Ep. 215: Carpal Tunnel Syndrome Detected by Ultrasound

00:00:00: Welcome to EANcast, your weekly source for education research and updates from the European Academy of Neurology.

00:00:15: Thank you very much.

00:00:25: have moved a lot of improvement in the last time.

00:00:35: We just had some other topics about ultrasound and we specifically are oriented to their peripheral system.

00:00:45: I'm Pierre Giorgio Locke now, I am professor of neurology at the university on Hamburg Germany And i perform ultrasound from out-and-inpatient clinics a very important and guest, friend of mine.

00:01:04: He is Stefan Schreiberl Professor of Neurologicality Berlin A very good expert of ultrasound And I would ask him how are you?

00:01:16: Can you tell me something about you Stefan?

00:01:19: Well thank you very much Pia Giorgio for the introduction.

00:01:22: Welcome to The Listeners as You've already heard.

00:01:26: So there's two professors on neurology sitting here today that want to talk about Carpal Tunnel Syndrome.

00:01:32: So in fact, besides working as a general neurologist and being the head consultant of our Neurology department at the District General Hospital, ultrasound has been really one my focus points And I'm actually teaching neurosonology for more than twenty five years within The German Ultrasound Society, the Degum actually currently also as an executive committee member of the World Organization of Neurosynology.

00:02:03: So teaching of ultrasound in all sorts of formats is quite familiar to me, but this one has a podcast.

00:02:10: that's new.

00:02:11: so we have only words and no images.

00:02:14: I'm trying to explain things in detail if you would look onto the screen.

00:02:24: Okay, thank you.

00:02:25: This is very interesting and the sympathetic introduction from you.

00:02:30: I thank you.

00:02:31: And then coming to this topic Can you explain me for listeners?

00:02:37: What is Carpatunus Syndrome?

00:02:40: Yeah i think that's a good Introduction question.

00:02:43: So what are we talking about with this condition?

00:02:46: so it's a chronic chronic disease chronic focal compression neuropathy.

00:02:52: The median nerve is one of the three long nerves running from the brachial plexus to the wrist.

00:03:01: And during its course in the wrist, it runs underneath the transverse carpal ligament or flexor retinaculum and does this together with the flexor tendons.

00:03:13: so these are the tendons that bend your fingers at you wrist.

00:03:17: So actually if try make a fist then you bend your fists You will see those flexors tendons pop out.

00:03:24: For them to not pop out too very strong, there's this retinoculum that prevents you from doing it.

00:03:30: The nerve actually passes underneath the retinaculum and is bent together with these tendons.

00:03:38: so whenever we move our fingers or wrist a nerve is also being moved.

00:03:43: Now imagine in case of overstrain or some local compression or mechanical strain the nerve starts to get symptoms.

00:03:52: And then these kind of symptoms might start with like pyroesthesias, the tingling in the fingers quite frequently at night noctural pyroestersias and affected are those things that provided by the medial nerve which is the palmar surface or thumb index finger middle finger and radial half ring finger.

00:04:15: So these are the kind of sensory symptoms that show up with carpal tunnel syndrome.

00:04:20: and then there also might be motor affection because it's a combined nerve.

00:04:25: This is the tina muscle, so its muscles responsible for opposition in abduction inflection of the thumb...so this may be impaired.

00:04:34: In worst case scenario you have combination of sensory tingling.

00:04:38: painful tingling and muscle weakness quite strongly affect the patient and impair day-to-day activities like gripping, holding objects, fastening buttons or even just leaping through the night because you have these painful sensations in your fingers.

00:04:57: Absolutely!

00:04:58: I understand very clear detailed explanation.

00:05:03: A question for me is one condition that affects a lot of people And moreover do predispone missing factor such as age or other factors that could predispose to the patient who has this syndrome?

00:05:21: Right.

00:05:22: That's a very good question, yes because it is actually really relevant.

00:05:26: about fifteen percent of global population actually suffer from Carpathian syndrome during their lifetime.

00:05:34: It frequently affects middle-aged people, women more than men.

00:05:38: More elderly then the younger patients and there is like an incidence between three to ten cases per one hundred person a year.

