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Grand Rounds-Microvascular Decompression Surgery for Glossopharyngeal Neuralgia

William Couldwell

May 30, 2011

Transcript

- Ladies and gentlemen, thank you for joining us for another session of the doubleness operative grand rounds. The following session will be a discussion regarding surgical management of glossopharyngeal neuralgia. Our discussant will be Dr. William Caldwell, from university of Utah. Glossopharyngeal neuralgia is a rare disease. However surgical treatment is associated with very satisfying results. We therefore thought it would be reasonable to dedicate a session to it. We hope that you will enjoy, the session. Thank you.

- Bill thank you again for joining us this afternoon. This is the disclosure for the participant or the participants, none of which interferes with the presentation. Before we start the discussion about glossopharyngeal neuralgia. I think it's useful to present a patient's interview that we have reported recently. You're gonna see her surgical video at the end of the presentation, actually, and this is such a rare pain and the diagnosis is so important that I think just hearing it from the mouth of the patient is gonna be so much better. So let's hear the video of this patient's interview describing her pain in detail.

- Can you please tell us about your pain?

- The pain that I experienced was very excruciating. It's the worst pain I've ever felt in my life. And it would start in my throat area and it would just shoot up into my middle ear and then radiate down my jawline. And it would just, if it lasted very long, I would start coughing and choking because of the saliva. And I never did pass out, but I felt close to it a couple of times. The pain could be triggered by lots of different things. Sometimes coughing, sneezing, yawning, cold drinks, food never seemed to do it as much as drinks. Sometimes if I raised my voice, I could get pain and sometimes it just happened for nothing. It just would happen on its own. And it's just one of the most terrible pains a person could ever feel.

- So, now that we heard that story, I would like to ask you Bill about what is the pearls you have used both in the diagnosis and treatment of this problem. And then I'll jump in. And if you don't mind, review some of the basics.

- Sure, Aaron we use, it's a pleasure to be here. And this is a very rare disorder, as you mentioned. And so it's critical to select the patients well especially if you're considering surgical treatment. We look for a characteristic pain in the throat or the tongue and tonsil pillar, sometimes in the ear and it occurs paroxysmally and lasts for a few seconds to a few minutes. It may be initially responsive to medical therapy with one of the anti-seizure drugs that we use. And then we often use a topical anesthetic on the tonsil pillar to see if we can get aggrevation of the pain. Because I feel that it's a very useful tool to determine if somebody really has glossopharyngeal neuralgia.

- Thank you Bill.

- If we do diagnose them as such, we have no hesitation. If they're medically refractory we take them to surgery and proceed with microvascular decompression or nerve root section.

- Right. So it is an extremely rare disorder. It is so rare that if you see a hundred trigeminal neuralgias, a year, and that is your specialty to see that many, you only are gonna see one out of hundred. So, most people who have your experience who you treat a lot of trigeminal neuralgia, are gonna see maybe two or three of these a year. And so the diagnosis is important and a treatment is also critical because it is really effective if you select the patient correctly. And it most often occurs in the sixth decade of life. It's often misdiagnosed and we're gonna go over the nuance of diagnosis. And first of all, we have to make sure the pain is neuralgic. And the pain again, mostly in the throat. It shoots sometimes into the ear, the patient history, localization or radiation of pain, the character of the pain in terms of being mostly electrical. The cutaneous triggers are important in terms of swallowing and the relenting course and response to neuropathic medication often mix the pain to be more neuralgic rather than neuropathic. So let's focus on glossopharyngeal neuralgia specifically. It's a pain that originates in the posterior pharynx and tongue and tonsils and the pain can be often very much in the ear and otitic. In other words, the otitic component with the pain maybe most prominent and the patient may complain mostly of the pain that's neuralgic, in the ear or the eustachian canal or the side of the larynx, and that may cause some overlap with geniculate neuralgia, which is primarily an ear pain an ear canal pain. And the cause of the problem can be really primarily related to the ninth and 10th cranial nerves. But again, the pain has to be neuralgic, shock-like stabbing, in the back of the throat, often radiating to the ear can be scratching and like a foreign body in the throat. It is unilateral and often intermittent, and again, waxing and waning. What are the triggers for glossopharyngeal neuralgia? It is often spontaneous, swallowing acidic or spicy food may cause the thing to come about. Coughing, yawning or talking just like trigeminal neuralgia that has cutaneous features. These are the trigger factors for glossopharyngeal neuralgia. Movement of the jaw, touching of the ear and taking a shower may even cause the pain. What is interesting is that the pain can cause a syncopal episode that can be either life-threatening rarely. And what happens is that because of one of the triggers, the over discharge from the ninth and 10th cranial nerves may cause an asystole because of again, over discharge from the nucleus of the 10th nerve, the vagus nerve, the tractus solitarius and the patients may either require a pacemaker to prevent a complication of asystole. What are your thoughts Bill in terms of unusual presentations of glossopharyngeal neuralgia?

