Lessons From the Lab - Episode 18 - L5 Radiculopathy

[Music] hello and welcome to lessons from the lab I'm Devon rubben from Mayo clinic in Jacksonville Florida I'm here with you for another episode of lessons from the lab I am fortunate to begin this day with a great guest a very experienced electromyographer he's done this for many years and I'm going to present a case that's a pretty straightforward case something that you've all probably encountered in your practice but it has some twists in it that make us scratch our head we're not really sure what we're getting into so sit back and enjoy this episode

welcome to another episode of lessons from the lab it's a pleasure to have a wonderful guest and a wonderful friend join me Dr Carrie Levan Dr Levan is a professor of Neurology at Cleveland Clinic he's an expert EMG or neuromuscular physician and and I am excited to have you here Carrie nice to see you well well thank you very much for this invitation um I I enjoy talking about my favorite subject which is EMG well great well you you know what today is right uh today is Valentine's Day well that's not what I was gonna

say I was gonna say today is a special day that I get to talk to you but it is Valentine's Day yeah that's right and um you know I've known you for a long time we each have our own Valentine's sweethearts at home but I think of you a little bit as a work Valentine we've done a lot my my Valentine through work we've done a lot together we've written lots of exam questions given talks together so uh it's nice to spend a little bit of Valentine's Day with you and I feel the same way

uh Devon you and I have had not only a friendship but a working relationship that I've uh I've enjoyed very much I was thinking back this morning as I was getting ready for this and uh I don't know if you'll remember this this will date us a little bit but but a number of years ago we were I think at a meeting and was in California and we went on a little hike and uh I I remember the hike I don't remember exactly where it was but you you were teaching me or I was asking

you how WiFi works with our cell phones and I just this dates us because it was like right when cell phones were kind of coming out and I didn't understand how Wi-Fi works so I won't ask you to explain it today but uh but I've learned a lot more more than just EMG from you I would have to say that I I think this is an apocryphal story because I would not consider myself an expert on uh internet and Wi-Fi I think you just said you just pushed this button on your phone and you can

get service and I said okay I believe everything Carrie says so so uh our conversation today I think will be something you hope I know you will be able to explain to me and to our listeners um I know you've been doing this we both have for a long time but but you've been uh how many years have you been performing EMG uh over 40 okay do you ever get tired of it um you know I seldom do a full day of EMG but that can be tiring at the end of the day doing a

full day of EMG uh it's nice to have a diversity in uh the work you do uh and so having a combination of of uh procedural uh EMG and seeing clinical patients uh and being able to correlate those two I think makes a profession in neuromuscular medicine so much more rewarding than one without the other yeah I I agree completely I know we agree on almost everything I agree on the the the the days I'm the weeks I'm in clinic I think gosh I can't wait to be in the EMG lab and the weeks I'm

in the EMG lab fulltime the whole week I love it it's it's just fantastic but it's tiring when you know I'm sure at Cleveland Clinic at Mayo we do lots of emgs and lots of patients and sometimes there's it's just hard to sit back and sort of take a deep breath and think about the patients as much as we want and and that can be tiring in a good way in a good way yes and and there are challenges in both of those areas is they are challenging patients not only from the diagnostic and treatment

point of view but uh we're dealing with human beings and uh there are stresses in the EMG lab just getting a study done and getting a patient through a study um and there are challenges getting a a clinical patient through their illness yeah yeah absolutely well I'm going to give you a patient that I think will be challenging in some ways um one of the goals of this lessons from the lab are to uh help educate uh anyone who's watching this or listening on podcast as to how we might approach a patient that we might

encounter in the lab um as you know not every patient's textbook uh and so sometimes we have to scratch our head and think a little bit so I'd like to present you with a patient that we had in the lab a few weeks ago and see what you think about this so you up for it yes this is your Valentine Day present to to get a talk through a patient so I'm GNA um I'm going to just show a few slides here and share my screen so hopefully you can see that so so I'm gonna

