I will save the nerve transfer details for my next talk. Okay, here are my disclosures. So Sterling Bunnell, founding father of hand surgery, says, to someone who has nothing, a little is a lot. It's something for everyone to remember when they're treating patients with nerve palsies, especially devastating brachial plexus injuries. Probably one of the most important things for everyone in this room to know for the purposes of the test are just the anatomy. And you gotta go back to your anatomy books, memorize these things, the roots, trunks, divisions, cords, what peripheral nerves branch off of where, because those are very easily testable questions. So unfortunately, you just have to review this stuff and just have a general sense of which cords, for example, the peripheral nerves come off of. I like throwing this in here just because it gives you perspective on where these are in relation to the neck and the clavicle and how the plexus itself is very high. And another picture just showing kind of relevant anatomy. So here's a great schematic that the Mayo Group has in the greens chapter, but essentially C5, shoulder, C6 is responsible for elbow flexion. These are very generic things that you should remember for a test. Wrist, C7, wrist extension, and then C8, T1 will give you hand function. So this is very easy for them to say, injury, this is the exam, fingers are moving fine, but everything above it is out. So you should start thinking about lower trunk, C8, T1 sort of injuries. Got the slide from Dr. Bishop. The roots and trunks or proximal injuries are the most common, 71% of the injuries. Again, everything relative to the clavicle, just remembering how proximal these nerves are. So divisions, whether it's just protection from the clavicle above it, a lower percentage of injuries, and then the peripheral nerves. And cords have 21% of the injuries. So the mechanisms of injury, the most common are closed injuries, traction or stretch, motorcycle accidents are very common, falling from a height, you know, looking at that bottom picture. This is why the upper trunks tend to be more commonly injured as opposed to the lower trunks because of these forceful downward motion on the shoulder. Gunshot wounds, stab wounds, chainsaws, much less common, but definitely testable in something that you see in real life. Obstetric will be covered tomorrow in the pediatric section, and radiation, you know, you probably will not run into the test questions on that. John went over Seddon and Sunderland classification. Dr. McKinnon added type six with a mixed injury. Sorry. And again, in the real world, you're gonna see mixed injuries more often than not. You're not gonna go in and say, oh, this is a type three. And so this is testable stuff, but as John mentioned, not very applicable to real life. It's important to know kind of sensory distribution in terms of the dermatomes coming off. And then from a clinical standpoint, it's always good to chart these out when you're seeing these patients to get a sense of this is their physical exam. This is most likely where the injury is occurring. Common patterns of injury. Again, C5-6, you're gonna see very commonly just with downward motions of the shoulder. That gives you intact hand function. C8-T1's responsible for hand function. It's much less common in adults to have lower trunk injuries with the upper trunk spared. Total plexus injuries are devastating, but unfortunately common, and you essentially have a flail anesthetic limb. The types of injuries that you worry about, preganglionic, which is an avulsion, versus postganglionic, ruptures or stretches. From a real world perspective, you treat these differently. Here are things that are suggestive of preganglionic or avulsive injuries taken from Dr. McKinnon's ASSH talk a few years back. This is in the handout that you guys can refer to. Essentially, if you have proximal motor paralysis or muscle paralysis, you should start thinking about avulsion injuries. Horner syndrome's also something to worry about and easily testable. So avulsion injuries, you treat these differently than the postganglionic injuries. These are avulsed right out of the spinal cord. There's no peripheral nerve, or there's no reconstruction that you can do at that level. You're not necessarily plugging nerves or nerve grafts into the spinal cord, at least not in adults. So you should take these patients to the operating room early. There's no point in waiting because the nerves are not gonna come back. It's a little difficult to determine which patients have avulsions, but that's where a lot of diagnostic testing comes into play. So avulsive injuries, take them to the OR soon, everything else, you should give it a chance to recover. Things that'll tip you off to potential root avulsions, just dorsal scapular palsy, wing scapula with long thoracic palsies. Phrenic nerve palsies are usually something you should start thinking about, root avulsions. So upright chest x-rays are helpful. Elevated hemidiaphragm is what you would see on the x-ray. As I mentioned before, Horner syndrome, it's implying a C8 to T1 avulsion. It's caused by interruption of the sympathetic pathway, exits C8 to T2 spinal nerves. And then an absent tunnel sign in the supraclavicular region also should tip you off to a potential root avulsion. Atrophy of periscopular muscles, shifting of the head away from the injured side. Here's a total plexus patient. You see them compensate by lifting or shrugging their shoulder, firing their trapezius which is usually spared because spinal accessory nerve is a cranial nerve, not a brachial plexus nerve. So imaging, x-rays, if you see an elevated diaphragm then you worry about phrenic nerve involvement. Clavicle fractures, impact that it takes to fracture a clavicle, you should at least think about the brachial plexus. Rib fractures