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So as Professor Rolf Birch described in his classic manuscript that following a review of 13,000 nerves ended in combat. The first operation to the wound is the most important. Furthermore, as Sunderland's summarize in his 40 years of clinical experience and nerve repair, early repairs are better than late nerve coaptation is better than nerve grafts. Young patient's do better than old distal repairs are better than proximal and short graphs do better than long. So a reminder of the pathophysiology of nerve injury after a severe injury, what we see is valerian degeneration in the distal axon and distal to the nerve injury. We get muscle fibrosis and atrophy pretty much immediately, 60 to 80% of the muscle volume is lost by four months and functional re innovation is unlikely beyond 18 months. So early repairs do better than late repairs. There's also the concept of biotene secretary as demonstrated in this video where you can see the nerve retracting after it has been cut. So there are both physiological and anatomical reasons that the earlier the repair, the better. Whilst we go through this talk, these are the two main factors to be born in mind when considering the long term outcomes for nerves, a quick reminder that in dealing with nerve injuries, we also need to have a clear understanding of the environment that were deployed to and the kind of injury patterns we will see. We need to know what our facility is capable of, what specialist we have, what kit is available, what resupply we have and especially what our evacuation pathways. So for example, here we have a static field hospital with a good air evacuation or are we working in a mobile field tent with a much more difficult evacuation? Because this will help determine those timelines. And importantly, our our patient's going somewhere where there are the prerequisites to management the reconstructive elements. So we think of conflict injuries with this kind of a scenario causing this kind of a devastating repeatable pattern of a complex injury. I am not going to talk about the pathophysiology of blast and ballistic injuries, but a reminder about the specific ways that nerves can be injured. So you can have direct injuries, for example, from projectiles and adjacent fractures and indirect injuries, secondary to the blast, wind and the cavitation in these can cause long fraction injuries and also changes on a micro cellular basis. So what kind of injuries can we expect to see? This paper by Birch at al described all the nerve injuries from the Middle East conflicts. A total of 261 injuries of which about half had a prolonged conduction block. 1/5 had a complete rupture and the remainder had some form of degeneration. The majority two thirds were secondary to blast injury. Four were in open wounds and there is associated severe damage with the nerve injuries of fractures, arterial injury and significant loss of muscle. And the most commonly injured nerves with the tibial and the common peroneal nerves. So, the specific causes of nerve injury could be shotgun pellets, bone fragments, nerve compression from, for example, aneurysms or hemotomas and further down the line, there could be nerve injury from adhesions to repaired blood vessels, fractured bone and skin grafts. The vast majority of the injuries when open wounds like these, about 80% of patient's and the tibial and the common peroneal nerves were particularly vulnerable in the buttock and around the knee. But don't forget that even in these closed injuries, there can be significant long traction injuries, not only that, but you can also get by a tra genic injuries, for example, from fasciotomy knees, an inadvertent nerve suture and a misplaced skeletal fixator. So it's important to serially examine these patient's to avoid missed injuries, especially if they are closed. And if there are multiple injuries, the assessment and diagnosis of nerve injuries requires an awake and fully cognizant patient, which may not be possible in the immediate setting. And you will have to rely on a careful review of the wound with accurate documentation and it's key that we don't forget that clinical examination further down the care pathway. We we need to examine the for the all of the modalities of of the nerve motor and touch. Looking for loss of power and sensibility in a given target, sympathetic, noting a loss of sweating and discoloration and pain, especially if it's refractory to standard analgesia. And don't forget the simple examination tool of the Hoffmann tanel sign where light percussion moving from distal too proximal along the nerve pathway will reveal the leading front of the degenerative and regenerative elements. We also need to manage both our own and our patient expectations. So in the second part of the paper already described 80% of nerves with prolonged conduction block was showing some signs of recovery within six months of injury. Last injuries took slightly longer than penetrating missile injuries to recover. And 17% of these patient's required some kind of a repair. So in general, upper limb nerves tend to fare better than lower limb, but you can still get reasonable outcomes for recovery for motor power and sensibility. And these patient's that