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MVD for Trigeminal Neuralgia: Personal Reflections

Raymond Sekula

June 17, 2020


- Hello, ladies and gentlemen. And thank you for joining us for another installment of the "Virtual Operating Room" from The Neurosurgical Atlas. My name is Aaron Cohen-Gadol. And today we have with us Dr. Ray Sekula from UPMC. And I really wanna thank him for being with us. Ray has truly carried the torch and the legacy of Dr. Peter Jannetta. And has demonstrated really the next level of performance in microvascular decompression surgery for both trigeminal neuralgia, hemifacial spasm and many of the hyperactivity cranial nerve syndromes. So again Ray, thank you for taking the time to share your pearls of technique. I'm going to show a short video just to get us engaged if that's okay. And then we'll go ahead and review your incredible experience with thousand trigeminal neuralgia operations. So this is an interesting case. And I love to hear your comments, if that's okay. You can see the tortuous vessel on the right side in this case at the tip of the arrow. And this patient had medical refractory trigeminal neuralgia, Ray. We went ahead and did the MVD just to find out what we find. You can see pretty crowded loops of vessel there. And what we find in surgery is very interesting because sometimes these loops can be challenging to mobilize. And, here you can see the right sided entry into the CP angle. And at the beginning you may not see much because the vein is in front of you. I often preserve the superior petrosal vein, as you can see here. And I wanted to sort of take a moment and ask you first. Here you can see the superior petrosal vein right on the middle of our view. Do you regularly take the superior petrosal vein, Ray? Or do you try to preserve it if you can?

- Yeah. I was taught to take that. But we almost never do. And I'm gonna show that a little bit later. Our technique for preserving that as you do as well. We skeletonize all of those three or four tributaries.

- I see. And at the beginning when you come here, you almost don't see much action in terms of axial compression. And it's critical to sort of look in this area in the axilla of the nerve, that can often be very deceiving.

- I'm gonna ask you to pause that again. And the actions is gonna start down here, isn't it?

- Right, exactly. Right into axilla of the nerve. I agree with you. So let's go ahead and find what we see here. You can see the vessel right tucked in the axilla. Look, if you do mind taking off our webcams for the viewers to be able to see the whole video. And you can see that I'm trying to pull the vessel out and it's very difficult.

- Yeah, you do this the same way I do it. I'm gonna ask you to pause this. Peter Jannetta would have began the, start inserting pads here. And then he would have progressively pushed them out towards the porus trigeminus. And eventually this would pop out. But I feel like the way you're gonna show is a little bit more elegant.

- Well, let's review and keep your judgment to the end. I appreciate the kind words. So we went ahead. And as you can see, I try to pull it out. It's such a long loop, Ray. That it's very difficult to pull it out. It's just sort of stuck.

- There you got it, right there. You got that bifurcation.

- Correct. So we mobilize it out. We get it out there. But still we created another source of compression. So we have to sort of really mobilize the whole vessel. And here is the area you just talked about for Jannetta. But before we do that. This is just papaverine soaked gel form, just relieving spasm on the vessel. And in a second we'll go ahead and address the vessel compression. Here you can see the entire complex is moved away from the nerve and then gently dissect in a way, the entire vascular complex. After that we use those shredded piece of Teflon. May I ask if you use shredded Teflon? Or how do you implant your piece of Teflon?

- I think you'll see at some point, Teflon is a form of Felt made by DuPont. I use a form of Felt made by Bard. I don't think there's much difference. But in any event I use PTFE Felt from Bard.

- I got you. I use shredded Teflon because it lets me mold it to the area of the compression. I wanna make sure the artery is very, in a straight, relatively straight non-physio, I mean physiologic position. There's nothing underneath the nerve. Still work to do. The artery appears to be compressed. Hey Luke, can you get our video going? I lost the, I think we lost the video. Here you can see the Teflon was placed. And I continue, mobilize the artery. And again, placing more padding. Because the artery was very large and compressive. And we felt that this would be a relatively good product. The nerve is very much decompressed. Would you do anything else at this time, Ray?