00:05:48: so it's quite relevant condition.

00:05:52: And asking the question of risk factors Of course they are.

00:05:57: any mechanical strain Any special work that overactivates your hands and hand function might lead to such a condition.

00:06:08: And in some countries of the world, it's actually recognized as an occupational disease, Carpal Tunnel Syndrome.

00:06:14: It is not only the elderly and not only occupational.

00:06:18: There are also other conditions that predispose to Carpal tunnel syndrome.

00:06:22: So in young female that are pregnant for instance In third trimester there was some fluid retention And that leads to local compression and carpal tunnel syndrome.

00:06:34: There's other conditions like hypothyroidism, diabetes... ...and then a big group also related to carpal tunnels is trauma.

00:06:43: Trauma of course distal arm and wrist trauma in particular because it's so common distal radius fracture.

00:06:51: So this kind of condition we also frequently see carpal tumor syndrome.

00:06:55: Quite interesting, but I have another question.

00:06:59: and if you don't have these patients there are characteristics at risk.

00:07:05: Do we have some red flecks by some patient?

00:07:08: If the young patient or a patient with bilateral carpal tunnel syndrome can explain that?

00:07:14: Bilateral Carpal Tunnel Syndrome.

00:07:17: well then of course it makes us think about conditions some local compression, of course there's some hereditary condition so heredity neuropathy with compression palsies this kind of thing.

00:07:35: There is also conditions that are inflammatory paraphernal nerve disease but might involve in and this kind way and manifest its ways on these fields.

00:07:45: So yes indeed one would think more globally kind of disease rather than a local single compression.

00:07:54: Yes, do it also.

00:07:55: Okay and I mean

00:07:56: is there any systematic condition that could be recognized by this syndrome?

00:08:07: In the young patient or in older patients would be very interesting to suspect.

00:08:14: I remember that in one situation, we just diagnosed amyloidosis but bilaterpatholicin syndrome.

00:08:23: So i think it's very important as to recognize this red flex or mucophilicin.

00:08:30: Yes?

00:08:30: Okay

00:08:33: yes!

00:08:35: Perfect.

00:08:35: now if you have the patient with clinical symptoms and your suspect are you doing?

00:08:44: You're performing examination, an amazing history.

00:08:50: or move to the neurophysiological point of view.

00:08:54: Or make something more.

00:08:56: What is your way to diagnose this

00:08:59: syndrome?".

00:09:01: The approach of course to do it all and, of course we always start with an amnesia.

00:09:06: So We need to talk to the patient listen And see what the complaints are?

00:09:10: If they fit the kind of complains that I was talking about earlier then next step is Clinical clinical look at the patients.

00:09:18: so we don't Start with technical stuff.

00:09:20: if you look at a patient we palpate the tinnitus We test the sensation in their fingers.

00:09:28: there's some special testing their compression test if you want, where try to challenge the nerves.

00:09:34: or the phalanetest is one way that you angulate your hand strongly and see it can cause any tingling in fingers some sensory symptoms.

00:09:44: Or more directly compress retinaculum of Montenelle sign any sensation in the media medianus provided fingers.

00:09:53: so that would be sort of a start off course you look for motor function uc thumb abduction opposition works.

00:10:00: Something like that.

00:10:02: and then the next step infact is still not yet imaging.

00:10:06: it will still be electro physiology, so nerve conduction with the next steps to look or amdin classical carpal tunnel syndrome we expect a slowing of nerve conduction in the nerve conduction studies.

00:10:19: So, that classical electrophysiological parameter is distal motor latency That we measure.

00:10:25: so there's stimulus about six and half centimeters away from the wrist And then you measure time until the muscle twitches and at distal Motor Latency more than four point two milliseconds would be pathological.

00:10:38: There are other conditions We can add?

00:10:45: And the nerve conduction that you can also compare to the ulnar nerve, That runs parallel and of course does not run underneath the retinoculum flexorum.

00:10:55: So it's not affected so we can do side-to-side comparisons... So if the conduction velocity side to side Ulna versus median is more than eight meters per second then with high sensitivity and specificity, differentiate your carpal tunnel syndrome.

