Clinical Edge - 104. Peripheral nerve sensitisation & neural tissue pain disorders with Dr Toby Hall Clinical Edge - 104. Peripheral nerve sensitisation & neural tissue pain disorders with Dr Toby Hall

104. Peripheral nerve sensitisation & neural tissue pain disorders with Dr Toby Hall

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David: Let's talk about language, first off. So when we're describing neural tissue problems, how do you tend to think of it broadly or how would you describe it?

Toby: Well, that's a good question. There's so many different ways that people describe nerve disorders. We've developed a classification system over the years based a little bit on Bob Elvey's works originally. Bob was one of the foremost people in terms of developing neural assessments and ideas about treatments for neural tissue disorders. But he didn't really have a very firm classification system that was written down. So, Axel Schäfer did his PhD at Curtin University with me quite a few years ago and we wrote a paper in 2007 with Kathy Briffa, which was showing the classification of broadly neural disorders into three categories.

So we had those that have really severe neuropathic disorders and things like complex regional pain syndrome and specific types of that. And then we had the second group, which is more of a neurological compromise, something like a radiculopathy or carpal tunnel syndrome, some sort of compressive neuropathy and where there's hard neurological conduction loss.

And then a third group where there's more of a sensitisation of the nervous system, an inflammatory sensitisation where the nerve is sensitive to movement. It becomes mechanosensitive. So that's how we like to broadly categorise them based on their treatment intervention. So we decide which group the patient's in based on what we're going to do to that patient. It's for that purposes. We think we get different effects by treating the patients in different ways.

David: I'm really looking forward to exploring that treatment and how each of these areas affect or impact and that sort of thing. So I think we got some really great stuff to explore there. Okay, so you sort of break it into those three different categories, and so where it would be a good place to start, do you think?

Toby: Well, I would start in the more important one, which is the truly severe end of the neuropathic scale. We use a tool called LANSS scale. It's a questionnaire. It's called the Leeds assessments of neuropathic symptoms or signs. It's developed by a doctor in Leeds in the UK to help to screen for neuropathic pain. And it's what we used in our original research with Axel Schäfer to help to identify those people with the more severe forms of neural disorders.

Actually, we wrote an app and you can download an app now, it's on the... wherever you download... the app store, that's what it's called. So you can download this app called the LANSS and it gives you a way of trying to identify a possible patient. And you can do it on paper as well. It's translated with many languages, so it's available around the world. And this is probably not the most ideal tool. Now there's few more different ways of assessing patients using questionnaires - the painDETECT, and the DN4, and all sorts of other ways to do it. But because we're using the research, that's the way that we use in clinical practice.

So if you've got these unusual features in your arm or leg, you got burning, shooting, stabbing, electrical pain into your leg, you've got allodynia in the course of the distribution of the pain into your leg or arm or wherever the pain is, if you've got allodynia on testing the patient with light touch with cotton wool, if you've got hypersensitivity on touching a patient with a pen, these are the features that we look for that would give you a score of probably 12 or more, which would be a positive test for the LANSS. So if that's the case, then I would say, "Well, look, this patient's got a more severe neural disorder. I think we should treat this patient in a different way. But perhaps manual therapy, perhaps even exercise is not going to be suitable for this patient at this point.

And maybe we need to look at try to calm it down the nervous system." So that's why we would look for that, first of all. If that's negative, and we did a study in Germany, it’s Axel Schäfer who undertook it. He had 77 patients with leg pain and he evaluated them with this system and he found that about 25% of them fell into each category. So 25% of them had a positive LANSS. So it tells you that in a German pain clinic, you're going to have a certain proportion of people with that. If you're working in a private clinic or if you work for a sports team, it's probably going to be completely different, but just to give you some idea.

Then if the LANSS is negative, the next thing I would look for would be any conduction block. So if you've got a lack of conduction, you got anaesthesia, you've got reduced sensation, you've got true myotomal weakness or muscle weakness because of conduction block, then I would put you into a compressive neuropathy group. And for those groups, I think we can do something in terms of manual therapy and exercise and there seems to be some evidence that we can, so I would go towards treatment for that. Now, that would be the second group.

Now, if they have a negative LANSS, if they have normal conduction but they've got pain associated with neurodynamic tests and those palpation, then I would say, well the nervous system seems to be mechanosensitive and that we need to treat that with some techniques to help to desensitise and there's all sorts of ways we could do that. We could do that through different means and even drugs, I'm sure, could be helpful for that. But it's kind of a hierarchical system.

First, you need to look for the most important thing. If that's negative, you next look for the most important thing, which is the conduction, and the next important thing is evidence of mechanosensitivity. Now it doesn't mean to say that the patient comes to the clinic, couldn't have all three, but you would put them into the most important category, the first one. So it's this audit system, I think, that is important. And we did some research too to show that there is some validity in terms of the classification and that the patients responded differently to different treats. We could probably talk about that a little bit later, but I think that there is some evidence based on Axel's work that the system has some, first of all, reliability but also some validity.

David: So does everyone that come into clinic get the LANSS or do you use it for specific patients and when do you sort of use it?

Toby: Yeah, that's a good question. I wouldn't use it for most patients. So if your patient's localised back pain, to be honest, I wouldn't do it. If they've got a localised shoulder pain, you wouldn't do it. But if the patient's got severe symptoms, which are unusual in nature and they're talking about things like ants crawling on the skin or water trickling down their arm or burning, shooting, electrical stepping, those dysesthesias, that's a bit of a warning signal.

If a patient got more continuous pain that fluctuates for no good reason, they've got spontaneous pain into their arm or leg, wherever the pain is, then that's another warning signal as well. So those are the things that I would look for and again, they're pretty unusual. But if you're dealing with people after trauma, the classic one is after a whiplash, then you're probably going to see quite a few of those people that it might be worth doing.

There's also some evidence that Bob Nee did his PhD in Queensland and he did a study looking at whether the LANSS was predictive of treatment outcome and he found that if you've got cervical brachial pain with a positive LANSS, then you have less likelihood of having a positive outcome with some manual therapy and exercise. So I think it can be useful, but in the clinic, you'd probably want to prioritise where you should spend your time and if you don't have those unusual features or the more severe forms of pain, then I think you could probably not bother with it.

David: And so do you tend to use it when you'd go through your subjective, if they start to report those signs, do you then give them that LANSS or when at what point in time would you give it to them?

Toby: Yeah, I do it early. If you're filling in their body chart and they've got this unusual presentation of pain, then I would get them to complete that at that point. There's two parts of the LANSS that are part of the neurological assessment. So there's two aspects. You look at allodynia with some cotton wool and the distribution of their pain and if they get an exaggerated pain response with that, that would tell you that that would be a positive aspect of that. And you could also use a pin and look for punctate hyperalgesia in the distribution of that pain as well. So there's a few questions and there's also two parts of the neurological examination that you use to assess for the LANSS.

David: And using those results to categorise them into one of those three categories there that you mentioned and then that's helping you to identify if they're in that...

Toby: First category.

David: First category there, then you're not going to use your manual therapy. You said calm down the nervous system there.

Toby: There is some evidence that I'm aware of, at least three studies showing that if you're positive in the LANSS, then you're unlikely to respond to manual therapy and exercise. A study that Bob Nee did where he found that every positive LANSS, he didn't respond so well. Only 10% of patients responded who had a positive LANSS together with a couple of other things. It's not just the only feature, but it helped to direct the outcome. And a study by Axel Schäfer showed that if you had a positive LANSS, only a small proportion of patients responded to neural mobilisation techniques and exercises.

So I think it helps you to be a bit more careful about who you should treat and we don't just give those treatments to everybody. In the past, we used to give neural mobilisation to everybody who came into the clinic. We all go through these errors in physiotherapy. I can remember when I first graduated, it was the joint tear and we used Maitland mobilisation on everybody, then came the neural error and everybody got neural mobilisations with the work of David Butler, and Bob Elvey, and Michael Shacklock. And now I think we're a bit more educated and we know that we have to be a bit more selective and we have to examine the patient a bit more carefully to know what they need and now we're chucking away manual therapy completely anyway, so that's another discussion.

