducer right on it. I have the needle, and I go on an out-of-plane approach, which means that when I stick a needle in, I'm not going to see the entirety of the needle. I'm just going to see the tip at a certain point. And then I just drop it down into the muscle that I want to be at. And so I'll show you an example here at this video. You can see movement there. And there's my teres minor muscle there on the bottom. I'll show that again in case you didn't see it there. So you're going to see as the needle goes through here, and then it enters into this muscle right here. And then I know I'm in the muscle. And so for this individual, once I'm in the muscle. We can clearly hear that that's not a normal muscle. And so nerve conduction studies in this individual were fine. With our protocols that we normally use, we check things a lot more distally, and so didn't find anything super abnormal there. We did look at axillary motor on both sides, but even that was fine on both sides. With EMG, the only abnormality we found was those changes within that left teres minor muscle. Left deltoid is okay. Left infraspinatus was okay. So with this individual, what we were able to do is say that we had both EMG and ultrasound evidence of this. We call it non-localizable because it's really somewhere in between where the branch had gone to the deltoid and the branch had gone to the teres minor, but you had this left axillary mononeuropathy and spared the deltoid muscle. So you can see this in rotator cuff injuries. You can see this in quadrilateral space syndrome, which is where the axillary nerve will actually poke out in between the teres major, teres minor in the back there. And so a lot of the referrals we seem to get from this are from our sports medicine colleagues who want us to have some other evidence besides just ultrasound that maybe this muscle's sick. And so with typical needle EMG placement, we use our anatomical knowledge and then we use practical application of that knowledge. We palpate the structures. We stick the needle right in. If you do it correctly, and most of the things we check are pretty big muscles that we're pretty certain we're in that muscle, things are great. But if it's in those cases where you're just not quite sure, it may lead to an incorrect diagnosis if you're not in the right muscle. Say I had stuck the infraspinatus and everything looked fine, I could have said this was a normal study. You could also have these adverse events in some of these areas that you're checking if you stick a needle into a vessel, into a nerve, or into an organ in the area. So why use ultrasound-guided needle EMG? I use it in unfamiliar muscles. If a surgeon is asking for an EMG for preoperative planning, saying that they want to use, name a muscle we don't check very often, they want to use supinator for something, then I use this so then I can say, okay, I am for sure in that muscle. Use it in adjacent muscles that have similar activation patterns but different innervation, infraspinatus and teres minor, for example, sitting side by side. You can use it for non-adjacent muscles with similar activation patterns as well. Pronator teres, I think we're all pretty comfortable with sticking a needle in that one, but pronator quadratus, maybe we are, maybe we aren't, feel comfortable, might add some comfort just to be able to see it on ultrasound and say, hey, I know I'm in the muscle and I'm not sticking in things I shouldn't down there. Another time, and this is the time I end up using it a lot now, is if you have people who are not able to activate a certain muscle. For example, if you have a patient who has had a spinal cord injury and you don't know if the weakness that they have in that arm is from the spinal cord injury or if they had a brachial plexus injury on top of this, you can find lower motor neuron findings within a muscle if you stick a needle in that muscle, but you want to make sure that you're in the right ones and they can't activate it to show you that you're in the right one. It can be useful in that way, key findings, or key slide. Also, you can use it for if there's organs nearby, diaphragm, lungs, spleen, liver, all things you don't really want to stick a needle into if you can avoid it. With a diaphragm, you can, don't stick it in the lung. Which brings us to case number seven. So 75-year-old female who had shortness of breath, which worsened over one year but just didn't seek any help about it, just thought, you know, I can deal with it. But at one point, the shortness of breath worsened to the point where she was no longer able to cough and she was having difficulty swallowing on top of this as well, and now was having difficulty walking. It worsened so much that she just felt like she couldn't catch her breath, so she actually went to the emergency department. When she showed up there, they intubated her and she got admitted to the hospital. Generally speaking, her strength was okay on her exam. She had intact light touch sensation, although did have hyperreflexia, positive Babinski's, positive Hoffman's, fasciculations, I think I know, I think a lot of you probably know where I'm going with this. For her, this was a very focused study. The question while she was in the ICU was, is her diaphragm