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So I'm not a nerve surgeon. I've never worked in a peripheral nerve injuries unit. Um I'm just an orthopedic surgeon who's injured a nerve in the past and I suspect will injure a nerve in the future, not on purpose, but that's what sometimes happens. And so I've been asked to talk about the assessment investigation and the management, particularly in reference to the Fr CS, particularly for me, for the management of any nerve injury is one to know that it's there. And then is this nerve an injury in continuity or is it not in continuity? Because that's really what defines your practice is the Sunderland and the Snedden classification. But what I really wanna know are the tubules of this nerve in continuity. Will this nerve have a chance of recovery or not? As with all things coming up to the exam? If you haven't read the B OA standards, you need to go and spend a little bit of time on the BA website and read all the standards and just refresh your memory just before you do the exam because it's a winner. That's an easy question for an examiner because as an exam I'm not an examiner, but if I was an examiner, I would just have to go to that boast uh the night before and look through it and the boost for nerve injury is actually relatively small. Um There is a little bit of a guidance on, you know, the sensible stuff that you do after an operation. Uh I'm gonna read through the post guidance um on nerve injuries and this is one opt version. Uh There is another version um this is from September 2012. There is another one that came out a little bit later. So make sure that you get the correct one, essentially what the both guidance is telling you most of the time is to identify that there is a nerve injury. And every time you do something in clinical practice or in the exam is you want to a bit like uh at L go back and reassess. So you want to document the neurological injury, you want to reduce the joint, you want to document the neurological uh status. Again, you see someone uh in the e you document the neurological status, you see them in the post war round, you document the neurological status, you see them just as they're going into the anesthetic room, you document your neurological status and then uh when they first wake up so that you can see if there's a change. And that's most times when the mischief comes with nerve injuries is that no one's picked it up and then they don't know, was it there before we started or after we started and try and write clearly what you've done, not neurovascular intact, that's no longer acceptable, probably acceptable in my time, but not acceptable anymore. For those of you again, coming up to the exam, the QR code is there on the screen. Uh this paper by Dominic Power uh E four open reviews. So full text free access, uh talking about iatrogenic peripheral nerve injuries. So this is where you've caused the injury. Um This talk was more a generic talk on nerve injuries in trauma. Um but uh if you are looking for an up to date full text article, uh that's the one I can suggest for you in terms of the mechanism. Um you can stretch your nerve, you can lacerate your nerve, you can compress your nerve, you can fry the nerve or you can strangle the nerve with ischemia and a vascular injury and stretch injuries. Generally, uh don't uh rip the nerves to pieces. They can, well, the plexus from the uh cord but generally the nerve most often in continuity, for example, your primary nerve injury of the radial nerve. When you break your humerus, it's very seldom if it's a closed injury that you completely uh rip it to shreds if there is any open injury around a nerve or a nerve. Uh that's uh not working. I think that does mandate exploration, it may be partial or it may be complete. And so if you've got a partial injury to a nerve, again, in the short term, you want to be able to open it up because there is a high chance then that, that nerve is not in continuity compression. Hm. Uh So that can be at the time of the surgery from the bone ends can be from your plaster. Um Short ischemic times of less than eight hours don't normally lead to some irreversible deficits. Uh Generally you want to keep your pressure and your ischemia though down uh to uh less than a couple of hours, uh thermal injury that happens for us in orthopedics when you uh leak out cement. And so if you think you penetrated the bone, uh revision, hip or a uh elbow, revision shoulder, and uh you may be in the path of one of the major nerves. And if you think you have penetrated the humerus, open it up and make sure the nerve is safe because if you leave the cement there to set while it is uh uh heating up, you do uh often get thermal injuries and it is a real problem in the upper limb. The anatomy of the nerve um essentially has three layers, the endoneurium, the perineurium and epineurium. And those three layers come into importance. If you are going for a first, I think in terms of the exam and using the