00:11:15: And if you have all these things together then of course everything is very suggestive for the carpal tunnels.

00:11:22: but what we do not have at this point?

00:11:25: there's no information or nerve structure nothing.

00:11:28: You don't know where the nerve suffers from a local point.

00:11:31: This is when imaging comes in.

00:11:34: Yes that was the next question because I mean you have all this information, treat a patient.

00:11:42: but you have to add something more and this is that point of I think ultrasound coming.

00:11:50: What do you suggest in these way?

00:11:54: Yes if we talk about imaging of course in medicine classical radiological imaging like x-ray in CT.

00:12:03: That's of no use if we look at soft tissue, so that drops out off the options this MRI imaging that has a problem with spatial resolution In fact.

00:12:14: So it is good for soft tissue but spatial resolution isn't going to be as good and these results are low sensitivity and specificity And actually ends up working on ultrasound.

00:12:24: because an ideal approach to get, look at soft tissues where you need high spatial resolution and when you want...to do..want to get some specific information on a structure like an Earth.

00:12:39: So the next ideal step-to-choose would be ultrasound.

00:12:45: There's some protocol under…you need some probe frequency new models what you suggest for their new user for ultrasound?

00:12:58: Yes, indeed there's some things to consider for the ultrasound system.

00:13:02: So it should be an ultrasound system that is optimized from near field.

00:13:07: in Sonation for nerve isonography we usually use linear probes so do not distort distort the image.

00:13:15: and while comparing two for instance vascular imaging at their neck We have like seven to ten to twelve megahertz probes if we talk about a nerve ultrasound twelve to eighteen or perhaps even upto twenty four megahertz of insulation frequency.

00:13:32: so the higher that frequency are better than spatial resolution but also.

00:13:37: The more near the surface the insinuation depth will get smaller.

00:13:42: and if you do that look at the median nerves then we can quite impressive imaging because, We look at the nerve commonly in the cross-sectional area.

00:13:53: The nerve in a cross sectional area, the median nerve has a nice honeycomb appearance.

00:13:59: so it's still dots that you can see and the dots, the fascicles are surrounded by a hypoechegonic epinorium.

00:14:08: This is actually something important to notice.

00:14:10: So the ultrasound system providers have all sorts of post processing of B mode images.

00:14:17: And what you should make sure is to get nice image of course, but he shouldn't be able with your b-mode post processing just processing.

00:14:26: To see this honeycomb structure.

00:14:28: so some other techniques post processing lead to that?

00:14:32: You don't see any dots anymore But we see stripes or bars instead of the dots do need to adjust that We really got there's a true image and to see the past.

00:14:41: It

00:14:42: was quite interesting.

00:14:43: I mean better for the new users.

00:14:46: Do you think it there is or they needed a lot of experience.

00:14:51: Second, with what kind of science do you see in patients who have kapatuline syndrome?

00:14:59: I mean is there any swelling or other anomalies that you recognize?

00:15:04: Yes actually the lots of structural things we can see from the ultrasound.

00:15:09: but first just say... What are their challenges?

00:15:14: It needs some guidance at the start, and now we cannot show that with images.

00:15:22: We just have to describe it.

00:15:24: but it's quickly to be learned And of course if the ultrasound system has good settings as we've been talking before then its very easy.

00:15:33: If you take your probe which is used for parotid artery incernation Then it might more challenging to see all structures that will talk about right now.

00:15:45: So but it's easy to learn.

00:15:46: so I would say go for it and get a go for And look for the for the nerve ultrasound.

00:15:53: I would encourage you and not stop you.

00:15:55: do that What what?

00:15:58: Do we see in the ultrasound, so and what kind of pathological findings are there?

00:16:03: why Would

00:16:04: we do with the ultrasound In addition to be just clinical and electrophysicological studies?

00:16:09: because this is a lot of things to be seen at the compression sites.

00:16:13: So at the compression site, for instance there's anatomical variations.

00:16:18: The median nerve often is a single nerve on the level of carpal tunnel but sometimes in patients it's already a B-feet nerve so it splits into two branches.