viable, is it working? So we did bilateral phrenic nerve conduction studies, which were absent on both sides. Because she was in the hospital, in the ICU, intubated and on blood thinners, there was a lot of reasons we did not want to stick a needle into her diaphragm, and so we did not on this patient. But what we did do is we used ultrasound to take a look at her muscle. So you can see the subcutaneous tissue here, you have intercostal muscle here, rib, there's a little bit of a rib over here, and then you have the diaphragm muscle with the liver underneath. You can see how these muscles are pretty hyperechoic, you can see the diaphragm itself is very hyperechoic there. So this is the right hemidiaphragm on inspiration, and this is it with expiration. As you can see, there isn't a whole lot of difference for her, unfortunately. And so for her, as she tried to breathe in, there's not a whole lot of movement of the muscle itself, and maybe back and forth a tiny bit, but not as much as we would expect in a good, healthy hemidiaphragm muscle. And so we did ultrasound of both sides, and we found that there was little to no movement of either hemidiaphragm muscle. The right side did show maybe a tiny bit of thickening on end inspiration, but not enough to call it normal, it was not over that 20% that we look for. The left side was actually thinner on end inspiration, so we put that as, or we call that paradoxical thinning. And for this individual, we called it an abnormal study, she had bilateral hemidiaphragm paralysis with atrophy. We could not tell if it was neurogenic or myogenic, because we didn't stick a needle in there to help us to assess that, but knowing the rest of her clinical history, we had done an exam, we were saying that this was more likely related to a motor neuron disease. This is just her presenting symptom was the shortness of breath that led her to the hospital. And so hemidiaphragm paralysis, diaphragm muscle is innervated by the phrenic nerve, you can perform bilateral phrenic nerve conduction studies. Sometimes it's hard to get those though, if you have a patient who has a little bigger body habitus, as well as it's not super helpful if both hemidiaphragms are involved, you can't really see an asymmetry at that point. You can stick a needle into the diaphragm, it's often deferred by people, either based on patient preference, pain tolerance, or if the patient's on blood thinners. And then there's two ways you can kind of approach that and use ultrasound with it. You can either look at the diaphragm muscle, kind of like we did in this picture here, measure the depth to get there, mark it on the needle and then stick your needle in only that depth to make sure in the diaphragm, which is ultrasound assisted EMG, or you could actually watch the needle go all the way down into the diaphragm itself and that is ultrasound guided EMG. And so this is the view you want to get, and so usually for this you want to use a linear transducer and have the patient supine, so laying on their back, and then you want to go to that anterior axillary line in between the 7th and 8th or 8th and 9th ribs, and look at the space in between the two ribs. So it's nice to have at least one rib in the window here. Better image would probably be if I had both ribs there, but I got what I got on this one. And so you'll see the intercostal muscle that are in between, and you'll see the diaphragm. And then if you're on the right side, the thing that's underneath is the liver, if you're on the other side it's the spleen. When they breathe in, you can see pleura or lung come in if there is movement of the diaphragm. Things that you're looking for and things you can comment on as a sonographer during this is you can look at the thickness, you can comment on the echogenicity of the muscle, you can comment on if there's movement or if there's not movement, and then you can comment on the thickness ratio itself and calculate that. And I believe there's a bunch of other talks during AANEM that are going to be on diaphragm and more about that, so I'll leave it to them. But things that this is helpful for. Diaphragm can be involved in motor neuron disease, it can be involved in myasthenia and gravis in myopathies, isolated phrenic nerve injuries, Parsonage-Turner syndrome, or neurologic amyotrophy can have phrenic nerve involvement that then will affect the diaphragm. Or if you just have an unknown cause, if someone comes in with respiratory failure, you can analyze the diaphragm and see, is this something that's involved? Dyspnea, if they get a random chest x-ray and show hemidiaphragm elevation, you can then go and evaluate that with ultrasound and with your nerve conduction and EMG. This one is going to be a kid case for any of you who treat kids here. That's why I got little baby feet here. So this is a 16-month-old female with worsening gait abnormality. So she had a prenatal diagnosis of spina bifida, which was repaired at seven months and then again at eight months due to wound dehiscence. And then at 11 months, she underwent her third surgery and had this bilateral heel cord lengthening to try and improve her mobility of her legs. During that time, though, or after that, they noticed that the left ankle was pretty stable, pretty