Sunderland classification as opposed to the Snedden classification. Endoneural is the innermost layer. Um The perineum is the second layer and then the epineural is the outer collagenous layer which surrounds the fascicles. And so you have these uh groups of uh axons all grouped together which then form your fascicles. Uh and then the fascicles all grouped together, become your urine, uh your your nerve cell. As for the pathophysiology, it really depends on the degree of injury to the nerve. And so if you've just bruised the nerve, the neurapraxia or pressure, which is short lived, there are generally no changes. If you divided the axons, then they undergo wallerian degeneration. And it's this wallerian degeneration of the distal part of the nerve process that then uh gets you your nerve conduction studies. And the idea that there may be lack of continuity of the nerve because if you don't have one layer in degeneration, then, you know, in general, the nerve is in continuity. If you do have wallerian degeneration, though, you can't be sure if it's intact or not because it's then about the, the perineum, the the outer layer of the nerve. So uh in an axon ad meis, when you have just divided the axons, but your outer tube is still intact, um you will get larian degeneration distal to the injury in an integra fashion and gradually over the first hours, it resorbs the axons and the myelin, the myelin taking a little bit longer to go, it then activates, activates various cells and the macrophages to continue, uh clearing out the tubules. And that's generally complete at about 5 to 8 weeks. And that's why one of the theories or, or times when you might do your nerve conduction studies at about 4 to 6 weeks or six weeks. Um, when I was training, it would have been classically six weeks is you look at the nerve distal to where the injury has supposedly occurred. And if there is no conduction along that part of the nerve, it means that there's no longer any axons inside there. Um But you have to wait at least 5 to 6 weeks, 5 to 8 weeks for that process to be complete. And so if you see here and degeneration early at three weeks, then you know that some of the axons at least have been broken. But if you can't be 100% sure that the tidy up of the, the remaining electrical cables distally have been completed until you get to six weeks. And that's why classically they say do your more definitive nerve conduction studies at the six week mark when you have completely divided the nerve, the neo Ame. Um the pathophysiology are fairly similar in that you get the resorption uh distally of the myelin um and of the uh axons. Um but you tend to get more fibrosis and because the nerves are elastic, if you completely divide a nerve what happens is the nerves retract and they pull apart. And then what happens is you get scar tissue in the gap, which is why if you open up a nerve that's been completely divided at about four or five weeks, you will find that it's actually fairly fusiform at the injury site. It's swollen, it's bigger, it's thicker and that's all really fibrous tissue filling in the gap. When you document your examination, um you want to document it clearly before and after you document the motor component, the sensory component, the sympathetic component and what you're really looking for there is is there dry skin. And so if you've got a pen and you rub a pen over the tip of your finger, it has a little bit of uh uh moisture on it. And so therefore, it has some resistance. Someone has completely cut a peripheral nerve and there is no autonomic sensation will have dry scaly skin and the pen will just uh slide off it. And then if there has been a nerve injury, you want to document Tal's test or to sign and that's basically hyperesthesia or paresthesia when you tip over the point where the nerve is regenerating too. And so you tap along the path of the nerve, I have heard it suggested that you tap from distal to proximal and then you mark where it is. So you tap along the path of the ulnar nerve and you say Yep Ell's test is four centimeters or three fingers from the electron. And then 34 weeks later you tap and you see that the test or sign has moved distally. You can say that the canals is advancing, which would suggest to you that the axons are advancing that the nerve is recovering. Um And that's the the value of repeated testing in an ideal world. Um Not always ideal that we live in. We want the same person to be doing the assessment to uh deciding whether this nerve is recovering or not. Do your motor power with the MRC uh naught to five classically naught being no contraction, one being a flicker, two active motion, but without gravity, three can overcome gravity but no resistance. Four is just not full power and five is full power. Now, the a a chart was really set up for um your dermatomes and your myotomes more than for peripheral nerves. I don't know. Do you have a check function here? Sid uh there is uh people can chat in the, they can type their answers