Trigeminal Neuralgia Surgery

Podcast Transcript

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

Glen Stevens, DO, PhD:

A myriad of surgical options are available for patients with trigeminal neuralgia, whose pain is not effectively managed by medications. Choosing the option that's most likely to offer pain relief requires thorough clinical and radiologic assessment. In this episode of Neuro Pathways, we're discussing surgical interventions for trigeminal neuralgia and considerations around patient selection. I'm your host, Glen Stevens, neurologist, neuro-oncologist in Cleveland Clinic's Neurological Institute. I'm very pleased to be joined by Dr. Varun Kshettry. Dr. Kshettry is a neurosurgeon and surgical director of the trigeminal neuralgia program within Cleveland Clinic Neurological Institute's Center for Neurological Restoration. Varun, welcome to Neuro Pathways.

Varun Kshettry, MD:

Thank you. Appreciate it.

Glen Stevens, DO, PhD:

So Varun, I have the fortune of having you just two doors down from me in our offices, so I know you fairly well. But for our audience, why don't you tell us a little bit about yourself, how you made it to Cleveland, your background, those types of things?

Varun Kshettry, MD:

I'd be happy to. So I'm a neurosurgeon. I specialize in skull base and cerebrovascular disorders, which essentially just means we're working in deep areas along the base of the skull, where there's blood vessels and nerves. And I developed a particular interest in trigeminal neuralgia. I did a specific fellowship in skull base surgery and then, joined practice here in 2016. I can tell you a few things about our trigeminal neuralgia program and how I got interested, and the evolution of the program. Now, trigeminal neuralgia, for many of our audience who have seen patients with that, it's really striking, as patients literally getting electrocuted in the face. And to be able to investigate and help some of these patients get out of this state of pain can be very rewarding and fascinating. A few things, for our own program here, we've worked to develop a multidisciplinary program, where we really have shared decision making between the neurosurgeons and the neurologists, and have worked to refine our triage process, imaging protocols, standardized patient collection, and host some educational and patient advocacy activities.

Glen Stevens, DO, PhD:

So Varun, our conversation today will really focus on the surgical management of trigeminal neuralgia. Why don't you start off, you mentioned it just briefly, but why don't you start off and tell us exactly what trigeminal neuralgia is and who's affected by it, maybe some age ranges, that type of thing? What's the population look like that has it?

Varun Kshettry, MD:

The classic form of trigeminal neuralgia is a painful condition of the face. It involves a very sharp lancinating pain, that follows in a trigeminal nerve distribution. The pain is episodic, and it's typically triggered by either sensory or proprioceptive type movements of the face. There's typically an absence of sensory abnormalities, and this pain typically will respond to anti-epileptic medication.

Glen Stevens, DO, PhD:

So let's say I have a young person that comes, sees me, a 30 year old female comes and sees me and has trigeminal neurologist symptoms, anything unique to that population?

Varun Kshettry, MD:

Yeah, so maybe to take a step back, I would say that we have this classic form of the pain, but really, I always try and educate patients that there's a spectrum of facial pain and a spectrum of trigeminal neuralgia. And for any specific patient who's coming to the clinic, I try and figure out, "Where, on this spectrum, do I think your pain is?" Now, trigeminal neuralgia is a clinical diagnosis, so I tell them there's no imaging or blood tests that will actually verify this is trigeminal neuralgia. It's how the symptoms sound. And really, to simplify it, from a proceduralist standpoint, we have a spectrum, where, on one side, we have classic trigeminal neuralgia symptoms. Those patients tend to have the highest success rates with our procedures. Then, in the middle, we have trigeminal neuralgia with atypical features, where the majority of the symptoms are classic, but there are a couple features that are atypical.

They tend, on average, to have lower chance of success, but still decent results. Then, on the other side of the spectrum, we have atypical facial pain or the term "idiopathic persistent facial pain" now and a whole host of different other types of face pain, where really, these don't respond at all to procedures. And in the age of predictive analytics, we do have a lot of data, in the last 10 years, to try and risk adjust someone of what their chance of success is. So the main factors we look at is, what are the symptoms? Are they classic? How many atypical features are? The more atypical features, we start to question the diagnosis. What is the degree of vascular compression on their MRI? The more severe the degree of compression has correlated with higher chance of success and long-term benefit. Is it an artery or vein?

In general actually, arteries tend to have better chance of success than venous compression. Have they had other prior procedures that didn't work? Each subsequent procedure, on average, tends to have a slightly lower chance of success down the road. And are there overlapping pain syndromes? Maybe there's also occipital neuralgia or RSD, something that makes you question whether or not there's a central component or central mechanism of the pain. So we try and think about all these different factors for any given patient, to help counsel them on what the chance of success is with the procedure, because it's very easy to go on the internet and uncle John had an MVD for their face pain and never got pain again. But really, everyone's pain is different. Everyone's situation's different.

