All right, let's go ahead and get started. I want to welcome everybody to the AAP virtual didactics today. We're excited for today's lectures. First, as always, we want to recognize and appreciate those of us who have been particularly affected either personally or professionally by the COVID-19 pandemic, recognize that that has not been equitably distributed. So we appreciate those of you who have been most affected and you have our support. So as always, the goals of these didactics are to augment didactic curricula that are ongoing at your home institutions, to offload overstretched faculty due to some of the logistical challenges associated with this pandemic, to provide additional learning opportunities for residents who might be off schedule as a result of this situation that we find ourselves in, and then to develop further digital learning resources and support besides just in general during this COVID-19 pandemic. Housekeeping, as always, we're going to keep everybody video and audio muted. That's both to preserve bandwidth and to reduce distractions. If you have any questions, my name is Sterling Herring, I'm a PGY3 at Vanderbilt. If you click on participants, you should see my name near the top of the list. If any questions that come up over the course of the lecture, you want to ask the presenter something, please feel free to shoot me a message and I will pass it along to the presenter at the appropriate kind of designated question time. If you have any general questions as far as the series or suggestions or concerns, please feel free to reach out to us via email. That's Candice's email on the screen there. And you can find us on Twitter as well. So without further ado, we're super excited to have Dr. Leslie Ryberg with us today from Northwestern slash Shirley Ryan Ability Lab. Thank you for joining us. Welcome. Thank you. Thank you. A little bit about me. I was born in Chicago, did my medical school at Northwestern in Chicago, stayed on for internship and stayed on for residency and as faculty. So you might say I'm a little bit of a Chicagoan at this point. My favorite things about Chicago are the lake and Chicago-style pizza and the fact you never know what the weather is going to be like one day to the next. I will now try to share my screen and pull up my lecture here. That is not it. There we go. All right. So today we're going to talk about electrodiagnostic considerations and radiculopathy. So my areas of interest from a clinical standpoint are electrodiagnostic medicine. And I also do inpatient rehabilitation focusing on medically complex diagnoses, neuromuscular disorders, different neurologic conditions, and medical education. So today we're going to focus on electrodiagnostics. All right. So nothing to disclose other than I haven't actually done an EMG nerve conduction study since March 10th. That was the last time we were doing them here in Chicago. So hopefully I'm not too rusty. And I've been trying to stay busy and sane during this pandemic. And so here's a picture of my dogs. Basically, anytime I'm at home, my kids and my dogs want to be outside. So we have walked them to our abandoned tennis courts here and my kids and dogs get to run around a lot outside. So that's what I'm doing when I'm not in the hospital. In terms of what I'm hoping to cover today, so my learning objectives are to describe the anatomy that's relevant to radiculopathy and how that applies to electrodiagnostic testing, how to interpret electrodiagnostic studies geared towards the diagnosis of radiculopathy, and what are the limitations of electrodiagnostic testing for radiculopathy. I hope at the end of this you're all going to be experts. The other thing that I'm hoping to do is teach you using case examples. I'll ask for some audience participation via polls if we can get that up and running. So please respond. And the electrodiagnostic curriculum is a little bit tricky to balance when teaching residents because there's such a variation in electrodiagnostic experience and knowledge. So I'm hopefully trying to gear this so that it's relevant to pretty much everyone. If you're already an electrodiagnostic expert, hopefully a lot of this will be familiar for you. All right. So first case, we have a 45-year-old man who developed neck pain radiating down the back of his arm about three weeks ago. He notes some trouble using the arm but doesn't think he's actually weak. On his physical exam, he does have a little bit of mild weakness in the triceps and wrist extension, but his strength is otherwise normal. And on sensory examination, he does have decreased epinephric on the back of the arm. So when we're thinking about radiculopathy, so that really is our clinical picture that can consist of pain, paresthesias, and weakness are really the main symptoms that we're looking for. And the distribution of where this is experienced is in the specific nerve root. So anatomically, we're thinking is that myotome or that dermatome is where the symptoms are really going to be located. So just to review the motor anatomy, so the nerve originates in the anterior horn cell here at the level of the