- Well, I think you hit on the most important points. There is a crossover between genicular neuralgia, glossopharyngeal neuralgia sometimes trigeminal neuralgia. and I think it's very important to try and sort these out. And I can't tell you how important it is to have a good otolaryngeal colleagues to have to see these patients do a complete head neck examination and to help go ahead and do a local anesthetic test in the posterior pharynx to see if we can aggreviate the pain as a test prior to considering surgical treatment.

- Thank you. And I think you sort of mentioned very eloquently what are the nuances. You wanna MRI the brain and neck. You want a thorough otolaryngeal consultation in terms of ruling out a primary pharyngeal or otitic or ear problem. And after you have excluded the head and neck pathologies, once you mentioned the injection of cocaine, the 10% solution in the posterior pharynx. and the relief of the pain for two hours or so, but excluding the trigger points confirms the diagnosis. If a patient has a very classic presentation of also glossopharyngeal neuralgia, Bill? But they don't respond to the injection of the cocaine solution in the posterior pharynx, would you consider offering them a surgical option?

- I think that's a good question. I have not done that if we were unable to stop the pain with the anesthetic test.

- Okay, so in other words, that cocaine solution is a pretty important selection criteria for your surgical patients.

- Yes it is. It gives me more confidence to go ahead. Especially if we're considering on doing a microvascular decompression or nerve section in a patients such as this.

- Okay. Thank you Bill. So let's talk about medical treatments. I think tegretol is one of the first ones, but a number of patients become refractory and require surgical treatment. And again the correct diagnosis is really the most important factor in treating this condition almost much more technically challenging, I would say, than perform the microvascular decompression surgery. The overlaps with genicular neuralgia trigeminal neuralgia, and most importantly it overlaps with atypical regional pain syndromes can be so tricky at times that the patient may come and complain of this throat pain, but also lateral neck pain. And it's constant. There is a burning character to it. And if there is a burning character and numbness character to it, and there's no typical triggered cutaneous features or you know, swallowing food to cause the pain, I think that's a big red flag in terms of not making the diagnosis of glossopharyngeal neuralgia. Do you agree Bill?

- Yes, I absolutely agree with that statement.

- Thank you. So let's talk about surgical options because if the patient is selected correctly, this is really an amazingly beautiful operation, it's pristine and at the same time the patients do very well. So, what are the surgical options? One is intracranial in terms of microvascular decompression of the ninth and the 10th cranial nerve. Regarding, sectioning that is not being our practice. Our practice has been sectioning in the ninth nerve because the sequelae are so minor in terms of cutting the nerve and the microvascular decompression of the 10th nerve. We do not routinely section the upper rootslets of the 10th nerve besides sectioning the ninth nerve, as some others recommend. However, if you expose the lower cranial nerves and you section the ninth nerve, and you do not find a compressive vessel, either along the ninth nerve or the 10th nerve, by adequate inspection, it is prudent to proceed with sectioning the upper two rootlets of the 10th nerve. What has been your philosophy in terms of surgical treatment Bill?

- So I, I think this is an important discussion. I explore the patient and see what it looks like. If I'm convinced that there's a good vascular compression, we will do a simple MVD. And I actually perform a transposition of the artery to get it away from the nerve and leave nothing touch the nerve if possible. If I'm not convinced that there's excellent vascular compression, then we'll go ahead and do a ninth thorough section and then take a look at the upper two roots of 10 and may cut those And if there's a partial vascular compression I agree, We try to avoid cutting the upper 10 rootlets if we can. So certainly closest philosophy with you, Aaron, I really make the decision inter-operatively.