Glen Stevens, DO, PhD:

So MVD is microvascular decompression.

Varun Kshettry, MD:

Correct.

Glen Stevens, DO, PhD:

So trigeminal neuralgia, tell us a little bit about the fifth cranial nerve, specifically because I've always been a little curious about this, you have three divisions of the fifth cranial nerve. Can you get trigeminal neuralgia affecting any of the divisions? Or is it specifically much more one of the divisions than the other?

Varun Kshettry, MD:

Most commonly, we tend to see pain lower in the face, V3, but it can affect any of the divisions. V1, we tend to think more of forehead, but actually, it goes all the way towards the top of the head. Some patients have multiple divisions. That is important from the aspect to evaluating our imaging. Now, if a patient only has pain isolated to one division, it's critically important that, on MRI, we have a skull base protocol MRI sequence, that has fat suppression, where we can really follow that branch all the way, distally, as far, on the MRI, to the face. Because once in a while, we will pick up a tumor along the nerve or inflammatory changes that would suggest a different problem.

Glen Stevens, DO, PhD:

And just sort of getting back to the young person that I was mentioning, any other disorders associated with trigeminal neuralgia, certainly, in young people, that you have to be concerned with?

Varun Kshettry, MD:

Well, there's many, and this is really where drawing the expertise of our neurologists that specialize in facial pain is so critical. There's so many overlapping painful syndromes that can occur, from dental disorders, sinus disorders, temporal mandibular joint, and other forms of neuropathic pain. And really, for a proceduralist or neurosurgeon in training, we tend to have a bias that any face pain is trigeminal neuralgia. This can be critically important doing invasive procedures in a misdiagnosis. And so, in our shop here, we have all patients being evaluated by one of the neurologists who specializes in facial pain and really communicating with each other to feel, "What is our confidence with the clinical diagnosis here?"

Glen Stevens, DO, PhD:

Yeah, certainly one of the disorders that, as a neurologist, we always get concerned with young people with trigeminal neuralgia is multiple sclerosis, where they can have a demyelinating process. And I've seen a couple in my career with it. I've also read about it being potentially bilateral, because it'd be pretty odd to have a vascular loop as a bilateral problem, as it goes through there. So you're a surgeon, so you always see these patients later. They're usually, you're not the first stop on the road, but people that end up coming to you for surgery, do you have any idea of how long they've been living with their trigeminal neuralgia before the average person ends up having something done surgically?

Varun Kshettry, MD:

It's all over the map. I see patients who just started with their pain within one or two months, and they've done tons of research all over the internet. And I think that's part of the self-education that leads them to say, "I want to get an opinion as well from a proceduralist." I've seen patients that have been living with it 15, 20 years, some actually adequately managed for a while, some poorly managed, that just were kind of late to get considered for a procedure. So it's really all over the map. But typically, if I see a patient in clinic and I say, "When do we actually do procedures?" Because medicine is typically our first line therapy, is, "Is your pain not well controlled with adequate medical trial? Or are you getting too many side effects from the medications?" When the answer is "yes" to one of those two, that's typically when we consider a procedure.

Now, that being said, our thresholds are different. So coming back to what I was talking about, about the spectrum face pain, the predictive analytics of chance of success of a procedure, if I have a patient who has very classic symptoms, they have very severe pressure on their MRI from a vascular loop, that may be someone who has only tried one medication and failed, that I'd be comfortable to consider a microvascular decompression, versus another patient who has a lot of atypical features, they don't have anything clearly compressive on MRI, so this might be more of an exploratory procedure. They have other overlapping pain syndromes, and their chance of success is overall not going to be as good. That may be a patient that we try, with the medical provider, three or four different medicines, really trying to do everything we can before considering a procedure.

Glen Stevens, DO, PhD:

So I'm a primary care physician out there, and I'm listening to this. And I just saw somebody yesterday that had what sounded like typical right facial pain in a trigeminal distribution, sounded like they had TN. They're brushing their teeth, that bothered them. They're having trouble eating, losing a little bit of weight, that electric type pain. And I want to order some imaging on them. What should I order? Any specific sequences? What do I need to look for?