- No, that looks nice. I think you looked on the caudal surface. Of course you'd know all of that in advance from an MRI. I can't tell what's going on right here. But you know there's a limit to what I can see with the videos. But I generally try to leave these, I use a little more formed Felt paddy that looks kind of like a cigar. And then I insert them typically perpendicular to the nerve. And so they go under the artery and over this lateral or dorsal surface of the nerve. So that they can't, the artery can't come back. And I'm not opposed to slinging vessels which people talk a lot about. Over the years I've slung a lot of vessels. But, I don't subscribe to the idea that this material in and of itself, that's just a bloodstain that I was looking at. I don't subscribe to the idea that the material itself results in trigeminal neuralgia.

- So you're satisfied with this result?

- Yes.

- Excellent. Anything else you would do differently?

- That looks great. You've got it all the way from the root entry point into the pons out to the porus.

- Okay. And here's the opening. Which I think is pretty standard. I'm sure you're gonna go over that view for us. So with that let's go ahead and start your slides and videos. And I'm very excited to hear about your expertise, Ray.

- Okay, well thank you for the invitation. We first met in line at a coffee shop. And I don't know which one of us introduced each other. But we've been friends since. It's probably been a decade. I don't have any disclosures. And let's go to slide three, Luke please.

- I worked in a furniture store. And I was walking through the showroom. And, I actually thought that I was struck by lightning. The pain was so bad. And it continued to get worse off and on.

- [Man] What made it worse?

- Brushing my teeth, talking, chewing, chewing, eating was awful, awful pain. And I've been to several doctors. And they don't know what to do other than the carbamazepine.

- [Man] Did that help you initially?

- Initially it was great. I depended on it, absolutely. But over the years I don't know whether my body's become used to it. But it just don't work anymore.

- [Man] How would you say your overall quality of life has been the last decade?

- It's just been getting worse. And even in church on Saturday, I couldn't sing or talk or do the prayers that they asked. I'm sorry.

- Okay. Let's go to the next slide. Okay. So this is a woman with classical trigeminal neuralgia. And there's a lot about this case that's kind of sad. She lost probably a decade of her life to this condition. And when you think about the differential diagnoses for facial pain. Some of the big ones are classical trigeminal neuralgia. Which presents usually a sudden onset and it's lancinating, it's paroxysmal. And the patients are unequivocal about how painful it is once they're really into it. Essentially all women who've had children say it's worse than the pain of childbirth. Men will tell you it's worse than fracturing a bone. It presents rather closely to trigeminal neuralgia secondary to MS. But of course the treatments are different. There's some overlap with cluster headache and these other syndromes. Let's go to the next slide, Luke. Go ahead and play that video please.

- Started in 1996. Was drying my hair after a shower. I thought I was being electrocuted. I thought my kids left a hairdryer in the shower. So I didn't know what it was. I didn't know a pain like that existed.

- Hot poker shoved through the eye, intense pain.

- The last two years have been a bugger. A bugger, bugger.

- Right here.

- The pain is burning, stinging, jabbing.

- I can't eat. The pain is terrible.

- Okay. So that was a number of different types. Usually I have labels on them. But the first patient was a classical trigeminal neuralgia. The older gentleman was a fellow with postherpetic trigeminal neuralgia. I believe the next fellow was a fellow with cluster headaches. There was a woman with terrible trigeminal trophic syndrome after multiple ablative procedures to various portions of the trigeminal system that literally scratched her face off. The next one was another classical trigeminal neuralgia. The young woman sitting on the sofa was a woman that had an injury to her, the mental branch of her nerve during ormaxillofacial procedure. And then finally the last woman was a TN secondary to MS. So, we're not able to poll today. But of these patients, sometimes what I see is that microvascular decompression is a wonderful opportunity, excuse me, a wonderful operation but for a unique subset of patients. And it's been in many cases over-utilized. Microvascular decompression works very well for many but not all patients with classical trigeminal neuralgia. It does not work for trigeminal neuralgia secondary to MS or cluster headaches. It works particularly well for glossopharyngeal neuralgia patients. And sometimes it can be used in combination with patients who have tumors compressing their trigeminal nerve. Because sometimes a blood vessel will be sandwiched between the actual tumor and the trigeminal nerve. And we move to the next slide.

- [Aaron] Do me a favor Ray. You can advance in by next below the slide.