- Okay. So it seems like cutting the ninth nerve is pretty low risk, in terms of swallowing. I have never heard of a complication of swallowing if you just cut the ninth nerve without touching the 10th nerve. So if you cut the ninth nerve, really decompress very thoroughly as you very well mentioned, Bill. And if you don't find a compression at the 10th nerve or the root entry zone of the ninth or root exit zone of the ninth nerve, you'll go ahead and section the upper roots or so.

- Yeah I will. the first two rootlets

- Thank you. Are other options that have been described? Like percutaneous radiofrequency rhizotomy of IX and X cranial nerve at jugular foramen and peripheral rhyzotomies such as extracranial ninth nerve sectioning both of which I think more of a historical perspectives. Am I correct Bill?

- That's correct.

- Thank you. Let's go ahead and talk about imaging for glossopharyngeal neuralgia. Obviously brain MRI to exclude a structural pathology such as a neoplasm a meningioma `or epidermal . Let me ask you Bill, if you do a high resolution with sequences C sequences, the high resolution T2, a sequence of MRI, and you do not find any vascular loops, but the patient has characteristic features of GN and passes the mustard of the cocaine test. Would you offer them expolariton posterior foster surgery?

- Yes, I do In those cases. I don't set the bar as high as I do for trigeminal neuralgia for this disease. Because you do have the option of sectioning nine with very low, low morbidity, and also sectioning first roots of ten. So I have routinely offered them if I'm convinced clinically on their history and they've passed the anesthetic test of their pharynx, then we'll go ahead and explore them.

- Okay, that's very consistent with all the colleagues of mine and others that I have discussed this problem with. This is a patient that will see their surgical video very shortly. And as you can see here, there is a vessel just sort of a loop across the lower cranial nerves, compressing the brainstem and maybe a vessel loop around here often with the lower cranial nerves and maybe difficult to situate or localize the exact vascular loop with the location of the lower cranial nerves especially for a nine and 10. let's talk about intraoperative monitoring before we dive in into technical nuances. We routinely do intraoperative monitoring for the eighth nerve, but do not do monitoring for the 10th nerve or do intraoperative stimulation to make sure the upper roots do not affect swallowing by having a sensor on the ET tube to map the vagus nerve. What are your philosophy in terms of intraoperative monitoring for this disorder?

- So we routinely obviously monitor the ABR

- Okay. the VIII nerve because we're always concerned about brain retraction and putting traction on the eighth nerve. And we agree with you that we use a pickup on the endotracheal tube so that we can actually stimulate the motor rootlets of 10 and identify those. Cause if we do come to intraoperative decision where we're cutting the first two or three rootlets of 10, we want to make sure that we're not cutting the motor rootlets.

- Okay, so you have a sensor on your ET tube and you stimulate the upper two rootlets before you cut them If you have to cut the upper rootlets, as you go find a vascular loop. May I ask?

- That's been very useful because we can stimulate the lower rootlets and that's your positive control for your stimulator test. And then if you find no evidence of any stimulation with the upper two rootlets then we'll be comfortable cutting those.

- Okay. May I ask you Bill, what is the voltage or amperes you start with in terms of stimulating the vagus nerve intraoperatively?

- use 0.05 milliamps.

- Amps to start with, and how high do you go?

- Do go to 0.2 or maybe even higher. It depends. And we use the lower rootless as the control because we like to get positive stimulation with some of the nerve. And then back that off to the minimum possible

- Okay

- We can use.

- May I ask you a more difficult question? If you don't find the vascular loop despite adequate inspection and you stimulate everything and everything is stimulating because sometimes the nerve is so adhered or the rootlets. How do you make a decision to cut or not?

- Well, I think in a case like that, if, we couldn't sort out the rootlets of 10, we would just go ahead and cut nine and leave it at that.