and some people will be able to speak. I went looking last night for AAA chart like the Asia chart for uh myotomes for the peripheral nerves. So, you know, is there a chart somewhere out there that somebody else has created because you don't have to reinvent the wheel. Um But I couldn't find one. And so if someone knows of a chart or whatever Google search terms I need to put into to find a chart for radial nerve, median nerve, the nerve, anti nerve blah, blah, blah. Some nice way that you can then just Google those three search terms and find the chart. Put it into the chat. If anyone finds it ultimately or even better, makes one. if they could just text me or email me, that would be great. But so you can still use the Asia chart because it has the elbow flexor, it has the wrist extensors, it has the elbow extensors if you have a look at the chart on the right hand side. And so you still have the ability to put your MRC gradings in there. Uh at this point, you're not grading the nerve. Um but generally it's uh one nerve that supplies that power. OK. In terms of a sensory component, it's important that you pick the autonomous zones. There's a lot of overlap when it comes to the peripheral nerves. So this picture from the internet suggests that the all in pink, all in red is radial nerve. But in fact, the lateral antebrachial cutaneous nerve of the forearm will cover part of that part of your wrist. And so the autonomous zone is really just here for the radial nerve in the uh between the thumb and the index finger in that sort of web space. Uh the tips of your fingers for median nerve and the little finger on the nerve. So watch out there is still a little bit of overlap when it comes to uh peripheral nerves. Sometimes people are thinking it's superficial radial when it's LA PCN. If you want to document fine touch pinprick and uh temp temperature and if you can uh autonomic function, although autonomic function is normally something that comes later. A little bit of, I am not a neurophysiologist. I am not gonna tell you all about the, the, the speed of uh transduction. You're gonna have to read about nerve conduction studies yourself. But essentially what you want to know now is is this a nerve incontinuity or is it not? And what you're looking for initially is uh uh where is the block and that they can tell within a week because essentially the signal goes to a point and then stops and they can localize exactly where the injury is. So within the week, they can tell you where the conduction block is. What they can't tell you is is there an injury continuity or not? Because it takes time for the wallerian degeneration to complete its path, um might be able to tell you um if it's completely incomplete, if there are voluntary motor unit action potentials. Um So if they voluntarily uh they do needle M GS and they tell you well, move your hand, move your common flexor and they get voluntary action potentials, then that's more likely that it is incontinuity. So a good neurophysiologist, with addition of some em GS may be able to tell you whether it is in continuity or not. But generally, it takes a few weeks for the degeneration or for the neurophysiologist to be sure if there is or isn't any evidence of neurodegeneration. And so, um uh you may delay it. Uh When I first started, we never thought of doing nerve conduction studies before six weeks. Uh Then about halfway through my consultant career, people were doing nerve conduction studies uh at about three weeks and now starting to do it within the 1st, 1st week. But you get more reliable EMT S as the weeks go by or, or more reliable evidence. What you want though is to document the degree of injury and any signs of recovery. And particularly then at three months, now there is no magic number. But one of the problems with all nerve injuries is if your neuromuscular bundle, your, if the muscle is detached from the nerve, then the neuromuscular endplates gradually degrade. And certainly, if you've waited 18 months before you get the nerve signal down there, the neuro neuro uh no, it just gone out of my head. The, the endplates, the neuromuscular endplates uh disappear. So even if you bring the nerve back, um you will never be able to get that muscle working again. And so there is a little bit of a race if you have a complete injury um to get the nerve back down there, which is why it's always a problem, the more proximal your nerve injury is and the more critical time is. And if you're doing your canals test, remembering that the nerve recovers at a millimeter a day, you want your canal to be progressing or moving at about a millimeter a day. In terms of imaging, um high resolution ultrasound can track the path of most nerves. Um I think it's more likely to be better if it tells you that the nerve has been cut or if the nerve is stuck under a plate. Um So I think that that the radiologist can be more absolute about um if it's been stretched or partially injured or if you've got some scar tissue in the gap