spinal cord, comes out as the motor root, and then continues here where it joins with the sensory root into the spinal nerve. And then in terms of the muscles in the arms and the leg, it comes here through the ventral ramus and out into the peripheral nerves here. So this is really where the origin of the motor nerve is that we're testing for radiculopathy. So this is the terminal nerve. So we're testing the nerve that comes out from the anterior horn cell and goes all the way down into the arm or the leg. So here is not an exhaustive list, but here is an example of the cervical myotomes that we can assess from an electrodiagnostic standpoint. So for every nerve that we're testing, we want to think about what specific nerve root it's coming from, what muscle we're testing, and what the peripheral nerve is. So there are different charts in many different textbooks, different articles depending on where you look, and they mostly agree in terms of what roots innervate the specific muscles. So it's very important to have this knowledge ready to go, to recall this as you're testing so when you're thinking, gosh, I need a C6 innervated muscle, you can come up with the list off the top of your head. Now, I don't expect you to know every single one of these muscles because these are not all commonly tested muscles. So there's really a subset of muscles that are most useful in electrodiagnostic testing. When we're thinking about the paraspinal muscles, so this is another muscle. It originates in the anterior horn cell, comes here through the motor root, and then comes along the dorsal ramus to supply the paraspinals back here. So you can see that this is our nerve or the origin of the nerve that then comes out here to the paraspinal. So when we're thinking about EMG, what we're looking for on radiculopathy for EMG testing, what we're looking for is multiple abnormal muscles that are in the same myotome. So they're coming from the same nerve root. And we expect that within that same nerve root that the proximal and distal muscles will both be affected. But what we want to make sure is that we're assessing different peripheral nerves. For example, if we test two median innervated muscles, sure, they're from the same, they could be from the same nerve root, but they're from the same peripheral nerve. So let's just say that's not a median mononeuropathy. So we need to have different peripheral nerves that are coming from the same nerve root. And then the classic findings would be that the paraspinals would also be involved based on the pictures that I was showing you earlier. So when we're assessing our EMG findings, we're really going to identify the axonal injuries only. So if we're seeing abnormalities within the muscle, that's from an axonal process. So one of the limitations that we see within electromyographic testing of radiculopathy is that it's hard for us to identify a demyelinating lesion. So the way that we classically identify demyelinating lesions in the electrodiagnostic lab is through nerve conductions and stimulating above and below the lesion in order to catch slowing or conduction block at that point. And it is hard to do proximal stimulation at the level of the nerve root. For the sensory anatomy, so here we have the spinal cord. Here we have the dorsal root here, and it comes into the dorsal root ganglion. And so what happens in the majority of cases, we're talking about the nerve root level here is where the trauma, injury, or inflammation is occurring. And you can see that it's affecting the sensory nerve that is proximal to the dorsal root ganglion. So the terminal nerve that innervates sensation originates in the dorsal root ganglion. So what we're seeing is when we're testing on nerve conductions, when we're testing our sensory studies, the process is out here. So even if we have a huge abnormality affecting the sensory nerve root, it's going to synapse at the level of the dorsal root ganglion. And so we're not actually testing here where the problem is. We're testing distal to the problem. So classically in a radiculopathy, we would expect our sensory nerve conduction studies should be normal despite having pain and sensory symptoms. So this is one of the big take-home points is that our sensory should be normal despite symptoms. So here's just the picture of the dermatomes as a reminder. So you can go back and refer to these when you're thinking about which nerve root you think is most affected. So back to our radiculopathy case number one. So this is our 45-year-old gentleman with pain down the back of the arm, decreased the pinprick in the back of the arm. He's got mild weakness in the triceps and wrist. So we can launch poll number one here. I want you to vote on which nerve root level you think is involved. Okay, so please respond to poll question number one. I'm looking at the poll and trying to figure out how to vote on it. You're not able to select any of the options? I'm not, but let's see if we can find out here. Someone says it looks like you might have to answer all of them at once in order to submit it. And somebody says it was working, but now it's gone. All