- Okay just to stay safe. That makes sense. These are some of the slides we have discussed previously during our trigeminal neuralgia session with Dr. Janetta. And I briefly I'm gonna go over them and please interrupt me Bill, and give me some thoughts about posterior fossa surgery. This is the set-up in the OR. Often we place the nurse and the surgeon across the room from across the table from each other to provide an ease of transferring instruments. The anesthesiologists may be placed at the foot of the table, if necessary to create more space. We do a routinely do a lumbar puncture for two reasons. It really did compresses very nicely the posterior fossa space and to decrease the venous bleeding due to craniotomy. In addition, it helps to go around the cerebellum with minimizing the retraction while the patient's head is placed in the, in the maple head clamp, we do a lumbar puncture, drain about 30 CC. And as you wash your hands and come back in the room, we have one of our assistants in the room, remove the needle. Do you have any thoughts about a lumbar puncture or you feel like just releasing the fluid from cisterna Magna is adequate and this is not necessary, Bill?

- Yeah, we routinely don't do the lumbar puncture for this operation. Certainly for other types of operation, we do them all the time. For subtemporal approach to a basil for instance, but in this instance I usually find that aspirating CSF from foramen magnum is adequate. And you could actually just put a general retractor on the tonsil and find access to the glossopharyngeal nerve.

- Thank you. May I ask if you use a lateral position just in this illustration?

- Yes. A couple of points about that. I always use the lateral position because I don't like to bend the neck too much in people. And I think you've nicely illustrated the fact here that we pull the arm down the upper arm down out of the way. So I put the airplane rest, usually close to the break in the center of the bed. So I can actually put inferior traction and pull the arm down out of the way to give you more room for operating in the posterior fossa

- Thank you. Those are critical, especially for larger patients to create that special space where you have to work on the lower part of the posterior fossa. Thank you. This is the head clamp we use. I think you can put a pens right above the ear on both sides and make sure the single pin is ipsilateral to your surgical field at your surgical field. Also, we turn the head a little bit. Do you use the head parallel to the floor along its long axis? Or do you turn the head contralaterally just like this illustration, Bill?

- Yeah it depends on the exposure, but most of the time we would, I try to keep the neck as neutral as possible.

- Okay.

- And I do this as a habit and I teach our residents and fellows this, to try and avoid any kinking of the neck, but we'll rotate the head a little bit more if necessary. And it depends on the exposure we have and how big the patient is.

- Thank you. And I think that comments you're making is so useful for any posterior fossa procedure, even though glossopharyngeal neuralgia is rare. I think these are tips that we can use for almost any posterior fossa exploratory surgery. The shoulder can also fall forward and create even more space for you if you need. And then you can put a piece of tape over it to pull it down. We have a position in video. Again I thought I'll share that with you. And again this video shows how the pins are just above the ear on both sides. And ultimately, the patient is placed into a lateral position and the head can be parallel along its axis to the floor or slightly turned. And this position really keeps the neck in a very neutral position and most likely prevent some of the postoperative neck pain that you may see in some of the patients. Here is the illustration of the incision. We use a curvilinear incision, I know Janetta and many others, and most likely yourself using a linear incision. Isn't that correct Bill?

- Yeah, actually I use a little S shaped incision along the axis of where we're going to retract the posterior cerebellum. And it's a little lower than that. We try to do a very minimal incision and a very small hole for this operation.

- Thank you. The curvelinear incision, the only reason we have tried to use than we use that obviously years before And it does two factors for us. Number one, it's often prevents getting into the muscles of the neck by lift reflecting fairly and the extend of linear incision doesn't go into this muscles of their posterior neck. Second of all, it often avoids the neurovascular bundle. Where do we, how do we determine where we should put the incision? Is we a create a line between the inion to the root of zygoma that's the transverse sinus. Then we put a ventricle line from the root of mastoid or from outside the mastoid root perpendicular to the first line and that's gonna be summits of our incision. And then we just try to have our incision a little bit anterior to the mastoid root with a broad base to have adequate vascularity. This is a cross-sectional illustration of just for people who advocate the curvilinear incision, as you can see in a cross-section when you use a linear incision, there is bunching up the muscle up cutaneous tissues, and that can increase your working distance. And so there may be a longer distance across which you have to work to the nerve. If you use a curvilinear incision the flap reflects inferiorly in one layer again then musculocutaneous flap all in one layer, reflecting inferiorly and the working distance is less hindered Again every approach has its own advantages and disadvantages. Compared to trigeminal neuralgia where the exposure is more superior and medial. The exposure for glossopharyngeal and hemifacial spasm is inferior and medial. And this is sort of a roadmap.

