Peripheral Nerve Neurosurgery: Surveying the Field

Podcast Transcript

Introduction: Neuro Pathways, a Cleveland Clinic podcast, exploring the latest research discoveries and clinical advances in the fields of neurology, neurosurgery, neurorehab, and psychiatry.

Glen Stevens, DO, PhD: Peripheral nerve neurosurgeons are relatively few and far between, but they offer singular capabilities for improving function in minimizing pain and disability for individuals with acute nerve injuries, entrapment neuropathies, benign nerve tumors, and other nerve disorders. In today's episode, we're discussing the little understood subspecialty and its value within the nerve injury treatment landscape. I'm your host, Glen Stevens, neurologist, neuro-oncologist in Cleveland Clinic's Neurological Institute. I am very pleased to have Dr. Megan Jack join me for today's conversation. Dr. Jack is a peripheral nerve neurosurgeon and researcher in the Neuromuscular Center in Cleveland Clinic's Neurological Institute. Megan, welcome to Neuro Pathways.

Megan Jack, MD, PhD:Thank you so much for having me. I'm excited to be here.

Glen Stevens, DO, PhD: As stated in the introduction, peripheral nerve neurosurgery tends to be historically a little understood subspecialty, which you may take offense to, but that's okay. Set the stage for us. So educate us. What's the current landscape of peripheral nerve neurosurgery nationally? Who's doing it? Who should be doing it? Lay the ground work for us.

Megan Jack, MD, PhD: Sure, absolutely. No, I think I don't take offense at all. It's great to be sort of in the field. I find it very exciting, and I love taking care of the patients in the field. So like you said, I think it's a really growing field. It's an exciting field. What I really enjoy about the field is that we get to interact with a whole bunch of different specialists within the field. So between even just surgical specialties, we have plastic surgeons, orthopedic surgeons. I obviously interact very closely with neurologists and people from PM and R that help take care of our patients. And then even on down other caregivers involved like physical therapists or occupational therapists that help our patients regain some of their function. So for me, I love collaborating with other people within the field. So that's a really exciting part about my job.

The other part that you mentioned about is research. And I think the field for that is really wide open from sort of the more clinical care that we provide patients and developing new surgical techniques or new sort of innovations on different designs that we can help improve as far as devices that will help improve patient outcomes. That's really exciting. And then we have other more on a basic science level understanding how the peripheral nerve regenerates and what we can do to actually influence that and change that and improve that for our patients. But I think ultimately the best part of my job is working directly with the patients and helping them to restore function, helping take away pain, which for some of my patients really changes their lives. It gets them back to work. It gets them back to enjoying the life that they had. And so for me, that's obviously the most satisfying part.

Glen Stevens, DO, PhD: So can you talk to us about the patients who are best served seeing you?

Megan Jack, MD, PhD: Yeah. And it's a little challenging to kind of pinpoint down. And so what I usually tell people is that if you think a patient could benefit from a peripheral nerve neurosurgeon reach out, or I think any of myself and anybody else in the field are always happy to evaluate patients, because sometimes we have things up our sleeves that other people may not even think about. But typically any patient that has sort of a traumatic nerve injury are the type of patient that should be referred to us, anybody with a compressive neuropathy, because obviously we can do surgeries that can intervene and take away their pain and improve their function.

There are certain pain syndromes that when they can be localized to a peripheral nerve itself are great candidates for surgery. And then in particular for me, I do a lot of muscle biopsies and peripheral nerve biopsies for patients that need that as part of their workup to help determine what specifically their disorder is and what's going on with them. One of the more unusual things that peripheral nerve neurosurgeons can do is help treat patients with torticollis. So we have a specific surgery where we can de-innervate the muscles in the back of the neck to hopefully help improve the function of and straighten their head for both patients that unfortunately have that as one of their disease processes.

Glen Stevens, DO, PhD: Yeah. I was reading about that in some of your information about the torticollis. I thought it was quite fascinating. And as soon as I read it, I thought, boy, that seems obvious. How long has that actually been going on?

Megan Jack, MD, PhD: Yeah. So it's been going on for a really long time. It is a very old surgery that very few people across the country do. I learned it from my mentor. And again, those are some of the most gratifying surgeries because the patients are so debilitated. They can't work their jobs. They're in a lot of pain. They can't live their lives like they want to. But by doing the surgery, you can really give them back their life. And I've had some of those patients are the most happy patients that we have.

Glen Stevens, DO, PhD: So I'm sure when you go to clinic, you'll read why the patient's there and a median neuropathy at the wrist probably puts an easy smile on your face. And there's some locations that don't put smiles on your face. Just talk a little bit about some of the more straightforward nerves that you would work on and some of the more complex types of nerves you would work on.

