All right, team, sorry for the delay. I want to welcome everybody to AAP Virtual Didactics today. We're excited for today's lectures. As always, I want to recognize and appreciate those folks who are on the front lines of this pandemic, recognize that not all of us have been affected equally. So we appreciate those of you who have been particularly affected, either professionally or personally by this pandemic. We'll kind of skip through some of these goals. We do this every day. So I imagine folks are fairly familiar with the idea, but we're trying to boost what's already ongoing at your institution, offload some of the overstretched faculty and provide additional learning opportunities for residents and fellows, given the extraordinary scheduling difficulties that a lot of programs are facing. We're going to keep everybody video and audio muted. If you have any questions, my name is Sterling Herring. If you click on your participants button, you should see me up near the top. I'm a PGY3 at Vanderbilt, again, Sterling Herring. So you double click my name and you can send me a message in the middle of this, a content related question. If you have any big picture questions, you can shoot them to me, or you can email Candace at that email address, cstreet at physiatry.org, or you can track us down on Twitter. There's the AAP Twitter handle. So without further ado, we're excited to have Dr. Robert Bowers here with us today from Emory University. Welcome, Dr. Bowers. Thanks, Sterling. I appreciate it. I'm going to start my video up here just briefly. As I'm talking, I'm actually going to turn it off because I've actually given a number of these Zoom talks, and I actually find the video of seeing myself talking to be kind of distracting. So as I'm talking, I'll turn it off. I'll pop it back on if there's anything that I want to demonstrate. But probably not too much with this. We'll let the ultrasound images kind of speak for themselves for the most part. And I'm going to share my screen with everyone. All right, Sterling, can you stop sharing your screen so I can share mine? Yeah, it should give you an option. If you click that green button, it should say, do you want to take it away? I can't. I don't know if I can. This will stop. Okay. Yep. You're right. I should probably read first. All right. Here we go. Okay. Okay. You can see mine. Okay. I can see and hear you. All right. Perfect. So we're going to talk about peripheral neuropathies of the extremity kind of briefly background about me. I'm in my second year on faculty at Emory. I think it was Dr. Rydberg last week from Chicago kind of talked about how she was born and bred Chicago, kind of Chicago home around the same way with Atlanta, born and raised in Atlanta, played baseball at a small division one school called Furman University in South Carolina, major in exercise science, and then went on and got my, my PhD in exercise physiology at Auburn in Alabama. And just kind of along the way, I was doing a lot of weight loss, metabolism type of research and along the way, just got interested in medicine as I was working with a lot of physicians at the time. And so, you know, came back to Atlanta for medical school and then did all my postgraduate training at Emory transitional year, PM&R residency and sports medicine fellowship. And so I'm a huge Atlanta Homer, a tortured Atlanta sports fan. And and now as far as affiliations, I work at the Skyhawks, their head team position for they're the G-League team. So the NBA minor league team for the Hawks. And then my primary interest from a sports standpoint is upper extremity throwing athletes. And so I get to work with Georgia Tech baseball as well from that standpoint. And then, you know, from a day to day clinical standpoint, generally work on the in the outpatient setting, do a lot of diagnostic and interventional ultrasound for the most part, don't do any spine anymore. But general MSK medicine from, you know, your weekend warriors to your high level athletes. So with that said, we will get started with this. And hopefully that is a hopefully we don't hear any screaming of frozen songs from outside my door by my daughter or my son just beating on the door and being a zombie. So we'll hope that that doesn't happen. I am going to come down here and let's see here. You would think by now that I would have figured out all this zoom stuff, but I have not. Let's see. Okay, there we go. I'm gonna stop my video real quick. That way I can see my whole screen. All right. So we'll get started with this. Looking at an ultrasound based approach to peripheral neuropathies of the upper extremity. This is something that I've started to do a lot more of over the last year. I've started to work pretty closely with our upper extremity surgeons at Emory, helping with the diagnosis of peripheral neuropathies in the upper extremity using ultrasound as either an adjunct or independently from electrodiagnostics. So every talk I give, I'm just plugging our baseball medicine program. It's a program I started at Emory just a few months ago. We have some sports civic programs. I started one for baseball and kind of throwing athletes. And so it's just something that we have, something extra that we had to offer for people. Disclosures. A couple of the ultrasound images are from Brian Scheipel, who's a physiatrist in Philadelphia who does really good work. And then Misha Zucallin, who I was a resident with. A couple of the just kind of general education peripheral neuropathy slides are from a talk I've done with him. And then just want to acknowledge two of our current sports fellows, Wes Troyer and Chris Cherian, who helped me get some of these images. I had been using Brian Scheipel's images for a long time and decided last week, you know, we got a really great Samsung machine. Let's get our own images. And so me and Wes and Chris last week went and got those images. So shout out to them for being good at what they do. So ultrasound here, or just objective here, sorry, is to understand the role ultrasound can play in the diagnosis and treatment of upper extremity peripheral neuropathies. Now this could extend