- Okay, pardon me. As you all know. There's these innocuous triggers of light touch, wind, chewing et cetera. One important sign though is the so-called sign of "tic douloureux." Which means painful spasms. So a patient will wince in their clinic. And if they don't do that it's probably not classical trigeminal neuralgia. And unlikely to be the type that's associated with vascular compression. Motor and sensory abnormalities are absent in the clinic unless you were using really sophisticated quantitative sensory testing. Which most would not do unless some sort of research project. So if you detect any amount of hypesthesia or numbness at the bedside. You're likely dealing with some other type of disease process. Now this is a really nice paper from Dr.Sindhu's group where they measured in cadavers the average length of the central myelin. And you can see that the length really correlates nicely with the incidents of cranial compression syndrome. So the longest, of course trigeminal neuralgia is more common than hemifacial spasm. It's more common than vago-glossopharyngeal neuralgia. And it probably has something to do with the central myelin length. This is a paper that's been particularly important to me by Dr. Peker Kurtkaya. And I often cite it. And this was really the first paper at least that I know of that documented nicely the average lengths of central myelin in the trigeminal nerve. So, this is the root entry point into the pons. And the porus trigeminus is out here. And so what they were able to show was that the central myeline, the length between the root entry point and the porus trigeminus never extends past half way. And that's important because this term root entry zone should be abandoned in neurosurgery. Because it really is an ambiguous term and really doesn't mean anything. And we'll talk a little bit about why that's been important to our group. But it's long been thought that vascular compression of the central myelin, that's really the more susceptible portion of the nerve due to the different thickness of the myelin et cetera. Now, I'm having trouble, sorry, seeing my slide here. So classical trigeminal neuralgia, there's a variety of different classifications, schema. And, really outside of the United States, the virtual classification is not used. And certainly we do not use it anymore. Because patients don't have type one or type two trigeminal neuralgia. That's really a statistical construct. And, there's the International Headache Association criteria. And then that was updated by this focus group, but I'm not sure, I can't recall if Dr. Zee, who's on the line was part of that group or not. But it's a nice update where, for years neurosurgeons have been trying to get neurologists and other facial pain practitioners to understand that blood vessels have something to do with trigeminal neuralgia. But, I think this classification schema goes just a bit too far. Because as you can see, they require this right here. That there should be a demonstration of morphologic changes of the trigeminal nerve by MRI. And we know from, and that's just their algorithm. And here it is again showing on the bottom that you need to have neurovascular compression of the trigeminal nerve. And to make a diagnosis of classical trigeminal neuralgia. But that is really not exactly correct. So I was going to ask this question if we could poll. And for now I'll just put this out there to the audience members who agree vascular compression is important for outcomes following microvascular decompression. And Dr. Cohen-Gadol showed that very nice video of what one would, one might term deformity of the nerves. So that would be a severe compression of the nerve. And I'd like to try to argue today that that is in fact very important for predicting outcome. So this was a terrific paper that was published by the Danish Headache Group. Where they looked at 135 patients with classical trigeminal neuralgia as depicted by, excuse me. As categorized by the International Headache Society. And a couple of findings are really important. First, you see here that they looked at the symptomatic and asymptomatic side by high resolution MRI. And you see that 11% of their patients did not have any vascular compression whatsoever. So what that tells us is that there are in fact patients with classical trigeminal neuralgia that do not have blood vessels compressing the nerve. And they should not be candidates for trigeminal neuralgia, for microvascular decompression. Further, you can see that when you compare the symptomatic versus the asymptomatic side. The percentages of severe displacement, severe compression and displacement is very different between the symptomatic and asymptomatic side. And that's probably important. So in other words this old concept that, oh, you just go in there and you'll find a blood vessel. Well, that's rather self-fulfilling. Because look at this, asymptomatic page side of these patients. 