just read this for those who are not watching but are on podcast so the patient is a 40-year-old man who presented to the EMG laboratory with left leg pain and weakness and he his story was that he had a long standing history of low back pain it had been going on for over a decade and he would have these flares that he would call a few times a year uh he never had surgery it was always treated conservatively and then about five or six weeks prior to his presentation this time he developed pain that was

unprecipitated by any type of injury or uh trauma and the pain radiated in his left buttock down into the hamstring area he did report some numbness which he described as a loss of feeling in the bottom of the left foot and the top and bottom of the toes on the left and he noted that he was a pretty active guy and he noted that during this time he had difficulty standing up on the toes on the left foot so he saw his primary care physician he was treated with a do a Medrol dose pack and

about a week prior to him coming for his EMG he felt that there may have been some improvement in the pain uh but he still had all the other symptoms and um of course what we always do when we see a patient he didn't have any other real medical problems that were significant so real no systemic medical conditions he was healthy and then I'm just going to give you you know the exam of course is very important and his exam was pretty straightforward it was all normal except for an absent left Achilles reflex and he

had some weakness in his left gastr nmia the other muscle rength in his leg were were was normal so so that was the story that's how he presented he was sent for an EMG for this so have you have you ever seen a patient like this um many times I I would say let me ask you in 40 Years of doing this how many patients have you would you say you've seen if you had to guess that have been sent for symptoms similar to this oh uh you know hundreds yeah okay sometimes I think this

is just in the side I think of um I don't know sometimes when I'm bored and I'm needling a patient and I think how many motor unit potentials have I seen in my life have I recorded my life you think you think you've recorded you think you would have hit the million mile club like on the you like the Airlines million Mile Club the million motor unit potential Club yes I I I think so I sometimes I I think about how many emgs I've done in a year and although I've cut back a little bit

because I have other administrative duties I I may do um a thousand or more emgs easily on a yearly basis and so over the course of years that adds up yeah and if you think about in a in a patient I've thought about this again this is how my mind thinks if in a patient in in any muscle you collect 20 motor units and you do about five muscles in a patient on a routine patient that's 100 motor unit potentials so you're doing a 100,000 motor unit Potentials in a year so you're at the four

million Club you know the thing the interesting thing to reflect on is that in spite of how many you've done and how many I done I enjoy doing normal patients of all ages because by normal I mean they have symptoms but you don't find much it it just further refines my range of normal um and therefore allows me to have a more refined sense of what is abnormal and where I shouldn't be overstepping my diagnostic skills and overdiagnosing because there's a spectrum of normal uh there are some patients who have bigger motor units and it

doesn't mean that they have abnormalities yeah yeah I agree I mean how many patients if you think about it do you start needling the leg like maybe a patient like this you're doing a needle exam in the anterior tibialis and you sit there that's your first muscle and you're not sure and and you know on our grading scale I don't know if in your grading scale of size you have a plus minus on your scale so meaning equivocal we tell our residents they can't use that that's only for staff that can use equivocal they have

to commit but I use it all the time and just like what you're saying that I don't know for this patient it seems maybe a little bit large but maybe this patient's motor units are large so I'm not sure until I see the other ones yes and and in our lab we have the uh descriptor 0-1 plus and I I remind so irrespective of what column we're talking about the fibrillation column the facul column the large motor unit column and I do tell our trainees that it is the last Refuge of the EMG scoundrel but

it's trying to be honest yeah right I I I I tell them you can't use it they they're showing me a waveform you can't use it you have to commit you can't say plus minus what do you I say what do you think so they'll either say well I think it's normal or I think it's plus one and they'll say what do you think and I say I think it's plus minus so we're allowed to if you've done this for over a certain number of years you're allowed to equivocate right yeah and I think in

this kind of a case uh when you go to the actual study yes you're looking at the Gast Dr me but you're also interested in what do the other muscles look like and because you're building a case you can't build a case on one muscle yeah yeah so backing up then so for this case if you maybe share what you would be thinking before you start doing any testing in the lab and this is the information you have what what's going through your mind so I I I first of all want to confirm with the

patient the symptoms the side of the problem is there anything that might also be going on on the other side at the same time or in the past um and um I want to think about um what we we do have the luxury in my laboratory to have technical staff who do the nerve conduction studies so I scrutinize those uh and make sure I agree with the waveform analysis that the uh and the nerve conduction study metrics that have been generated by uh the technologist um before I decide well what's my attack plan for the