to the lower extremity as well, but that would be a much longer talk, so we'll focus on upper extremity here. So the focus of this is not going to be on nerve anatomy and different types of nerve injury and stuff like this. This is just kind of throw in understanding epineurium, perineurium, endoneurium, all things that as physiatrists, physiatry residents, because of the amount of electrodiagnostics we do that we're going to understand as well as, you know, myelin, myelin sheath and axons, just the general kind of basics of nerve anatomy, I'm not going to get into that. And as far as the neuropathies, we're probably going to discuss the most today from an ultrasound standpoint. It's going to be more your compression neuropathies. So you think your neurotimesis, we're not going to talk about those bad stretch injuries you get from a joint dislocation or a fracture, which gives you the more axonotimesis or the high level traumas where you get nerve transection or neurotimesis. So most of these where you're going to be using ultrasound and helping diagnose or treat is going to be more of your compression neuropathy. So here in talking about pathophysiology fits in more with the neuropraxia than it does with axonotimesis or neurotimesis. And then certainly we all know the presenting complaints and symptoms of people with nerve type of symptoms, burning pain, numbness, tingling, burning, get some weakness, muscle wasting in severe cases, all in their respective anatomical areas of these nerve distributions. So let's get into talking about some specific upper extremity entrapment neuropathies and how we can use ultrasound to help with these. So first we'll talk about median nerve coming from C5 through T1. And as we track down going into lateral medial cords of the plexus, and as we'll see, it lies close to the brachial artery as we track down to the elbow, and as we come down below the elbow, we're going to then pass between the two heads of the pronator teres muscle. As it kind of gets through the pronator teres and starts to emerge from the pronator teres, we're going to branch off the anterior interosseous nerve, which we'll talk about a bit later as well, and then we're certainly going to pass through the carpal tunnel of the wrist. As far as nerve supply as a median nerve, again, things that I'm going to not beat with a dead horse as far as just getting into all the muscles that we're supplying, pronator teres, flexor carpi radialis, flexor digitorum superficialis, and you're going to get your AIN muscles of your FPL, FTP1 and 2, and pronator quadratus. AIN, just kind of going off on a brief tangent, is going to be that okay sign where you're flexing, you're making that okay sign, you're flexing the FPL, you're flexing the FTP1, making that okay sign, you're able to hold that tight and can hold it and someone can't break it. AIN's in good shape. If you're not able to hold that, then that's kind of the major test we're going to use to look at AIN neuropathy. And then the loaf muscles in the hand from a median standpoint, and certainly we all know I'm treating a lot of carpal tunnel syndrome, that radial three and a half fingers are going to be the primary areas where I'm going to get sensory changes. So carpal tunnel syndrome, just a little bit of epidemiology here. Certainly in our diabetics and pregnant individuals at higher risk of carpal tunnel syndrome, look at some just interesting data that it's in, you know, it's been published in things like fish processing, it can be up to 73%. From an ultrasound standpoint, let's look at the median nerve at the wrist, this one of Brian Scheipel's images. And as we're looking here, we see that everything's labeled, we see the median nerve right here, we see the transverse carpal ligament is coming across right here within the carpal tunnel, you're going to have nine tendons, you're going to have the FPL, along with four FDS tendons and four FTP tendons right outside of the carpal tunnel, you'll see FCR sitting here, your radial artery here. And then if you have a palmaris longus, it'll sit right outside on top of almost directly on top of the median nerve. And another brief tangent, palmaris longus, another good thing for ultrasound here, is you can tell whether or not someone has a palmaris longus. So other extremity surgeons will send a patient to me and say, hey, do they have a palmaris longus, I want to use it for a tendon transfer or a tendon graft. And it's an easy way to check and definitively see if there's a palmaris longus as opposed to, you know, them just putting their their pinky and thumb together and trying to figure out if they have one or not. So we'll move forward and start looking at diagnostics. And so 2008 study by Hobson and Webb showed a ratio of median nerve cross sectional area at the lunate divided by the measure 12 to 14 centimeters proximal to the lunate should be less than 1.4. And so we see we measure, this is at the carpal tunnel, we'll measure the cross sectional area of the median nerve at the lunate at the carpal tunnel. And then we'll come proximal at this point, it's 14 centimeters proximal, look there, this ratio for this one is actually 7.3. So much higher. So a very dramatic case here, which sometimes you're not going to see that there's a huge median nerve right here. But has been shown to be as accurate as EMG nerve conduction study with a ratio of greater than 1.4 for these two areas. This study out of the Journal of Ultrasound Medicine, looking at using ultrasound to diagnose carpal tunnel syndrome, it's a good review article from 2016. So abnormal cross sectional area looking at the median nerve at the carpal tunnel is going to be anything greater than eight and a half to 10 millimeters squared, probably for median nerve and ulnar nerves, the major number to keep in mind, it's 10 millimeters squared for a cross sectional area generally, based on the literature that's out there, if you have a cross sectional area greater than 10 millimeters squared, that is abnormal. And then that range of kind of between eight to 10 can kind of be a gray area. The rule out as you see here below eight millimeters