Megan Jack, MD, PhD: Yeah, that's absolutely a really good point. So obviously any of the more, very common compressive neuropathies like carpal tunnel, ulnar nerve syndrome, those are great patients because they oftentimes come in with severe pain. They may have some weakness, but they do really well after surgery. And so they're always really gratified and it's gratifying for me. Some of the more complex ones are patients that come in with a total brachial plexus injury where they're unable to move their arm. And while we do have some great surgeries to get them back function, unfortunately it's always sort of tampered with what is the realistic outcome for these patients? Many of them will not return to their jobs that they had. They may have severe pain throughout their lives. You can get them back some very important functions, but I really wish I could give them back what they had before the injury. And that's just unfortunately not possible in our field at this time.

Glen Stevens, DO, PhD: I remember seeing patients over the years that had brachial neuritis or Parsonage Turner disorder where they sort of have this autoimmune inflammatory process that looks like their brachial plexus isn't working, but of course they then end recover and do well. And I think it just sort of speaks to the multidisciplinary approach that needs to be taken and how we need to have the neurosurgeons, the neurologist, EMGs, ultrasounds, imaging, all those types of things to help us understand best what the injury is. Is it demyelinating? Is it axonal? All of those types of things. So it truly is a multidisciplinary approach and I'm sure it's always a cautionary tale when you see patients initially. It's a little more obvious if somebody puts a razor through across the nerve-

Megan Jack, MD, PhD: Exactly.

Glen Stevens, DO, PhD: In that case, but that's usually not the time that it does it.

Megan Jack, MD, PhD: Right.

Glen Stevens, DO, PhD: When's the right time to intervene then? This is I'm sure a loaded question and has a lot of caveats, but who do we intervene on or who do you intervene on?

Megan Jack, MD, PhD: Sure. And I think like you were just mentioning, I think, early referral to a peripheral nerve neurosurgeon. I think one of the unfortunate things that I've seen throughout the field is that, like you just said, nerves take a long time to recover. So we watch our patients very closely. But as that continues on, it moves them more and more out of that surgical window. Typically, like you said, laceration, we like to repair within three days, but that's pretty rare. So most patients, we like to intervene anywhere from three to six months, if we haven't seen recovery either clinically or on an EMG or functionally recovering. And so for those patients, it's sort of a race against time to where you're giving those patients enough time to recover on their own if they're going to recover, but you don't want to go so far that the de-innervation changes that occur in the muscle and sort of those more permanent loss of muscle makes it so you can't functionally get back any of that muscle weakness that's occurred even after surgery.

So it's sort of threading the appropriate needle to intervene when necessary but doing it in the appropriate time. So I always say, refer your patients early to us. We like to get a good exam early on. So that, that way we're able to follow them to determine is the patient recovering property. Like you said, for Parsonage Turner, almost 80 percent of patients get better on their own, but it's those 20 percent of patients that don't. And we want to make sure that we intervene early enough that we can actually change the outcomes for those patients.

Glen Stevens, DO, PhD: So I guess I'll ask, are you running a multidisciplinary clinic or how are you doing that currently?

Megan Jack, MD, PhD: We are. So Dr. Dennis Kao is one of my plastic surgery partners, and we are getting up and running a multidisciplinary care. So that, that way we can provide not only peripheral nerve neurosurgery, but we also have the ability for tendon transfers, muscle flaps, anything that a patient may potentially need throughout their course in particular, as well a follow-up for the physical therapy, occupational therapy, those sorts of things. We also have the orthopedic surgeons involved, which is very helpful. So we're attempting to get that up and running at Cleveland Clinic.

Glen Stevens, DO, PhD: And can you talk about nerve growth? How fast does the nerve regenerate?

Megan Jack, MD, PhD: Yeah, so nerves are very slow growers. So typically what I tell my patients is about one inch a month is kind of what you can expect or about one millimeter a day. So obviously very slow. And so when you're talking about, say brachial plexus injury, where it's coming from a neck down into the hand, we're talking years, and we just know that the changes that occur in the muscle unfortunately that far distal don't recover well. So that's where we can intervene to hopefully provide some options to make that either faster or circumvent it with say a peripheral nerve, distal transfer, something along those lines.

Glen Stevens, DO, PhD: So I'm a neuro-oncologist. So I look after a lot of tumors and historically we also looked after a lot of the NF patients. And fortunately, we're actually starting to get some medications

that we can use to hopefully decrease it. Can you just comment on doing surgery on a peripheral schwannoma versus neurofibroma in terms of your ability to resect it and where the nerve lives?