David: Yes, indeed. That's just like you're using more of that, you're identifying the patients that are more likely to respond to it and then using it in those sort of patients rather than just giving that willy nilly.

Toby: Yes, I think so. We still got a lot to know in terms of when these sorts of treatments are going to be effective, but I think we have some preliminary information and we need to build on that and use that in the clinic.

David: Yeah. And you mentioned there if they've got a positive LANSS. So what's a positive LANSS?

Toby: A positive would be just 12 or more. You got a scoring system on the app or you got a score system on the questionnaire. So each question has a slightly different weighting. So if you have all these questions positive, then it's clearly going to be well above that 12 cutoff point. Anything less than 12 would be a negative LANSS, on the negative, and so you don't need to worry about it.

So if you don't have burning pain, if you don't have allodynia, if you don't have shooting pains into the leg, if you don't have any changes in sensation and the painful limb in terms of maybe heat, some people say that their leg feels hot and burning or their leg is red or pink. It's got some sort of autonomic feature to the problem. So these are the classic features for the positive LANSS. So if they don't have any of those features, it would be unlikely that they have a positive test and it would be less than 12. If you're not sure, you can use the app or you can use the paper-based questionnaire. David: Now, when you're looking at that second category, you're looking at that neural compromise, what are some examples of some of the clinical things that people might see or that fit into that category?

Toby: So the second one, the compressive neuropathy, this is the classic carpal tunnel syndrome, your classic radiculopathy, tarsal tunnel syndrome. There's all sorts of tunnel syndrome out there that we've talked about, but the most common would be carpal tunnel syndrome. But the more common there I think is a spinal related nerve root problem where it's being compressed. Disc prolapse. We're talking about patients with spinal stenosis.

There's some sort of compressive disorder which is altering the conduction of the nerve, which means you're getting anaesthesia or reduced sensations. You're getting weakness, which is in the spine would be myotomal and in the periphery would be related to that nerve innovation territory. So those are the classic features. It's alter conduction, basically. Some compressive disorder... I mean, there are some nasty problems that cause altar conduction, so we always got to be mindful of red flags. But the main part where we're thinking about compression in the spine, disc prolapse, spinal stenosis.

David: And then when you're looking at your third category of sensitisation, what sort of things fit into that area?

Toby: Well, this is again, usually, most commonly affected from the spine, in my view, I think, and typically it's associated with some sort of degenerative process. You see it most commonly in people who've got some sort of internal disruption of the disc. That's what I'm surmising. There's fissures and there's all sorts of bad chemicals leaking out of the inflamed internally disrupted disc and those chemicals leak onto the nerve root and cause the nerve root to swell and become inflamed. And we know this is the most common cause of radiating pain with the leg radicular pain, much more common than a true radiculopathy where we've got some sort of compressive disorder.

So there are some sort of change at the nerve root because of this inflammatory process commonly coming from some abnormal disc, maybe also from some degenerative facet joint. I'm sure there are different causes for these chemicals to irritate the nerve root. And once that nerve root becomes inflamed, it becomes abnormal to move.

But it's not just the nerve root, it could be that your median nerve becomes inflamed within the carpal tunnel. It could be that you're ulnar nerve is inflamed in the cubital tunnel at the elbow. There's also places where nerves can become irritated and inflamed because of some sort of adjacent problem. And when you think about the patients who've had torn hamstrings who develop citing nerve sensitisation following their hamstring injury, there's all sorts of places where nerves can become inflamed secondary to some other problem.

David: Oftentimes, you find that with this area of sensitisation that it happens up closer to the spine. It can be related to some of those inflammatory or degenerative processes up at the spine, but it can also happen further at the periphery, like they restore the elbow or the knee or hamstring or something like that.

Toby: Yes, exactly. And that then becomes the difficulty because you have this middle aged patient who's got features of carpal tunnel and also cervical spondylosis, cervical features maybe where the nerve roots are affected in the neck and it's hard to know which is the primary driver for the patient's problem. And maybe there's a combination of different features that need to be addressed in that patient.

And it's not possible to identify a single origin for the inflammatory change affecting the nerve. But the nerve would be altered and if you have a cervical problem, it could affect the roots that contribute to the median nerve just as much as the carpal tunnel can affect the median nerve. Now, if you were to do a neurodynamic test and both of those situations, you would find a positive neurodynamic test and it would be impossible to know which one is the origin for the patient, which is the source of the problem, but you have a positive neurodynamic test.

David: I think that gives us a good idea about that. So you're going to get those positive results regardless of where if it is further out in the periphery or you know more centrally.

Toby: Yes, I think so. And you know, I think some people try to differentiate the origin by altering the sequence of testing and things like that. But I'm not so sure that we have information that can show that that's the case, that the sequencing can give as much of a clue about how we can identify the origin of the patient's problem.

David: And so just within what you were just talking about that you mentioned radiculopathy, fitting into the more like compressive category, and then your radicular pain fitting into more of the sensitisation. Just so if people aren't familiar with those terms and what they might involve, tell us a little bit about what's involved in each of those and how you can differentiate them.

Toby: Yeah. So the classic case for radiculopathy is patient should have or must have, to be a true radiculopathy, they must have altered conduction. So they must have weakness of the muscle or some altered sensation into a dermatome. So that's why we have to do a very thorough and comprehensive neurological evaluation on every patient with referred pain to the leg because there are some studies to show that we're not very good at identifying people who have neurological compromise just based on the pain distribution.

You'd say, well if you've got leg pain that's traveling down your leg all the way down to your foot, then you've got a nerve compression disorder. But if you've got proximal pain, you've got a somatic referred pain disorder. But evidence shows that that's not necessarily the case that we can do that, so we have to do a comprehensive neurological involving testing reflexes, testing sensation, testing muscle power, and those are the important features that we need to identify for a true radiculopathy.

Now, if we have normal conduction but we got a positive neurodynamic test, a straight leg raise test is positive and it reproduces the patient's leg pain, then that can be altered by some sort of structural differentiation, for example, by a dorsiflexion.

Then you could say, well, it's more likely that the pain is arising from the nerve root radicular pain, so that's abnormal sensitivity, mechanosensitivity, which I would classify as peripheral nerve sensitisation.

First of all, neurological. Neurological is normal. It's definitely not radiculopathy. Do they have any tests when we stress the nerve root? Yes, they have positive tests stressing the nerve root, must be a radicular pain disorder.

David: And so somatic referred pain, is that a thing? I mean, how does that fit into it?

Toby: That's a good question, isn't it, because you do get patients who have pain in the leg arising from the disc itself? The disc is a nociceptive source. It's been shown in research that when you stimulate the disc, you can have projecting pain to the leg irrespective of the nerve root involvement. Also, we know that the nerve tissue, the connective tissue of a nerve, the epineurium, the perineurium, the endoneurium, they're all innovated by the nervi nervorum the nerve to itself, the nerve to the nerve.

So if a nerve is inflamed, then the nervi nervorum would become sensitised and could be a source of somatic pain. So you kind of have a somatic pain disorder of a peripheral nerve or nerve root. It's a little bit confusing because the pain is coming or the nociception is coming from the connective tissue of the nerve. So it's not truly a neuropathic disorder, but it is affecting the nerve itself. Some people include that within peripheral and neuropathic pain, but I think it's probably important to differentiate that from a truly neuropathic disorder.

So I would say that if you've got an inflamed peripheral nerve or nerve root that that would fall under somatic pain because the pain is most likely to be arising from the nervi nervorum. It is quite complex. It's difficult to truly say that because it is also possible that inflammation can invade a nerve and affect the axons themselves and once that gets into the axon, the axon becomes abnormal and the axon develops mechanosensitivity.