squared, generally things are fairly normal at that point. And to rule it in is a huge median nerve at 14 millimeters squared cross sectional area, that's something that you're not going to see a ton of a lot of times someone comes in, they have bad symptoms, and they wind up being nine millimeters squared, eight millimeters squared. And that's where a lot of your your clinical experience comes in. So understanding what the literature shows, what are these reference values and what is known to be abnormal from literature, and then how does your clinical experience fit in to determine the diagnosis. So other areas of median nerve entrapment, which are going to be extremely less common than carpal tunnel syndrome. So pronator teres syndrome as a median nerve courses through the pronator teres, it can get compressed there. It's going to have very similar symptoms to carpal tunnel syndrome will, but it's going to exclude the pronator. And then anterior interosseous nerve syndrome after the AIM branches off from the median nerve, either within the pronator teres or just as it exits the pronator teres, you get compression of the AIM, it's going to be purely motor, not going to have any sensory symptoms, not going to have any pain, purely motor weakness. And generally with that patient, they come in and they say, I'm having problems buttoning my shirt, and they just notice weakness. And then these are just some other areas, again, much less frequent, as compared to carpal tunnel, even pronator teres, so think about that, just these other areas that I'm not going to get into very much here. So when we're scanning and looking at these nerves on ultrasound generally will start, and if you've looked at any education videos, a lot of the education videos will start with this home-based approach, the anterior elbow, when we're looking anteriorly. And so we start right here, you can kind of see where it is, where the probe is going to be. You see the humerus down here, brachialis muscle here, biceps tendon right on top. As we look to the left over here, you see the median nerve right in here, brachial artery, and you see the radial nerve over here. So when we want to look at the median nerve, you start with this home-based approach, and then you just branch off over here to the median nerve, and we begin to track it down. And so here, we've tracked down to below the elbow, and we're getting into the pronator musculature. So if we look over here, on the right, you see where you are, just kind of just distal to the elbow here. You see median nerve in short axis between the pronator heads, and so we see the median nerve sitting right here in between the humeral head of the pronator teres and the ulnar head of the pronator teres. Over here is the FDS and FCR. We're interested right here. We can then flip our probe into long axis, and we see the nerve running along here in long axis. And this view is helpful just to show us if there is any focal compression. So you could be coming along here and then see some focal compression here. One thing to remember is with not just here, but any nerve that's compressed, you're going to have compression, but we're actually looking for the enlargement of the nerve, which happens just outside of the area of compression. So here's just a video, and it's just going to show some dynamic, how the median nerve looks with dynamic pronation between the pronator heads. We see here, just as we're pronating, you see the ulnar head and the humeral head activating. And pronating, and we see just dynamically, this is normal, but what the median nerve looks like there. So let me make sure I didn't skip anything there. Okay, good. So AIN syndrome, like I had already mentioned, purely motor. Patient comes in, has trouble buttoning, buttoning the buttons on their shirt, they can't hold that okay sign, like we had talked about, have weakness of FDL and FTP, and it can be caused by generally compression, can have a direct injury. But what we see here on the ultrasound image is we're still within the pronator musculature. We see the median nerve here and the small AIN has branched off here. So if they do have AIN type of symptoms, and it is fairly clear when they have these symptoms, all motor can't hold the okay sign, you can put the probe on, look at the AIN, and you could go in and try, scan, look at the AIN, try a little hydrodissection procedure. Here, as you see this picture of Dr. Scheiple, you can see here what he would be doing with that, putting the needle in, and then basically just blowing a halo of medicine around the AIN to try to release any entrapment or help with any inflammation of that nerve. So we'll transition over to the ulnar nerve next, coming from C8 to T1, going into the lower trunk and medial cord. We're gonna descend along the medial triceps within the arcate of struthers, and that's just a fascial band that's connecting the brachialis to the triceps that the ulnar nerve runs through, not a common area of entrapment of that ulnar nerve. And when we start getting into the sulcus, the retrocondylar groove, and then the cubital tunnel, we're gonna get the most common places for ulnar nerve entrapment. And so from the retrocondylar groove down to the cubital tunnel, which is between the two heads of the FCU, so cubital tunnel proper is there. A lot of times you're gonna hear people call cubital tunnel basically anything with the ulnar nerve at the elbow, but cubital tunnel proper is gonna be between your two heads of the FCU. And then we can track that ulnar nerve all the way down through the forearm and down to the wrist, where we can look at it through Guyon's canal, which we'll look at images of that as well. So again, not something to focus on here, but muscles that are supplied by the ulnar nerve. So in the forearm, flexor carpi ulnaris and flexor digitorum profundus three and four, and a separate set of lobe muscles in the hand. Then you're also gonna have your dorsal and palmar interossei, flexor pollicis brevis D-pen, your adductor pollicis as well. And then sensory, certainly something that we all know, the ulnar aspect of the hand, the one and a