- One comment, Aaron, on the reason that we use the S-shaped surgical incision, we actually keep it in a tangential direction. So it comes inferiorly and laterally so that you can work along the long axis of the surgical incision in the skin and the scalp to avoid the bunching problem that you nicely illustrated there.

- Okay. I appreciate that's a good nuance Bill. So you start more anteriorly and move a little bit posteriorly with your S-shaped incision.

- Correct.

- Okay. And that keeps the bunching fact out of your way

- Okay.

- Thank you. A burr hole is placed at the junction of the transverse sigmoid sinuses although a little bit inferior, because this is exposure of the posterior part of it, you know, inferior part of the posterior fossa and a bony exposure is gonna be more along the inferior part toward the floor. Where would you place your burr hole initially, Bill this craniectomy anatomy?

- So we keep the incision fairly small and we put it in the in sort of halfway down the posterior fossa exposure of surface a little bone. So I draw, as you have done here, I draw where the transverse sigmoid junction and the sigmoid sinus comes down and we target our hole alittle halfway down between the foramen Magnum and the transverse sinus to start our hole because we're really interested in keeping in it fairly with this approach and the farther fairly the better, because we don't really wanna retract the cerebellum over seventh and eighth. We're really more interested in retracting the cerebellum inferior aspect.

- Right. In other words that it is sort of an elevation and medial retraction rather than a pure medial retraction to avoid stretch on the VII and VIII nerve. Isn't that correct?

- That's correct. you're gonna actually lift the inferior aspect of the lateral cerebellum up to expose IX and X.

- Okay. So that's an important new aspect Bill. You just mentioned that for hemifacial spasm and lower cranial nerve decompression surgeries. We're gonna lift parallel to the IX nerve rather than parallel to the VII and VIII to prevent traction on the VIII nerve specifically. So this is sort of a little bit more superior than usually we place the burr hole as Bill mentioned, the burr hole is on the more inferior we do not need to see the edge of the transverse sinus. And eventually the master air cells are drilled away. Maybe a little bit of bone over the sigmoid sinus is removed. The signal sinuses are waxed. The dura open in a C-incision along the floor and along the sigmoid sinus, is that how you open, the dura Bill?

- Yes. We usually open it up in either a C-incision which is excellent or a stellate manner. But the idea is you want to get your opening really far laterally adjacent to the sinus.

- Thank you. And here is sort of what Bill mentioned in terms of lifting up the cerebellum along the vector, medially and superiorly where the petrous bone turns into the floor of the posterior fossa, just along that beginning of that turn. And this is a intraoperative video, again showing the petrous bone as it turns toward the floor. And here is you access these cisterns and release CSF and open the arachnoid membranes and especially open the arachnoid membrane over the VII and VIII to avoid the traction on the sensitive VIII nerve, as the bears are monitored. And that may be performed using sharp dissection. And here it is with the final surgical exposure. Any other thoughts up to this step, Bill?

- You know, it's interesting. I find that you can locate IX, X and XI very easily. It's actually, they're easier to find and you come in low and lift up the cerebellum as you mentioned and you'll find IX, X, XI, right there. They're very recognizable. I always look for the spinal accessory coming up from the spinal canal along its superior course to mark XI and then IX is usually separate. So it's easy to see it's a very characteristic and easy nerve to find.

- Okay. Thank you. And here is the illustration of the vascular compression along the brainstem also specifically right at the root exit zone of the IX nerve and also along the root exit entry zone of the X nerve. And that's really what we would love to see. And as you can see, it requires almost good amount of retraction on the cerebellum and watching the choroid plexus. And that's why having a very good adequate CSF release, being very patient with opening the arachnoid membranes over the VII and VIII, as well as lower cranial nerve is important to prevent the bears from changing and potentially placing hearing at risk. Do you have any other nuances because this is really a very medial look into the sublopontine nerve juncture. Any other thoughts Bill about.

- Well, I think that you've covered all the issues well. I think you have to open up the arachnoid very well along the inferior aspect and along the most medial aspect to see the root entry zone. And it's often hidden by the cerebellum. And then you'll see the choroid plexus coming out of the foramen of Lushcka it can be in your way. But you need to see the brainstem at the root entry zone. And it takes some dissection to get down there.