Varun Kshettry, MD:

We refined our imaging protocol, and there's a few key sequences that are necessary. One is a post contrast fat suppress skull base imaging protocol, that, as I mentioned, allows us to visualize the distal branches of the nerve, make sure there's no tumors. We want to have a flare or T2 sequence looking for any demyelinating plaques or signs of multiple sclerosis. Then we typically get a high resolution T2, which, depending on the machine, might be a CISS, C-I-S-S, or FIESTA. And that really gives us the best view of the cranial nerves within the spinal fluid spaces around the brainstem. And we can actually visualize, very clearly, the trigeminal nerve, see if there's any vascular conflict. Lastly, we supplement that with a MRA, which can help us to, in some cases, distinguish arteries versus veins, when that's of question.

Glen Stevens, DO, PhD:

Do individuals need an angiogram at all? Or no?

Varun Kshettry, MD:

We typically never need to do angiograms with these, unless there's actually a distinct evidence of a vascular malformation, but a typical vessel loop, that's causing compression, not necessary.

Glen Stevens, DO, PhD:

And CT scan helpful? Not helpful, in general?

Varun Kshettry, MD:

CT scan generally is not that helpful, unless there's concern about sinus problems, which getting a CT sinus or a specific temporal mandibular joint, in some cases, those patients might get imaging. Some patients obviously cannot get MRIs, and we've been able to very clearly identify vascular compression with the CT angiogram.

Glen Stevens, DO, PhD:

Yeah, I was actually going to ask you that, because obviously, there are people that cannot get an MRI. Just do thin cuts.

Varun Kshettry, MD:

Yeah, thin slices, one millimeter slices with a CT angiogram. Now, a more extreme version would be a CT myelogram, injecting contrast in the spinal fluid spaces. I would typically start with a CT angiogram, and in many cases, we'll see obvious conflict. But in a more subtle case or maybe a negative CTA, the myelogram would be a more definitive test.

Glen Stevens, DO, PhD:

You're a neurosurgeon, so we should really talk about the surgical options for trigeminal neuralgia. So go through some of the procedures that are available or how you think about it.

Varun Kshettry, MD:

So once we feel confident about the diagnosis and we want to do a procedure, really, there's two buckets. The first is, essentially, one procedure, the microvascular decompression, where we think the source of the pain is a vascular compression on the nerve.

Glen Stevens, DO, PhD:

So tell me a little bit about the vascular loop. Arterial? Venous? Could be both? Only one.?

Varun Kshettry, MD:

Yeah, so when we look at the microstructure of the trigeminal nerve, the myelin sheath, when it first comes off the brainstem, comes from oligodendrocytes. There's a transition zone, where that myelination is formed by peripheral Schwann cells. And that transition zone is often thought to be a weak area, where some sort of compression, whether it's a tumor or a loop, a vascular loop, can cause demyelination or dismyelination in the nerve focally, causing trigeminal neuralgia. So classically, that location is at the root entry zone, where the nerve comes off the brainstem. But histological studies have shown that that transition zone can occur anywhere from exactly at the brainstem all the way to about 50% down the nerve in the cistern, when you make a line from the brainstem to Meckel's cave. And to answer your other question, both arteries and veins can cause trigeminal neuralgia.

The issue becomes the degree of compression does correlate with the long-term benefit. And veins, when they have conflict, more often, tend to be abutting the nerve and not necessarily what we call indenting or distorting the nerve. The other aspect is that veins tend to be much more common in the general population. So I'll say one of the misconceptions I sometimes see when patients come to the clinic is they think their MRI diagnosed trigeminal neuralgia, and we go back to the original part, which is that this is a clinical diagnosis. And actually, asymptomatic volunteer MRI studies will show, depending on the study you look at, arterial compression at the root entry zone is in 20 to 40% of patients. And venous contact is almost 50% of patients. So this is very common in the general population, even though none of them ever go on to get face pain. So we always have to think, "Is this the cause? Or is this a red herring or a coincidence?"

Glen Stevens, DO, PhD:

So tell me, go through the microvascular decompression, then you can tell me the other bucket. I kind of interrupted you there.

Varun Kshettry, MD:

Yeah, that's a brain surgery. Essentially, what we do, it requires full anesthesia. We make a small incision behind the ear. We make a bone opening, typically slightly smaller than a quarter, and then, we're looking with microscopes and telescopes in the spinal fluid space. And we can see all the anatomy, the nerve, very clearly, and any blood vessels, we can explore all sides, up and down along the nerve. And anything that's contacting, we can gently release it, mobilize it, and then, the last part requires some sort of way to keep the vessel from coming back.

In many cases, that may be Teflon, and I'll just talk about a slight nuance, where I think some of the practice is shifting, in my own practice, but also, some others, where, in a best case scenario, we like to transpose the blood vessel away, secure it to some other location or membrane, and really, leave nothing touching the nerve, rather than kind of just wedging a piece of Teflon in between the two. I think there's potential for better long-term relief and also, can minimize any foreign body reaction that theoretically could cause some inflammation on the nerve, but the data has not been investigated to really see the difference between those two. But that's my personal preference is transposition when possible.