half fingers on the ulnar side, so half of the fourth and the fifth finger. So entrapment sites, as I had mentioned, arcate of struthers, that fascial band between the brachialis and triceps, uncommon. The cubital tunnel, which here does kind of refer to retroconjugular groove down to the cubital tunnel proper is gonna be your most common area, and then down in Guyon's canal. So we'll see it with like a cyclist here, that ulnar nerve that is tracking along the pisiform. You can get some entrapment and some irritation of that nerve there, also with wrist ganglions and rheumatoid arthritis as well. So our clinical presentations, we see here a lot of times what we'll see if someone has bad ulnar neuropathy, they'll come in and they'll have this atrophy of the FTI musculature. It's giveaway that they have some ulnar neuropathy of some sort, and patients will come in with this, and they won't even know it, and all of asymptomatic ulnar neuropathy, but they have this hollowed out FTI, certainly something that a lot of us have seen, or people that do a lot of EMGs will see that. As well, the ulnar claw hand from a physical examination standpoint, frohman sign, which is, think of it, almost the opposite of the okay sign, and so you're holding that piece of paper between those two fingers, and if they aren't able to use the adductor pollicis in some of your hand intrinsics, what you're gonna, to hold that piece of paper firmly there, what they're gonna do over here, you see, they're gonna flex that FPL to hold it, so they're using their AIN musculature to hold that piece of paper, so it's kind of the opposite of what you're doing with the okay sign there. And then Wartenberg's sign, you passively abduct this patient's fifth finger, and you do it on both sides, and then you ask them to adduct the finger. On the normal side, they can adduct it normally. On the abnormal side, they're not able to adduct that fifth digit. So, ultrasound images here, generally when I do it, I will start at the retrocondylar groove, right at the elbow, that's where I'll start, and I generally like using this setup right here. So, they're laying on their back with their arm abducted 90 degrees, next one will rotate in. That's generally how I'll start. I'll start at the elbow. We'll see the medial epicondyle here with the ulnar nerve right here and the medial head of the triceps right here. When you're in this position, what you can do is you bring the patient into deep flexion, and when you bring them into flexion, if they are going to sublux or fully dislocate that ulnar nerve, you'll see a pop over here. And I just did one of these two weeks ago, and I should have copied that video and put it in here, but I thought about it last night and I didn't. But you bring them into deep flexion, and you clearly see that ulnar nerve pop over the medial epicondyle right there. And so that's where you're going to look for the ulnar nerve subluxation going on here. And then generally what I will do is I get a measurement here, and then I track proximally. I'll take a proximal measurement. Generally, that's not somewhere that we're going to see a lot of pathology is proximal, but we'll always measure above and below the elbow, and then we'll come down into the cubital tunnel, which we'll see next. So we're in the cubital tunnel now. We've tracked more distantly into the forearm between the two heads of the FCU, so FCU1 and FCU2. We see the ulnar nerve sitting clearly right between the two heads. This is the most common place that I'll do any sort of procedure with the ulnar nerve, or if one of the upper extremity surgeons has a patient with cubital tunnel syndrome, asks me to do an injection for them, it'll be in this area. It's just the easiest way that I find to get access to the nerve where I can see other structures and things like that. So we'll come in, and then we will blow a halo of medicine. So whether we're just using some saline to do a pure hydrodissection, or there's some corticosteroid involved to help with any inflammation or irritation of the nerve, we can inject right above the nerve and below, and just kind of create a halo around the nerve to kind of hydrodissect around it. So looking at the literature and what it says about using ultrasound to help with the diagnosis of cubital tunnel syndrome, this was a meta-analysis in archives back in April, 2018. And their conclusion is, you read at the bottom, I'll read it, because ulnar nerve cross-sectional area in healthy participants of various locations rarely exceeds 10 millimeters squared. This value can be considered as a cutoff point for diagnosing ulnar nerve entrapment at the elbow region. So again, we see that 10 millimeter squared number. So generally that, if we're just looking for a hard and fast number to think of for the ulnar nerve and the median nerve from a cross-sectional area standpoint, you think of that 10 millimeters squared. Now, I had mentioned previously, what is your clinical experience? And frequently what I see is patients come in, they have ulnar nerve symptoms, they have focal enlargement of that ulnar nerve through the corticosteroid, they have focal enlargement of that ulnar nerve through the cubital tunnel, but it's somewhere like eight millimeters squared. But if you track proximally and track distally, that cross-sectional area comes down to four millimeters squared. So they certainly have proximal, or they have focal enlargement of that nerve. However, they just don't reach that 10 millimeter squared number. So again, that's where your clinical experience comes in. We know from the literature, think of 10 millimeter squared number. If it's above that, then it's highly probable that they have this cubital tunnel syndrome and trapeze neuropathy of the ulnar nerve. But focal enlargement of a significant amount can also be an indicator of that as well. So now we've tracked down, we've come more distal and we've tracked down all the way down into the hand. We see it here, we see the pisiform and that's where that ulnar nerve is gonna sit right up against that pisiform. And if we look, or kind of looking around, coming more radial, you