good, but the right ankle just kept getting worse. And so as we did the exam of this patient, you had, grossly, the left leg strength was just better than the right. It's kind of hard to, I mean, for those of you who treat kids and try to do a physical exam on kids, they're very squirmy, so it's hard to really get a good number of values on a lot of this. But she was moving the left leg a lot more than that right leg. She had low tone on both legs, below the knees, and then low muscle bulk below the knees compared to the thighs. Her left patellar reflex was intact, but the right was completely absent. And then if you looked at the range of motion of her ankle, the left ankle got to 90 degrees, but the right ankle wasn't quite getting up there. And there was bilateral knee, or sorry, the bilateral knees had normal range of motion as well. So at the time when we did this study, we did not have the ability to do a sedated EMG, which in little kids would probably be a good thing to do because then they don't move quite as much, and then it's more tolerable for them. We didn't have that, so it made it a little more difficult. So in this patient, we did not do any nerve conduction studies, and the needle EMG that we did was kind of limited due to patient discomfort. It's a little baby. I've got a 20-month-old kid. I can only imagine her trying to go through this exam, much less someone who's four months younger than this. But her right TA, when we looked at it, had normal insertional activity. There was no abnormal spontaneous activity, and there was also no motor unit potentials present at all. And then on the right, vastus lateralis, there was increased insertional activity. There were fibs and positive sharp waves, and then there were more of these neurogenic units that we saw. So you probably know where I'm going with this, but with a limited EMG, how can we gain more information? We use ultrasound. Ultrasound doesn't hurt. It's non-invasive, and generally is pretty well-tolerated by kids. And so we looked at the left TA muscle just as an example here. We ended up looking at lots of muscles, but I'll just show you a little bit here. So the left TA, you can see that there's some areas of hyperechogenicity over here, over here. This looks a little better in here. This goes more into that moth-eaten or that patchy distribution that Dr. Comer was talking about a little bit earlier. You can see kind of the whole boundary of the tibialis anterior muscle with the tibia right there. And then we get to the right tibialis anterior. And the right one, you can see, is much, much smaller. And there's not a whole lot of good-appearing muscle in there. There's a lot of fibrosis. There's a lot of fatty infiltration. The muscle itself is very atrophied. I mean, if you just look at the difference side to side here, it's pretty apparent, pretty incredible. And so as we did this ultrasound exam, we went through a lot of muscles. And we could see that the right quadriceps muscle on the right tibialis anterior had this atrophy and had this increased echogenicity that had the point of that blurring of the border, which would be a HECMOT 3, like Dr. Comer had mentioned earlier. As we went up more above, sorry, not above, but we went to some of the other muscles. We went to the bilateral fibularis longus and bilateral medial head of the gastroc. It looked slightly better, but not quite to the extent of calling this normal by any means. But then the left quads and the left TA looked more normal is what we called it at the time, especially comparably. Looking back on it, there were some abnormalities in the TA, but they just weren't quite as apparent as the right side. So interpreting this is a little challenging when you don't have the nerve conduction studies and when you don't have a complete EMG on top of this. But ultimately, what we said is that there was evidence of bilateral L5-S1 polyradiculopathy, which was probably from the spina bifida, but also involvement of the right L2-4 root level, which indicated either a larger right polyradiculopathy than the left side, or a possible right lumbosacral plexopathy on top of that. Without the nerve conduction studies, we can't really narrow that down as much, but at least we can give more of an indication that there is asymmetry. There is something else going on there that it's not a symmetric process side by side for her. And because of the asymmetry, we could more confidently say, even without the nerve conduction studies, that this probably wasn't a length-dependent polyneuropathy. You can't completely hang your hat on it, but you could say it a little bit more. So, with kids, there's a lot of really good pluses to using ultrasound. It's painless, it's better tolerated, unlike EMG and nerve conduction studies. We have adults who don't tolerate the EMG and nerve conduction studies as well. Just imagine with kids. The distribution of muscle involvement, you can look and see, is it a single muscle or is it multiple muscles involved? Is there a pattern to it? Is it diffuse or is there patchy involvement of the single muscle? Ultrasound can be quick, it can be flexible. You can be looking at a muscle. If the kid kicks or turns over, you can go to a different one. You don't have to keep them still