You've got axonal mechanical sensitivity. You've got inflammation affecting the nervi nervorum and these are all different situations that can be on the periphery and they're out of neuropathic pain. They're not truly a neuropathic disorder because the nerve is not altered in this conduction. And that's the definition from the International Association for the Study of Pain. They have a series of means of identifying neuropathic disorders and one of the important things is some kind of altered conduction of the nerve.

David: So somatic referred pain doesn't have any of that altered conduction of the nerve. What sort of symptoms might they report with that?

Toby: Well, that's a good point. In the past, again, we used to think that we could differentiate somatic referred pain from radicular pain, but I don't think we can more often. And there are studies to show that perhaps only 30% of people with radiculopathy have a distinct pattern of pain, we used that as described in the textbooks. If you look in orthopedic textbooks, they show that radiculopathy pain has got a distinct pattern, but that's not the case based on studies of large samples of people with radiculopathy. It does occur in some people, but in others, it can be quite different and it's outside of typical dermatome or it's not even dermatome at all.

David: As opposed to radicular pain, does that tend to be dermatomal?

Toby: Well, again, no, I don't think it has to be. It can be, but it's not always the case that it's following a typical distribution. David: It's a tricky area, isn't it? Like there seems to be a lot of variation between people with dermatomes and which areas, by the sounds of it here, are getting irritated or inflamed and so that causes lots of different patterns.

Toby: I think so. I think that's what's the issue is. It's not a simple thing. It's not black and white. It's not easy to just say well, this is the situation of the patient because we also don't really know. I mean, we look at imaging and we look at nerve conduction studies and these aren't always clear cut either, that they're necessarily helpful in terms of diagnosis.

David: When you're looking at different nerves, I think that really nicely summarises the different types of pain and the different presentations that people might have. So when we're looking at sort of factors that might be leading up to some of this irritation, what are some of the common things that you think, you've mentioned there degeneration, and you mentioned fissures, and some of those sort of factors, but are there any other sort of mechanical factors you can often relate it to? Because, yeah, you look at different patients that come in and they might perform tasks that put their nerves under a sustained or repeated compressive loads and others that do the same thing that are painful that don't. So is there something that we can relate mechanisms of injury to?

Toby: That's a good question isn't it? You know, people say, "Look, I've been doing this activity all my life. Why I've suddenly now got pain? You're telling me that I've done something to my nerve and that's the problem. But how can that occur?" I think there are many factors involved in why nerves become inflamed. Repetitive loading.

The classic one is a middle aged person who decides that it's good whether and they're going to go out and clean all the windows that they haven't been doing for the last six months and they do all the windows in the house over the weekend and on Monday morning, they've got this pain going down their arm. That's a classic example where, just as same as for any musculoskeletal disorder, you can cause irritation and the development of inflammation because of repetitive stress on a nerve. Maybe they've got some osteophyte or they've got some small prolapse which is causing some irritation of a nerve, but the repetitive movement of the arm or the leg causes that to then develop into a more inflammatory reaction.

And that explains why it also settled down quite quickly as well because once that reaction is reduced, the symptoms tend to settle over time. It's easy to understand how it is associated with some sort of soft tissue lesion as well from an inflammatory reaction.

And we think about tennis elbow is lateral epicondylalgia as a good example where inflammatory chemicals from the tendon and the insertion of the tendon can cause changes to the adjacent radial nerve, for example. Or the golfer who does a lot of golfing and maybe hits the ground a few too many times and stress goes to the medial epicondyle, which causes an inflammatory reaction. Initially, they have some localised soft tissue problem, but then that spreads to inflammation of the ulnar nerve. So there's all sorts of situations that you can think of where there's abnormal stress that the body's not used to, which causes some changes to the nerve.

David: When you're looking at patients that are coming in, and you mentioned there are a couple of really good examples, someone that's been cleaning the window, they've been out on the weekend and doing some unaccustomed load, spending the whole looking up, painting the ceiling or cleaning the windows or playing golf more or that sort of thing that can irritate it. And also, you mentioned there that chemical irritation from overload of the local structures there. So are there any sort of, within the subjective history, anything that you'll often look out for to help to guide you towards understanding that there is some sort of nerve sensitisation or compressive irritation going on?

Toby: I think it can be difficult. So one thing we're talking about when we're talking about spinal related problems, we're talking about referred pain into the limb. So if a patient has referred pain into the limb, I think I have to routinely look for neural involvement. I couldn't say for sure whether there was going to be a neural problem. And we did a study a long time ago with Bob Elvey and we had 200 patients with chronic shoulder region pain and we examined them all for the presence of neural problems. And I think we found that about two-thirds of them had some signs. Some of them were minor signs, some of them were quite significant signs, but a lot of them had localised shoulder pain and they'd been told that they'd had a shoulder problem. But when we examined them, we found significant features of sensitisation in some of them, not in all of them.

And I think you sometimes have to do a broad screening of your patient. And we have some quick screening tests that we use to help to identify the presence of, for example, mechanosensitivity at the neural tissue and what I call peripheral nerve sensitisation. So I would use those quick screening tests. If they're negative, forget about it. If they're positive, maybe we should do some more tests. Those further tests say oh, well, there's nothing here so we can just focus on the other parts of the examination.

David: Any sort of other subjective clues? You mentioned that it sometimes can be a little bit hard to tell, but are there anything where you... you mentioned before as well that if they start to report that they've got any burning, shooting, allodynia, and that sort of thing that you're going to run a LANSS on them. Are there any sort of other clues within the history that you're looking for to help to identify that there could be some other peripheral nerve sensitisation or some other sensitisation or compressive lesions?

Toby: Yeah. Well, a classic one would be parasthesia, altered sensation, numbness, tingling, those sorts of things. If a patient says I've got medial elbow pain and that the pain radiates towards the medial aspect of my wrist and I've got some tingling in my little finger, then clearly that's going to be something that we'll need to evaluate in terms of some compressive disorder.

If the patient has pain that radiates, I think you would suspect that there is some possible neural problem and you need to examine for it. But it's not always the case that that's going to be neural related. A lot of patients have got arm symptoms or leg symptoms, but they're not always going to be in your problem. We have to have a broad examination to determine what the cause of the problem is. So broad based pain in a limb makes you think more about the neural system. Pain traveling along the course of the nerve makes you think about more of the neural system. Paraesthesia, anaesthesia, heaviness, tingling, those sorts of features, they give you some clues. Altered sensations in terms of hot, cold, any of that kind of symptom means you should examine a little bit more.

David: And with any sort of aggravating or easing things that are commonly reported to you?

Toby: Well, if you've got a mechanosensitive disorder, then movements that tend to elongate the course of nerve would be painful. So shoulder elevation it's going to be causing some stress to the brachial plexus. If you've got a sensitised plexus, then anything involving adduction particularly or elevation of the arm would be painful and maybe rotating the arm would be less painful. So anything that puts the nerve under tension is going to be a problem.

Having said that, if you got severe sensitisation of a nerve, even small movements of the nerve can be very painful. So you think about a patient with a radicular pain, when it's very severe, even small movements can be very painful and sitting can be a big problem for patients with radicular pain. But that can also be a problem for a patient with hamstring tendinopathy. If you've got tendinopathy approximately and your hamstring and sitting is painful, you need to look for the neural system, but equally likely, it could be that they've got some local pathology in a tendon.

It raises more examination but just need to be really mindful that we're not looking at very minor signs in those patients. If you can't sit because you got severe buttock pain and you got some minor limitation of neural tissue, then I think you should be looking somewhere else. So always keep in mind that keep the relative information from the examination in terms of the severity of the problem.

David: I think you brought up a really nice point there about having a hypothesis or a differential diagnosis in mind as you're going through it and okay, just because they got this sort of broad based pain through their buttock when they're sitting that you're keeping a number of different structures in mind that you'll be testing for and screening throughout your examination.

Toby: That's very true.

David: When you look at those aggravating things they'll often report, you mentioned there putting those nerves in a lengthened position can be irritating for them, like shoulder elevation, abduction and I think that's some really good clues. Is there any sort of easing factors that people commonly report?