needle exam and and just in terms of I don't think this is a surprise but in terms of what you're thinking before you do anything with this case in terms of possible localizations what what would you be thinking um well I'm going in with the bias that this is an S1 radiculopathy um and I'm already thinking about how am I going to prove that and will there be uh roadblocks in the way uh I can already imagine having done so many of these that I may be thwarted uh with a limited examination I'm going to

need to look at proximal muscles as well as distal muscles I'm going to have to frame uh the abnormality to make sure that I'm convinced that it's a single root lesion and what the localization could be okay and and in your lab in Cleveland are the conduction studies performed first or is the needle exam performed first we almost always do the nerve conduction studies first I think that helps understand uh the context in which the needle examination has to be performed for instance uh we might find out in this patient he's only 40 but uh

if he has sensory conduction study abnormalities that will change my thought process about how I understand the needle examination and what I'm going to have to do to rule out or rule in other things that are going on on top of what I end up finding okay so and and it's similar with us most most patients we do the nerve conductions first we're like you we have great technicians who perform these um I'm curious in your lab from the nerve conduction standpoint do the texts just go in and they have the protocol um and they

know what to do or do they ask you first which conductions and if they did ask you what conductions would you tell them to do in this case so um our studies in terms of nerve conduction studies are quite protocolized so that uh we get a sense from the referring diagnosis and uh the symptoms and signs that have been provided to us that uh we're going to be doing a leg uh or we're going to be thinking about a bilateral problem um and the technologists therefore have a road map to begin with now they are

also trained uh and experienced well enough that they Branch out into other things uh depending upon what they find so if in a case like this the surl is absent uh they're going to check the other side uh they may not check the other side if the serl is fine on this side uh because we're going to need to know is there laterality of that problem or is this a symmetrical issue and how does that play into the rest of the exam okay so your your routine studies in this case would be you would do

what a couple Motors fib fibular and tibial motor yes exactly we do both of those we do a sural uh and we do a superficial paranal sensory uh response and we do an H reflex okay and if the H reflex is abnormal we always compare with the other side what do you I'm curious the a I'm going to show you some waveforms here but for so you routinely do H reflexes and what what do you use and we don't do them very often so this is why I'm asking do you use an absolute latency prolong

is there an absolute latency prolongation that you use or how do you interpret it if you're looking at one side that it's abnormal uh we don't pay pay much attention to the latency uh we pay more attention to the amplitude of the Solus M response and to the actual H reflex amplitude and our cut off is uh one molt for the uh H reflex amplitude and if it's less than one that automatically signals uh need to do it on the other side um and um so that's kind of our our goto if it's absent the

H reflex uh we always check the other side um you know there there are lots of patients who may end up having absence on both sides and that could be technical uh uh because of body habitus uh it could also be because you're over 60 that's kind of our cut off for expectation of the presence of an H reflex um would you be comfortable calling an S1 radiculopathy only on the basis of an abnormal H reflex with everything else including the needo exam being normal no okay I had an interesting H reflex just in the

side a week ago we had a patient again we don't do this very often we do it about a handful of times a year and mostly to show the text and the residents how to do them but we had a patient this not this patient that had came in with with left buttock pain going on for a couple weeks a little bit on the right and had absent Achilles reflexes bilaterally and the ne everything was normal needle and ner routine nerve conduction studies were normal and it was the last case of the day and I

said well let's just do H reflexes for the heck of it and uh and you know we often I often thought well if they have absent Achilles reflexes we're not going to get a good H reflex anyway so we did it on the affected side and it had a beautiful H reflex High amplitude beautiful and we went to the other side and I couldn't get one on the unaffected side it didn't make sense it was the wrong side actually we got something but it was a very low amplitude so I said this is why we

don't do them I don't understand I mean he may have had an old process affecting that rout in the past but which is probably the case yes but yeah I would have been interested in the Solus M responses as well was there an asymmetry there as well and I mean because that might have informed you about why there might have been a low H yeah and I didn't and I didn't needle the unaffected side the gas truck um so there may have been a little changes too but I'm I'm well aware of the kind of

sometimes mismatch between uh presence of reflexes and absence of Achilles reflexes and it does give you pause and sometimes it's the other way around also yeah and I think with the technology too you know I think you know when I learned when I was a fellow I learned yes if you don't have an Achilles you're not going to get an age but I think now with the technology and the sensitivity of the machines and the ability to change the sensitivity that when I do do them even if I don't think I'm going to get something