right, it looks like from the chat, it sounds like you have to answer all of them. Sorry for the technical glitch here. Just answer number one and then answer A for all the rest of them and see if that works. All right, looks like about a third of you have responded. So looking at question number one, we have 85% of you voted for C7. All right, so let's see here, see what we have. So on nerve conduction testing, we have our median motor nerve conduction study. Amplitude looks relatively normal. Our conduction velocity is normal. Our ulnar motor nerve conduction study is also normal. Our sensory nerve conduction, so our median, ulnar, and radial on the affected side are all normal, and the median and ulnar on the contralateral side are symmetric. So we have normal looking standard motor and sensory nerve conduction studies. So on EMG testing, we looked at the deltoid, the triceps, the biceps, the pronator teres, the first dorsal interosseous, and the cervical paraspinals. So we saw evidence of insertional activity and spontaneous activity in the triceps muscle, the pronator teres muscle, and the cervical paraspinals. All right, so to summarize our electrodiagnostic findings, normal median ulnar and motor, normal median ulnar and radial, and abnormal findings on EMG in the triceps, which is a C7 radial innervated muscle, pronator teres, which is a C7 median innervated muscle, and the paraspinals. This is a pretty good standard case for a C7 radiculopathy, so good job. All right, case number two, this is a 62-year-old woman with a car accident about six weeks ago. She has difficulty lifting her arm above her head. She has three out of five strength in shoulder abduction and numbness in the outer arm down to the thumb. So I'm going to relaunch polling again. So answer number two this time, and then just select A for all the rest of them. All right, looks like about half of you voted, good. So it looks like the vast majority of you selected C5, C6, very good. So on our testing, so for motor nerve conductions, our median motor study is normal, so we have a normal amplitude, normal conduction velocity. Our ulnar motor study is also normal. In terms of our sensory nerve conductions, so we went all out, so we tested the median, the ulnar, the radial, the lateral antebrachial cutaneous, and the medial antebrachial cutaneous in this case, all of which were normal, with normal amplitudes and normal beats. So here are our results from needle EMG. So we looked at the deltoid, the biceps, the triceps, the pronator teres, the first dorsal interosseous muscle, and the cervical paraspinals. And you can see abnormalities here in the deltoid and in the biceps, so there's increased insertional activity and three-plus spontaneous activity in both muscles, and then two-plus, one-plus spontaneous activity in the paraspinal. So to summarize this case, there's normal median and ulnar motor evoked potentials, abnormal sensories with a really widespread testing, and there's abnormal findings in the biceps and in the deltoid, which are both C5, C6 innervated muscles that come from different peripheral nerves. So this is a pretty clear diagnosis, pretty classic diagnosis of a C5 slash C6 radiculopathy. However, it'd be nice if we could tell the difference between a C5 versus a C6 radiculopathy. So how can we tell the difference, how can we differentiate between the two? So let's look at poll question number three. So again, select A for all the other ones, but for poll question number three, which muscles can be used to differentiate between a C5 and a C6 radiculopathy? And you can choose more than one muscle. Okay, looks good. So here's our results here. So which muscles can we use to differentiate? So the one that was selected the most was rhomboids, second most was supraspinatus, and third most was pronator teres. So rhomboids is a great one to test because it has C5 only. It does not have any C6 in it. And so if the rhomboids are abnormal, then we know then C5 must be involved, right? If pronator teres is abnormal, it has C6 in it, but does not have C5 in it. So it's another good one to test because it doesn't have a direct overlap. So rhomboids was abnormal and pronator was normal, that would push you towards C5 or vice versa. All right, someone who voted for supraspinatus, can you answer in the chat why you picked that? All right, so supraspinatus is certainly a good one to test because it has C5 and C6 in it, so we would expect that it would be abnormal. We have one vote that it's mainly C5 with less C6, and that certainly could be true, but I like to use, I do think of it as a C5, C6 muscle personally. So I would use thromboids or anything like pronator teres to differentiate. So that's my approach. All right. All right, so on the studies we've done so far, you've noticed that we've tested paraspinals in every single patient, and they've been abnormal in every single patient. So when we're thinking about you doing the textbook proper electrodiagnostic workup for radiculopathy, you always do the paraspinals, okay? I find paraspinal testing to be challenging, and so I don't like doing it, although I