Toby: Let me tell you a story about myself. I had a very severe radiculopathy a couple of years ago and I was lifting a weight at home and I lifted this weight up and I felt something going what I thought was my hip and I was plodding around in my hip thinking I've got some sort of trigger point there. But the next day when I woke up, I was shifted away from my leg pain with my back shifted towards the opposite side and I had this severe pain going down my leg to my knee. That time, I also developed significant weakness of my quads and numbness around my knees.

So I think I had a classic L3 radiculopathy and I can tell you, it was extremely painful, from the most painful things I've ever had in my life. I couldn't sleep at night and I can really understand why a patient with that disorder will end up going to a casualty department because it's so severe. I knew what the problem was. I knew what I should do. So I tried to position myself to get some relief, but it took so long for the relief to occur that I was always already trying to change again to try and find another position. So for a patient at night, trying to find some position of ease, you get into a position, it might take you 10 minutes before the pain would start to subside, by which time you've already changed because you found that nothing has changed with that position. So I think it can be very difficult for patients to find positions of ease.

Some people do find that you know when you've got a sensitised brachial plexus, you will tend to elevate the shoulder girdle. You might laterally flex the neck to one side. If you got a nerve root sensitisation disorder, you might shift your body towards that side, take the tension off the sciatic nerve by plantar flexing the foot, by flexing the knee a little bit, some classic unloading position. But I think a lot of patients don't find those by themselves.

And the classic one that you see in patients with the neck is when the patient's sitting in the waiting room with their hand on top of the head. They've got this severe radiating arm pain and they found by chance that when they have the hand on top of their head, their arm pain is relieved. So some people do find antalgic positions by chance, but not always the case. Those tend to only occur when patients have got more severe neural disorders anyway. If you had an intermittent problem, you probably wouldn't look for any of that.

David: And what about 24-hour patterns? Have you noticed anything there that correlates that will help to guide you towards more of a neural tissue involvement?

Toby: I don't think there's a direct pattern for 24 hours. I think it's really related to stress, on the nerve, mechanical stress. So anything that puts some focal pressure onto the painful nerve or anything that elongates that painful nerve would likely to be more painful. When you get up in the morning, if you've not been moving all night, you're likely to have more significant problems. But that might wear off a little bit with movement. So the more you move, the better for people like that. But I don't think there's a distinct pattern for the daytime other than that.

David: And any other subjective clues that you look for?

Toby: I don't think there is anything else I particularly look for that springs to mind. I think that's subjectively and it's the nature of the pain itself, the LANSS features that we talked about, the presence of anaesthesia and dysesthesias and those sorts of things. And spontaneous pain is an important one for the more severe forms of a neural disorder. But from a mechanosensitive point of view, for peripheral nerve sensitisation, I don't think there's anything that springs out. David: And when you come back to, just for a second, you mentioned there mechanism of onset and we were talking about it before, do you always need some sort of a mechanism of onset?

Are you looking for a sudden onset or will a gradual onset still be associated with it or what's your sort of mechanism onset that you're looking for an association? Toby: I think a lot of times, there is a gradual onset where there's no known reason for why these symptoms develop. So I think it can be a slowly developing inflammatory process that can occur. Clearly, it could have a traumatic event that set the whole process off, but I think more often than not, we're talking about degenerative process in many of the patients we see in the day to day clinic where they've had this gradual onset of symptoms not necessarily associated with a specific event and that's caused their inflammatory reaction to occur, which has then created these symptoms and abnormal sensitivity.

David: Okay. So just because they don't have that sort of sudden onset, it can still be included in your potential list of hypotheses or diagnoses.

Toby: Definitely, yeah.

David: If we move on to the objective, because I think there's so much to explore within this, so tell us a little bit to start with, if we're working through that objective for someone where you suspect from their subjective they had these signs and symptoms that were related to, what you suspect may be neural tissue related, whether that's a compressive or some sort of sensitisation? When we look at the observation, what sort of things might we be seeing with some of these patients? And you mentioned there are a couple. You mentioned that the patient might be waiting in the waiting room with their hand on top of the head. It could indicate that they found that as a comfortable position. Anything else that you might see when you're looking observation-wise? Toby: I think the observation move is that important, but postural evaluation sometimes can give you very little information unless they're really severe. If they've got a severe pain disorder, they're going to naturally adopt an antalgic position and it will be pretty obvious.

I think that if you've got significant sensitisation, you're trying to shorten the course of the nerve and take the tension off it. If you got a compressive disorder, if you got some sort of large prolapse that's compressing the nerve root, that's very painful, then you would try to unload that and put your spine into a lateral shift position, which will try to increase the space around the nerve roots in the acute situation.

That can give you some clues straight away. If you got right leg pain and the patient shifted with their shoulders towards the opposite side, then you're thinking that they probably got some sort of compressive disorder. Should we then look at the movements that provoke the symptoms involving compression? And then if the patient shifted towards the leg pain, then maybe we should think about a sensitisation problem, maybe where we're going to test the movements to elongate the nerve tissue. Now, it could be that those further tests show nothing, but it gives you a starting point of where to start.

David: Okay. Yeah, that's good. So sometimes, posture will give you something and oftentimes, it doesn't give you a lot. You're looking for some of those aspects that might tell you whether they've got that compressive or sensitisation depending on whether they're shifted towards or away, which makes sense. Anything else that you might observe?

Toby: Well, the next thing would be movement. If I was to look at a patient's movement, then I would do a quick screening for the presence of peripheral nerve sensitisation. If you've got an L5 nerve root problem and forward bending is painful, if you add neck flexion and ankle dorsiflexion to that movement and the pain is much worse, that gives you some more clues that you should be looking for peripheral nerve sensitisation. If you've got a leg pain and it's associated with extension movements of the spine, extension and hips lateral movements combined together reproducing the leg pain, then that movement pattern is more consistent with a compressive disorder.

So if you look at simple active movements and then it gives you some clues as to which kind of problem they might be dealing with. Having said that, you might have a patient who's got a disc prolapse, which is causing significant leg pain, but there's also a significant inflammatory process. So they've got a combination of different features and it's painful to elongate the nerve, it's also painful to compress the nerve, so the patient would have pain in all directions in that case. But I would prioritise the compressive element for that patient.

David: Yeah, nice. So you're looking at that as a quick screening test. So you're getting them to say they're potentially low back pain with some referred pain or even your low back pain patients, you're looking to check that flexion in standing and then add your cervical spine flexion to see if at that increases their pain when they add in the cervical spine flexion?

Toby: Yes, exactly. You put them into provocative positions, as long as they're not too severe, and then add neck flexion or dorsiflexion. Personally, I prefer to take them out of the provocative position, change the neck or foot position, and see if alters their range of lumbar flexion. It's a little bit less provocative and you can just gently guide them because you don't want to get them to force them into the painful movement because with these movements, they can easily aggravate themselves. And once you to stir them up there, there's no going back doing that examination. You've got to wait until the next time.

David: Yeah, you don't want to blow your chance to examine them fully and just stir them right up. So you take them out of that a little bit and then you add in the neck flexion, see if it reproduces symptoms, bring them back down and then see if it's taking them out of cervical spine flexion. So cervical spine extension, if that decreases their pain, then you're considering that as an indication that's involved.

Toby: Yeah, exactly. So that's a very safe way to do it. So you can be sure that you're not going to hurt them by doing that. It's not going to be completely accurate. That's why if that test is borderline, it means you have to do some more testing. If it's clearly positive, you have to do some more testing. If it's completely negative, then clearly we don't need to focus on the neural system in terms of mechanosensitivity. We should focus our attention on what we can find as more important.

David: So you're using this like a sensitive screening test. Toby: Yeah, that's right. Although there's no studies to show if those tests of any diagnostic accuracy, but I find them useful in the clinic.

David: Definitely. And you mentioned there dorsiflexion. So tell me how you get people to go into dorsiflexion when you're doing that test.