can see the transverse carpal ligament and the median nerve sitting over here. But the ulnar nerve right here, not something we look at terribly frequently. From time to time, I will, from time to time, one of the surgeons will send me something and say, try to delineate with ultrasound where you see abnormalities between whether it's the elbow or at the wrist, and we'll look in both places. And then from time to time, I will think that there's more abnormalities seen at the wrist and we'll do an injection around the wrist right here, a hydrodissection of that ulnar nerve there. So just kind of wrapping up, the median nerve and the ulnar nerve. Another good paper from 2013, looking at ultrasound and diagnosis of entrapment neuropathies. And so things that they, conclusions that they came to as far as ultrasound being diagnostic for entrapment neuropathies. So we have a cross-sectional area, more than two standard deviations above the mean reference cross-sectional area. I think the issue with that is that finding the reference cross-sectional area, because from a review of the literature, there isn't a definitive, this is the norm. So I think that you get a little bit of an issue there. So I think that's probably the one that you would use least of all of these. And then we have the cross-sectional area, 1.5 times or greater than the cross-sectional area of the unaffected portion of the nerve. So in the situation like I had talked about before, where you see an ulnar nerve that's seven and a half, eight millimeters squared through the cubital tunnel, but then proximally and distally, it's four millimeters squared, you're gonna get this ratio that is diagnostic. So I think using this ratio is helpful as well. And then especially, you can also use it from side to side as well, looking at one side versus the non-affected contralateral side. Numbers to keep in mind with the median nerve. Again, the 10 millimeter square number has been above that being abnormal, and then that Hobson-Webb wrist to forearm ratio of 1.4. The ulnar nerve at the elbow, think abnormal is nine to 10 millimeters squared with the max cross-sectional area versus unaffected area of 1.4 again. And then there is some data in the literature showing that at the wrist, a cross-sectional area of greater than eight millimeters squared as being abnormal. However, this is of unclear diagnostic utility just because there isn't a lot of data out there on the ulnar nerve at the wrist. So now we're gonna move into the radial nerve. All right, doing okay on time, good. So moving into the radial nerve, coming from the C5 and T1 roots into the upper middle and lower trunks down to the posterior cord. It's gonna descend between the long and medial head of the triceps along the spiral groove of the humerus. And then at the elbow, it's gonna come into the anterior compartment. As we come distally, it's gonna split into the deep motor branch of the radial nerve and the sensory branch or the superficial radial nerve. So one thing that I do after discussion of this to kind of remove any confusion is technically when the radial nerve splits, as it goes into the supinator musculature, it's still the deep motor branch of the radial nerve. And as it emerges, it's the posterior interosseous nerve. After discussing this with some of our upper extremity surgeons, we've kind of all decided to remove any confusion to just refer to it as a posterior interosseous nerve the whole way. So we have the radial nerve proper, it splits in the posterior interosseous nerve and the superficial radial nerve. And that's the terminology that we use. So from here on out, mostly I'm gonna refer to that deep motor branch or posterior interosseous nerve as the posterior interosseous nerve. So again, the innervations and the sensory areas, I'll kind of skip over some here, but the acronym is TAVYS PIN. So you have your triceps, your anconius, your brachioradialis, your extensor carpi radialis longus and brevis, and your supinator. And then your posterior interosseous nerve, we start getting into the extensors of the forearm, extensor carpi ulnaris, extensor digitorum communis, extensor digiti minimi, et cetera. I mean, we can look up and talk about the muscle innervations, but we won't go too deep into that. So what are the common entrapment sites? So your crutch palsy where I'm just, from using the crutches that can give you a compression neuropathy of the radial nerve, which is gonna give you a weakness of your radial interventor muscles. And then at the spiral groove, you have this Saturday night palsy or the honeymooners palsy where you get a compression at the spiral groove from someone laying on it, or you passing out in a certain position, and you'll get that wrist drop as well. So if we're looking at ultrasound images here, we're gonna look right here at the spiral groove. This really isn't an area that I look at a ton. I think it's just interesting to see kind of how close it sits to the bone here. So we're at the spiral groove. Here's the humerus. We see the radial nerves. It's right next to the humerus here. So a fracture of the humerus is spiral groove. You have a high risk of getting a radial nerve injury with a fracture at this area. And so we've tracked down from here. So we're gonna track down next. We're gonna come down towards the elbow. And as we know, the elbow kind of moves in the anterior compartment. And if we think back to our home base, we're sitting right in the middle of the elbow where we have median nerve along the medial aspect, just go to the lateral aspect. We come over and we see the radial nerve right here. So this is a radial nerve, all in one, just proximal to the elbow. As we come down to the elbow, we're gonna see the bifurcation of the radial nerve. So we see the superficial radial nerve here and the posterior anterosseous nerve or deep motor branch of the radial nerve right here. And so that's just helpful to do as you track distally. Start at spiral groove, come down, see it at the home base area of the elbow where it's all one, track down a bit more distally, it's gonna split into two. And so we'll talk about entrapment