achieved good outcomes, which was over half that was with motor power of greater than M four and sensory with no pain or hypersensitivity. So they had good function. So to further things to note from this paper, so a third of patient's had persisting or significant neuropathic pain that needed some kind of a of a revision operation and this was usually because of either bone fragments, heterotopic bone or retained fragments of suture material as well as scarring. The other thing is that half of the patient's had a none foot at the beginning, but had recovered within two years in about 50%. So these two papers looked purely at nerves that had been completely severed and um and how they were treated and the important things to note were first of all, the workhorse graphs which were Cyril nerve, sometimes the medial cutaneous nerve of arm and forearm and the superficial radial nerves. And the second thing was that as we've already talked about, there were poorer outcomes if the repair was more proximal, if the interval was greater than four months and if the length of the nerve grass was greater than four centimeters. So I'm going to move on to what, what we're actually going to do. Um Because now we've got that knowledge, we, we now need to think about what we're actually going to do in the operating theater. So the principles of damage control, resuscitation, damage control surgery, we already know and have been well covered. So the thing with nerves is that because they, because treatment is often dictated by life threatening injuries, we have to buy time for our injured nerves because we need to think about the principles of reconstructive surgery later on. So for example, when we debride, obviously, we have to do an adequate debride mint, but don't forget about spare parts surgery. So useful donors in the future such as a serial nerve and that medial medial containers nerve of arm or forearm, you should be aware, not too overly debride and lose those potential donors when we're dealing with the arterial injuries to make sure we decompressed any hemotomas that may be compressing a nerve. When we performed fasciotomy, knees try to avoid any iatrogenic injury to nerves. the nerves themselves should be carefully inspected and they may need to be tagged to avoid any retraction. And what's really useful here is very careful documentation, pictures and drawings to help assist with the second stage and further reconstructive surgical procedures with respect to bony injuries, make sure that any fragments that have been removed that may be causing persistent injury to a nerve. And we'll come back to discussing analgesia um in a few sides. So the take home message is really good wound care is important. This shows that before and after debridement that goes all the way back to the sciatic nerve. This is an intra operative photograph after the removal of a metal fragment from the common peroneal nerve. And there are a different procedures that you can do to help reduce further trauma. For example, shortening the bone to relieve tension on a traumatized nerve or flexing the joints when applying an Xbox. A couple of other things where neurology is important. Clearly, decision making an amputation. There are some absolute indications such as um the avulsed extremity, unconcern, reconstruct a bulb only damage and severe combined injuries. But what we have has already demonstrated from the papers we've discussed that neurological dysfunction should not be part of the criteria used to decide on amputation. So another mention about analgesia, um we've already talked about the difficulties of are forward deployed setting. And as I was discussing earlier, knowing what you've got available in your facility because forward surgical facilities will have less available to them than back in our role, three role for hospitals. And this is going to have implications on the range of analgesic techniques on offer. But as an absolute minimum, we should have paracetamol opioids and ketamine as a backbone. And also think about adjuncts for neuropathic pain such as pregabalin, amitriptyline and gabapentin. It's really key to get good and early absolute pain control specifically, with respect to pain catheters. There's no evidence for long term reduction in either phantom limb pain or neuropathic pain, but they are really good for getting early and complete control of pain. So depending on what you can get hold of, will determine what your standard operating procedures are. But clearly anybody who is giving these blocks needs to be appropriately trained, knows how to monitor the patient. Um and can also ensure that concerns such as the development of acute compartment syndrome, the patient is being appropriately monitored. One clear contra indication is if the pain if the patient has developed coagulopathy because of the risk of hemotomas. So these were uh sorry. This paper is a description of different types of missile induced peripheral nerve injuries. Again, the bottom line is that we need to take pain seriously. It shouldn't be dismissed and especially pain that's not responding to standard analgesic techniques of the patient's in this, in this paper, the ones who had the ones who had developed a clinically significant pain syndrome, 80% needed some