try to do it as much as possible because it is indicated and appropriate in the workup. But why is it so hard? We'll skip the poll on this one, so why is it hard to use the EMG of the paraspinal muscles? There's a lot of reasons. So the number one thing is if you're sticking a needle in the paraspinal muscles along someone's back or neck, they can have a really hard time relaxing while you do this. So you may get them in the perfect position, have them on their side, get the needle in the exact right place, and they can't relax to give you reliable information. If someone has had surgery in the back, then the muscles, the paraspinal muscles may be abnormal forever. We just don't know how long it may be abnormal, and so we can't really interpret the findings in a patient who's had surgery in the back or the neck. Even if they have abnormalities from a radiculopathy, you may miss it, so it can be hard to get in the exact right spot, so you may not catch something that's abnormal. There's a lot of patients that it is challenging to test in, so I don't want to stick a needle in someone's neck who is on anticoagulation. So our lab does do electrodiagnostic testing for people that are on anticoagulation, but we stick to the peripheral muscles, so we don't do anything in the back or neck. But what does that mean? Does that mean full-dose anticoagulation with warfarin or globinax? What about aspirin? What about Flavix? Things like that. So it's always a little trickier to do paraspinal muscles in people who are on anticoagulation. Once you've done your paraspinal muscle testing, it doesn't localize to a specific nerve root level. So you notice in the report, I'm always saying upper, lower, middle cervical paraspinals. I'm not relating back to a specific nerve root level because of the way that it is anatomically. And then also an abnormality is not pathognomonic for radiculopathy. So they can be abnormal in other diagnoses such as myopathy or motor neurone disease. And then most importantly, it can also be challenging to identify the paraspinal muscles in people depending on their body habitus and ability to position, so it's challenging for a lot of reasons. I do see a question. Not if they have had anterior surgery, is the EMG still unreliable post-op? If they've had an anterior cervical approach, then I would still feel comfortable doing paraspinals in the neck. I would do them. And I would probably assume that they would be normal after surgery, but I would take that as a caveat when I was doing the study. Great question. All right, case number three. This is a 27-year-old man with neck pain radiating down into digits four and five. So he's weak with FDI testing, and otherwise his strength is normal, and he has numbness in digits four to five on light touch and pinprick. So for question number five, go to the poll here. What nerve root do you think is affected here? Question number five. All right, this one looks more straightforward, it looks like 92% of you said C8 T1. I did note on question number four, I did note on question number four, I know we're not polling on that one, but 8% of you thought I was too lazy to test the paraspinal, so that's awesome. It's about right. All right, so here's our motor nerve conduction studies. So our median motor is normal, and you can see in the Ulnar motor, we actually have low amplitude there at that 6.2 and bold. So low amplitude responses with normal conduction velocities and normal latency here. And there is a significant side to side difference here, 6.2 versus 9.5. For our sensories, we have normal, median, and Ulnar sensories with pretty healthy looking amplitudes here. And then on EMG, we see in the first dorsal interosseous, the abductor pollicis brevis, and the low cervical paraspinals, we see abnormal insertional activity and some spotting. So to summarize that, we have normal, median, Ulnar motor evoked potential, abnormal Ulnar motor evoked potential, normal, median, Ulnar sensory evoked potential, and abnormal findings in the first dorsal interosseous, which is C8 T1 Ulnar innervated, and abnormalities in the APD, which is C8 T1 median innervated. And with abnormal paraspinals, it's a pretty good case for a C8 T1 radiculopathy. And then how many muscles should we test on EMG to assess for cervical radiculopathy? And did we test enough in this case? So we did 1, 2, 3, 4, 5, 6, 7, one of which was the paraspinals. So did we test enough? So there was a study by Lauter et al looking at what percentage of cervical radiculopathies we can identify based on how many muscles are tested. And so if you do less than six muscles without testing the paraspinals, your likelihood of identifying cervical radiculopathy is very, very low, so 23 to 85%. So including an additional muscle is helpful, but really to increase your likelihood of identifying cervical radiculopathy, the paraspinals are very important. You can see we did six muscles, including paraspinals, and that gives us a 92 to 96% chance of identifying cervical radiculopathy. All right, case four. So this is a 75-year-old man with left-sided foot drops for one week. On exam, he's weak in