sites. So the primary entrapment site for the radial nerve that I wanna talk about in the primary one that I look at is this posterior anterosseous nerve syndrome or supinator syndrome, where the posterior anterosseous nerve goes into the supinator musculature at the Arcade of Frosch. And then you also have this terminology of radial tunnel syndrome. So radial tunnel syndrome, textbook wise is more proximal to the supinator musculature, but oftentimes you'll hear people say radial tunnel syndrome and they'll use it in the same vein as with posterior anterosseous nerve syndrome or supinator syndrome. So just know that those things oftentimes are used altogether, but radial tunnel syndrome from a textbook standpoint is more proximal to the supinator musculature. So generally this entrapment neuropathy is a pure pain syndrome. You can get some weakness of your wrist extensors and finger extensors. Don't get any sensory deficits. You can have a little bit of weakness, but you have tenderness to palpation, distal to the lateral epicondyle. So this is something to check for if someone comes in with lateral elbow pain, all lateral elbow pain is not tennis elbow or lateral epicondylosis. Always check and make sure that kind of try to rule out they have any symptoms that are consistent with posterior anterosseous nerve syndrome or radial neuropathy. And so again, we're gonna look here as well and come back and look at these areas. So we're looking, number one is right here. We have the radial nerve at the elbow. We come again, we come more distal and we're gonna see where it splits into the superficial radial nerve and posterior anterosseous nerve. And as we come down even further, we're gonna see the posterior anterosseous nerve as it comes into the supinator musculature. So PIN coursing through the supinator musculature right as it sits on top of the radius. This is my preferred area for doing any sort of hydro dissection or injection for the posterior neurasius nerve. It's just easy to see, it's easy to access right here as it's in the supinator musculature, sitting right on top of the radius. We come right in here and can do an injection right around that posterior neurasius nerve right here. So that just happens to be my preferred area to do it. This is the way Brian Scheifel did it and this is how I've seen him teach it. And it's just what I've taken and used as my preferred area as well, so. And as I just said, probably should have waited until this slide, but again, this is my preferred area for injecting posterior neurasius nerve. This is what it's gonna look like when you actually have the probe on the arm. Probe's gonna be on the arm here and you're coming in through this side. You're gonna inject right here. Like I said, hydro dissect. For any of these hydro dissections, you're just creating a halo of injectate around the nerve. For this one specifically, if you have any lidocaine in your injection, it will give them some extent of wrist drop for the half-life of lidocaine for an hour or two afterwards. So just something to let them know. And this is just a video. So we're gonna see, as we track down, you're gonna see the posterior neurasius nerve, which is right in here. It's gonna come across and then it'll kind of dive down here. And that's what it looks like as we're tracking distally. And I'll show it again. And this is what it looks like as we're doing this. And we are, as I'm tracking distally, I'm kind of looking at that nerve and coming. And right as we get on top of that radius is generally where I'll stop and decide, okay, this is where we're gonna do our procedure. And then come down there. So other areas of radial nerve entrapment at the wrist, this wristwatch syndrome, handcuff palsy, shirralgia parasthetica, it's just compression of the superficial radial nerve over the radial aspect of the wrist here. And it's gonna be all sensory. So you're gonna have numbness and this burning, tingling pain. So superficial radial nerve, we will track that. You can, after you see a branch, you can track it all the way through the forearm, all the way down to the wrist over the radial aspect, kind of overlying the first dorsal compartment and kind of coursing over between the first and second dorsal compartments as you get down that far distal. This is proximal to the wrist here. You see the radius, you see the superficial radial nerve sits right here. And then we'll see in this video, the superficial radial nerve is gonna come across right here and then it kind of pops over the radius at one point and we'll see that. Nerves right here, it pops over. So we'll look at that again. Nerve here, pops over the radius there. So whether you're diagnosing a superficial radial nerve problem or not, we do do a lot of injections of the first dorsal compartment for de Quervain's tenosynovitis. We've even gotten to the point where we're doing ultrasound guided releases of the first dorsal compartment, which I do a fair amount of. And you always wanna make sure you identify the superficial radial nerve over this area to make sure you're not gonna injure it and create an aroma because those aromas are terrible to try to manage and they're awful for patients, they're awful for the physician. And it's just something we wanna make sure we totally avoid. So whenever you're doing anything around the first dorsal compartment from a procedural standpoint, we always want to identify the superficial radial nerve just to make sure we're away from it and we're not gonna injure it. So as far as ultrasound evaluation of radial neuropathies at the elbow. So there are no definitive reference cross-sectional areas in this paper just in March of 2019. There are no definitive reference cross-sectional areas. So the 10 millimeter number doesn't fit here. So remember that 10 millimeter number we talked about before, think of median and ulnar nerve. When it comes to radial nerve, we don't have any definitive cross-sectional areas. The best thing to do for radial nerve from a nerve cross-sectional area standpoint is to compare to the contralateral side. So you look at your area of focal nerve enlargement, say it's