Megan Jack, MD, PhD: Yeah, that's a great point. So neurofibromas are always much more challenging than schwannomas. Sometimes they can be taken out depending on what the imaging looks like, but obviously typically for a neurofibromas where all of the nerve fibers are running through the tumor. So it puts that nerve at greater risk if we were to do surgery. Schwannomas on the other hand typically involves usually one fascicle that's non-functioning. So it makes surgery for us much easier. The issue that comes into play with schwannomas is the size. We usually like to intervene before they've gotten over three centimeters. They're usually much more challenging to take out when they're larger. So the smaller the tumor, the better for us.

Glen Stevens, DO, PhD: We do a lot of CP angle surgery here, and unfortunately, sometimes the seventh cranial nerve gets affected. And I know the facial plastics guys have been involved with doing a lot of that type of... Are you going to be doing any of that or not necessarily?

Megan Jack, MD, PhD: I typically leave that up to the facial plastics guys. I think they're great at it. And they've done that. I typically tell people kind of my intervention is sort of the neck down. I will obviously do spinal accessories or occipital nerve neurectomies, things of that nature. But generally any sort of cranial stuff, I usually leave to somebody else.

Glen Stevens, DO, PhD: And I think I was reading that ulnar nerve injuries versus median nerve that the recovery's different. Can you explain that to me why that is?

Megan Jack, MD, PhD: And we don't know. I wish I had the explanation. So there are different nerves are known to recover better. So same thing for tibial versus peroneal. Peroneal is much more sensitive to injury and it doesn't recover as well as tibial. Why? We don't know yet. And that would be great to understand, but we just don't know what the difference is.

Glen Stevens, DO, PhD: Yeah. I sometimes see patients in the hospital, especially if they've lost a lot of weight and been in the hospital for quite a while and they're laying down and they'll affect the ulnar nerve or the peroneal nerve. And I always think, well, maybe it's just a demyelinating problem and it should recover. But I guess now that I know a little bit more about the ulnar nerve for you, maybe I need to be a little more concerned about these.

Megan Jack, MD, PhD: Yeah. And I think usually in patients like that, where they've been bed bound for a while, where they run superficial, those are typically demyelinating or pressure palsies. They usually get better on their own, but it is definitely something that needs to keep an eye on. And we have seen even patients that get pressure palsies, there is a study that suggests even decompressing those patients. While they will likely recover on their own, their recovery may actually be quicker with surgery.

Glen Stevens, DO, PhD: So I used to see a lot of individuals out there doing ulnar nerve translocations.

Megan Jack, MD, PhD: Yeah.

Glen Stevens, DO, PhD: And I think maybe too much of that was being done. What's happening with that these days? Are they kind of leaving it alone a little more?

Megan Jack, MD, PhD: I think the data out there isn't great to suggest what you should actually do. I guess my feeling is the ulnar nerve is supposed to be there for a reason. If you are showing signs of compressive neuropathies, I will decompress it. The only time I really do a transposition is if there is evidence that the nerve is subluxing. Beyond that the nerve can live there.

Glen Stevens, DO, PhD: And if I'm your patient and I had surgery, and obviously there's a lot of nuances to this, but what do you tell me about my recovery? What's going to happen? What am I going to notice?

Megan Jack, MD, PhD: That's a great question. When we're talking about compressive neuropathies, obviously you're going to have pain after surgery. We do like to give the appropriate medications to help treat that. But my hope is that you wouldn't start to notice either your sensation loss or the pain that you're having from that, and even potentially the motor symptoms of those that are involved should slowly start to recover over the next few months. Again, the nerves take a while to recover. And that's the same after sort of any injury, whether it be traumatic or a compressive neuropathy. But the hope is that you should get better.

Glen Stevens, DO, PhD: And what nerves can you fix replace sensory motor pain? Is there a limit to which nerves you can fix?

Megan Jack, MD, PhD: Yeah. At this point in time, there's really not. So, I think the field for a long time focused mostly on the motor symptoms, but I think we've recognized how important sensory is now as well. And so I think that's a growing aspect of our field. So we're doing oftentimes safer brachial plexus injuries. We'll do primarily sensory transfers say to the median nerve to hopefully help regain some hand sensation, whether that be for recovery itself or in the future if that patient's going to have a prosthetic placed. Similarly, I think there's a wide open field for treatments of neuromas or post amputation pain, where we have some options, the ways that we treat nerves at the time of primary surgery to hopefully either A, help prevent that, or if they do end up going on to develop ways that we can treat that. So that, that patient's not having pain anymore.

Glen Stevens, DO, PhD: I see patients have Bell's palsy will get synkinesis where they get aberrant regeneration of the nerve. Do you see that when you transplant to nerve or not?