Glen Stevens, DO, PhD:

And the outcomes for a typical trigeminal neuralgia, that looks like a vascular loop outcomes, how long does it take for the pain to go away? They wake up and they feel better?

Varun Kshettry, MD:

In most cases, it's immediate.

Glen Stevens, DO, PhD:

Okay. And how long does the pain relief last?

Varun Kshettry, MD:

The chance of success really depends on patient selection. So the more strict you are with selecting the right patients, the higher the percentage success rates. In our own practice, we see around 90, 95% of people become completely pain-free off medicine. One or 2% of people don't get too much improvement, and the other group of patients get improvement, but not the strict definition of pain-free and off medicine. So the initial success rates are high. The issue is always, how long will that last? And in general, we can see about one to 2% of people per year can get recurrence of their pain. So by 10 years, up to 20% of people got recurrence of their pain. If they make it to 10 years with no pain, then it tends to drop to about half a percent per year. And then, usually, if someone makes it to 15 years with no pain, they're in that lucky group of patients that don't ever get pain again.

Glen Stevens, DO, PhD:

So I take it the other bucket is rhizotomy patients?

Varun Kshettry, MD:

Correct.

Glen Stevens, DO, PhD:

Tell us about that.

Varun Kshettry, MD:

So the other bucket is where, if we do not see a clear vascular compression, then what we're actually trying to do, how I explain it to patients, is we're trying to create a mild controlled injury in the nerve. Okay? I always tell them, "Yeah, I know it sounds goofy. Why do you want to injure the nerve? Well, simply it makes a nerve less able to transmit the pain sensations." But the flip side to that is these bucket of procedures have more risk of causing numbness in the face. And so, I tell patients, "I would not consider an ablative procedure, unless you're willing to accept some chance of numbness in the face in exchange for the chance of pain relief." And we also clarify that this is not droopiness in the face. This is a sensory phenomenon. Now, how we do that can vary, ranging from so Gamma Knife, which is a two millimeter spot of very focused radiation right onto the nerve.

We can insert a needle in the cheek, with the patient under conscious sedation or general anesthesia, and bring the needle back through the foramen ovale to Meckel's cave. And from there, we can do one of three things. We can inflate a balloon that creates a mechanical disruption. We can inject glycerol, which is a chemical irritation, or we can do a radiofrequency ablation, which is a thermal injury to the nerve. And in general, all of these things have very similar outcomes, in terms of effectiveness and durability. In general, for effectiveness, instead of that 90% range, we're more in the 60%, that we can get pain-free and off medicines. About a 25% improvement, but not necessarily pain-free completely or completely off medicine. And a 15% chance of someone saying it didn't help a whole lot.

Glen Stevens, DO, PhD:

So I guess your decision making with the patient is, if they have an obvious vascular loop and they have a typical presentation, you're probably going to recommend the vascular decompression, unless they're a poor surgical candidate.

Varun Kshettry, MD:

That's correct. If someone's healthy enough to undergo surgery and we see a clear loop, we, in most cases, offer MVD, because of high chance of success and longest durability.

Glen Stevens, DO, PhD:

Then how do you decide on the other, the rhizotomy options?

Varun Kshettry, MD:

Well, first thing, coming back to the young patient, I caution against starting rhizotomy procedures in young patients. The reason is durability. So median pain-free survival may be about three years. So for a young patient, that's potentially setting them up for needing many rhizotomies over their lifetime. Now, a single rhizotomy has a low risk of something we call deafferentation pain, anesthesia dolorosa, which is a different kind of a constant numb burning pain, that's very difficult to treat. But someone who's had many rhizotomies over their life, their risk starts to increase of that problem. So I tend to caution and avoid doing them in young patients.

Now, to answer your question, between the three options, really, in our practice, we've moved towards two, balloon compression and Gamma Knife rhizotomy. The radio frequency is nice, because it can be selective, but you have to waken patients during that and actually deliver electrical shocks, to map out where you're delivering the treatment. And for patients, that can be a bit uncomfortable. And glycerol is also a good option. But actually, around the time of COVID, there was more issues with pharmacy availability of this, that we went exclusively to the balloon.

Glen Stevens, DO, PhD:

And you mentioned, with the vascular decompression, they can wake up and feel better. What about with these rhizotomies? What's the time period for improvement?