78% of them had some form of contact. So in fact if you're not doing a careful evaluation of your patient and you take them for the surgery. You'll likely find something four out of five times. But that doesn't mean you are performing the right operation for that patient. So, we received IRB approval when we were performing microvascular decompression on hemifacial spasm patients. To take a look at their trigeminal nerves. And we categorize them like DeSouza did. So what you see here is on the upper left, this is just the artery in close proximity. On the upper right, this is an artery contacting the nerve. On the lower left there's a vocal compression. And on the lower right there's frank distortion. Similar to the first case we saw from Dr. Cohen- Gadol. Okay. And we used high resolution imaging. Like I mentioned earlier, we identify the root entry point of the nerve, the porus trigeminus. And then we mark the halfway point. And we've asked our radiologist to concern themselves with this first half of the nerve. These are just the parameters we use for our MBD protocol on a 3-tesla magnet. And it looks like this when we apply what we learned from Dr. Peker Kurtkaya on the left. And apply it on the right. So the arrow, the white arrow head is the root entry point of the nerve. Again, we've abandoned the term root entry zone. The white arrows are the porus trigeminus. And the yellow hash line is the halfway point. So everything from the arrowhead to the yellow line is what is important to us. And then here's just examples. The white arrow head is making contact with the nerve depicted by the black arrow. And here is an arrow, the arrow head on the artery that's making a focal compression of the nerve. And then this case is similar to Dr. Cohen- Gadol's original video. The arrow is on the nerve. And the arrow head depicts one branch of the superior cerebellar artery. And you can see that this nerve is really bowed and distorted as opposed to this asymptomatic nerve. All right. So in that particular study where we looked at hemifacial spasm patients without facial pain. We had approval to look at their trigeminal nerve. These were the demographics. As I said, we looked from the root entry point out to the porus. Our neuroradiologist was actually completely blinded to the aim of the study. So, and we asked them to grade as simple contact compression or deformity. There were more women than men in the study. And more left side than right side. And here are the interesting findings. Any type of neurovascular compression was seen in two-thirds of patients by MRI. Intraoperatively 85%. And I would suggest you that that's probably because with the drainage of cerebral spinal fluid. The artery or vein will fall into the nerve. So again that concept of, you just have to go in there and find the blood vessel is misleading. Because you almost always find a blood vessel even in patients who don't have trigeminal neuralgia. But look here, you don't see any cases in our series of deformity. So that just got us thinking that actual deformity must be important. And I've already mentioned this. So won't belabor it. And then we looked at what about the significance of the degree of neurovascular compression in surgery for trigeminal neuralgia. And we looked at 79 consecutive patients. And here were our results. So there's a mix. But less than 80% woke up pain-free without medication. Again, we were operating on a variety of different types of patients in terms of vascular severity. And when we looked at their MRIs in these 79 patients. You see in yellow that almost 60% of the symptomatic nerves had severe neurovascular compression versus less than 10% on the asymptomatic nerve. So that caused us to try to wanna make a scoring system to preoperatively predict who might respond to microvascular decompression. And we use these three clinical characteristics that have been written by others as well. And so we look to see, is there classical or non-classical? And we assigned a point value to that as well as do they respond to medications? The only medications that we concern ourselves with are carbamazepine and oxcarbazepine. Because they're clearly patients with classical trigeminal neuralgia have a different response to these medications than other patients. And in fact, our lab across the street has been actively investigating this area. Because for instance patients with sciatica do not respond to carbamazepine like patients with classical trigeminal neuralgia. And then we assigned a point value to the degree of vascular compression. So if there was a vein or was absent they got a one. If it was just contact, they got a two. And if it was deformity, they got a three. We didn't differentiate between contact and focal compression. And here was our results. So if you're a grade five on average three and a half years after the operation. 93% of patients were pain free without any medication. If you're a grade three, so in other words. You could have classical trigeminal neuralgia, respond to medication at least early in the course of the and have a vein. You have a 44% chance. And in fact, last week I had a patient, classical response to those medications. Very large vein compressing in the nerve. Counseled him, showed him this work. Was concerned about the operation. Did the operation, went perfectly well. He left the day after the operation. No relief of his pain. Alrighty. So I'm gonna move on to technical nuances. At least some of the ways I think about the operation. And so when I was taught to perform the operation, there's certainly nothing wrong with this. The patient is in a rigid fixation and head point. And we've, some years ago abandoned that. And can we play that video. Aaron, can you hear me talking?