Megan Jack, MD, PhD: Generally not. The way that we coapt nerves when we do that, we suture them together. So typically they are we growing into sort of that distal portion. The issue that we see sort of that synkinesis or the aberrant outgrowth is in those times where you actually do a neurectomy or cut nerves. If those nerves tend to sprout to the skin, those are the patients that are going to get those painful neuromas or pain at the site that you did surgery. And so you have to do something to the nerve, either implant it into muscle or suture muscle around it, or implant it into a different nerve in order to prevent that aberrant outgrowth. But typically when we're doing, when we're suturing nerves together or using some sort of grafting technique, the nerve to nerve is really what we're doing. And so you really don't see that aberrant sprouting.

Glen Stevens, DO, PhD: So the rubber meets the road when you disengage from the spinal cord itself. What can we do if someone has a trauma and the motor root gets avulsed?

Megan Jack, MD, PhD: Yeah, that's a good point. And so one of the things initially that I say is, it can be hard to tell completely if it's avulsed. So we have imaging techniques that help us with that. Either imaging techniques like MRI or CT myelogram can give us an idea, but they're not a hundred percent. So really at the time of surgery, I do nerve testing to determine are MEPs or SECPs present that help us determine is that nerve still functional? So say C5, is that really avulsed from the spinal cord or is it not?

And so what's helpful is we can utilize that if we see that it's everything suggested up until the time of surgery that there was an avulsion, but intraoperatively, we have neuromonitoring that suggests it's not, that's great for that patient because we can utilize that nerve root to either graft into some other distal target or utilize that in our surgery to hopefully regain more function than we were even anticipating. So nerve root avulsions are very challenging in our field. They make our job much more challenging. Therefore we have to utilize other nerves that aren't attached to those nerve rootlets to overcome them.

Glen Stevens, DO, PhD: So you mentioned earlier, and I guess this is the direction for it about research. What's going on in your particular area of interest? What are you interested in? What are you looking at? Where's the exciting stuff?

Megan Jack, MD, PhD: Yeah. I think clinically there's a wide variety. So one of the things that people are now starting to do is to look at C7 nerve root transfers for stroke to hopefully help with spasticity and even potentially regain some functions that are lost. So I think that's a really exciting field that we're seeing more on a clinical basis. I think, like you mentioned, any of the patients with neurofibromatosis and some of the new drug treatments that are coming out and how do that affects some of their plexiform neurofibromas or other schwannomas is a very interesting field that will be ongoing as you know.

And then I think from more of a basic science aspect, I think the field for that is really wide open. One of the aspects I'm really interested in is, is trying to find other treatments that can help aid in surgery. So one of those is we know after a nerve injury or after having surgery, neuro inflammation kicks in within the peripheral nerve. And how we might be able to utilize different techniques, I'm particularly interested in looking at exercise and how that sort of modulates neuro inflammation following and performing nerve injury and can we harness that technology to improve outcomes after surgery or after a nerve injury? So I think they're looking at many different things, whether that be stem cells or different ways to treat pain. There's a variety within the field that I think is so exciting.

Glen Stevens, DO, PhD: So I know the stroke folks have a lot of interest in transmagnetic stimulation for stroke recovery. Are you aware of anything? Does it affect the peripheral nerve?

Megan Jack, MD, PhD: That's a good question. I don't know of any actual research looking at how that affects the peripheral nerve. But it would be really interesting to see.

Glen Stevens, DO, PhD: Well, you can put me down as a sub PI.

Megan Jack, MD, PhD: Exactly.

Glen Stevens, DO, PhD: When you submit that. Anything else that we haven't covered that you think's important for our listeners to know?

Megan Jack, MD, PhD: I really think it's important just now that we have this subspecialty here and we're trying to collaborate not only with orthopedics and plastic surgery, but across Cleveland Clinic to help develop this, refer your patients early. We're always happy to see them. We may not have a surgical intervention, but at least we've rolled out that we do. And no patient is missed that we could give them opportunity to improve.

Glen Stevens, DO, PhD: Well, Megan, this sure was educational for myself and I'm sure for our listeners/readers. Thank you very much for joining us today. And we look forward to working with you in the future.

Megan Jack, MD, PhD: Thank you so much. It's been great.

Conclusion: This concludes this episode of Neuro Pathways. You can find additional podcast episodes on our website, clevelandclinic.org/neuropodcast, or subscribe to the podcast on iTunes, Google Play, Spotify, or wherever you get your podcasts. And don't forget, you can access real-time updates from experts in Cleveland Clinic's Neurological Institute on our Consult QD website. That's consultqd.clevelandclinic.org/neuro, or follow us on Twitter @CleClinicMD, all one word. And thank you for listening.