are important if you're going to do intercostal nerve transfers. I'll get into that in my next talk. In terms of diagnosis, the gold standard for tests is myelography and CT myelography. I will say in the real world now, most people are doing MRIs, but myelograms are still considered the gold standard. They give you the best picture in terms of root avulsion. MRI, again, varies per institution. It varies per the radiologist and who's interpreting things. But considered by many to be the new gold standard is the one that we tend to get in real life. So electrodiagnostic testing, kind of adding on to what John was talking about in the last talk. Usually you want to wait after some sort of nerve injury. There's going to be neuropraxia. You want to wait four to six weeks. And then because you want to try to differentiate between a root avulsion and some sort of rupture or stretch, you actually want to get another EMG or repeat EMGs within those six months to see if there's some recovery because that'll determine what you do treatment-wise. And they can give you a lot of information that I'll go into. So denervation injuries, you'll see fibrillation potentials at rest. Absent motor units make you think that there's a complete injury. Reduced motor units, you should think about partial injury. And then if your electrodiagnostician is good or you should specify it, they will test more proximal muscles and that may also tip you off to a root avulsion. Types of injuries, I like throwing this in just so you take a look at this dorsal root ganglion here, which John talked about. But in pre-ganglionic injuries or avulsions, the dorsal root ganglion's intact. So the sensory neuron cell body is still attached. The distal axons do not undergo valerian degeneration because they're still connected to the cell body. From an electrodiagnostic standpoint, you're gonna get sensory nerve action potentials on the exam because that circuit's still intact. But the patient's totally anesthetic. This is pathognomonic for a root avulsion. So algorithms, something easily testable. Any sharp injury to the brachial plexus, you should explore it. It's very rare that you can just repair these without tension. A lot of times, even acutely, you have to use graphs. But essentially, you want to go in and then Dr. McKinnon has this great algorithm here. Anything that's messy, then you should wait. But sharp, transected nerves, you should repair, reconstruct immediately. Gunshot wounds, again, something that's easily testable. You delay surgical exploration for four months. The initial injury is often secondary to heat and traction from the projectile and may recover spontaneously with time. When I give talks like this to the residents and fellows, I like, many of you have probably seen the video of a bullet going through a big thing of Jell-O and you think about all the force. Essentially, the nerves get pushed out of the way. And so that's the reason you tend to wait on gunshot wounds for nerve injuries. Easily testable. Closed traction injuries, again, you want to wait for the neuropraxic time period to resolve. So that's anywhere from four to six weeks or even six to eight weeks. And then if there's some evidence of recovery or some motor units there, then you want to get serial EMGs. But typically, you want to take these patients to the operating room if they're not showing recovery. You want to take them to the OR within six months. So there is a golden window of six months for nerve reconstruction. Tendon transfers, there's no time limit. You can do these 10 years after the surgery if they have good donors. You get immediate results, which is very satisfying for the patient and the surgeon. Free muscle transfers, complex surgery, less predictable results. You do these outside of the six-month window. These are not the ideal ways to reconstruct plexus injuries, but sometimes when patients come in late, that's all you got. So I borrowed this slide from Alan Bishop. You know, emergency, so when you take them to the OR, you have open injuries, like I mentioned before, concomitant vascular injuries. You take care of things. You're looking at the nerve, and then you decide what to do then and there. Early, within six to 12 weeks, you take them to the OR if you suspect a root avulsion. If you don't think there's a root avulsion, then you should wait. Routine timing for surgery, three to six months. You suspect a rupture, you're planning either nerve grafting in the plexus plus peripheral nerve transfers. And then late is when they come late after the injury. It's a delayed reconstruction. You don't have many options. You have free muscle transfer and tendon transfers as the options. Nerve transfers are not great options beyond 12 months. So treatment options, neurolysis, nerve repair, nerve grafting and transfer, and free function muscle transfers. So for direct nerve repair, sharp, clean lacerations only. The repair must be tension-free. Nerve repair with nerve grafts. Questionable outcomes, especially in adults. The HSS group has, and Mayo Clinic is coming out with some more favorable outcomes. But again, the level of evidence isn't great. Nerve transfers are the current mainstay of reconstruction. They give you faster and superior muscle reinnervation. So in humans, as John talked about, this is something I tell all my patients, but it's also important to remember for testing purposes. Nerve regeneration in humans is very slow. It's slower than rodents that you see in the lab. A millimeter per day, inch per month, foot per year. The rule of 18, because it takes an inch per month for nerves to regenerate, if the location of the injury is greater than 18 inches proximal to the target muscle or target motor end plates, then it's probably not gonna get there in time. And so nerve grafting, as many of you know, or all of you know. John