Okay, you guys have seen this before. Again, nerve transfers, you take a functioning donor nerve, presumably with redundant function that's expendable, and you transfer it to a denervated nerve recipient closer to the muscle that you're trying to re-nervate. You're essentially, surgically robbing Peter to pay Paul. I won't belabor this point, but essentially, if you're doing stuff in the neck, there's no way it's going to reach the hand in time to re-nervate. So sorry for all the redundancy, but again, the power of nerve transfers is that it shortens the distance to the target muscle, thereby decreasing your regeneration time. So indications for nerve transfer, the proximal nerve stump's injured, incapable of re-nervating distally. This is the case in root avulsions, where nerve transfers are your only option. Even if the proximal nerve stump is functioning, the distance to the target muscle's too far, and in situations, messy, crush, or plus-minus open injuries, broad zone of injury, you don't think that you're going to be able to, you know, do any good nerve grafting in that situation, or you're going to need really long nerve grafts, then you should think about nerve transfers to get out of the zone of injury, closer to your target muscles. Other indications of nerve transfer, presence of a superior reconstructive option, being outside the golden window of six months, or the fact that there are no donor nerves that are good. The HSS group, Steve Lee, demonstrated that you need at least M4 out of 5 motor strength for your donor nerve to actually give you meaningful function for your nerve transfer. So C5 and 6 injury, I'm going to break it down by level. Very common injury, again, the most important function you want to restore is elbow flexion. Double fascicular nerve transfer, you are relying on the fact that the C8T1 function is intact. Oberlin described an ulnar nerve fascicle to the FCU, transferred to the biceps branch of the musculocutaneous nerve. Susan McKinnon described the same concept except for the median nerve, taking a fascicle of the FCR and the proximal arm, transferring that to brachialis. It doesn't matter which one you take to biceps versus brachialis. These two combined is considered the double fascicular transfer. The Oberlin transfer is the classic transfer, just a single transfer. So Oberlin transfer in a schematic. The McKinnon transfer and the double fascicular transfer, this is all in the proximal arm. Oberlin's initial study was performed on cadavers, just to make sure this was anatomically feasible. We had four cases. Three of the patients had four out of five strength afterwards. One patient had three out of five strength. None of the patients, you know, there were only four, but none of them had ulnar nerve deficits. Susan McKinnon's study, looking at double fascicular transfer, looked at 29 patients with a mean follow-up of 19 months. Ninety-seven percent of them regained elbow flexion, eight of whom recovered five out of five strength, 15 recovered four out of five strength. None of the patients had any lasting donor nerve deficits. What I tell my patients, and it's true even in this study, is everyone has some sort of transient numbness, paresthesias, and weakness distally, but that recovers relatively quickly with these types of reconstructions. The therapists then work on wrist flexion to eventually give you elbow flexion, and they do it with both arms. Here's a clinical case just showing double fascicular and the proximal arm. You know, as John was saying, we can mute all these, as John was saying earlier, age is important. This guy's 22 years old. He's already showing some active elbow flexion because of the nerve transfers two and a half months after surgery. Here he is eight months and 13 months. You can see, you know, for someone who had no elbow flexion before, this is a great option for patients with intact C8T1 function. Shoulder function, second most important. Spinal accessory nerve is a cranial nerve. It's usually spared. Spinal accessory to suprascapular nerve transfer is a common transfer. You're essentially borrowing from the trapezius to give to supraspinatus, infraspinatus. You can do this through an anterior approach versus a posterior approach. This is a very common transfer and easily testable. Anterior approach, spinal accessory is right there under the trapezius. Posterior approach, as described by Dr. McKinnon, gets you theoretically closer to your target muscle. And then focus on contraction of the trapezius muscle to get shoulder contractions. Another very common nerve transfer, as described in the last talk, was the triceps to axillary transfer. So there are three branches, obviously, to each