Varun Kshettry, MD:

Yeah, for our needle rhizotomies, it's, again, also immediate or within a couple of days. One exception is for Gamma Knife rhizotomy, there's a latency period, time for the radiation to work. Median is about four to six weeks. I've seen some patients that get it immediate relief, but others that may take even three or four months. So someone who comes in in very severe pain, they can't even eat, they tend to move towards MVD or a balloon rhizotomy rather than Gamma Knife.

Glen Stevens, DO, PhD:

So this may be too specific a question, but if you're going to do Gamma Knife, do you do it at the dorsal root entry zone, up against the brainstem? Or do you move further along the nerve? Because you're mentioning, microscopically, it's a little hard to know exactly where the effect might be best, right?

Varun Kshettry, MD:

Yeah, that's a great question. And there's been quite a bit of debate in the literature in the last decade on the optimal Gamma Knife target. And the data, in our own practice, has shifted a little bit towards moving slightly distally on the nerve. The main reason is that this, in larger series, has been shown to have equal success rates with less chance of numbness.

Glen Stevens, DO, PhD:

Okay, great. So I think that we sort of covered really the procedures, and you mentioned it a little bit, but just go through, a little bit more detail, some of the potential complications for us.

Varun Kshettry, MD:

Correct. So with any rhizotomy, there's a chance for numbness. And this is one thing that's often easier to tell a patient, but not necessarily for them to fully comprehend or experience what that feels like. And in general, we see, with rhizotomies, about a 20% chance of some degree of long-term numbness. We do see, with needle procedures, there's probably higher than that, like an initial spike of numbness, but a lot of that will go away within a month. And the long-term is about 20%. Whereas Gamma Knife, we don't see an initial spike, but when we go out a year after the procedure, those patients also reach about 20% chance of some numbness. The risk of a deafferentation pain on a first time rhizotomy, whether that's Gamma Knife or balloon, is still very low. It's about 1% or less.

Glen Stevens, DO, PhD:

And one thing we didn't mention, radio frequency ablations, that's still being done?

Varun Kshettry, MD:

That's still being done. Again, that's a center to center practice difference. Again, in our own shop here, we've shifted away from that, mainly for the main aspect of that it can be quite uncomfortable for patients having to wake up and get electrical shocks delivered to map out the nerve.

Glen Stevens, DO, PhD:

So training needs to do this? It seems pretty obvious, I think, if you have this type of process, you want to go to someone that's doing it. But the training, for most people that do these things, what's the training? You mentioned a little bit the training you did, but tell us what people should be doing.

Varun Kshettry, MD:

Wonderful. I think there's two aspects. Definitely, from a patient perspective, there's an advantage to seeking out providers or places that do all of the procedures. Unfortunately, there are many places around the country where, if someone gets referred, pretty much, they're only going to be offered one or two of these procedures, at most. So that's very important to go someplace where you're going to be offered all of them. So you can really pick out the nuances of what might be best in your case. In terms of specific training for microvascular decompression, that's a procedure that's been around since the seventies, but over time, we've done it through smaller and smaller incisions, smaller bone openings, using more minimally invasive keyhole techniques. And really, with that, have been able to minimize hospital stays. Our patients don't go to the ICU. In fact, they go to a regular neurologic floor, and we have a large percentage of patients that are actually able to get out on post-op day one. So trying to do it in a more minimally invasive fashion to reduce the risk and get patients recovered faster.

Glen Stevens, DO, PhD:

Excellent. So we've covered a broader range of topics here with trigeminal neuralgia. Any takeaways for the group or anything we haven't covered you think is important?

Varun Kshettry, MD:

Well, I would say a few summary takeaways. One is to emphasize the importance in an accurate diagnosis and pulling in as much expertise to rule out other mimics or competing diagnoses or problems. And also, having shared decision making, to really get a consensus on the confidence in the diagnosis. And that threshold of when someone's going to undergo a procedure, that's a shared decision. And then, lastly, to understand that there's a spectrum of face pain that we can try and in the era of precision medicine, help patients really understand where they fit on that, their chance of success. Lastly, I'll say that I think the future steps of this is we're starting to appreciate and understand that trigeminal neuralgia is a spectrum of different disorders, and it's not just vascular compression or multiple sclerosis. And doing more research and investigation and focal demyelination, understanding channelopathies or central mechanisms of pain, to really be able to pinpoint, for any given patient, what is the source of their pain.

Glen Stevens, DO, PhD:

Well, listen, Varun, it's been a fascinating discussion. I have the pleasure of working with you on an almost daily basis, and the care that you give to your patients is really to be admired. And I really appreciate your joining us today. Thank you.

Varun Kshettry, MD:

Thank you so much.

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.