I sometimes there is a really low amplitude one that's consistent so uh you still can pick it up sometimes when they don't have a good reflex I think the other point about H reflexes is there's an art to doing them and um we sometimes run into trouble even with our experienced texts that they overall anx which really isn't there um so we we're kind of I'm kind of a stickler as far as the expectation that the amplitude of a normal H reflex should increase for a while as you increase the voltage uh of the stimulation

uh and uh it should then Decline and uh but it should be uh relatively robust to begin with and then decline uh but if you don't get that then I think there is either a technical problem uh or you somehow have to explain it yeah well good that's a good conversation discussion about h reflexes which we did not do in this patient so uh but it's but it's good I mean because we think about it and and like I said I did do it in another patient so I don't think there's I don't think uh

I don't think they shouldn't be done I think there is value in them certainly if patients have mainly sensory symptoms and you don't find changes on on the routine studies too so let me ask you a an unrelated question which is if the question is polyneuropathy or GBS uh not that they're the same but a polyneuropathy question or an A GBS problem would you question would you do H reflexes in general in those patients well I'll be interested in your answer but my answer as as I said we we don't I think for a for

a routine poly neuropathy and I know there's data that s suggests they very sensitive but for me because I'm looking at a distal length dependent process I think the routine conduction studies are going to be more useful for me the but the times that I'll consider doing them in a in a GBS or even a a a cidp type of problem is in in a GBS that's sensory predominant or a cisp you know the chronic inflammatory sensory poly radiculopathy where the patients have severe sensory profound sensory loss abent reflexes and the routine studies are all

normal and I'm looking for uh you know a proximal block of uh this the sensory pathway so those would be the and those are rare but those are the times that we'll do them how about you um it is part of our routine workup for a poly neuropathy I'm reminded of what uh Dr Jun Cura uh told me years ago which is um that it and I think this is has been backed up by some uh electrophysiologic research on diabetic neuropathy that loss of the H reflex may be one of the very first features of

diabetic neuropathy maybe even before sensory responses drop at the foot uh so uh you know like the sural or or uh superficial paranal so um we we do do them yeah good well that's interesting well let me show you what we did do here I'm going to show you a couple waveforms um so we did do we we we start with the fibular motor and you can see um what's nice for those who are watching and I'll just mention for those who are listening if you're looking at this green is normal so our nor these

were all within normal values the latency amplitude and induction velocity you would you agree I don't know if you can see that well but yes uh the molt amplitude is uh 4.4 4.8 uh so yes yeah and no and the things that we look for not necessarily in the P patient where we think is a ridicul opathy but looking for similarity and all the things looking for dispersion and block and we don't see any of that here do you perform f-waves uh we do on the uh tibio response but not on the EDB why not

on the EDB unreliable okay well we did on the EDB what do you think about that there's a bit of an artifact here ignore that I don't I'm not sure what that artifactual is is but this is the f-waves would you agree these are reliable there yes okay I agree that in often times we don't get them in the fibular nerve so so do you when you do f-waves let me just ask you this do you look do you interpret them based on absolute latencies or do you do a calculated estimate um we'll do an

estimated uh the staff may do an estimate if there's an abnormality apparent um yes okay so we always calculate our machines are set up to calculate an F estimate based on the the the routine conduction velocity between the knee and the ankle and the distal latency so we assume the conduction times the same in a normal nerve all the way up to the spinal cord and back so we we calculate the estimated latency was 55.8 and it was 54.4 so that that was good and then we did oh go ahead um latency and velocity if