and uh it, it may be a little bit more difficult to say whether it's definitely completely ruptured or not. Um But it's certainly worth speaking to your radiologist and asking them um what they think they may be able to see uh and to be able to document uh where the nerve is uh the continuity of the nerve. Does it follow right up to the plate and then disappear? SS for MRI in the presence of metal. Uh postop, it is very difficult. But one of the values of MRI is it does show you muscle denervation, we get this um edema that happens within a few days uh within the muscle. If the muscle has become denervated, the other value of an MRI is to show a large hematoma. And I'm thinking more now, hip surgery and the sciatic nerve palsy, uh but potentially anywhere, uh where you've got a postoperative or postinjury uh uh nerve uh problem. If there is a large hematoma, putting pressure on the nerve, then you may consider decompressing the hematoma. Um Just to show you a little bit of what aeration edema would look like. Here, we see an anterior dislocation of the shoulder and on these axial CT S, you'll see that the shoulder has gone a long way. Uh You don't need emg S, you don't need um uh special tests to know that that axillary nerve has been stretched. And so, you know, uh class, we're gonna know that it's the uh axillary nerve. He had a weakness and loss of power of elevation at uh eight weeks to document that he's uh cuff was intact. You did have a great tuberosity fracture. It's unlucky that you'd injured your uh supraspinatus and greater tuberosity. Um But to document that the cup was intact and then having a look at that denervation edema. And it's the there so beautiful, the fat suppression images, the water images, the stir images are what you are looking at. And as we are expecting, we are expecting axillary nerve and so axillary nerve supplies, deltoid and Teres minor and we can see it there on the images. This is deltoid glowing, this is deltoid here on the outside glowing. And then at the back, at the inferior part of the infraspinous fossa, we have a infraspinatus uh which looks really nice. And at the lower edge of infraspinatus, we have Teresa classic denervation edema in the axillary nerve distribution. And that you can normally pick up three or four days after an injury. So if you can't assess them clinically, you can see the denervation edema uh within the muscle interesting in this patient. He also had some denervation edema of the inferior aspect of subscapularis, which is really the lower subscapular nerve, the first nerve that you come to if you're coming under the coracoid. Um that's just an interesting thing that you know its thing. This is the pattern of axillary nerve and teres minor and we see axillary nerve and teres minor. Uh This is what happens is if you get denervation uh for a long time, it starts off with denervation edema. And then months later, I can't give you an exact number of months later. Um you then get fatty atrophy and the fatty atrophy that you see with the denervation edema is different to the fatty atrophy that you see when the tendon is detached. And so if we look at the sagittal images here of the shoulder, this is the bony windows, you can kind of make it out on the bony windows. But if you have a look at the soft tissue windows, you can see the atrophy of supraspinatus and infraspinatus. Uh You can see the uh fat replacement. Um This is a CT scan uh looking at it, it's obviously oops better done with an MRI, you see it better on the T ones because you want to see the fat. Um And so this is long term denervation edema. Um and it's a, the pattern of uh fatty fatty atrophy is slightly different to if you've disconnected the tendon, um you would then look to see, make sure that the tendon is continuity, but this is long term denervation of the suprascapular nerve involving supraspinatus and infraspinatus. We see a beautifully well developed in uh Teresa, a nice deltoid, a really nice subscapularis in the front. Uh That's the value for uh sort of MRI s. The treatment really depends on whether you think this nerve is in continuity or not because if it's in continuity, uh in general, the nerve will recover at a millimeter a day. And as long as you've got a year, uh I don't want to wait 18 months for the nerve to get down there. Um There should be some element of recovery, but if it's not in continuity and, and then you wait three months and then you connect it and you're quite proximal, then uh when the nerve fibers finally get down to the motor end plates and they've gone away for the winter, um They are never coming back. So there is a little bit of, uh you want to get there as quickly as you can. Most times if it's open, you want to explore it and you want to explore it within the 1st 72 hours. And otherwise, what happens is that elastic retraction makes it more difficult for you to put the nerve ends back together again and to repair them. If you've had a blunt transection of the nerve. In other words, the