dorsiflexion, EHL, and eversion, and he's got numbness on the outside of his lower leg. So symptoms have been going on for one week. So I'm going to launch the poll now, and I want you to answer question number seven and question number eight. All right, I'm going to end the polling here. Okay, so here's our results. So for number seven, 70% of people said L5, 30% said L4, and 8% said S1. And then, when should we do electrodiagnostic testing? So 11% said now, 41% said at two weeks, 38% said at three weeks, 16% said at six weeks, and 3% said never. I like that option. All right, so let's think about this. So what is the time course of electrodiagnostic changes on EMG? So in a case where we have a very clear onset, so we know day zero, this is when the radiculopathy started, acute onset of symptoms. In that first week, your EMG is actually going to be pretty normal. You may be able to catch decreased recruitment when you're testing motor unit analysis in the affected myotomes. But you're not going to have a great idea of what's going on in the first week. In 10 to 14 days, you're going to start seeing fibrillations and positive sharp waves, but only in the paraspinal muscles. The paraspinal muscles are the first thing to become abnormal. At two to three weeks, then you're going to start seeing fibrillations and positive sharp waves in the paraspinal muscles and in the proximal muscles of the affected myotome. For example, in L5, you might start seeing these in your gluteus medius muscle, but you might not start seeing them in your anterior tibialis muscle. That's more difficult. Okay, at three to six weeks, you're going to start seeing the fibrillations and positive sharp waves in the distal muscles of the affected myotome. In that example of L5 myotome, then you would start seeing it in the anterior tibialis at three to six week time period. At six weeks to three months, you may start seeing that the fibrillations and positive sharp waves may still be there, but they may start to resolve. But that's when you're starting to see evidence of reinnervation. Reinnervation, that's when your motor units have your large amplitudes, your polyphasic units, and you see that in all muscles, but you tend to see that in the proximal muscles first and in the distal muscles later. What's the correct answer on when to do the electrodiagnostic testing? This was one of our answers where it was the most widespread in terms of what you guys thought. I think that's appropriate because there's no one right answer. So I think you can do the test at two weeks as long as you know what you expect to see. As long as you know the expected time course, if you do the study at two weeks and you see abnormalities only in the paraspinals or you're starting to see some proximal, hypothetically, L5 innervated muscles with normal ones distally, as long as you know that it's a little bit early to see all the changes, I think you can interpret the study appropriately and can get useful information out of it. You know, if you want to get the full host of abnormalities, the distal and proximal muscles in the myotrome, you may want to wait for at least three weeks. And if you want to make sure that you're getting all the abnormalities, potentially seeing evidence of re-innovation, you can wait even longer. But as long as you know, as long as you're familiar with the time course of expected EMG changes, I think you can get information out of a study at any time. All right, so his electrodiagnostic test was eventually done at four months due to not following up in clinic and insurance issues. So here's what was found. So corneal or fibular, depending on where you trained, had normal amplitudes, normal latencies, normal conduction velocity. The tibial motor studies had normal amplitude, normal conduction velocity. And his sural nerve conduction study, again, was normal. And most interesting findings, obviously, needle EMG. And so he had abnormalities in the tibialis anterior, peroneus longus or fibularis longus, gluteus medius, and the lumbar paraspinals. And so you can see this was done at four months. So he still does have some spontaneous activity that we're seeing here, right, with the three plus fibs and positive sharp waves. But we're also starting to see some evidence of increased duration, increased complexity, increased amplitude in some of the muscles that were tested. And he does have the classic paraspinal abnormalities here. All right, so the summary here. Normal peroneal or fibular and tibial motor studies, normal sural sensory potentials, and abnormal findings in the tibialis anterior, which is an L4-L5 innervated peroneal muscle, peroneus longus, which is an L5-S1 peroneal innervated muscle, and the gluteus medius, which is a good L5 proximal superior gluteal innervated muscle. And then we have the lumbar paraspinal. So this meets our multiple different peripheral nerves. Paraspinals are abnormal. Sensories are normal. So it's a classic L5 radiculopathy. Okay, so how do you decide which sensory nerve to test when you're assessing for radiculopathy? So do number nine here. So which sensory nerve do we test in