Toby: You can just use a rolled towel as a wedge or you can use just a foam roll or something. It depends on how mobile the person is. Sometimes just a small wedge is enough and the foot particularly seems to be more significant for people than cervical flexion, most of the time. Unless you're in a really flexed position, the cervical flexion has less impact than ankle dorsiflexion, so for most patients, I would use ankle dorsiflexion as a more sensitive stress on the neural system than cervical flexion.

David: Yeah, okay. So you roll up that towel, put it under their toes, their dorsiflexion, retest their flexion and standing and see if that increases their pain or decreases their range of movement.

Toby: Yeah, it's a nice, easy test that you can do and you can then move forward and just think, "Well, I've eliminated that, so let's focus on the most important thing to the patient."

David: Yeah. So you often use that as one of your quick screening test early in your examination?

Toby: Yeah, I use that one at the beginning and the same for the neck. If you got arm pain and you look at abduction, elevation. Abduction is limited. Reproduces their pain that's radiating into the arm. If you then bring them down at lateral flexion to the opposite side of the neck or wrist extension, you're going to increase the stress through the upper limb neural tissue.

And if their range of abduction is then more limited, that's going to give you some idea that there's a potential for mechanosensitivity of the brachial plexus or the median nerve, for example. So then we should do some more tests to come to confirm or negate that.

David: Okay, so you're adding in the lateral flexion of the cervical spine element and then the wrist extension component as well to check if that alters their movement pain with their upper limb.

Toby: Yes, and you can bias it to the ulnar nerve. If you've got a patient with median elbow pain radiating down the arm, if you were to look at elbow flexion and then add in contralateral flexion of the neck and wrist extension, you could put some more stress quickly on the ulnar nerve, sort of an active movement screening test, which might give you some clues as to whether the ulnar nerve is affected or not.

David: Have you ever found, because I had one just recently, where you're doing like lumbar flexion say and you're getting it them to perform your cervical spine flexion and the flexion eases their pain extension, increases their pain, like opposite to what you think. What sort of info does that tell you?

Toby: Well, that happens. That does happen. So that tells you for sure that the neural tissue is not mechanosensitive and that there is some other surrounding tissue interface problem that we need to address or need to look for. So if the nerve was the problem, it would be the other way around. It's definitely not mechanosensitive in that situation. So we need to focus on there, the other tissues that could be the potential for the irritation or for the symptoms.

David: Do you find that's the same when you look at... I mean, we haven't talked about straight leg raise yet, but if you're doing a straight leg raise and you find that plantar flexion is more painful and dorsiflexion less painful, does that tell you the same thing or does that tell you that potentially one of the other branches, like peroneal, is involved? What sort of info does that give you?

Toby: Well, there is the potential for a peripheral nerve problem, so we have to be mindful of that. If we're examining the spine though and we think that the source of the problem is in the spine, and that situation occurs, some people have postulated that may be a disc prolapse and the position of the prolapse relative to the nerve root was affected can cause differences when you add neck flexion and dorsiflexion, which could be kind of opposite to what you would expect. But I think the evidence for that is quite limited. So if I get an increased range of movement by adding neck flexion, then it tells me that they're definitely not mechanosensitive, so I should be looking for something else as the structure that needs to be treated as it were.

David: That clarifies it nicely because I was looking at again, well, it, obviously, doesn't seem like it, but it would be interesting to know. I definitely want to run that one pass you to find out what your thoughts were there. So that's good. And tell us a little bit about some of the other results. So let's just say that you got a positive with some of those, so you added in dorsiflexion and the flexion in standing or you added neck lateral flexion in some of their shoulder tests or wrist extension, where do you go to then? What do you do with that info?

Toby: That tells me that I've then got to do some more precise tests, neurodynamic tests and nerve palpation. So I think if you have neural tissue mechanosensitivity, you should have those active screen tests positive. Passive neurodynamic tests like straight leg raise, slump test, and the median neurodynamic tests, they should also be positive and we could talk about what a positive test is. And then finally, we should have abnormal sensitivity on nerve palpation to confirm the presence of mechanosensitivity.

Sometimes you find patients have minor features, maybe one of them, which tells you that they are some minor signs of mechanosensitivity that perhaps there's something else that's the dominant feature that we should focus on. But if we have all three signs strongly positive, then I think there's a strong case that we should include, to some point, mobilisation of the neural system as a part of treatment.

David: Can you talk through some of the examination strategies when they've got that positives in the initial screening? What sort of tests will you go to in there?

Toby: Well, let's say you've got a patient with leg pain and they've got pain with forward flexion. And when you add neck flexion or dorsiflexion, the pain is increased. You've got no evidence of a compressive disorder based on the other movement test that you've done. So then we'll move on to the straight leg raise as a neurodynamic test, straight leg raise, I would expect in that situation to be limited on the painful side and I would expect to reproduce the patient's leg pain by doing straight leg raise and expect that changing the neurodynamics by adding dorsiflexion to straight leg raise would increase the patient's symptoms.

So in that case then, I've got an active screening test positive as well as a passive neurodynamic test positive. For a passive neurodynamic testing to positive, I think you have to have a reproduction of the patient's symptoms. And that's always the goal is to reproduce symptoms during a provocative test, which can alter by structural differentiation. And what I mean by that is you can alter their symptoms and their range of movement on straight leg raise, for example, by adding again, ankle dorsiflexion for the rotation of the hip or adduction of the leg or some combination. All those movements seem to increase the stress on the nerve tissue during the straight leg raise movement, and if it's painful, more painful than without those movements, that's giving you more evidence that they've got some mechanosensitivity.

David: I like that you talked about that you're looking for that limitation of their painful movement on their painful side, reproducing their pain, and then you've got the confirmation of with a passive and an active test there. And I guess by the active test, you were talking about that flexion in standing, is that right?

Toby: Yes, yeah, the flexion in standing. That's the active test. So quick screen test, I like to think of it as, in that way, something that you can do to point you towards testing using the straight leg raise or not. But then at the end, I still look at nerve palpation just to confirm.

David: When you're looking at those findings, that's what you would consider a positive test of having all those positives with reduction of pain and the other things you mentioned there.

Toby: Yeah, it's always the goal and sometimes, it's difficult to find those. Patients don't always follow neat patterns, do they? They maybe have a combination of different things and you have to weigh in your mind which is the dominant feature, which thing should we focus on. Maybe it doesn't matter. Maybe if you start on one of them, the patient gets some improvement and maybe later, you can add in other treats for other aspects that you found. But for me, if I was to start for neural mobilisation treatments, I would want to see some positive findings on those three tests, those three aspects.

David: And you mentioned there are a few different elements that you'll add into straight leg raise as well. You mentioned dorsiflexion, hip internal rotation, and adduction. When do you add each of those elements in?

Toby: Well, adduction and internal rotation always a bit tricky to do on a patient. Dorsiflexion is easy. That was my master's studies. I looked at a group of people with L5 and S1 severe radiculopathy and there we looked at the effect of cervical flexion and ankle dorsiflexion as sensitising maneuvers, differentiation maneuvers, and we found that ankle dorsiflexion was much more consistent than cervical flexion.

So that's why I use ankle dorsiflexion because it's easy to do and it's much more consistent. Sometimes it's not always possible to add ankle dorsiflexion because they have another issue, maybe some problem with their ankle, and they don't have range of movement. So you could use the hip to sensitise the movement, joint straight leg raise. But it's not so easy, so I prefer not to use it.

David: Okay, so you don't normally add in all the elements. You would normally add in dorsiflexion, then internal rotation, then adduction. You normally…

Toby: It would be very provocative if you added all three. So if you got a patient severe leg pain and you did all three, I think you might not see that patient again.

David: Okay, good stuff. All right, that makes sense. And so when would you time the different... do you think about different biases when it comes to the upper limb or the lower limb? Are you looking to identify or test each of those like your tibial nerve bias or your peroneal nerve or sural nerve or any of those?