of the heads of the triceps. You borrow one to go to the axillary nerve. You can only do this if the patient has intact triceps function, but this is a easily testable nerve transfer that will show up on tests. Leach-Veng-Vong's described taking the long head, Dr. McKinnon describes taking the medial head. It doesn't really matter which one. And you do it through the posterior arm-shoulder region using intraoperative stimulation. You focus on elbow extension to gain shoulder function. So Leach-Veng-Vong's had, this is one of the seminal papers, 15 patients, small series like all of these, C5 and C6 avulsions. All patients underwent spinal accessory to suprascap, triceps to axillary nerve, and the Oberlin transfer for elbow flexion. All patients recovered elbow function fully, and all patients recovered some deltoid function. Thirteen of them recovered M4, two of them recovered M3. So the triceps to axillary nerve transfer is well accepted and could easily be on a test. Here's a case example. Patient was isolated C5 injury, had some C6 involvement, but that recovered. You know, he's got a reasonable suprascapular nerve transfer, but he's got a weak axillary nerve. So he's got some shoulder abduction and external rotation. This patient showed up late. Again, just the general concepts of nerve transfers, you're trying to hit your target nerve with as many axons as you can, doing thoracodorsal and triceps. In this patient, you could show intraoperative stimulation of the thoracodorsal, intraoperative stimulation of the triceps, and I only did this because the patient showed up 10 months after his injury. So here he is six months afterwards, very happy, 12 months, and again, just showing this as kind of the power of nerve transfers. I'll kind of go through this. Spinal accessory to suprascapular, double fascicular transfer for elbow, nerve transfers for shoulder function, spinal accessory through the posterior approach, and then triceps to axillary with the double fascicular in the proximal arm, nine months post-op, already showing some function. So started with nothing, gaining function. If anything, his limitation was stiffness in the left shoulder. C8 to T1 injuries, so much less common than the upper trunk injuries. Brian Carlson out of the Mayo Clinic had a very good paper comparing Oberlin or single transfers for elbow flexion versus double fascicular transfers, essentially demonstrating there's no difference in strength. Therefore, as Dr. McKinnon says, she realized you don't really need your brachialis for full elbow flexion, and this has led to another nerve transfer, brachialis to AIN, to restore FPL and FTP function to the index and long finger. You can do it for C8 to T1 injured patients, you can do it for tetraplegic patients, and you focus on elbow flexion to gain thumb, index, and long finger flexion. C8 to T1 injury, brachialis to AIN transfer. In the peripherally-nerved injured patients, you have to chase your branch all the way up the arm, unfortunately, unlike the tetraplegic patients. In the downsides of nerve transfers, it takes a really long time for these to recover compared to tendon transfers, which gives you that immediate result, but as Dr. Hausman said, there's no or little immobilization, and then things can be augmented with tendon transfers. So this is brachialis to AIN, in addition to some tendon transfers to restore hand function. Pan-plexus injuries, there really aren't many options for these patients. Spinal accessory, again, is always a donor, but intercostal nerves, assuming that they don't have any rib fractures, is usually the only real donor. Spinal accessory, intercostals, the intercostals, unfortunately, are very weak. It's an extraplexal nerve transfer. It's used for total plexus cases. The common recipients include musculocutaneous, axillary, long thoracic, or to power free-functioning muscle transfers. Greg Merrill did a meta-analysis looking at over 1,000 nerve transfers in 27 studies. Seventy-two percent of the intercostal nerve transfers to the musculocutaneous nerve obtained greater than or equal to three out of five motor strength. Deep breathing exercises to gain elbow function. Just showing some cases. This is fourth and fifth intercostals. You can do motor and sensory transfers for these, either two-level or three-level, depending on what you do, and you sew it to the musculocutaneous nerve proper in the axillary region. Contralateral C7 nerve transfer, it's worth discussing. It's controversial. Can it be done safely? Does it work well enough to justify the risk? Can independent function be relearned in adults? So you're essentially borrowing part of the C7 from the intact side with a vascularized nerve