symptomatic on the right side, go over to the left side, look in the same area and compare from side to side. And then also something that has a little bit, there is evidence for all nerves for this, but might be used more based on literature for radial nerve just because of the lack of the reference cross-sectional areas is to examine with Doppler. And if you have increased blood flow within the nerves that also can be helped to be diagnostic for entrapment neuropathy of the radial nerve is putting on Doppler and looking at increased blood flow through the nerve. Like I mentioned, you can do that for all nerves, you can do it for any of them and increased blood flow within the nerve is gonna help you realize that there is some abnormality within that nerve, but might be more useful based on the literature again with the radial nerve just because of the lack of reference cross-sectional area. So we just have a couple more that I wanna talk about, musculocutaneous and suprascapular nerve, and these are both fairly quick. So musculocutaneous nerve, not an entrapment neuropathy we see very common, innervates, biceps, brachialis and coracobrachialis. Like I said, entrapment is a rare trauma, strenuous exercise. So you'll see a weightlifter that comes in with some weakness of flexion of the elbow and also some sensory changes over the lateral arm because of the lateral anabrachial cutaneous nerve branches off of the musculocutaneous nerve. And that's kind of the patient to think of is weightlifter comes in with some weakness and elbow flexion, think of musculocutaneous entrapment neuropathy or compression. And what we do when we look at the musculocutaneous nerve, you're gonna be up here at the biceps and you see the biceps musculature right here, the brachialis sits right underneath it. We see the humerus down here and that musculocutaneous nerve is fairly flat, sits right in between the biceps and the brachialis. So if you did have that patient that came in, the weightlifter with the weakness and elbow flexion, sensory changes over the lateral arm, you could do a hydrodissection procedure with the musculocutaneous nerve by coming in and hydrodissecting around there. If you track up and down and you see an area where it seems to be focally compressed with some focal thickening as well. And we can flip into long axis and see the same thing. So we flipped in the long axis here, we see the brachialis underneath and the biceps on top and that musculocutaneous nerve tracking straight through here. And by looking at it in long axis, you can look and see if there's any, seems to be any area of focal compression. That's all I want to mention about musculocutaneous nerve. Something fairly rare, they probably won't be looked at a lot, but something that is from a nerve standpoint is fairly easy to look at and identify. And the last thing I want to discuss is the suprascapular nerve. We have a few minutes. Okay, so that's good. Is a suprascapular nerve. And this is something actually that I am actually doing a lot of suprascapular nerve injections and suprascapular nerve blocks for shoulder pain. We have a treatment algorithm for thoracic outlet syndrome that I work with some of our upper extremity surgeons on or one of them primarily, where we do lots of suprascapular nerve blocks and injections of the pectoralis minor. With that said, I left thoracic outlet syndrome out of this talk. It's something that is super interesting and fascinating to me and Dr. Eric Wagner at Emory who does a lot of thoracic outlet work. I've worked with him on this and developing some ultrasound protocols for it. And super interesting, but I think we could give a whole separate talk on that by itself. So I left it out of this for that reason because it's not necessarily peripheral either. But just know that there are also ultrasound applications for thoracic outlet syndrome from a diagnostic and a treatment standpoint there as well. I mean, you can get good images of the vasculature and the nerve and the plexus behind the pec minor. You can have the patient contract the pec minor and look to see if there's compression behind it, but I don't wanna get too sidetracked or tangential, but are definitely some good ultrasound applications to thoracic outlet syndrome. Back to the suprascapular nerve, innervates the supraspinatus and dampraspinatus muscles. It's gonna give about 70% of the sensory innervation of the shoulder. So glenohumeral joint, AC joint, subacromial bursa. So in some of these patients that just have chronic shoulder pain and subacromial injections aren't helping and charticular injections aren't helping and they've done therapy and it's just not better. They don't have a good surgical option. A suprascapular nerve block can be a good injection option for them to try to block some of this pain sensation to their shoulders with chronic pain. So the suprascapular nerve compression sites gonna be much more common at the suprascapular notch than the spinal glenoid notch. At the suprascapular notch, you can get the supraspinatus and the dampraspinatus. It's always a board type of question. You have a compression of the suprascapular nerve at the suprascapular notch, what muscles are affected versus at the spinal glenoid notch, what muscles are affected. So suprascapular notch gets supraspinatus and dampraspinatus. You're gonna have this deep, dull, posterior and medial shoulder pain. When we say medial shoulder pain, it's more of this kind of as you're getting into this upper trap musculature kind of over in this area right here. So just kind of periscapular, deep in the posterior shoulder, deep in the medial shoulder is where you'll feel this type of pain. You might have some weakness with abduction and external rotation, not all the time, but it can be there. And as this goes along and progresses over time, you can start to see some atrophy of the supraspinatus. At the spinal glenoid notch, again, you would just have weakness with external rotation because you're just getting the dampraspinatus. You can see some atrophy there as well. And many times this is more of a painless neuropathy and just notice some