a radiculopathy evaluation in the electrodiagnostic lab? All right, so we have a good number of responses here, so if you look at number nine here, so we have 29% saying always the same, an arm due median and ulnar and a leg due serral, and then 68% say depends on which nerve rate you think is involved, S1 equals serral, C8 equals ulnar. So the textbook answer is test the sensory nerve where you are considering that nerve root to be involved. So for example, if you think that it's a C6 radiculopathy, you can test the lateral antebrachial cutaneous nerve, or you can test the radial nerve to the thumb, median to the thumb, and median to the index finger. So the reason for this is if you think that C6 root is involved, then you want to make sure that you're proving that that C6 sensory nerve is normal. It doesn't help you to say that, oh, the C8 sensory nerve is normal, because we would expect that to be normal if it's a radiculopathy or if it's a flexopathy or something else, because that's not in the distribution of the symptom. So we need to think about what nerve root we're thinking about and then test at that level. So in the upper extremity, it's pretty simple, because in general, the routine study usually looks at the C5, or the median to the index finger, which looks at C6, C7, and then with the C8 ulnar to the fifth digit, we're doing a decent screen there of multiple levels. If I'm thinking that it is more likely C5, C6, I will test the radial sensory to the thumb as well. So it's easier in the upper extremity, because we're getting a pretty good picture from our routine sensory. In the lower extremity, the sural nerve is the easiest nerve to test, right? So S1 sural nerve is our standard nerve conduction that we're testing. Some people choose to do the superficial peroneal or superficial fibular, and if it's an L5 radiculopathy, I do try to test that, but as you know, in people who age, as you get older, we may not be able to get a sural or superficial fibular, superficial peroneal in anyone, just as an age-related change, and in some people, it's hard to get that superficial peroneal, superficial fibular, because of body evidence. And then for the L4, for the saphenous nerve, it's even harder to get, because that saphenous nerve kind of dives under the tibia there, and so it can be technically challenging to get the saphenous nerve. So I would say, in theory, it's best to figure out what nerve group you're interested in, and then test the sensory nerve that correlates with that. In practice, it certainly doesn't happen all the time, and that's because it's not practical to test every single sensory nerve, and some of them are really challenging to test, especially in the lower extremity. So the textbook answer and the practical answer are unfortunately not always the same here. All right, so case number five, we have an 81-year-old man with unilateral calf pain times two years. He has a normal strength exam, except for atrophy in the foot muscles, and he has numbness in the bilateral lower extremities to the ankle and a stocking distribution. So what nerve root do you think is involved here? So last poll from All right, so it looks like we have 83% said S1, 5% L4, 10% L5, and 12% is still thinking. Nice job. So for his motor nerve conduction studies, he had a normal tibial response, an amplitude of 1.8 being normal in someone who's 80, with relatively normal-looking conduction velocities and latencies. For his sensory studies, so his sural sensory was absent bilaterally, unable to guess. And on his EMG, he did have some insertional activity and spontaneous activity in the right gastrocnemius, the right pronus longus or fibularis longus, a little bit of insertional activity in the right glute med, increased insertional activity in the lumbar paraspinals, and you see a little bit of increased duration, increased amplitude, increased polyphasicity. And in the gastroc, you're only seeing a couple different motor units. So we have a normal tibial motor study, absent sural sensory evoked potentials bilaterally, and abnormal findings in the tibial innervated gastroc, which is S1, S2, the pronial innervated pronus longus, which is L5, S1, and sorry, that was the glute max, which is a good S1, does have L5 and S1, and then our lumbar paraspinals. So this is consistent with an S1 radiculopathy. However, the absent sensories complicate things, right? So in a radiculopathy workup, we expect that sensories should be normal. However, if you are looking at patients who are 80, there's a relatively good likelihood that you're not going to be able to find the sural sensories because of age-related changes. And in someone who does give you a clear history of a stocking distribution sensory loss, there's potentially a history of diabetes or other cause for a peripheral neuropathy that limits our ability to interpret the study. So in this case, our EMG findings were actually classic enough for radiculopathy that I felt comfortable making this diagnosis, right? So we have three different S1 innervated muscles that come from three different peripheral nerves, and we have the abnormalities in