00:16:29: and these cases without the B-feed anatomica variant are frequently prominent.

00:16:36: arteria mediana.

00:16:39: That's anatomical knowledge that perhaps a surgeon might want to know before opening the place and decompressing retinaculum.

00:16:49: More importantly, more important too seeing all these anatomica variations and also pathological conditions near the nerve is the reaction of the nerve through local compression itself.

00:17:01: so nerves if they have local irritation react with swelling, very commonly react with swelling and we see the actual swelling with the ultrasound.

00:17:11: And that's proximal and distal to...to the actual compression site.

00:17:17: for this We have actually normal values.

00:17:20: so we can look at the cross-sectional area and See for instance that from a cross sectional area From a certain number onwards.

00:17:30: This argues in favor of couple tunnel syndrome or not if there is no swelling.

00:17:35: So, do you have some cut-off value that are confirmed by electrophysiological examination or only consider the swelling from this pathological medial nerve compared to other nerve which is your experience?

00:17:54: Yes.

00:17:54: We have normal values but there's a challenge because receiver operating curve, ROC curve.

00:18:04: Let me explain that in detail.

00:18:06: so if we take a cutoff value of for instance twelve square millimeters then almost every patient is symptomatic and has more than twelve square millimetres actually have a carpal tunnel syndrome.

00:18:20: so specificity is really high but sensitivity at the same time it's not very high because have carpal tunnel syndrome with a cross-section area of only eleven square millimeters.

00:18:36: So if we reduce to eleven square millimetres, then specificity gets lower but sensitivity is getting higher.

00:18:45: so A lot people who are with the eleven square mm cross sectional area also have carpa tunnel syndrome depending on what Lab what lab settings are.

00:18:55: most of the lab setting start with a cross-sectional area more than ten or from eleven square millimeters onwards.

00:19:03: As I started that and they add one other additional information, but is called the wrist forearm ratio.

00:19:11: so we do there as we compare the swollen nerve where them all proximal parts off on earth.

00:19:18: So we go to the lower forearm, ten-to-twelve centimeters proximal of the wrist and measure cross sectional area build a ratio.

00:19:27: Usually that should be around one.

00:19:29: so it doesn't change a lot between the forearm in the cross sectioned area on the wrist.

00:19:35: In pathological conditions if the ratio is more than And you have the cutoff level of eleven square millimeters, then You get a very high sensitivity and specificity.

00:19:49: Applying these to that cross-sectional area and the wrist forearm ratio we are reaching with ultrasound Sensitivity in specificity up to ninety percent.

00:19:58: So that's for diagnostic modality.

00:20:00: quite good

00:20:03: Very clear explanation.

00:20:05: I would think all These information to get together with the clinical context and electrophoresiological examinations as well.

00:20:17: But did you have any surprises when you are doing ultrasound?

00:20:22: And do you discover other pathological condition outside the carpal tunnel syndrome?

00:20:30: or I had another question for me, Do we ever some protocol that combine in your examination the nerve and muscle?

00:20:43: Yes, we actually have not yet spoken about sort of local protocol.

00:20:49: And that involves answering this question.

00:20:52: so perhaps for those to understand how For carpal tunnel, I would study the patient in a sitting position so that they could sit in front of me.

00:21:06: The patients have supporting cushions on their lap and the hands and wrists are resting under support cushions.

00:21:14: And then my protocol is not starting with nerves but muscle.

00:21:19: Why?

00:21:20: Because muscle is sort of substitute for EMG because if there's relevant axonal Damage the muscle changes and alters.

00:21:31: of course there's atrophy in this condition.

00:21:33: we already talked about atrophy, but also an axonal damage.

00:21:37: There is changes in equinicity or the muscles so the muscle gets brighter.

00:21:42: So I get a quick idea.

00:21:44: if looking at the muscle that Tina mussel hyperic organic changes on not as indirect science off axonal damaged And then i just change to the nerve.

00:21:54: And then where would you start identify the nerves?

00:21:58: so reading about it a lot recommend to look at the nerve and started perform because they are.