kind of a surgical procedure that done. So the bottom line is keep it simple stupid, those behind your bridges and these are the general principles to leave you with. So my experience was largely built from the wars in the Middle East and in Afghanistan when we received large numbers of UK military personnel who had been injured in combat operations and repatriated for definitive care in the UK. So today I'm going to focus on what happens after colleagues in the deployed setting have undertaken their definitive early management of the combat wound and how we then judge what to do next. And I'm going to talk about the classification of nerve injury and how that helps us decide when to operate what to do. And then specifically for the lower limb, I'm going to talk about managing neuromas, either neuromas from injury or neuromas associated with an amputation. So many advances in nerve surgery follow war when there are multiple young patient's with severe limb injuries with nerve injuries. And Professor Sir Herbert Seddon in 1943 described the classification of nerve injuries that we use today. Neurapraxia, meaning that the nerve is bruised or not working axon tom assis, meaning that the axon is damaged and Neurontin assis meaning that the nervous cut and although this classification has been developed further effectively, it still stands true today. And we use those three original classifications neurapraxia, John Thomas's and your autumn Asus to decide on what to do when we're managing a nerve injury. So when we examine a patient after an injury to a limb, we're looking for the red flag warning signs of an injury to a nerve. So of course, there may be an absence of sensation or feeling and there may be paralysis. But the important findings are that the patient may have neuropathic pain, dry skin in the periphery due to damage to the autonomic fibers and the Tinel's sign at the site of injury. And, and these should be the red flag, three red flag signs for the examining clinician. And I get asked many times, do you do any imaging of nerves? Um very rarely in actual fact. And in actual fact, neurophysiology is not done routinely in the management of an acute nerve injury. What you should have is a tape measure, using a tape measure, the injury that hasn't been explored or a nerve injury that may be associated with no significant wound can be monitored. And an advancing Tinel's sign can reassure the clinician that the nerve is regenerating. Well, it's not necessary or indeed advised to explore a nerve at every wound. Certainly not in the acute setting where there are multiple fragmentation wounds such as this. But as a guide, there are some suggestions for when a surgeon should explore a nerve acutely. So sometimes there is a hematoma that requires decompression. There's severe displacement of fracture fragments associated with a nerve injury. Occasionally there's a severe vessel injury that requires prepare and the nerve can be inspected at the same time. But often the decision to explore a nerve is later because the nerve has failed to recover. Now, this slide is rather busy but it illustrates when you may need to operate on a nerve. When the nerve is thought to have a conduction block or neurapraxia surgery can still be required when the nerve is thought to have an egg zonal injury with ag Zonta missus recovery can be anticipated and can be monitored by serial examination. Although neural isis may be required for scarred nerves that are painful and nerve reconstruction is required for high grade ags on tom Asus and Neurontin Asus injuries where the nerve recovery is stalled. And the surgeon must have a number of different techniques available including decompression repair graphs and nerve transfer. And in order to manage pain, I'll be touching on neural isis and neuroma surgery including targeted muscle re innovation. The problem with dealing with a Neurontin missus injury acutely is it's not clear how much nerve should be debrided, debride, mint and skeleton stability can be achieved and the nerve can be tagged for later reconstruction. When the nerve is re explored after several weeks, it should be debrided until a healthy structure is visible with clear fascicle arrangements. Now, this is my algorithm for nerve reconstruction. But if we just concentrate on the green, most injuries in the lower limb are discontinuity, neuroma in continuity, mixed nerves in the lower limb. So these are the main nerves such as the sciatic nerve, the tibial nerve and the common peroneal nerve. And if surgery is beat to be performed to repair the gap, then it requires autologous nerve grafting and typically cables of a donor sensory nerve are used to reconstruct the gap in the damaged nerve. And these are secured with fine micro surgical sutures and figuring glue. The common site for donation of a nerve in the leg is the sural nerve. But other cutaneous nerves may be used in severe trauma as spare parts surgery. When the gap is longer than seven centimeters, the outcome of nerve grafting is less good and nerve transfers can be considered as part of the reconstruction. So the indications for nerve transfer are late presentation of a nerve injury. A very long gap, a poor surgical bed. If your first nerve repair or reconstruction surgery has