Toby: Yeah, I think they can be helpful. Particularly, thinking about the upper limb, when you find a predominant neural tissue mechanosensitivity disorder, you want to try to treat that by gradually stressing the nerve that's most sensitive. So if the median nerve is the most sensitive, that's the one that you want to work towards, do sensitising in the treatment. And so if you know at the beginning which one you're working towards, you can use that to guide your exercise, your slider exercises, as well as the manual techniques that we do in terms of trying to first put the patient in a position of comfort so that you can start some basic manual therapy mobilisation techniques within your system. So if you know which one is the most sensitive, you know it can guide you with your treatment progression from the beginning and also for your exercise.

And it might also give you some idea about differential diagnosis if you're thinking about a cervical related problem if you're thinking about a classic C6 radiculopathy causing arm symptoms, then you would expect the median nerve and the radial nerve to be affected by that process and you would expect some positive tests. But if you tested the ulnar nerve in that patient, you wouldn't expect to find so many features. So it might help you by doing the test. It might help you to eliminate different parts of the neural system in terms of being a little bit closer to where the problem originates. So it's partly diagnostic, but partly also from treatment planning and getting the progression of treatment.

David: You're using the area of pain there initially, so if they had pain along the distribution of that nerve, is that guiding you to which test you're more likely to use?

Toby: I think so. I think that's a good point. So that medial elbow pain radiating to the medial hand, it will tell you that you should test the ulnar nerve, although, sometimes pain distribution in the upper limb as well, just like in the lower limb, it's not really that much of a guide as to where your problem is coming from. But it does give you some information as to potential tests that you should do.

So the area symptoms, some clue, but if a patient's got vague pain around the shoulder that's radiating towards the neck, I think it could be very difficult to know which nerve is going to be a problem. I don't think you can really predict tennis elbow, may be another situation, lateral epicondylalgia, and if you've got lateral elbow pain, I think it's more likely to be a radial nerve problem, but you have to do test to find out if that's the case.

David: So you'll tend to screen them all and do each of those tests to identify if there's any positives there?

Toby: If you had clearly lateral elbow pain associated with specific movements, then I would screen the radial nerve and perhaps the median nerve. But if the ulnar nerve, I think it would be unlikely to be affecting in that case. So I think you would be a little bit selective in which test you do.

David: Great. Yep, okay, excellent. And what about with the lower limb? What sort of guidelines do you tend to use for when you're trying different biases there? Is it a similar thing? Would you be looking for different pain patterns or what tends to guide you there?

Toby: I think there are some clues. There are some studies looking at people with patellofemoral pain, for example, that they have positive tests on the femoral nerve testing. So I think if you had a patellofemoral pain, it would be unlikely that you had some sciatic nerve involvement, for example. So I think the area of pain there would be an indicator to look at the femoral nerve.

If you had lateral foot pain following an ankle sprain and you also had pain radiating up the lateral aspect of the leg towards the fibula, then I think it would alert you to the possibility of perhaps some peripheral nerve involvement of the common peroneal, common fibular nerve. So you would do some testing for that. So if you've got a specific injury, like an ankle sprain, it's telling you that certain nerves are more likely to be affected. It would alert you to do the testing for those structures.

David: Excellent. You mentioned there femoral nerve. We haven't gone into that one much. So tell us a little bit about that one and how you go about testing it.

Toby: Well, in the old days, we used to get the patient prone bend the knee and that was it. That was the prone knee bend test. It's difficult to know other symptoms because you're stretching the femoral nerve or because you're stretching the rectus or some other muscles. So we use a side-lying slump position where we get the patient to lie with the tested leg uppermost and the bottom leg is in a maximum flexion to try to really slump the patient's spine, to flex the spine as much as possible. And then we measure the range of hip extension with the knee at 90 degrees flexion. Then we change the position of the neck. In this slump position, neck flexion has a better chance to influence the course of the nerve. Testing hip extension with the neck in two different positions gives you that structural differentiation for the femoral nerve as from the muscles and the anterior thigh.

David: So the side-lying with the one you're testing uppermost and the other leg is flexed up towards the chest or what do you?

Toby: Yeah, they're hugging on to that leg.

David: Okay, and then you're flexing the knee to 90 degrees, and then keeping it in at that 90-degree bend, and then taking it through hip extension, is that right?

Toby: Exactly.

David: And then looking for any reproduction symptoms and then doing similar to what you did before, you're adding in the cervical flexion and extension components to see if it reproduces symptoms in a decreased range with those sensitising elements of the cervical spine flexion.

Toby: Exactly, yeah.

David: And so any other sort of tests that you would tend to use or are they the main ones?

Toby: No. The two main nerves, that sciatic nerve and the femoral nerve, there are all sorts of terminal branches from those nerves and it could be that they have a specific problem of that nerve. We hear about people with heel pain associated with the medial calcaneal nerve, which can become entrapped, compressed, can also be sensitised. So that happens in people with chronic heel pain. There's all sorts of peripheral nerve disorders that can be localised in nature from some sort of entrapment or from some inflammatory problem. So it's down to knowing the history of the patient's problem and as well as the screening tests that we've gone through in terms of neurological examination and neurodynamic testing.

David: And that brings up a really interesting point because you mentioned there medial calcaneal nerve, so say you've got a heel pain patient coming in. How would you tend to identify if their pain is due to medial calcaneal nerve irritation or if it's from the plantar fascia?

Toby: I think there must be something wrong with it because I think I've just had every musculoskeletal disorder known to physiotherapy because I had medial heel pain and the pain, I could turn on and off by putting myself into a slump position, dorsiflexing my foot, and everting the foot.

And it was very painful, but it was easily... it was such a mechanical compromise and it was quite painful for a couple of weeks but it disappeared. So I think I experienced that and I could see how easy it was to identify that pain and distinguish from some sort of localised, soft tissue problem in a slum position, putting more tension on the nerve with dorsiflexion and eversion gave me my pain, which I think is what you look for in a patient.

David: Sometimes it's kind of interesting having these pain experiences where you can use yourself as a bit of a guinea pig, isn't it?

Toby: It is. I wouldn't recommend it, especially for radiculopathy. That was a very interesting experience and a bit of a running tragic. And I like running. So when I am developing this radiculopathy, I didn't want to lose my running fitness, so I forced myself to run on a treadmill. I was teaching overseas at the time, but I was in a shifted position. So I was on a treadmill in a shifted position and kind of limping along about a very low rate, trying to maintain my fitness, which didn't happen.

But I found that actually after doing this, after about three weeks, my leg pain resolved. So I forced myself to run on a treadmill and now, I know there's good evidence from animal studies that if you force animals that have been given nerve injuries, similar to radiculopathy, they get better within about three weeks from doing exercise that's forced on them, either swimming or running on a treadmill or running on a running wheel. So rats are these, but I was like a rat and I forced myself to exercise, not because I thought it would help myself get better, but because I wanted to keep fitness, which didn't happen, but my leg pain resolved. It took a long time, six months, for my weakness to resolve and it took a long time for the numbness around my knee to resolve.

But I think that was a very valuable lesson to me that sometimes, if we force ourselves to do things, it does take time but we do get better. So I think we need to encourage people to be more active when they've got some of these neural disorders and there is good scientific evidence from animals that exercise, particularly, is helpful. But exercise on those rats when they've got painful nerve problem, just like myself, it was painful. But in time, I got better. The rats get better. Not saying that everybody gets better, but more often, I think if we people to move, there will be a positive outcome.

David: So you treated yourself like an experimental rat or a guinea pig and got yourself on the treadmill and your pain resolved after a few weeks.

Toby: It did. It was very painful to run, I can tell you, and it was painful afterwards. But in three weeks, I was better. Well, I was just a single case study one. But the animal evidence shows that if you do force animals with injured nerves to move, they get better. You can do it through passive movements. You can do it from neural mobilisation and animal models. You can do it from swimming. You can do it from running, you can do it from treadmill, from running wheel, all sorts of things, but they do get better if you make them exercise.