weakness and some atrophy. But kind of the classic is they'll say that there's a cyst at the spinal glenoid notch, not something you see a ton of in clinical practice. So these are just a couple headers from some studies as far as what suprascapular nerve blocks have been shown to work for based on high level studies. So from a physiatry standpoint, and no matter what you're going into from physiatry, whoops, so post-stroke shoulder pain, which we see in that hemiplegic shoulder, patients often will complain of having pain there. It can affect their therapy. So there was a randomized controlled trial done where they just did the standard therapy in these post-stroke patients versus doing a suprascapular nerve block with therapy. And the patients that had the suprascapular nerve block progressed through therapy better than therapy alone. So it's definitely something that can be helpful in the hemiplegic shoulder and post-stroke patients. And if you're a resident or a fellow on the inpatient side, it's something really valuable to learn how to do. You can do your own suprascapular nerve blocks. When I was a resident, we would, before I started doing a lot of ultrasound, obviously, we would consult pain to do it, and it'd take a few days, and it'd just take time, and you're bugging them. As we get more and more ultrasound education in our residency programs, residents learning how to do this procedure on the inpatient side, it definitely can be something that's very helpful on our post-stroke patients. Even rotator cuff, I mean, this paper's from 2006, so they're still using terminology of tendonitis, which should be tendinopathy or tendinosis, but we'll leave that for another time. But it has shown that suprascapular nerve blocks can be helpful in this recalcitrant rotator cuff pathology. If they continue to have pain and they're not able to progress through therapy, you can do a suprascapular nerve block if a standard kind of subacromial injection has not helped, and those patients have done well. Also has some applications in adhesive capsulitis as well. So a lot of applications with pain around the shoulder, periscapular pain for suprascapular nerve blocks, and it's something that I've begun doing a lot of, and patients have done really well with it just from a clinical experience standpoint. What it looks like on ultrasound is we're kind of pulling away, that we're looking from behind. We're pulling away the trapezius here, and I forgot to get my own image of the, we can get a much better picture of the suprascapular nerve than this. I just forgot to get one when we were getting pictures the other day. But we pull back the trapezius. We go, you put the probe right along the spine of the scapula, and as you come over the top of the spine of the scapula, you just angle that probe down a bit, and what you'll see is, you see the suprascapular nerve sitting right here within the suprascapular notch. It can have some vasculature around it, so you wanna make sure that you avoid that. Always pull back on your, this is an area, I always pull back on my needle and make sure we're not in any vasculature before we do the injection. But we always are gonna come from a medial to lateral approach with this injection. If you try to come lateral to medial, you run into bone and you can't get down to the area. So I know some people, you know, like we're doing it on the other side. I like using my right hand if I can, but this is one where you have to use your left hand to come down to it, just because you run into bone trying to come lateral to medial. So we come in medial to lateral, and we can inject right around this suprascapular nerve here, whether that's just a pure nerve block with lidocaine, or you're putting some corticosteroid in there as well. This is where we're going to inject it. So that's the last thing I wanted to discuss with this. We could go further and talk about other nerves, and like I said, we could go down the rabbit hole of thoracic outlet syndrome, which we've come to learn, at least in our clinical experience, that Emory is a little bit underdiagnosed. And we could go down that rabbit hole, but hopefully that was somewhat helpful to see those images and just realize that in the treatment of upper extremity peripheral neuropathy is at least, ultrasound is definitely something that we can use and have at our disposal. We can use it as an adjunct to electrodiagnostics. We, there are some diagnostic criteria. If we do have to use it outside of electrodiagnostics, it's just something else that we have in our toolbox to ask physiatrists to diagnose peripheral neuropathies. And the last thing I kind of wanted to say, I think we're all products of our mentors, and this is something that was beat into, something that was beat into my head as I kind of went through training with my mentors. And it's just this confluence, and I end a lot of my talks with this, is this confluence of individual clinical experience. What does the patient want? What are their values and expectations? And what does the literature show you? And kind of that confluence of those three things or what's ideal for that individual patient. So you can't just be hard line one way or the other. It's the confluence of these things and knowing the literature on a certain topic, something you need to know. What have you been seeing in clinical practice? How does that stack up against the literature? And then what does this patient want? And I think that's just something I try to remember as someone that's early in my career and something that was really taught to me. And I think something that's just, it's helpful for all of us to go back and remember that. So with that said, I'm all done. That's my email if anyone has any questions, whether it's about this or anything else, I'm always happy to help as being someone who's newly out of training, help any residents or fellows anywhere around the country. I'm happy to provide advice or help out in any way.

peripheral neuropathies

ultrasound

entrapment sites

median nerve

carpal tunnel

abnormal cross-sectional areas

ulnar nerve

radial nerve

treatment options