nerve has just been ripped apart and it has been said not as a nerve surgeon that you may want to wait a few weeks for a little bit of scar tissue to form around the perineum. So you've got something to hold on to, um so that you can repair, cut back to healthy ends and then repair the nerve if it's a closed injury, generally, it's conservative. Um though a little bit of controversy, but you would want to ultrasound it. Uh you would want to uh get some relatively early nerve conduction studies to document the state of the nerve, follow it clinically, particularly to cyst and repeating the nerve conduction studies and making sure that there is uh uh recovery or improvement in the post guidance. They talk about uh contacting the nerve nerve injuries early and probably certainly for the exam, I would be saying, uh if anyone had a nerve injury is to contact, um and uh alert the la local peripheral nerve injuries unit as for your treatment options Well, first option is just a neurolysis that may be just external or internal, then you can afford a direct repair, but there's no point connecting a nerve under tension. And so if you can't connect it uh as a direct repair, and you may consider grafting it, you can graft it with autograft, you can graft it with artificial tubules, uh just plugging the nerve ends into the tubules. Um Again, I am not a nerve surgeon, so I am not gonna go into the latest uh techniques in that. Um Think about, for example, if uh you do have a nerve injury and a humor shaft fracture, a radial nerve injury, you can transpose the radial nerve anteriorly dramatically shortening its path and achieve a primary repair. You can do the same with the ulnar nerve transposing it anteriorly particularly if there's a contusion or a zone of injury. Um And so think about re-rooting the nerve if possible, if it makes it shorter, allowing you to direct for a primary repair. Generally, the joint only requires immobilization for three weeks for the nerve to be healed enough to allow some traction on it. Make sure you refer them to the physiotherapist occupational therapist and impress on to the patient the importance of maintaining a passive range of movement while you wait for the nerve recovery to happen. No point getting a nerve down to a joint that's so stiff. It's no good to man or beast. And start early with controlling the pain. Any patient that's had a nerve injury, start them on their neuromodulators early, get them on the gabapentin or the pregabalin. Get on top of their pain. How you do it doesn't matter, but make sure that you control the pain, the less pain you have in the start, the less sensitized you become and neurogenic pain is disabling. It's horrendous. It's one of the reasons I decided not to be a pelvic surgeon. You injure your sciatic nerve. Everybody's crying for a long, long time. In terms of staging and the classifications for the exam, the two would be Seddon and the Sunderland. Seddon is the simpler one. That's the one I like the neuropraxia and it's with an A not with an o the axonic mess and the neuro meis, the neuropraxia is just a conduction block. You can have degrees of injury or, or degrees of neuropraxia. Um So, but generally what happens in the neuropraxia is you don't get involvement of the axons and so you don't get the distal wallerian degeneration. So, distal to your injury, if you connect your nerve conduction studies, you can still conduct the electrical path along them because they don't have any wallerian degeneration. Axon A means means that the outer tubule is still intact, but your axons have gone and so they will recover because they can travel down the tubules um with the neurosis. When you get complete disruption, you do not get any option or, or opportunity for primary healing. Uh They do require surgery, they require exploration and connecting the nerves back together. Again, Sunderland described it in five degrees. The first degree, the neuropraxia, which is very similar to s and the second degree, which is uh an a, a mess. And then basically in the new A me, he divided it into another three levels. Um I have never really found for me, some of them to be of much value because what I really want to know is this not a new or isn't it watch out a little bit for calling everything a neuropraxia because not all neuropraxia will recover. And in that E four open review, you will uh read Dominic Power. He talks about the uh prolonged conduction block. And so this is the patient who isn't recovering within 3 to 6 weeks, 6 to 8 weeks. His 10 now isn't progressing and they may have an element of myelin involvement. They may still require exploration. Um Maybe there is still a localized area of constriction. Um And so yeah, not all neuropraxia will recover and if they are taking their time, you might consider uh referring them to a nerve injuries unit. Uh Looking for this concept of conduction block, which is the high grade of neurapraxia. I'm gonna stop there, sir. Um I don't know if anyone has any questions