Very powerful evidence for patients to show them and say to them, "Look, well, you know, in these rat studies, it took them three weeks to start to show signs of improvement. In those first three weeks, they weren't showing any improvement." So patients often say to you, "Well, how long do I have to do this before I get better?" But these studies show you will, on average, get better within about three weeks and then as you continue, you will further improve.

David: Do you think that impacted your treatment or how you approached it after experiencing?

Toby: Yeah, but now I think we're a lot more pro-exercise and movement and keep moving and less on trying to protect things and stop movement. I think in the past, we were too much trying to be protective to help people, but I think it's counterintuitive. So we need to get people to move. We need to get people off drugs and onto exercise. There's a nice study on rats where they gave some rats some nerve lesion and then they gave them, 10 days later, some morphine for five days, some opioid.

And they found that compared to a control group, the ones who took those drugs took twice as long to recover. They took eight weeks to recover compared to four weeks in the rats that didn't take those drugs.

Now, if you imagine that, if I went to the emergency department with an acute radiculopathy, severe pain, they'd be pumping me full of drugs, which I think, probably, based on this evidence, could well be causing people to have prolonged symptoms. Normally, you don't stop taking those opioids after five days. And we know that people who start taking opioids are still taking them one year later. A third of people are still taking them one year later. It's no wonder people have persistent problems. Now, there's so much evidence now showing that what we did in the past was probably not ideal and we need to change the interventions. Be more active, which is good for us because that's what physiotherapy does. We do movement, we do activity, and we can help people, but we need to know the right way to help people.

David: Interesting. And so there's been a number of studies looking at the role of gabapentinoids and those sort of drugs when it comes to low back pain and sciatica. Is there a role for those at all? I mean, we're sort of skipping ahead a little bit to treatment. Is there a role for anyone with those drugs or are these things causing more harm than they're helping to solve?

Toby: I'm not sure that I'm the person to ask about that. I think based on my reading, that management of patients with radicular pain is very difficult from a drug perspective because most of the drugs don't work for it. If you think about Lyrica, which is something that was commonly prescribed for people with leg symptoms like that, a study recently has shown that it's no better than placebo.

So we know that simple over-the-counter analgesics don't work. We know that anti-inflammatories don't typically work very well, they've got harms. We know that these drugs, as you mentioned, they don't seem to work any better than placebo.

So I don't think there's a great way to help people from a drug perspective, but we have a great drug in exercise and that drug is very powerful, has very strong positive effects outside of what we're talking about. So I think it's something that we should encourage as much as possible.

David: For sure.

Toby: We should be more like rats.

David: More like rats. The moral of the story… is be more like rats, which is a wonderful take-home message. And when we look at, you mentioned within that in your case study too about slump and that's something that we haven't explored yet. So tell us a little bit about where you think slump compares to your other tests and how you think it should be used.

Toby: Yeah, we're slump's a very strong test, potentially. So I think you've got to be a little bit careful with it because it can be a little bit too aggressive for some patients. So if a patient has a more severe limitation with leg pain, I think you would find the information you need from doing the straight leg raise test. Personally, I wouldn't bother with a slump test at that point. If you're dealing with an athlete who's got some minor nuisance problem that's persisting with some posterior thigh pain, that's residual to some hamstring strain that was done quite a few months ago and you find that the straight leg raise has got a minor limitation of movement, but it's not possible to reproduce the symptoms, then you might go towards something like the slump test to really be a little bit more aggressive so that you can put that system under a bit more stress because that's when they're in trouble. It's when they're under that more extreme stress.

So I think it can be useful as a progression and rehab. Maybe if he started by looking at straight leg raise test, you've seen them five times, their movement is much better, but they've got some less severe symptoms now, then go towards testing the slump test.

So as a progression or in a patient with more minor symptoms, I think it would be useful. I don't think it tells you a lot more than doing the straight leg raise test.

David: Okay, just a little bit more aggravating.

Toby: A little bit more aggressive.

David: Yeah, that's good. That gives it some guidelines on that. And tell us a little bit about palpation, where you think that fits in.

Toby: Well, palpation the final piece of the puzzle. If you've got some structure that's inflamed, then it would be painful to move that structure and it would be painful to touch that structure. I think nerve tissue is no different to any other structure. So it's another form of mechanical stimulus that can be useful in diagnosis because we can be a little bit more precise with palpation in terms of localising the stress. With neurodynamic test, we're putting a longitudinal stress with palpation. We're putting very precise, defined stress with palpation directly over the nerve itself. Bearing in mind that not all nerves are superficial and not all of them are possible to differentiate in isolation, but many of them are.

Think about the elbow. You've got the ulnar nerve on the medial aspect, which can be easily identified superficially. The median nerve medial to the biceps tendon, which can be easily distinguished from other local structures. You've got the radial nerve on the lateral aspect of the anterior aspect of the head with the radius. So somewhere around the elbow, you could easily structurally differentiate the different nerves. If you think about the sciatic nerve, if you go to the back of the knee, you can easily palpate the continuation of the tibial nerve because that's really superficial at that point. The common fibular nerve on the lateral aspect of the fibula is very superficial.

So many nerves are easily identifiable. Some of them are deep. If you look at the sciatic nerve, it's quite a long way deep in the buttock and it can be difficult to know if sensitivity on palpation is due to the muscles surrounding it or whether it's the nerve itself.

I think you need to often move away from that and go to a more superficial nerve. We looked at some studies in terms of reliability of palpation in the lower limb and we found that it was quite a reliable method and other people have also looked at that showing that you can reliably palpate nerves in the upper and lower limb.

David: So we can reliably palpate them and you mentioned there some really good points that you can help palpate them. Now, looking at sort of one point of palpation along the nerve, is that right?

Toby: Yes, yeah. Although, sometimes, you might want to look at multiple points. And if you've got patients, like we mentioned before, who's got neck and arm pain, if they've got some arm symptoms and you're trying to work out, do they have a neck related problem or do they have a carpal tunnel problem? If you palpate the median nerve just before it hits the carpal tunnel, and it's very sensitive, you palpate the median nerve, median to the biceps tendon, and it's less sensitive, you palpate the median nerve up in the axilla, and it's not sensitive, it's giving you a bit of a clue that the source of the sensitivity is more towards the wrist. And so I think you can move along the course of the nerve and look for different levels of sensitivity to give you a clue as to where the problem may be originating from.

David: What would you consider a positive when you're doing palpation of the nerve?

Toby: That's another good question, isn't it? Because you're looking for pain locally. We're not looking to reproduce the patient's arm pain. That would be a Tinel sign. If you were to tap over somebody's wrist and they get shooting symptoms into their hands, that's a positive Tinel sign. But if you palpate the median nerve gently and it's very sensitive on that side, locally sensitive, and compare it to the palpation on the opposite side and there's no sensitivity, then I think he tells you that the nerve is abnormally sensitive to gentle pressure.

And we're talking about gentle pressure, I would use as a guide a pressure with your thumb so that the nail bed goes white.

If your nail bed goes white, that's a very soft, non-noxious stress. If that's painful, that tells you they've got abnormal sensitivity to palpation. I can't give you any research about that, but I think it's a nice guide to people. It's very consistent, and it's something that shouldn't be painful. If it is, it's a bit abnormal.

David: Okay. So it's not pressing really strongly. You're just looking to cause some pain, as you mentioned there, not reproduction of their symptoms with palpation at that single point, but for it to be tender.

Toby: Yes, exactly. Yeah. So the nerve is tender to touch.

David: Okay, more than the other side.

Toby: Compared to the other side.

David: Okay, great. You'd palpate those areas. If you've had a positive, do you tend to use this after getting your positives with your straight leg raise or your upper limb tension tests or one of those?

Toby: Exactly. So it's something I wouldn't bother to do. If those previous tests were negative, then you can forget about doing this because it's not going to give you any further information. But if the tests are positive, then I'll do it because I think it just adds to my confidence that this is the problem. The more things I have that I can say yes, yes, this is showing that this is a problem, the more confident I'm about my intervention, I think.