- [Aaron] I can hear you just fine.

- Okay. So there's no audio on this slide. So basically we've positioned the patient on a horseshoe rest. Which we find works very nicely. Now we're marking a line between the zygoma and the inion. Which nicely out, characterizes the underlying sinus. And now we're marking the digastric groove. Where the sigmoid sinus is lying. And I do this every single case. And some of our trainees are kind of quick about this. And don't spend the time. And I think that's a real mistake. Because if you spend the time to mark this out nicely, you'll likely pay dividends. So now we've got our incision there. Doesn't matter how long your incision is. Ours happens to be about four centimeters on average. We're just clipping the hair here. And getting ready to put the ear bud in to monitor brainstem auditory evoked potentials. Chances of losing hearing on a microvascular decompression for trigeminal neuralgia should definitely be low. Less than 1%. And okay, we'll go back to the presentation. I thought there was more to that video, but that may be it. Okay. So what we did there was we improved our line of sight by moving the shoulder. I always make sure that I'm holding one end of the tape while the other individual is, has the role in bringing it to the bed. Because you can really injure the brachial plexus. If you're choosing to use head points. Be careful with those points. Because remember the greater occipital nerve, on average is about a centimeter off of midline. About three centimeters below the inion. And it pierces the semispinalis muscles. So you can put your pin right through the greater occipital nerve. And you can relieve someone of trigeminal neuralgia. But leave them with a life of debilitating occipital neuralgia. With the type of beds we use, we always turn the bed in the opposite direction so we have more leg room. And that is something Dr. Jannetta always did. And I find that to be helpful. And those superficial markings come from these papers from John Day. Who's out at Arkansas. And was also one of my teachers. And so if you haven't read these papers, they're really helpful for understanding this surgical anatomy of the posterolateral cranial base and the superficial landmarks. As I said, plan the incision carefully. I don't use computer assisted navigation really for much in the posterior facet. Because, I have a lot of experience and just don't feel like I need to. Like I might in the super tentorial area. Even for acoustics, I don't really use it. But certainly nothing wrong with doing it. Certainly can be an adjunct for you. I like to open the muscle really sharply. So we utilize cautery sparingly. The only way to injure the vertebral artery is just to get too low or too coddle. But you have to be mindful of frame and magnum. You can injure the lesser occipital nerve very easily. And I'll show you that in a second. And you need to plan your incision in such a way that you really, whatever type of retractor you're using will sit squarely over where you want to make your craniectomy or craniotomy. This is a nice little technical note that was published by Dr. Fujimaki. And they talked about their technique for avoiding the lesser occipital nerve. And here it is. The lesser occipital nerve, and just for clarity here, at least in terms of surgical terms. This is would be considered medial. And this would be considered lateral. The lesser occipital nerve runs along the medial belly of the sternocleidomastoid muscle. And so it's often exposed during a suboccipital or retromastoid procedure. I can't overstate this enough. Let's say Dr. Cohen-Gadol is clipping a complicated Acom aneurysm in the morning. And then he's got a 40 year old man who weighs 260 pounds and is five feet eight. And he's on for the second case of the day. Well, it's not a sinister thing. But sometimes our anesthesiologists have a little bit different goals. They're worried about hemodynamics. And so I've had to counsel them over the years to really restrict fluids prior to the dural opening. In that way I don't have to worry about any types of lumbar drainage. Because if, it's not unusual for someone that's been sitting in the pre-op holding all morning and early afternoon to get a couple liters of fluid. And then when you try to open that posterior facet, it's just all coming out at you. And really dramatically increases the morbidity of the operation. I don't use a physiologic dose. I use on a simplified method for mannitol. I give 12 and a half if it's an old elderly frail person. And I give 25 grams for most other people. And I try to give it early. Even though you don't have to in part for training purposes. We open the cerebellomedullary cistern on every single case. And God forbid, you get into problems with brain herniation, put your finger over the wound and push the brain back intradural and then regroup and figure out what your plan is going to be. So this is touching on what Dr. Cohen-Gadol talked about. So here's your confluence of the tributaries of superior petrosal vein complex. And here is the tributaries. And here's your trigeminal nerve. And often time, especially this tributary is right in the way. Because your actions are gonna be down here. The first part of your action like you saw him doing in his operation. So let's go ahead and play that video of sparing these tributaries, please. So we're working between the tributaries. And sharply cutting this arachnoid. Now you can start to see the trigeminal nerve come into view. He did this for a couple of reasons. I mean, the truth is you can get away with sacrificing these tributaries many, many times. And that's how I was taught. But I think occasionally you can end up with a stroke from taking these. And secondly, I think it just makes you and your trainees better surgeons by