00:22:04: the nerf is nicely visible between the flexor muscles flex or digitorum superficial superficiales in profundus.

00:22:12: The muscles are relatively dark, and there's no with honeycomb structures bright.

00:22:18: I myself really start directly at the kappa tunnel level, and then i'm actually following the nerve.

00:22:27: I am looking for swelling on my wrist more distally but not stopping there although the question is only kappa-tunnel.

00:22:45: close to the axilla.

00:22:46: of course it's easy to follow the nerve and then talking about surprises.

00:22:50: yes one can get surprises because sometimes well we have inflammatory neuropathies where you swelling of the nerve, not at the carpal tunnel.

00:23:00: There's everything fine but you see swelling in a non-compression site.

00:23:04: so we're talking about neuralgia that go along with nerve swellings.

00:23:08: and yes this kind of surprise might show up!

00:23:12: Of course you do NOT want to operate somebody on Carpal Tunnel Syndrome if the problem is actually inflammatory.

00:23:20: Interesting clear explanation.

00:23:22: I mean, without images you explain to us how can we do really very good protocol and overview of the nerve more?

00:23:32: And is there any new development of ultrasound in less time that could be showed by or described shortly?

00:23:42: Yes!

00:23:42: There's this development going on although i want start with something important.

00:23:49: Before we talk about the new developments, we should really keep in mind that not even every patient goes for operation gets actually imaging with the ultrasound.

00:24:03: So imagine any other operation from Carpal tunnel.

00:24:06: would you let the surgeon operate on without having done any prior imaging?

00:24:11: I think not.

00:24:12: And that's something we should also get into practice for our patients, so there is even in this very basic approach to do it... ...something to be done!

00:24:22: But now the question of any new developments?

00:24:25: Of course there are lots interesting developments going on related to new techniques available and new ultrasound techniques.

00:24:36: So you can actually check for the rigidity And that's also something you can apply to the nerve.

00:24:44: So an affected nerve will have a sort of change in hardness, and it is possible to visualise with ultrasound approach.

00:24:53: if we have an astrography feature then there are some effects on the nerves usually changes in vascularisation.

00:25:02: so new modes of vascular imaging color flow imaging that allows more easily and more impressive vascularization in this region.

00:25:15: And perhaps even more important is the very common nowadays popping up keyword artificial intelligence, and of course artificial intelligence will be relevant to image processing and image evaluation.

00:25:34: And so far our measurement of whether the nerve is swollen or not, it's still manually.

00:25:40: So we encircle the hypoacheginic nerve with a honeycomb structure.

00:25:45: We do NOT include the hyper echoginic epinaurium which just stay underneath when you do it manually without trackball!

00:25:54: So AI will be really great help to these kind of image analysis and make much easier measure cross-sectional area.

00:26:04: However, so far into my awareness there's no commercial machine that is sort of directly applying this kind of AI image analysis.

00:26:14: but it will come and be a great help.

00:26:17: Perhaps also the combination of image processing on one side, together perhaps to put in with clinical information.

00:26:27: In such an AI system I could give them clinical information and I can give electrophysiological information... ...and imaging of the nerve.

00:26:34: that might help get more focused and individualized decision strategies for what to do to do conservative treatment or interventional treatments?

00:26:48: Absolutely correct and I will thank you for your clear explanation.

00:26:54: So if i just summarize what we have spoken about, carpattuna syndrome is a very often condition affect fast five persons Of the population of fifteen, depends on their age.

00:27:10: There are characteristic risk populations but we have to look after red flecks in Capatumna syndrome and not only based on clinical history but also examination and electrophysiology.

00:27:25: We've another possibility is ultrasound.

00:27:30: The ultrasound can be done in the diagnosis and then after therapy to control work of the operator, if the carpal tunnel syndrome is operated as well.

00:27:46: As a new neurologist we have two...to be curious!

00:27:52: To see the anatomy.

00:27:53: there are more possibilities for the future from Alprasandre.

00:27:56: I would thank you Stefan For your very clear discussion and of course, Ian.

00:28:05: And I hope that with this podcast new inputs for the ultrasound came to us.

00:28:12: Bye-bye!

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