David: And do you need that to be positive to confirm your hypothesis that it is nerve-related? Let's just imagine for a second that you've got a patient, they've got you had low back pain down their leg and they've had a positive with dorsiflexion and cervical spine flexion in their flexion in standing. You've gone on and tested their straight leg raise and they had a positive. You reproduced their pain, they had limited range of movement, and they were also sensitised when you added in dorsiflexion into their straight leg raise. So you started to lead towards a picture where they've got some peripheral nerves sensitisation. And then you go to your palpation. So, do you need this next step of the palpation to be positive to confirm it or are you basing it on the previous findings or where do you draw the line?

Toby: To be honest, you probably don't need to do the palpation. But to me, I just like to have more tests to confirm what I think the problem is. I mean, there's probably an upper limit about how much testing you want to do to people, but it's a very quick screening system that you can do for that typical patient you just mentioned there and you could palpate the nerve tissue in a very few seconds and if it's strongly positive, then it gives you just more confidence that this is something that is causing some contribution to the patient's problems that could be addressed with some manual therapy, and exercise, and so on.

David: Okay, good stuff. And coming back for a second to some of those other tests you mentioned, like straight leg raise, now, is there a way we can use our straight leg raise or any of the variations there to differentiate some of which lumber nerve root or area you might be thinking that's involved like L5 or S1?

Toby: Yeah, that's something we've used in the past. If you do a femoral nerve screen test, as we mentioned, in a side-lying position and the test is negative, then you know that the L2, L3, L4 nerve root is not sensitised because that's where the femoral nerve originates. If they have a positive straight leg raise test and those tests that we just talked about, and they are painful, then you know that it's probably going to be L5 or S1 because you've already eliminated L4 by doing the femoral nerve test. So the possibilities for that patient are most likely to be L5 or S1.

And we have a test that we've used for many years where we try to differentiate the stress on the L5 and S1 nerve root by altering the position at the lumbosacral junction. So you had the patient in side-lying, a bit like the femoral nerve stress test, you do a modified straight leg raise test where you're doing the extension with the foot in the neutral position. And then you modify the lumbosacral position, and look at the change in response during that straight leg raise test.

And this is based on some work that was done by Australian researchers on cadavers quite a few years ago that showed that the cause of the L5 nerve root that was affected by the lumbosacral position. So it measured the length of the course of the L5 and S1 nerve roots with the lumbosacral junction in either flexion or extension and they found that extension put more longitudinal stress on the L5 route. So that's why we use this modified test for those patients.

To be honest, it's a difficult test to do for many people because for one thing, the patient's heavy, it's difficult to change their position, and just to modify the lumbosacral junction. For others, the patient's too stiff and too difficult to move. So it's not something that we would use routinely. It's a test that was described many years ago. In fact, it was the first research paper that I ever published was looking at the effect of these postures on people doing straight leg raise in normal health of people and showed that between flexion and extension on that lumbosacral junction, there was a small effect on straight leg raise movement. But nothing's ever been done in terms of diagnostic accuracy or looking at that in people with significant radiculopathy. So it's an idea, but there's no research to back it up, really.

David: And would you tend to use it or is it just more of you know, or if so, when or is it more just something you could use it, but it's not really going to help guide you too much?

Toby: It would depend a little bit on what you're going to do. If you were thinking about giving the patient a root sleeve block, you'd want to know which root sleeve to inject. We used to work in a pain clinic and the anesthetist knew that the physios were much better at diagnosing the problem than they were. So they'd say to me, "Should I inject the facet joint or should I inject root sleeve? If I should, which one should I inject?"

So there's a bit of pressure on you there to get the right level so that your patient's not going to be peppered with needles and that's what we used to have to work out. And that was a useful test then to know if you're going to do a root sleeve block, which one to do, or if you want to know which level is the source of the patient's problem from a surgical perspective. If you don't have confidence from imaging, then maybe that's something else that you might do. So I think it could have some benefits, but it is a difficult test, so I wouldn't put a lot of emphasis on it to be sure.

David: Interesting. And we see study around that. Was it comparing to diagnostic block?

Toby: No, it was a very simple. It was back in the 1990s. So this was simply looking at the reliability of testing people in two different positions. Could a physiotherapist assess a normal person and find a difference between two different lumbosacral positions? And that seemed to be okay, but doesn't tell me really if it's got good diagnostic accuracy and people with pain.

David: And how did it go when you're working with that, you mentioned, radiologist and looking at diagnostic blocks?

Toby: Well, patients seem to get some relief from having those blocks, whether they have good long term change, I don't know. That's not something we tend to do anymore. So I think we've moved away from those diagnostic blocks now.

David: For sure. Yep, okay. All right, that's really good. We've been chatting, this is such an interesting topic with so many areas and I think looking at the testing and the subjective, there's so much within this that we've been able to explore. It sounds like that there's a lot of treatment that we can use, particularly with these, the compressive or the sensitisation elements. There's a lot of treatment that we can use with patients. You mentioned there, exercise, but it sounds like there's a lot of other things that we can actually do to help to improve symptoms and that sort of thing in patients. Is that right?

Toby: Yeah, certainly. Once we've made this diagnosis, then I think we would try to match the treatment according to the patient's problem.

So if they've got a predominant peripheral nerve sensitisation issue, then the goal is to try to desensitise the nerve tissue as much as possible. The sciatic nerve is sensitised, the L5 root is sensitised or C6 root is sensitised. So the treatment is to desensitise it as much as possible. And that's where we would target some manual therapy with some simple slider mobilisations or some slider exercises and to try to help to gradually reduce the sensitivity. And then as the patient gets better, we gradually increase the stress on the nerve tissue so that they're gradually loading it more and more as they become desensitised. Just like if you load a tendon that's become painful and you gradually increase the load on that painful structure to increase its capability, you do the same for the nerve tissue. You find a starting point that they can accept and then you gradually load it with some desensitisation as they get better and encouraging them to move and be active with exercise at the same time, just like the rats.

David: Perfect. And I think that will actually be... we've been on here for about an hour and a half now and I think that if you're open to it, I really love to get you back on the podcast and have a chat to you about that treatment that you just mentioned there and how we can actually go about incorporating that in practical ways that people can use it. Are you interested in coming back on the podcast and having a chat about that on a follow-up edition?

Toby: For sure. Yeah, that'd be fine. That'd be great. Talk more about some rats.

David: More about rats. Yeah, exactly. That's what it's all about. That's what we like to focus on here, treating ourselves like rats. So that's great. You've shared an absolute ton of information on the podcast today and I think there's a lot of people this is really going to help to clarify where this sits within their clinical assessment and understanding of neural tissue disorders and you help to identify it and test it. So we really appreciate you coming on and sharing all that with us. This has been amazing.

Toby: Thank you. Thanks. I really enjoyed chatting with you. There's some interesting topics that we can talk a lot more, I'm sure.

David: Yeah, for sure. Now, tell people, where can they find out more about yourself and what you do?

Toby: If you want to look at the courses where we have an offer, we have a website We run various programs around the world. We've got a program at Perth at Curtin University as well that we run every year. So if you go to our website, you can check that out or you can be in touch with me on Twitter. My Twitter name is @DrTobyHall. So you're welcome to ask me questions there or by email, Anyway that you want to contact me, I'm happy to do so and help you out if you got some questions.

David: Perfect. And it was D-R Toby Hall, was it, on Twitter and

Toby: That's it.

David: Perfect. All right, well head over to the website, have a look at the great stuff and hopefully, when everything settles down with COVID and the courses kick back off, people can get along and attend some of your courses too.

Toby: Thank you. I hope so too. I hope we can all settle down to a normal life again as quickly as possible.

David: Indeed, indeed. So thanks again for joining us and sharing all that and I'm really looking forward to our follow-up podcast where we can talk all about treatment.

Toby: Thank you.

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