the lumbar paraspinal. Plus we have the vastus and the tibial, so we do have normal muscles here to show that this is not a widespread process where every muscle is involved. And so these are L4, L4, L5 muscles up here. So despite the fact that we are limited, in this case, by the sural sensories being absent, I did feel like we had enough information to make the diagnosis. And then how many muscles should we test on EMG to assess for lumbosacral radiculopathy, and did we test enough in this case? So here we tested six, including paraspinals, and I argue that we caught it, we made the diagnosis of lumbosacral radiculopathy, so we have enough, right? But if you look at a study by Dillingham, ideally, so we tested six muscles, including paraspinals, so that should identify 98 to 100% of radiculopathies. And so we actually can probably get away with fewer in the lower extremity as compared to the upper extremity, because even with four muscles plus paraspinals, or five muscles with paraspinals, we're actually getting a pretty high percentage of those. And then if you are not doing the paraspinals, more muscles are needed to identify. So that's the argument for doing paraspinals whenever it is possible from a technical standpoint, from an echo-regulation standpoint. All right, last case, radiculopathy case six, we have a 32-year-old woman who is postpartum with proximal left leg weakness. On exam, she has four out of five strengths in hip flexion, hip adduction, and dorsiflexion. She has numbness to light touch and pinprick in the medial leg all the way down to the medial ankle. So what level of radiculopathy do you think this is? All right, so no poll on this one, though. So her routine motor studies look normal. So her peroneal or fibular has normal amplitude, normal latency, normal conduction velocity. Her tibial conductions here are normal with a normal amplitude, normal latency, normal conduction velocity. So her Searle test was normal, and her Staphanus test was done and was also normal. So then if you look at her EMG, so the vastus medialis was increased insertional activity and spontaneous activity. Her tibialis anterior was increased insertional and spontaneous, and her lumbar paraspinals were abnormal as well. So we have normal motor evoked potentials, normal Searle, normal Staphanus as well. And we have abnormal findings in the vastus medialis, which is L2, L3, L4 femoral innervated. We have abnormal findings in the tibialis anterior, which is an L5 S1, and we have abnormalities in the paraspinals. So we have two different peripheral nerves at the L4 level that are abnormal. We have an L4 radiculopathy. And with a normal Staphanus, that is reassuring as well. So we have the classic pattern of normal sensory multiple peripheral nerves coming from the same nerve root and the abnormal paraspinal. Okay. All right. So advanced question here. So how can you tell the difference between an L4 radiculopathy, how can you differentiate that from a femoral neuropathy or a lumbar plexopathy on electrodiagnostics? So in all three of those diagnoses, we're going to have femoral abnormalities, right? Because the femoral nerve has L4 and the femoral nerve travels through the lumbar plexus, right? So femoral nerve conduction and femoral innervated muscle should be abnormal in all three of those diagnoses. So what tests can we do on EMG or nerve conduction studies that can help us tell the difference between those three diagnoses? So if anyone wants to venture a guess in the chat, let me know. Oh, I have one vote for saphenous. Very good. Any mussels we should test on EMG? Adductor longus, very good, excellent choice, all right, snap normal and L-floor radiculopathy and abnormal and lumbar flexopathy, exactly, you guys are getting this, paraspinals, yep, adductor, saphenous, very good, all right, so here is my chart, so all three diagnoses will have abnormal femoral motor, right, so when we're thinking about that radiculopathy, so if it's a radiculopathy, you expect that classic pattern with the abnormal paraspinals and the normal sensory at that distribution, right, so symptomatically, all three of these diagnoses may look pretty similar, so we have to really figure out how we can differentiate it, right, so if it's a femoral neuropathy, so if it's a nerve problem or a plexus problem, we expect our paraspinals here to be normal, right, so this is why paraspinal testing is huge in differentiating out these conditions, right, when we're thinking about that sensory, that snap, so in a radiculopathy process, we would expect it to be normal and in the femoral nerve or lumbar plexus, we expect it to be abnormal, okay, so the first dividing pathway is let's check the paraspinals and let's check the appropriate symptoms, okay, so hopefully that will help you differentiate between is it a root-level process or is it at the level of the nerve or the plexus, right, but then the next thing to look at is here, so the adductors are really helpful in differentiating between a femoral nerve process and a lumbar plexus, right, so the adductors are L4 innervated, so they're going to be abnormal here in our