the entire time. You can move with it. It's quite nice, actually. You can follow changes over time. And you can see, this is what the muscle looks like now. Take a picture of it. And if you are reevaluating the kid in X amount of months, you can look at that same muscle again, take another picture, and get side-by-side views to see what are the changes, have there been changes, and is there progression of a disease process? And like nerve conduction studies, it is easy to use with sedation as well. You take away the squirmy aspect of it, but you can go through quite easily and look at all these muscles, too, for these kids. And it doesn't require movement like EMG might in a lot of circumstances. So in summary, and again, key slide here, muscle ultrasound is just an adjunct to your physical and your electrodiagnostic examination. It really helps when you're looking at things like congenital muscle variations or additions or absence of them. And the more you look at muscle after muscle and nerve after nerve, even, the more you'll realize what normal looks like and things that are abnormal will stick out more readily to you as well. And then just about specific things, ultrasound in muscle disease, generally speaking, in muscles it's gonna be atrophic, it's gonna be hyper-echoic, and oftentimes there is a pattern of it, whether it's proximal involvement for more of these inflammatory myopathies or hereditary myopathies, whether in the IBM where you have the finger flexors and you have the knee extensor weakness, there is a pattern in a lot of these that you can help see, literally, with ultrasound. You can use ultrasound of the diaphragm. You wanna look at both sides so you can look at the thickness, the echogenicity, the movement, and the ratios. Ultrasound guide EDMG, which I'm a huge proponent of. I just think it's awesome and such a cool way to combine these two things. But it can assist in identification in needling obscure and uncommon muscles. It can help in plegic muscles, if that's something you're looking at for your practice that you have. And then pediatric ultrasound. It's painless, it's quick, it's informative. You can follow changes over time and you can use it with or without sedation. And so it's really quite a good thing to use on kids. So that's my portion of it today. I think now we can open up to questions and comments. Thank you. Thank you very much. Hi, thank you for the interesting talk. I have two questions, like one for each of you. On the muscle side of things, oftentimes you can see hyperechoic, those changes. Sometimes you'll have patchy denervation and such. Have there been any studies that have looked at a muscle biopsy that have definitively correlated what you see? Because not always what we see in ultrasound necessarily is what we might think it might be. It can look different and not normal, but what is it really? And that might give us some better ideas of the pathophysiology. That's question number one. And maybe I'll ask for an answer and then I'll go to question number two after that. I'm not aware of many studies, actually, that have looked at the biopsy correlate. I'm not sure if you're aware of any. I'm not either. Yeah, because we mentioned the fiber fatty infiltration, neurogenic atrophy, those types of things, but we don't really know if we don't really see things. EMG is a great biomarker that tells us what's going on. I'm actually interested in spastic muscle, and we've published on a modified hecumen. In spastic muscle, we see changes much more patchy and not diffused like a myopathy would show. And we just have some data looking at EMG abnormalities in these individuals. And certainly as the muscle is more and more abnormal, we see more fibrillation potentials and reduced insertion activity, but it's only about 56% of the patients. So it's just curious that that population probably needs muscle biopsy to understand. And I was wondering if you knew of anything else. It sounds like maybe not. Can I ask a question back? Sure. That was louder than I thought. In the spastic muscles you see, are these patients who have had Botox? Botulinum toxin, yes. Okay, botulinum toxin, thank you. And so, because you can't, I mean, botulinum toxin does denervate a muscle, and so you can actually get patchy appearing muscles too, purely from the treatments that we are using as well. That's actually somewhat debatable. There are some studies that would say yes, some would say no. You can get muscle atrophy, but not necessarily echogenic changes, per se. And so it's a really open-ended question. My other question is, real quick, is about the muscle, you showed the palmaris longus, those types of things. We know, like, for example, the bifid median nerve, when that was first seen, everybody thought that was related to carpal tunnel syndrome, then it found out, well, that's just a normal variation not related to carpal tunnel syndrome in most people. So I was wondering, in some of the anomalies that you showed, are they related to pathology, or just showing us things that could be, you know, uniquely different as humans? Only if big enough, and then causing an entrapment, usually. Oftentimes, we just find these incidentally, and it's usually in asymptomatic people, and that's not really causing