- Thank you. Here is a routinely cut the knife nerve for these, and I creates more space. I can mobilize the artery more then mobility is solved at all So here it is, after the arteries perfectly pushed away and the nerve is cut. Obviously you wanna watch the tip of your scissors, use a curved scissor if possible, not injure any vasculature. And after that, you can mobilize the artery or transposition as Bill very well mentioned, mobilize it away from the 10th nerve. One new nuance often there's a perforator from the PICA, which is most often the vascular loop and those perforaters can be behind them the 10th nerve You don't wannna be too aggressive and avulse the perforators. Any thoughts at this step, Bill?

- Yeah, I think the one thing that really helps, as I mentioned, I prefer to transpose the vessel if I can, if it's possible, and you have to really open up the arachnoid widely. And so you may have to take a section of the artery if it's the PICA and really open up the arachnoid widely to be able to offer you the opportunities to move the loop out of the way. And you really only achieve that by opening up the arachnoid over a significant length of the artery loop.

- Thank you. And here it is, the vascular loop is found and going from above and below the nerve, you lift up the nerve potentially to the suction and then place a shredded piece of teflon to make sure the artery is away from the brainstem and not just away from the nerve. Because the artery cannot contact the root entry and exits zones of the vagus nerve, It has to be away both from the nerve and the brainstem. What do you, how do you eat the cushion or the teflon implant at this stage, Bill?

- So if we have a nice mobile loop and it's able to be transposed away from the root entry zone and the nerve. Then we can try to fashion a sling, if we can, you have to use teflon to make a sling, and then we can suture it to the dura of the skull base and try to pull the nerve or hold the artery and away as possible. If that's not going to be possible, then I'll use the teflon sling as an inner position as is illustrated here.

- Thank you. Here is the final intra-op of the video image again showing the Teflon mobilize an artery both on the 10th nerve and the brainstem. This was before mobilization. You can see the artery, the ninth nerve there, and after mobilization, the piece of teflon separating the artery from the brainstem. let's go ahead and jump into our surgical videos Bill. And here's a left sided exploratory posterior fossa operation for medical refractory glossopharyngeal neuralgia To orient you. This is the lax over the masculine cells and this edge of the sinus transverse sigmoid junction is about the spell. This is the bone that almost is joining the floor of the. Posterior fossa and here is trying to expose the three lower cranial nerves by gently retracting on the cerebellum we place a rubber dam or a piece of glob over the cerebellum, and then ride the carcinoid over the cerebellum. And as you can see, just like you mentioned, Bill, you identify the 11th nerve right here. You identify the lower cranial nerves and you're very patient in terms of opening the arachnoid membrane sharply, not placing with traction on the cranial nerves Again, no retractor is used at the initial steps to assure that there's no traction on the VII and VIII that's up here and everything is micro surgically opened. Any thoughts at this juncture?

- No, it looks beautiful Aaron, you've got nice exposure. You can see IX very easily there. You're opening up the arachnoid up by VII and VIII now. And ah, you're now exposing the root entry zone. There's the choroid plexus coming out of foramen Lushcka there and it looks like you've got some vascular compression, just anterior to IX and X. I'm expecting.

- Thank you, bill. And I think at this juncture, we're just testing out how the vessel, how mobile it is. And as you can see dented in the brainstem already, I think would you have cut ninth at this juncture at this point and then decompressed 10? Or would you have just placed the teflon and preserve IX?

- No, I think, I think probably I would just go ahead and cut nine. There's just so a little morbidity with that. And then you can take a close look and see how much it's compressing 10 and decide, but it looks like you've got pretty adequate vascular compression here, but we would do a microvascular decompression.

- Thank you. And here it is sort of placing the arachnoid as I tracing the Teflon patch between the artery and the brainstem again, going all the way to the front, making sure it is separated from the brainstem. The artery isn't adherent underneath the 10th nerve pushing the teflon superiorly. And there was a perforator actually from PICA and moving just a little bit more laterally, and it's not evident here. That's why we had to look on both sides. This is another case of a patient. Again, a left sided approach Bill. I skipped the initial parts of the operation and you can see this field that is even more red that I would like it to be. This patient was an older patient with anticoagulation this anticoagulation was stopped nonetheless. Here you can see there is a artery that is compressing, but I wasn't very much convinced that there is a big compression on the 10th nerve. As you can see, there is really no differentiation between the ninth and 10th nerve here.