you will um relatively unreliable in a focal lesion because um this is a conduction across a very long distance and uh the abnormality across the very short distance at the root level will be diluted out by the very long normal conduction along the f-wave so um we're more interested yes we look at latency but we're more interested in is it there yeah that's that's a good point and and in fact I'm not sure in this case why f-waves were performed because we've we've changed our protocol in patients and we did this a number of years

ago in patients who are sent for radiculopathy where there's that's the high index of Suspicion so neck pain back pain we stop performing f-waves rout routinely because we we felt that they for the reason you said they're not very sensitive they're not very reliable and we were uncomfortable if the f-wave was just slightly prolonged and that was the only abnormality calling that a radiculopathy so we we do perform them in neuropathy because we're looking for proximal slowing but if it's just a a single limb radiculopathy we often don't perform the f-waves but they were performed

here so and then here's the tibial motor so you think amplitude is 5.3 at the knee 5.8 at the ankle velocity is 47 lat 5.2 it's looking okay to me yeah looks pretty good and then our tibio our tibio F waves were also nice and reliable and within the estimated latency they're interesting in terms of how long they are um yeah this I don't remember seeing f-waves that are so prolonged but um looks like almost like a dispersion yes yeah interest and and yeah this is it is always interesting because as you know f tibio

f waves always are a little bit dispersed probably because you're picking them up from multiple different foot muscles we don't pay attention I know you mentioned June cira who's done a lot with f-waves and and other parameters in terms of f-wave dispersion and we don't look at that and maybe we should that you know measuring out the dispersion and comparing that to to normative data that would be an interesting thing to think about yeah so here's the sural so uh patients 40 years old we perform I don't know if you do this we perform at

three sites a b and c so 7 cmet 14 cm and 21 cm and our reference value for amplitude we use at 14 cmets and it was three microvolts here so this is a an excellent example of what well you may prove me wrong but uh that my technologist would come out and saywell we got a small surl and I would look at this and say there is no surl okay so you think this is just Baseline yes okay I well I think we agree on most things but I'm I'm not sure I agree with

you on this so I think it's it's it's messy I agree with that I think my S looked better than this when I was 40 well yeah I don't think this is Norm I'm not sure this is normal it's the amplitude is three it should be higher than that for a 40y old and and that's interesting because a three microvolt response does come close to the Baseline uh kind of oscillation that we can see yeah but what do you think I mean do you think if you look at these three just look at the you

know the the the latency shift and there is a you know there is a way seems like there's a wave for here in any event at his age it's abnormal yeah would you agree yes yeah I and and what I would do just from a technical standpoint what I would have done they average four to six responses and I would have averaged more I would have probably averaged 10 or 12 just to clean that up make sure that these are real responses but I think those are real okay also I know the case so but

but that doesn't change anything so then they they did the medial plant art here so do would you have done that or just done The Superficial fibular uh well if we were looking for neuropathy uh and we thought the S was there we would do a plantar but um I I'd say that um that in a case where we're looking for a radiculopathy we probably would not have gone to a plantar unless we thought this was a tibial neuropathy in which case then we need to be looking at uh specific tibial related responses okay I

don't think that's there either yeah this one I was just about to ask what do you think about this what what would you grade it an ABC or D or F uh I'd give it an F okay so you don't think there's anything there at all I mean is that a shock artifact that come not a shock artifact but a motor response that it's uh you know that comes after it it's just unreliable yeah and I here I agree with you this this one when the text if our texts are fantastic but we all know

some patients some nerves are tough and there is a large shock artifact and when I when they come out with this I I say I don't like this we need to redo it or try it again and I don't know do you if you I don't know how much you because you have great text too so I don't know how much your hands on doing conductions but do you would your taex or would you have any tip on how to clean this up or may see if it's reliable I think it may be harder to

do um in the foot than it is in and the fingers where you can isolate the fingers and lift them up a little bit so that you're getting less uh volume conduction from uh you know close by uh structures uh I'm not sure how easy it is to isolate at the muel yeah yeah sometimes what I'll suggest is trying to move that stimulator a bit more distal so you're not directly stimulating the fascia or the muscle so it go with distal but that that will drop the amplitude but sometimes that will be enough that gets

rid of some of that shock art effect so you actually can see if there's a a reliable response that's a little tip that might be helpful but I agree these can be difficult um if if if we assume that this is a response it's seven microvolts so again that's kind of borderline for someone his age in our lab if that's real so they did go to the other side to compare like you said earlier and the S on the other side do you believe that one yes okay good and it's 10 the amplitude at B