failed. If you have a lesion that you can't reconstruct such as a route avulsion from the lumbosacral plexus, or you may choose to do a nerve transfer at the same time as your primary reconstruction to improve the outcome. So a nerve transfer has a live nerve in green and a nonworking nerve in red to a more important muscle and the donor nerve is sacrificed and it's sutured to the recipient nerve to restore function in the more important muscle. Now, word on pain, pain is one of the red flag features of a severe nerve injury. And it's important to distinguish between nociceptive pain and neuropathic pain, not deceptive pain is a physiological warning of tissue damage. And neuropathic pain is a feature of damage or disease to the nervous system. So this is a case that illustrates a scarred nerve from a penetrating wound. It's the sciatic nerve and there is preserved function but tether where its adherent to the hamstring muscles. This is a neuroma in continuity. And here it's possible to see an end neuroma of the posterior cutaneous nerve of the thigh. So, following neural isis, it's possible to see that there is preserved function in the sciatic nerve that the patient couldn't stand up straight because of the tether to the hamstring muscle. The nerve has been neural ized so that it's no longer tethered to the muscle. But because of the retained function, the neuroma is not excised and this is an operation for pain called neural ISIS. I wrap these injured nerve sites with a collagen membrane to prevent further scar. Next, I'm going to talk about management of neuromas and we have options to relocate the nerve proximately to cap the nerve to prevent sprouting and further adhesion. And a technique called targeted muscle renovation, which is effectively a nerve transfer to move a amputated nerve stump into a motor branch to a nearby muscle. So when we're dealing with a neuroma, on the left hand side of the screen, we have a nerve that we can reconstruct because the distal nerve is available to us. And on the right hand side of the screen, we have a number of techniques we can use when there is no distal nerve stump such as in an amputation. So I'm going to illustrate the management of neuromas with too short cases. This soldier lost his left leg below the knee following a blast injury. He was unable to stand on his right leg to use a prosthesis because of pain. And he presented to us with pseudo paralysis. He had had a fasciotomy because of a fragmentation wound through the right leg that was otherwise undamaged. He experienced pain in the superficial perennial nerve distribution with a strong Tinel sign at the cross on exploration. There was a neural isis of the deep perennial nerve and a superficial peroneal nerve neuroma was dissected free from scar. This had been the cause of his pain for nine years, being unable to walk with a prosthesis and was probably an eye, a tra genic injury sustained during fasciotomy ease. The nerve was resected and capped to prevent further sprouting and it was very deep in the muscle. He was managed to perioperatively with a nerve catheter on the perennial nerve. His pain fully resolved. He returned to wearing a prosthesis and had a full time job within six months of this operation, the pseudo paralysis resolved. The next thing I wanted to touch on is targeted muscle renovation. There is strong evidence from randomized controlled trials to support the use in amputations in the lower limb. And it helps both phantom limb pain and to a lesser degree residual limb pain from neuromas. There are a number of different TMR techniques depending on the level of the amputation. For instances, the red shows the tibial nerve which could be transferred to the soleus nerve in a bologna amputation. And one of my favorite techniques is the saphenous nerve can be transferred to one of the motor branches to vastus medialis. Often multiple nerve transfers for targeted muscle renovation are performed at the same time when dealing with an amputation. Uh but sometimes you have to make up an operation. This patient had a static neuroma in heterotopic bone in a scarred pelvic floor and the neuroma was lengthened in this case using nerve allograft because he didn't have autologous nerve graft available. And this was proximately relocated into muscle above the pelvic floor is a direct muscle implantation because no TMR was possible. So to just conclude, my talk, nerve injuries are common in limb trauma following conflict injury, timing, reconstruction, nerves is complex and depends on many patient factors and wound factors, closed injuries should be monitored closely looking for advancing. Tinel's sign. Most decisions to operate are largely based on the clinical examination alone. Lots of different techniques can be applied to nerve injuries in the lower limb. Generally, the results of combat injuries are less good than those seen in lower energy civilian trauma. And generally the outcome for lower limbs is poorer than in the upper limb due to the requirement for greater strength to support the body weight. And in addition, the re innovation distances are longer. Unfortunately, nerve pain affects about one third of patient's long term. And TMR can help manage residual limb pain and phantom limb pain after amputation.