- Right. The artery is there, but just didn't feel like it is very compressive on the brainstem. So I went ahead with your advice and cut the ninth nerve and the upper rootlets of 10 and still mobilized that artery just to make sure the patient doesn't have any problems Here it is the teflon patches placed on both sides of the ninth and 10th complex. Go ahead Bill please.

- Yeah, I think this is an interesting case. So I agree with you. You gonna go ahead and now differentiate nine from 10.

- Right. And it's more distal usually if you don't see them approximately when they enter the foramen and you can identify them a little bit better. Go ahead please.

- And in this case, I might've done more dissection of the arterial loop and saw if I could mobilize a little bit better, but I definitely would've cut nine in this case.

- Okay.

- I will consider cutting 10 as well. If I wasn't convinced there was much microvascular decompression or compression.

- Thank you. And as you very well said, Bill, the ninth nerve is cut and the 10th nerve upper rootlets is cut. We did not do stimulation in this case. And the patient woke up with no pain, had slight swallowing difficulty that disappeared within a month or so has stayed pain free. But I think as you can see, maybe more dissection would have been helpful and replace additional pieces as well. So let's go back to our slide show and review some of the basic concepts. Here is a postoperative CT scan typically shows the hyperdense teflon patch with no complicating features. What are the in the big series? And I'm interested in your opinion. in your series is 85% have good relief. What are the complications transient nine and 10 paresis and swallowing difficulty can be up to 10% of patients who have their upper rootlets of 10 cut. Permanent paresis is in terms of swelling difficulty is small 8% occasionally I've heard patients have hypertension. Again, this is in Janetta series up to 10 to 20% again, may have transient swallowing difficulty if the upper rootlets are cut. What is your experience in this instance?

- Yeah, I agree with all of that. I must admit if you cut the upper rootlets of 10, the patients often complain of a little bit of swallowing difficulty, but it's been my experience that over time, this goes away.

- Okay. I haven't had much of a problem with terminal paresis with the stimulation techniques that we've used. The hypertension is an interesting one. And perhaps just to go back to the intraoperative, I always warn the anesthesiologist when we start to manipulate nine and 10, because people can have autonomic dysfunction during the time of the microvascular decompression and the manipulation of those nerves. Hypertension has been a problem in a couple of our patients, We look forward post-operatively, they get hypertension post-op and we haven't had problems in the long run with it

- Thank you.

- So it's important to if patients have really problems before surgery with this and have a syncopal episode during surgery, maybe even have a pacer on their heart and be very careful manipulating the lower cranial nerves.

- Right. So very basic pearls and pitfalls. Let's see eighth nerve pearls is important untethering the nerve important retract parallel to the ninth nerve not parallel to the seven and eight use retractors judiciously address the decrease in the bears by repositioning the retractor making sure there's no vascular compromise on the seven and eight and the brainstem. And again, untethering, the seven and eight more adequately. It's important to remember the conflict is at the root entry zone of the ninth nerve and the exits zone of the 10th nerve along the brainstem. And it's important to really have a very good look right around the turn of that cerebellar hemisphere to make sure that no vascular conflict has been missed. And that may be requiring good amount of dissection, as you mentioned, and I'm cutting off rootlets of 10 I think we talked about that the possibly of multiple offending vessel has to be considered. And again do not give up too early and do not perserve too late. And the perforators are very critical. I've cerebellar retraction inadequate exposure usually leads to adequate decompression and with adequate microsurgical techniques, we should be able to decompress and see wherever we need to be in terms of exposures surgery and waxing in and waxing out. I think that's where we Janetta in terms of preventing postoperative CSF leak. And I think we address both of these very well. I think you brought them up in terms of monitoring and in stopping arrhythmias in these patients. So Bill as always, I wanna thank you for your great input and your expert wisdom in terms of really improving this presentation for us. And we look forward to working with you again in our future presentations. You have any closing remarks, please?

- No, I think this is, these can be life changing surgeries, very gratifying and relatively straightforward and easy to do. And it's a wonderful part of your practice. And I really enjoy these cases and I think you've done a beautiful job that sort of demonstrating the the pearls and the pitfalls in the intraoperative nuances. Thank you, Aaron. It's a pleasure to be involved.

- Thank you ,Bill.

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