operating in this manner. And makes clipping aneurysms and other types of delicate procedure easier if you know how to do this. And we're basically gonna work through those windows we develop to decompress the nerve. So once we've developed adequate window. We probably, in this case start working right here. We don't need to be anywhere down here. We've been talking about the use of calcium phosphate cement in cranioplasty for a number of years. And the first paper we published on this was rejected by both of the top tier neurosurgical journals. And we put this in the British Journal, "Neurosurgery." Which I think is a good journal. But doesn't get the same readership. And then the second paper again was rejected and put into the "World Journal of Neurosurgery." But interestingly we've not had a cerebral spinal fluid leak probably in five years. And I started using this in 2009. I think we've had one leak since 2009. And that was actually a patient with a dehiscence tegmen. So I'm not even sure that's fair. Let me go back to that though. But we're looking at our data now. And what we're seeing, and we'd always try to be just totally transparent. What we seeing in the clinic is that, for instance we're just looking at a specific cohort of about 350 hemifacial spasm patients. It looks like we've identified five patients with some late wound dehiscence. Two or three of which were sterile. And two or three of which were actually infected with bacteria. So there's definitely a small incidence of late infection to at least in our series. And we'll be publishing that. So it's kind of interesting. I mean, we've seen some of these pop-ups six months, 12 months, 18 months after an operation. And haven't dug completely into that and why that may be happening. But certainly we'll be publishing it. But I don't think it negates the use of calcium phosphate. To my mind, the real value of calcium phosphate is it does reduce the leak rate. And I started using this after I worked with a few of my neurotology colleagues. Who essentially took their leak rate, which is in line with the international leak rate for acoustics. When we were doing trans labs down from 10% down to close to zero. In fact, our leak rates looked so good that I think the journal reviewers may have thought we were just making this up. But it really is a game changer in terms of CSF leaks. Our rate prior to that was about 2 to 3%. Okay, let's get ready to wrap it up with this video. So this is kind of putting it all together. This is how we look at a blood vessel and a nerve. So this is a severe compression on the left side. Again, here are the markings that we use. We draw a line from the inion to the zygoma or the superior aspect of the to mirror the transverse sinus and the digastric groove. Small incision. But that's not important if you don't have as much experience. You may wait a bit. You can see we're using sharp cautery here, to try to not burn the muscles very much. I use a craniotomy. And there's nothing wrong with performing a craniotomy. But the cranioctomy allows me to do a cement repair. And we've gotten the intersection of the transverse and sigmoid sinuses identified. This is a little bit misleading. This is back when I was still doing some endoscopic MVDs. This is not exactly how I do the decompression typically. But you can see a nice view here with the endoscope. I just didn't find that it really was a useful adjunct to our practice. And I think if you look at what's been published on it, it does not, they really haven't even been able to meet the success rate with microscope. I generally wouldn't insert. I felt this way with a microscope. But with an endoscope this was what was necessary. Cause I try not to touch the nerve. Because I think anytime you're touching and rubbing the nerve, it's not entirely a, it's a kind of a microvascular decompression with a little bit of ablation. Future for MVD is the recognition and advantages and limitations of MVD for classical trigeminal neuralgia. In my practice, if we get one of those 10 or 15% who have classic TN, but no arterial compression. We do something ablative for them. And we, generally I stick with glycerin. Because I think glycerin and balloon are the least destructive. But certainly that's up for debate. Analyzing a cost analysis. And some of that's already been done between MVD versus other procedures. And it'll be interesting when Dr. Zee's study comes to the US. Which it's supposed to start in September. Whether this medication will be so good that we will not need to do as many MVDs as we're currently doing. Obviously we use, we rely heavily on high resolution, heavily weighted, T2 imaging. But we've dabbled in DTI over the years. We've never been totally satisfied enough to really publish something that we felt we could confidently share with our readers that made sense. But I think there's some, there's a future there. And then just getting gentler and gentler with the surgery. And then this last statement is not so much for microvascular decompression but rather, there are times when we wanna, for the old dandy procedure. But we don't have a great ability to interrogate the dermatomes. We've tried a lot of different techniques with our clinical electrophysiologist. But we've not been as successful as I would like. And then I would just like to thank Dr. Cohen-Gadol. Who's a friend and someone that I admire quite a bit. I can tell you that all of our residents use your resources to better themselves. And as well as I do. And then I'd like to thank Marion Hughes. Who is just an outstanding neuroradiologist. Jeff Balzer. One of our clinical physiologists. Michael Gold. Who's my scientific partner across the street. And then Colmore Eubanks. Who you met just earlier. One of my nurse practitioners. So thanks for your time.