went over different donors, but seronerve grafting for plexus is the most common donor. These are intraplexal nerve graftings still done and should be done in brachial plexus patients. But you see kind of how long it would take a nerve grafted brachial plexus to reach the distal extremity. So nerve transfers become kind of the mainstay now. It's relatively newer, but has drastically increased outcomes for brachial plexus reconstruction. And the beauty of it, you're robbing Peter to pay Paul. Okay. Sorry. And your regeneration starts at the distal end of your transfer. So to give you perspective, here's nerve graft for musculocutaneous nerve. Nerve regeneration's gotta go a long way to reach the biceps, which is the target muscle, whereas a nerve transfer, that I'll get into in the next talk gives you much faster, shorter regeneration. Reduces the distance to regenerate. Again, nerve regeneration's very slow. So in terms of brachial plexus, important for everyone to know, the priorities of surgery are elbow flexion. Elbow flexion is the most important, bringing your hand to your mouth. The second most important is shoulder stability, abduction, external rotation. And then as you go down the list, it becomes a little more debatable what's most important, sensation versus finger and wrist flexion extension. But the most important two, elbow flexion, shoulder function. Surgical approaches for the plexus. Essentially, you can go supraclavicular approach, you can osteotomize a clavicle, and infraclavicular approach. So here's just a schematic of the supraclavicular approach and infraclavicular approaches. So again, in summary, direct nerve repair, only for sharp, clean lacerations. Most of the time, you're gonna be grafting. And then nerve transfers are the newer, reconstructive option that give you the best options. You're robbing Peter to pay Paul. You're taking redundant motor fascicles that are expendable, and you're transferring them, and you're getting them closer to your motor end plates. I'll end with a case where we use grafts and transfers. 24-year-old female, attempted suicide, had a right clavicle fracture. Again, the clavicle fracture should tip you off to some sort of involvement of the brachial plexus. Examination concerning for C567 involvement. EMG was concerned about C6, avulsion, MRI, concerning for C567 involvement. Again, sometimes it's a lot of guessing, but you have to get all these diagnostic tests and incorporate them with your physical exams. This is her pre-op. Spinal accessory is spared, usually, for these patients because it's a cranial nerve. Doesn't have any shoulder function on the right, no elbow flexion. Triceps on her were weak. So it took her four months after surgery, or injury. Spinal accessory to suprascapular nerve transfer, which I'll talk about next. Multiple nerve grafts, intraplexal nerve grafting, and then double fascicular transfer for elbow flexion. Here's spinal accessory to suprascap. Opened up her neck, C5 neuroma, cut it out. When there's a gap there, you can actually reconstruct it. Tensoral nerve grafts, double fascicular transfer. So I'm trying to show a case where we used both grafting and nerve transfers. Are you guys able to play these videos? OK, we'll move on. Free-functioning muscle transfer for... Some of my videos aren't working. OK, gracilis muscle is the most commonly used muscle and the most commonly transferred free-functioning muscle. This is used for elbow flexion. Again, for patients that come in in a delayed fashion. There are different free muscle transfers you can do for prehension, elbow flexion, and finger extension. For finger flexion in stage two, you co-opt them to the intercostal nerves as your motor donors. And then you can get some elbow extension against antagonist flexors. Co-opt to the third and fourth. Again, intercostals are sometimes the only options you have for some of these flail or total brachial plexus palsies. Secondary procedures that are used, tendon transfers. So upper trapezius to deltoid transfer, also known as the SAHA transfer. It's good for shoulder stability, not as good for shoulder abduction. Latissimus dorsi transfer, so bipolar or monopolar latissimus transfer to restore elbow flexion. This is something that's testable. Essentially a bipolar latissimus transfer, assuming the thoracodorsal nerve is spared. You secure it to the coracoid approximately, and then into the biceps tendon distally. Peck muscle transfers can be used for elbow flexion. Lower trapezius transfer to infraspinatus to improve external rotation of the shoulder. And then, unfortunately, shoulder arthrodesis sometimes is the only option for people with very unstable shoulder joints. Modified Steinler procedure. Flexor pronator, essentially moved to get some more elbow flexion while maintaining their inherent function. Two, three. And then here's a patient with latissimus transfer for elbow flexion. And then for the wrist, wrist arthrodesis is usually, you know, the patients have a wrist drop. Wrist arthrodesis is usually the option for these patients. So therapy, key to success, gotta keep joints supple. Motor reeducation is huge. So in summary, it's important for the test to know the anatomy of the brachial plexus. You gotta go back and just kinda know the basics of what nerves come off of where. Examination is important. Diagnostic testing and imaging is also important. And then it's important to know the timing for avulsions versus anything that's reconstructable. And then delayed presentation versus early presentation. Priorities of surgery, importantly. Elbow flexion is the most important. Shoulder stability, abduction, external rotation is the next most important. And then there are different ways to treat them.

brachial plexus injuries

anatomy

mechanisms of injury

diagnostic testing

surgical approaches

nerve repair