Point's 10 and it was three on the other on the effect ected side if it was there and they did a medial plant art and looks nice it's 11 microvolts and clearly a nice response there so so that's that's all the conductions they didn't perform superficial fibular centes here just those and they didn't do hes as we discussed so if if you so with this case just what we have now what's going through your mind we have the low Sur and medial plant are but everything else is normal right so I'm a little concerned that

uh S1 tibial sensory fibers are affected on the symptomatic side um it would have been uh interesting to know what the H reflex was on this side uh because that plays into the question of a tibial uh proximal tibial neuropathy or perhaps a tibial neuropathy even uh at the paal FAA but um in any event uh I also think about the possibility that sensory S1 fibers could be affected in a an intraspinal Canal lesion uh such as a ridicul apathy um and uh in my experience that's much less likely than if we're talking about an

L5 and a superficial paranal response where the likelihood of a dorsal gangion an L5 dorsal with gangion in the uh fan or uh internal to the fan or intraspinal much more likely anatomically then the uh S1 drg so that we do see cases of loss of The Superficial paranal response with L5 radiculopathy due to intraspinal lesions but in my experience much less likely uh at the S1 level okay and we haven't brought up plexopathy could this be a sacral plexopathy sure I mean at this point it's anything from uh the exit Zone uh of the

S1 nerve root down through the sacral plexus uh the sciatic nerve uh and Below Tibi okay so if you were going to do your needle exam which we would do can you tell me the muscles that you're anticipating that you're going to examine and I know it depends on what you find but if you kind of are going into this you're thinking these are the muscles I'm likely going to examine uh we usually do our routine and then I'm going to add so uh I start with the tibialis anterior because it's most of leg muscles

it's fairly easily tolerated and the patient gets used to what it feels like to have a needle in a muscle uh then I go to the app Dr halis um because uh that will be a little less comfortable for some people and I don't want the foot to cool off before I uh do that muscle so I would do ta then abductor halis I do the posterior tibialis muscle some people do the flexo jorm longus muscle um I would do gastrus and then an anterior thigh muscle and then I would review well what do I

have um I am if I find abnormality and any of those muscles below the knee uh and with the nerve conduction studies that we have um I'd be needing to do posterior thigh muscles and uh and end up uh in gluteal muscles okay that's good a good yeah and of course it depends like you said on any of these you know I think a good teaching point for everyone especially if someone's new to this is yes we go in with an anticipated idea of these are the muscles I think I'm going to do but that

might shift depending on what I'm finding so it's never a set textbook or cookbook approach uh because sometimes we find things we don't expect to find in muscles so so I'm going to just show you the table of what was done just for the sake of time and want to get into a few points um so our approach and this is interesting when I do these everyone's approaches is a little different so from so we I started with the anterior tibialis which was normal and went to the medog gastr nemus which showed two plus fibrillation

potentials and a mildly long duration here's my plus minus long duration motor units so for me I I wouldn't go down to the foot knowing that the Gast truck's already abnormal to me I don't I wouldn't think that ah would add anything um and then the vastest medialis was normal and then I kind of so my approach kind of Skips the thigh muscles and just goes straight up to the hip girdle muscles knowing that if they're abnormal then I might avoid having to do some additional muscles in the thigh but if they're normal then I

would go back down to the thigh so that's just a little different but in this patient the gluteus maximus showed three plus fibrillation potentials with some mile long duration modium potentials so it's just the G medial gas struck me the tensor F was normal and so the medial Gastro and the gmaac showed a lot of fibs and then I went to the S1 paraspinals and I didn't find any fibrillations and I stuck it three times mean three different sacral levels no around the S1 so but I but I you know very close to S1 but