- Thank you so much. Really a spectacular talk. Very kind words. We really appreciate it, Ray. As I said again, you have taken the legacy of Jannetta single handedly to a new level. And that's much appreciated for our patients. So I wanted to go to some of the questions. I think you may see the questions that are being chatted right now. And if you don't mind going through them and answering the ones that you feel like they're most important. Obviously it's impossible to answer all of them. What about any experience with craniotomy for MVD? What do you think of that?

- No, I haven't done it. But I'm not opposed to it. I think it might be, I know there's been some experience. Do you do it at all?

- No. I just, patient comfort is too important. And I think within a week craniotomy can be uncomfortable.

- I just worry. And again, I don't wanna demean the work of others who are in this area. It's such a small space that if for instance you had a less experienced anesthesia personnel or a finicky patient that moved while you were doing a hemifacial spasm, you could lose the hearing. And I just wouldn't forgive myself. So, I'm not sure I'm gonna go that direction.

- I think it makes sense. Any movement can be quite challenging. Therefore, I will not do that either. The other question that I like somebody asked here. Is, what about a large, just giant vertebral arteries that really sort of compress the artery nerve so badly that a sponge may not be as effective? What do you do there, Ray?

- Well, a couple of things. And we're not here to toot our own horn. I mean, sometimes I will sling those if I feel I have to. And in those cases I usually use TachoSil. T-A-C-H-O-S-I-L. And I'll use that to sling it. And then I might still insert some Felt between the two. But I can remember a case, oh gosh. Probably about five years ago on a real nice fella that, I mean it was just treacherous. And what I didn't appreciate was that between the basilar and the trigeminal nerve was AICA. So when I got the basilar up in a way and inserted my cushions. I inadvertently compressed AICA against the trigeminal nerve and caused him to have a stroke. So, when you're doing those cases. You really need to make sure that you're not doing that exact issue. I do think the operation can be done safely. And it's certainly when you can do it safely, it's certainly superior to an ablative procedure. But it's on another level.

- I agree with you. Have you used muscle instead of Teflon for any purpose of decompression?

- I haven't. He's a great surgeon. And I don't mean this untoward way. But Dr. Carson used to use muscle. And so did Dr. Jannetta early, early on. And when I've redone those operations. The amount of scarring is so intense that it caused me to stay away from it. I don't know what you think.

- Yeah, no. I don't use that either. I agree with you. It just doesn't fit as well as a Teflon in my opinion. There are questions about, I know Jannetta describes this hypertrophied petrosal bone that can cover the distal edge of the nerve. He had a name for it. What did he call that Ray?

- He used to call that "Kamal's Hump." And that was based on Kamal Kalia that was one of his trainees. And I guess Kamal Kalia always commented on it and would talk to him about it. So he nicknamed it "Kamal's Hump."

- Yeah. We'd drill that. If it's really, it prevents us from seeing the nerve very well. I assume you do the same. Is that correct, Ray?

- I haven't found myself drilling it. But I think there's nothing wrong with that. And, yeah.

- All right. And the other question we do use sequences for diagnosing the conflict.

- We have GE machines. So we use a FIESTA and we use a 3-tesla magnet in our paper, for anyone who is interested. We have all of the specs that we use.

- Okay.

- Pretty sure doesn't mean it's the best, it's what we use.