graft, or flap. And so you're potentially injuring an intact, like their only good arm, to give them maybe some function in the injured arm. So the Mayo Clinic group and JBJS looked at 28 patients, they had poor results. One patient had severe donor-side motor and sensory deficits, and this was an important paper because they essentially denounced the use of the contralateral C7 transfer, and they no longer do it. Phrenic nerve transfer, also controversial. Decreased exercise tolerance, you need to get preoperative pulmonary function testing. It is very commonly used in Asia, it is not well accepted in the U.S. I'm not really familiar of any American groups that are doing this, but in Taiwan, where I spent some time, every patient got a phrenic nerve transfer because it's right there by the plexus, very strong donor. But I think in the American population, they probably would not tolerate the reduced exercise tolerance. Moving distally in the arm, there are nerve transfers to give you intrinsic hand function. This is a nerve transfer that will most likely appear on your test. Ulnar nerve palsy, again, covered by Sanj Kakar earlier, but the AIN to ulnar motor transfer in an end-to-end fashion will probably be on one of your tests. I throw an end aside because it is something that is becoming more well accepted. Maybe will show up on self-assessment exam, but not necessarily the CAQ. So AIN to ulnar motor transfer, in this series, eight out of eight patients re-innervated in a mean follow-up of 18 months, getting significant improvement in pinch and grip. Again, as I mentioned before, the Wash U group did a lot of animal work demonstrating that end-to-side nerve transfers give you comparable axon regeneration to end-to-end. And so, again, probably will not be on the CAQ, but may show up on self-assessment exams in the near future as it becomes more well accepted. Here's an example of an end-to-side in a patient who had partial function after a traumatic injury at the elbow. Focus on finger abduction, adduction, and work with therapists on lumbrical function, pronation exercises to give you strength. And here's this patient, 19 months. I'm going to go into this very quickly. Don't think these are going to necessarily be on the CAQ. They will potentially show up on self-assessment exams too, but we're learning much more about nerve transfers. There seems like there are new nerve transfers being described every year. This is one that's popularized by Dr. McKinnon, taking redundant median nerve branches to restore radial nerve function. In this series, 12 out of 19 demonstrated good to excellent thumb and finger extension. Two out of 19 had M3 recovery. Five out of 19 had poor recovery. So you're essentially taking, and I'll show you a case, 73-year-old patient, elbow scope, bagged her PIN. She did not want me to take any nerve grafts from anywhere, and she didn't want me to use any allografts, and I don't know if I would have used allograft. But she was very well-informed and actually had the paper on median radial nerve transfers and wanted to give it a try, despite her age. So this is where you use synergism to give you the function that you want, same concept or similar concept as tendon transfers, FCR to PIN, so wrist flexion to give you finger and thumb extension, wrist extension, or finger flexion for wrist extension. And then a tendon transfer just for static stability. Here she is nine months. As Sanj Kakar mentioned, the EIP is last to recover, so that index finger is lagging behind. As Dr. Hausman mentioned, this is something that can be used for tetraplegic patients. Supinator and PIN come off different levels, and because they're right there next to each other, as he mentioned, it's an easy nerve transfer to do just through a dorsal form. Again, this is something, at least in tetraplegics, that's being done more commonly. We'll see if it shows up on tests. This is just a case. I want to show the power of nerve transfers. This is a patient. Electrodiagnostic testing demonstrates that he's got an isolated spinal accessory nerve palsy. You can see how important the trapezius is for shoulder function. That's him trying to abduct the shoulder in the bottom left. No chance of recovery. Took him to the OR quickly. Susan McKinnon has a couple papers on this. Robbing Peter to pay Paul. Getting you close to the target muscle. Young patient. Makes us look good. So nerve transfers, you can expect some muscle contractions around six months, but you've got to follow these patients long term. Their recovery can take up to two years. That's when you're going to know kind of what you've got.

nerve transfers

injuries

proximal nerve stump

nerve grafting

donor nerves