angling the needle one rostral and codal and Central and then kind of moved a little bit uh because I expected to find them there and I didn't so what how what do you make of all this um well we know the leion is proximal but we don't know where it is proximately it could be at the sacral plexus level uh it could be at the intraspinal level and we haven't been bailed out by the paraspinal muscle to help us localize um what I'm reminded of is some very old literature that tells us that um the

paraspinal muscle inovation can vary up to four to six segments different from the segment that you think is involved and so I would have gone to lower sacral uh levels um and we did a study of single Lumbo cycal radiculopathies and looked at the presence or absence of paraspinal fibrillation in those lesions and we found that there was the least likelihood of finding fibrillation in proven single radiculopathies based on MRI findings the uh paraspinal abnormalities were least likely to be found in somebody with an S1 radiculopathy and the more proximal the lesion the more likely

you would find fibrillation so in other words an L5 lesion uh you could find fibs at the S1 level at the l34 level you'd start there but if it wasn't fibrillating there you'd be going down and so um I think it's uh on us as emgs to make sure we've sampled enough segments uh to convince ourselves that that we've fully assessed the potential level at which the Paras the fibrillation may be occurring so I'm not surprised that there's no fibrillation at the S1 level so I think this is a a fantastic point and really what

I wanted to get at and so you think this is a radiculopathy this is a root problem and it sounds like I'm if I'm putting words in your mouth less likely a plexopathy but and wait a sec okay I won't put words in your mouth um the um the needle exam gets us this far but the ner conduction Studies have to be aligned with there has to be internal consistency among all the data when we make our interpretation and so we still have a mismatch here we've got a a high root levish kind of leion

on needle exam and we've got a uh problem with sensory S1 sensory respon so we have to have to somehow reconcile those two things so how would you Rec reconcile what would you what could you do anything else because this was my predicament in this case this is exactly what was going through my mind what do I what do I think here what do I say in the report is there anything else I can do to clarify this in the EMG lab um I'm not sure I think uh um I'm not sure what we could

do to further Define this Legion knowing the data we have um and we're going to have to be uh careful about how we in make our interpretation in the report how about outside of the EMG lab is there any way we can clarify it well this person is destined to have an MRI scan of the lumbo sacral spine yeah and this and that's that's what they had of and I agree completely there wasn't anything else I could think of but at the L5 S1 level to the left side there's a large extruded fragment here it

might be hard to see but you can see the narrowing yes so that helps it does um I think that um it's hard to deny the likelihood that that could be contributing to the patients's EMG findings and symptoms yeah and I think and of course this is an obvious point but in the context of the the patients history you know a young healthy man not having this continuous Progressive problem with which might make you think of a plexopathy if it was slowly Progressive has a long-standing history of intermittent back pain it sounds ridicul sounds like

an S1 ridicul apathy you have an Imaging so yeah I mean to me this is pretty clear but even in my report what I said I because you can't be entirely sure is I said this is almost you know this is most likely an S1 and while a sacral plexopathy can't be a completely excluded it's much less likely or some wording like that I'm interested in the uh Radiology uh assessment and is this in the lateral recess is this actually invading the fan because is it possible that the drg is affected in this Legion yeah

and that's kind of you know you started alluding to that and and I'm going to just show real quickly you know this whole issue of what you already alluded to and this is this is your paper which you well know and is is cited so much it's a great paper about The Superficial fibular censor response in L5 radiculopathies that can be certainly be affected you presented a number of cases and there have been other studies showing a certain percentage of patients due to the location of the drg um so I you know I think not

everyone knows this but this for those of you watching or listening should know this that The Superficial fibular can be affected in a l fiber dick but what about the sural and an S1 and as you said that doesn't happen very often and there are other papers I'm not going to go through all this but there are are other papers looking at both L5 and S1 showing and I think you alluded to your series to where it's a very small this paper only 2% of patients with S1 radiculopathies had seral involvement and and I think

that's and you talk about this in your discussion I think it has to do with the location of the drg and the S1 drg the S1 root and tell me if if this is in correct but the S1 root when it's affected is usually an L4 L5 disc so it's more proximal to the yes to that or an L5 S1 disc but but that's not where the uh the foraminal exit zone is because that's already in the sacrum um so so it's they're they're not kind of colocalized the the dis Legion and the right and