- And if the MRI is negative, you still do the exploration if they have typical trigeminal around you, don't you Ray?

- I do not, I do not. In those cases, like I said. I think there's 10 or 15% of patients who don't have vascular compression. I think our MRIs are detailed enough that we're not missing something. And so those patients would be stratified to glycerol rhizotomy.

- Okay. You do glycerol I do use balloon.

- I think they're very similar outcomes.

- That's fair. And then the, one of the last questions is. Could you clarify again, the clinical relevance of myelination of the trigeminal neuralgia please?

- Well, let me try to be clear here. Dr. Cohen-Gadol asked me to mostly focus on the surgical part. And I didn't get as much into, I didn't get into the etiopathogenesis. But doctor, if you wanna go back and look, Dr. Marshall Devor published a paper in 2002 in the Journal of Neurosurgery. Where they had approval in Israel to look at 12 patients who were undergoing microvascular decompression. Now under, it's a great paper. It's really interesting. If you follow me, they didn't have the kind of imaging we have today. So they didn't have that benefit. So they went in and did an exploration on all 12 patients. Only seven of the 12 actually had vascular compression of the nerve. They were given approval to take a biopsy of all nerves. So in the seven of the 12, they took a biopsy at the site of compression. But in a total of 11 of the 12 patients they found demyelination and or dysmyelination. So what that tells me is that demyelination, dysmyelination is probably important in trigeminal neuralgia. But whether it has anything to do with the blood vessel. I think their data argues against it. Dr. Zeiske is asking about internal neurolysis or combing. Well, that's kind of a very old, sort of a different name for the procedure. I mean it's, I don't do it. Because it's very difficult to instruct patients or to let patients know how much numbness they're gonna end up with. I think it's something to think about and debate. Have you performed that Dr. Cohen-Gadol?

- I haven't. I agree with you.

- I kind of think that procedure takes us back in time rather than forward. But that's my opinion.

- What do you do for recurrent trigeminal neuralgia after MVD?

- I scan them. And I add an SPGR sequence. So I can make sure I can see through the Felt. And if there's no compression I go with an ablative procedure.

- Okay, fair enough. So I believe procedure is the way to go for you.

- Yeah.

- And I agree with you completely. I think recurrent trigeminal neuralgia and redoing MVD probably has more risks than desire.

- And I really think, and in fairness this is something Dr. Burchiel said. Cause, when I was with Dr. Jannetta we did a lot of recurrent procedures. And most of the time you get through it just fine. I can remember a Christmas Eve when I took apart the and really injured this lady's nerve. It was like soup. And I'll never forgive myself for that. But I'll tell you apart from that story. I just think in general pulling off is really an injurious procedure. And I think that we can do that better for patients with more controlled procedures like glycerin, balloon, RF, those kinds of things.

- I agree with you completely. Okay, with that I really again wanna thank you so much for being with us today. Ray, a tremendous contribution you've had to neurosurgery. And hopefully we'll have you again in the future. We wish you best for you and your family. And I wanna thank all our participants who have been interested and been joining us for the next three sessions. We're gonna have Dr. Juan Carlos Fernandez Miranda from Stanford University. We're going to have Dr. Roberts Spetzler from Barrow Neurological Institute. And we're gonna have Dr. Mustafa Baskaya from University of Wisconsin. And Dr. Juan Uribe from Barrow again. Who will be talking to us about minimally invasive approaches to spinal disorders. So we have a host of very exciting speakers just like Dr. Sekula today. And I wanna thank you for joining us.

- That's a great line. I gotta just answer one more question from Dr. Zee, I don't know if you know her. But he's a real thought leader in facial pain. And she asks, I think one has to accept that TN is a multifactorial condition. So in summit is the sodium channels. I totally agree. And Dr. Zee will be having two papers on sodium and GABA channels in this year coming out. And I hope you'll read them and we can discuss them.

- Beautiful. Thank you. Ray, thanks a million. We'll have a recording of this available hopefully. Most of these are now recorded. But we'll try to do this one and have it available on the Grand Rounds section of the Neurosurgical Atlas website. On the behalf of the team. I wanna wish everyone who has participated today best wishes for them and their families. And Ray, thanks again for your time.

- Thank you.

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