the thing. Interestingly enough, I've talked to a couple of the surgeons that I work with about the bifid nerve, and we will comment on it all the time when we do ultrasound in the lab, and sometimes they're like, well, I don't see it, when I open it up and I do their carpal tunnel release, and sometimes it's because the bifid appearance that we see is actually still kind of encased all within that same epineurium, and so it appears bifid to us, but it looks like one thing to them, and so they don't, sometimes, some of them care about it more than maybe we do, or vice versa. Yeah, less than we do. All right, thank you very much for the nice presentation. I just want to know the details for your ultrasound-guided needle EMG, because we always have to apply gel, and the probe, I think the transducer, you are using the regular probe, right? So after you apply the gel on the skin, on the surface of the skin, you get the transducer on the top of the skin and the targeted muscle. Do you remove the gel to put the needle? Because usually for the needle EMG, we have to use the alcohol prep to clean the skin, but at that time, you already had the gel on the top of the skin. I do, so I still have the ultrasound there. There's gel underneath the ultrasound itself. I will wipe away the gel that's right in front of that. I will wipe it away. I will clean that area with alcohol, and then that becomes the site that I'm entering in with the needle. And I enter at an angle so I can actually see the tip, because you have to be able to get under the ultrasound beams. And so yeah, there's gel under the ultrasound transducer. There's no gel at the part that I'm sticking the needle in because I wiped it away and I cleaned it. All right, so you can only see the tip if you're using the sort of like the regular transducer. When you're going out of plane, yes. If you're going in plane, you can see the entirety of the muscle. Okay. Or sorry, the entirety of the needle going into the muscle. Right, but my understanding is that that has to be done with the special probe. No? I've had no issues in any probe that I've used. Okay. Like, you know, for the, after you put the needle in, do you still, you know, hold the ultrasound probe or just? So it depends. I've done it two different ways. During my fellowship, we had one machine that had the integrated ultrasound transducer with the EMG machine. And then the other EMG machines did not have the ultrasound built in. And so I had two machines. It kind of felt like a command station. I had my EMG machine, I had an ultrasound here. And so I did, I kept the ultrasound transducer as I stuck the needle in and kept both there because I had two separate screens and things. Now where I work, all the ultrasound transducers are integrated in with the EMG machines. And so with the current programming, once I have the needle in the muscle, I switch off the ultrasound and then I'm just listening to the EMG. But I've had my hand planted and I'm not moving the needle at all. And so I take the, I take it off at that point. I hear that there is in development ways to be able to see both at the same time, just waiting to see that. Is this is the one with the native machine, the integrated transducer? Is this is the native machine? That is not the one I'm using, no. No, okay, because I see you are using the Caldwell. Is that right? I don't know if I'm allowed to say any brands here. Because I don't have that type of integrated ultrasound transducer with the needle EMG. All right, thank you. You're welcome. Hi, great talk, thank you. I had a question, if you had any like age-related considerations like losing your ankle jerks or surals can be normal in people over 75, do the muscles look a little more hyper-echoic or in any kind of certain pattern? I've run into, you know, muscle ultrasound in patients in their 80s and 90s and everything looks a little hyper-echoic. Obviously you try to use internal controls, but I'd be interested if you had any thoughts. Yeah, I mean, I believe there are a number of factors that can affect echogenicity that have been published. I believe age is one of them. I believe BMI is another and height even. So there are a number of factors that can definitely affect echogenicity and muscle thickness. Are there any certain muscles that like, you know, the feet tend to be more hyper-echoic or in any kind of pattern or just sort of everything? I'm not sure about the feet in particular. I don't ultrasound the feet all that often, so. Yeah, I don't either. Yeah, all right, fair enough. Thanks. Thank you. I just had a quick question about how often are you inputting things into Jay and do you know if there's any ultrasounds that are starting to incorporate that as just in their machine or have like a program for that? For the quantitative? Yeah. I'm not aware of any of the major ultrasound manufacturers integrating that yet. Several of the EMG manufacturers are starting to integrate ultrasound. And I think probably have plans to include quantitative methods as well.

AANEM Annual Meeting

muscle ultrasound

Adam Comer

neurogenic vs myopathic

HECMAT rating scale

grayscale analysis

muscle atrophy

technological advancements

Duchenne muscular dystrophy

AI and deep learning

diagnostic precision