uh the root right right and I think in that image that I showed you I think I don't have that radiologist report but I suspect that that that drg was affected wherever that drg was located was affected here I think it's a good teaching point for all of us and this is certainly an instructive case for me that at the S1 level if we're going to try to be internally consistent with the data we have and what we know now clinically and radiographically that one would have to say that the S1 sensory fibers were also

affected in this patient yes the the sensory fibers from the drg or distal or distal yeah yeah yeah no I yeah and and I think going back to the point of the paraspinals to be honest the these are the ones these are the cases that I get frustrated kind of with myself that and and it's happened with L5 too where you you know the patient has a prominent L5 ridicul their fibs in all the L5 muscles I go to the L5 paraspinals and I just can't find them and I do stick several different levels and

I think there are several reasons you alluded to the I think the primary reason that that the L5 root where we're putting the needle may not be in the part of the paraspinals that are interated by the Alim root um I think the other things is sometimes people may not tend to go deep enough that the the deeper layers of the muscle may show the fibs and sometimes people are a little scared to go too deep in the paraspinals and get down to the lamin I don't know if you've had that experience yeah so the

so-called multifidus paraspinal muscles are that it said they have more localizing value and um I'm afraid I'm blocking on the name of the Physical Medicine Rehabilitation physician at the University of Michigan who has looked at this and with a number of studies um oh yeah Dr heg who did the perispinal mapping and yes yes his point is that uh go deep young man go deep kind of thing you know yeah and check multiple levels which again it's uncomfortable you don't want to do that to the patient but I think when it's important in this case

cases like this that that you know to check several levels make sure re- angling and but don't be afraid to do that I think is very important yeah so so well well this is wonderful I I I'm glad to pick your brain I know this seemingly you know I think what's interesting is it's a seemingly straightforward case that we see all the time right with we see radiculopathy that's the most common thing we see in our lab but yet you get into it as you said at the beginning and sometimes the data just doesn't fit

the textbook there's some unusual findings that make it more challenging to know to to to to be as comfortable and it's it's important for everyone to be aware the of the variations that can occur in this from the anatomy yes and um I think uh it also points out the fact that we need to be honest about the way we interpret our data that there needs to be internal consistency uh in the data and how we report them and uh we shouldn't be afraid to be uh equivocal or have a differential diagnosis uh from the

EMG as opposed to having to be uh absolutely dogmatic about the diagnosis yes and going back to the very basics of putting the findings in the context of the patient's clinical features and I know if you if you you know there's this movement towards Ai and automatic interpretation of the data and if you threw this data into a machine and said where's the local ation it's going to come out as sacral plexopathy yeah and so you have to take this into the context of the patient absolutely well this has been the best Valentine's Day present

it's better than eating a box of chocolates it's a box of knowledge with with Dr Levan so I I appreciate you taking the time Carrie taking your hour to discuss this it's really wonderful to see you and and always learn from you well it's a pleasure and I think it's the other way around about the learning process uh I learned I've learned more from you than you've learned from me but in any event uh I very much appreciate the opportunity to talk about my favorite subject EMG well great well thanks and next time we see

each other we'll go for a walk and we'll talk about how um Wi-Fi works again or AI or chat GPT we'll figure that one out all right well be well look forward to seeing you thank you thank you byebye well I hope you enjoyed this episode that was really a tremendous discussion and as you heard or saw there are lots of intricacies to evalua in a patient who we suspect has a lumboy radiculopathy uh I always learn from these that there are different approaches Dr Levan performs certain studies that we don't usually rep perform we

perform some that he doesn't perform but I think the most instructive points as we said at the end were that not everything fits the textbook that sometimes um we obtain abnormal sensory studies in L5 or rarely S1 radiculopathies sometimes the perispinal muscles aren't always abnormal and there are reasons for that and it's important to consider that and think about the patient and the findings in the context of the patient as you come to your diagnosis so I hope that this has been helpful uh enjoy learning enjoy thinking about these cases and look forward to next

time byebye [Music]