radic, but adductors will be normal in a femoral process and should be abnormal as they go from the obturator nerve that goes through the lumbar plexus, okay, and the L4-L5 innervated tibialis anterior should only be abnormal in these three diagnoses, should only be abnormal in the root-level process, okay, so we can differentiate electrodiagnostically between these three processes which look pretty darn similar clinically as long as we do the right tests, okay, so take home point, always do the paraspinals if you can, always do the sensory at the correct level, and then think about exactly which muscles can help you differentiate between your different diagnoses, okay, got it, all right, so here's my take-home points, so electrodiagnostic testing is awesome and we should be using this to help extend our physical exam and help localize lesions, it can help us with severity of lesions, acuity of lesions, but it has some limitations, we can't detect early lesions, so in the first week we may not be able to find it, we can't assess demyelinating lesions, so we won't be able to pick those up, we cannot identify primarily sensory radiculopathy, so this is one of the main challenges because we can't test, we can't pick up a sensory or pain-only radiculopathy, so the study may be normal even if they have really severe symptoms that are in fact related to the root level, we can't always isolate out the specific nerve root, so sometimes it can be hard to tell difference between those C5, C6, or C8, T1s as I was talking about, we need to make sure that we're testing enough muscles so that we can catch the radiculopathy, so we're not falsely reporting it as negative, and the paraspinal muscle testing is important but can be challenging, and then when we're thinking about the classic electrodiagnostic findings, so our sensories are classically normal, our motor responses for our nerve conductions can be normal or abnormal depending on the severity of the lesion, our EMG should be abnormal in the affected myotomes with different peripheral nerve renovations, and our paraspinal muscles should be abnormal. All right, and hopefully I didn't put you to sleep too much during this lecture. All right, I think we have time for a couple questions. Oh that was great, thank you very much. Anybody have any questions about this? I think it's fantastic, I think you did a great job of kind of walking us through cases I always feel like are appropriate because they help with both clinical scenarios and also kind of studying and preparing for boards and whatnot, so thank you for that. Question came up over here, is it valuable to pay attention to the motor unit actual potential remodeling for radiculopathy? Yes, so I definitely plan to pay attention to the way that the motor unit action potential looks, so when we're seeing that remodeling over time, you're starting to see evidence of polyphasics, increased duration, increased amplitude, it can absolutely help you come up with a time core, so it can tell you that it's more of a chronic process as opposed to more of an acute process, but oftentimes what we're seeing in the electrodiagnostic lab is more the chronic radiculopathy, so someone's had leg pain for three years and now their pain is worse, and so sometimes we only have chronic changes to guide our diagnosis, so it's absolutely important to take a look at that. There's another question over here, role of H waves, H reflex in radiculopathy? I do love the H reflex, so I use it primarily for S1 radiculopathy, and I honestly don't use it that often because the majority of the time I will look at the EMG and see if I can find abnormalities in the S1 innervated myotones, obviously, and so if you find abnormalities on EMG, then you've already made the diagnosis and you don't need to use the H reflex, so I usually use the H reflex if I have somebody that I'm looking for an S1 radiculopathy, clinically they look like their S1, my basic nerve conductions and my EMG are negative, and then I will do the side-to-side comparison of H1 reflex to see if I can catch the S1 radiculopathy when I couldn't find it on the EMG testing. Great, thank you. All right, I think that is all our questions. Thank you so much for joining us, we appreciate it. We're going to move on to our next lecture. Thank you so much. Again, this is Dr. Leslie Rydberg from Northwestern slash Shirley Ryan Ability Lab, a true Chicagoan, so thank you very much. Hope you guys are doing well up there. Again, for anybody that has any questions that came up during the course of this lecture, anything you want to ask after, that is her email address there on the screen. You can track us down on Twitter, and again, the schedule changes on a regular basis, or we update it on a regular basis, and it's there, physiatry.org slash webinars. We are going to have just a second before our next speaker starts, so give us just a minute.

electrodiagnostic considerations

radiculopathy

virtual didactics

ongoing curricula

residents affected by the pandemic

digital learning resources

motor and sensory studies

limitations of electrodiagnostic testing

paraspinal testing