Grand Rounds-Technical Nuances for Managing Challenging Cases

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- Hello ladies and gentlemen, and thank you for joining us again for another session of the AANS Operative Grand Rounds. Today we have Dr. Will Couldwell from University of Utah. He's been a great mentor, truly a master surgeon. He's gonna be sharing with us some of his great cases.

- I've chosen a series of cases today, sort of a broad range of skull base and vascular cases. And that include some skull-based tumors, some orbital tumors, aneurysms, and I look forward to sharing these with you. Today we're gonna start with this left transmastoid approach for resection of the 7th nerve tumor, and a 6th nerve tumor. This is a very interesting case and unusual case of the four year old boy, with a history of strabismus, and left lateral rectus palsy. He also has a new left facial nerve palsy. You can see on the scan, the 6th nerve tumor in the cistern, and an enhancing tumor in the region of the seventh nerve, within the mastoid. So what we'll do is we'll plan a trans mastoid and middle fossa approach. Here he is in pins, on the table, and we'll do this with our otologist, Dr. Clough Shelton. We use this large C shaped surgical incision to incorporate the middle fossa, as well as the master approach. So Dr. Shelton now is doing the mastoidectomy, and we identify the fallopian canal, and the 7th nerve within the fallopian canal. You'll notice that when we're identifying the seventh nerve here, he removes the incus, and the seventh nerve is enlarged, it's sausage shaped, and it's enlarged over a long length within the fallopian canal. He continues to dissect the tumor from the fallopian canal. And we amputated it normal nerve distally, and remove the region of the 7th nerve with tumor. Next, we'll go middle fossa approach, left middle fossa approach. Identify the nerve and the tumor in the floor of the middle fossa. He identifies the remainder of the tumor, just at the apex of the fallopian canal, and also as it enters the tympanic segment. We biopsy the nerve just as it leaves the internal auditory canal, and we find it's free of tumor. We'll now go ahead and open up through the petrous apex and remove the sixth nerve tumor. This is the inferior petrosal sinus that I'm packing off. We're opening up the region of the posterior fossa, and you'll see the sixth nerve within the cistern. There's the tumor, a small neurofibroma involving the six nerve as well. And we'll remove this now through the same approach. Amputate the nerve, beyond the tumor, elevate the tumor, and then remove the tumor. Now we're measuring the length of the facial nerve that we need to reconstruct with an interposition graft. And we'll go ahead and obtain our sural nerve graft, from the left leg. Sural nerve graft is in place, and we'll trim this to the proper length, and do an end-to-end anastomosis of our interpositional nerve graft. 9-O suture, the anastomosis both distally and proximally, here's the proximal anastomosis. And then we cut it to length, and perform the distal anastomosis as well. So we've replaced the entire segment of facial nerve that was involved with tumor. Closure, we placed fat in the mastoidectomy cavity, replaced the bone flap and cover over the mastoid defect.

- May I please ask you, what is the facial nerve outcome on these patients, in your opinion, with a junk graph such as this?

- So I'm quite optimistic. He's been about six months or so already, and is closing his eye well, He's young enough that he'll do very well. I suspect he'll end up with a grade 2 face in the long run. And obviously what's in his favor is his youth. And the fact that we replaced the facial nerve quite quickly after he started losing facial nerve function from the tumor. So the distal nerve was quite healthy. But he's closing his eyes already in six months. The highlights of this case is that, you can use the transtemporal approach, in this case also to remove a 6th nerve tumor within the cistern. By drilling the petrous apex, right to its fullest extent, you get this exposure right, anterior to the ponds, and it put us right where the 6th nerve tumor was as well.

- I agree, I really like the way you approach both with a nice complex casuist approach. Also the fact that you don't wanna have patients to lose their peripheral apparatus. In other words don't get atrophy because of a long-term facial nerve weakness. You really have to treat these quickly. And the moment that facial muscle atrophy occurs, it's really difficult to get even a grade two or three, no matter what you do, am I correct?

- That's correct, so, yeah, what we really wanted to do in this case, was take the opportunity to remove this facial tremor early on. When we identified that it was growing, and he is losing facial function, absolutely.

- Thank you, so I think the next case also, is as exciting, so if you could please go ahead.

- So this next case is a very interesting case. It's a young woman with progressive proptosis, and I'm doing this case with our oculoplastic surgeon, Dr. Booby Patel. So 22 year old woman with proptosis of the right eye, and she has a cystic lesion, involving the trigeminal nerve. And you'll see this lesion extends from the cavernous sinus, all the way out to the orbit here. And is producing proptosis. It's cystic and solid, and it goes right back to the region of the cavernous sinus. It's involving mostly the first division, and a little bit of the second division as well of the fifth nerve. Here's the lateral view. And you can see the extent of the tumor. So, we'll perform a frontotemporal approach to this tumor, and we'll do an orbital frontal removal, to expose the region of the orbit, as well as the standard frontotemporal approach. Immediately upon removing the bone flap, you can see the orbital part of the tumor here is exposed. So transcranial orbitotomy, and we're dissecting out the region of the tumor, above the globe. Then we'll go back to the region of the cavernous sinus, and we're following the tumor. We're gonna do an extra dural approach, lift up the lateral wall, of the cavernous sinus and expose the tumor within the cavernous sinus. You can see the extension of the cystic tumor here. And then we'll basically start to debulk the tumor, cystic and solid tumor. We're in the region of the cavernous now, we're lateral to all the oculomotor nerves, and we'll remove the tumor aggressively. Then we'll follow V1 into the orbit. And this has extension of the cystic and solid components, from the cavernous sinus, right up to the superior orbital region. So we're opening up the periorbita, and you can see the tumor being exposed in this area. Cystic and solid both. We remove all the solid tumor that we can identify. At the end, we reconstruct the periorbita, all the way out to the region of the orbital roof. Here's the end of the resection, we've got into the frontal sinus, with our overall frontal bone flap, we repair that, replace the bone flap, medpor cranioplasty and close. She's had a good cosmetic result, and her postop scan shows excellent resection of the tumor, and reduction of the orbit. The proptosis is now reduced.

- You know, Will, I think obviously this is very difficult tumor spectacular result. One of the things that you have discussed before, which is very important is that we don't have to be very aggressive, but we construct the floor, or say the roof of the orbits, to avoid endo thalamus. Would you mind share your experiences a little bit with us, how aggressive you are in your practice?

- So, over my career, I've become more aggressive at removing tumor within the orbit, and less aggressive at reconstructing the orbit. And the reason is at my early experience, especially with meningioma, is that I found that when I reconstructed the orbit, especially with implants and such, I couldn't get the globe to reduce. And so I've become very aggressive about removing the tumor within the orbit to allow the globe to reduce back into its normal position. And you can see in this case, the globe came back perfectly, and we didn't do any reconstruction of the orbit at all. And they often have diplopia for the first couple of weeks after you removed the tumor. But after the tumor is removed, they adjust to it very well. And within about three or four weeks, it's gone. And then the globe takes about three months to completely reduce. So I've been very much happier, with being more aggressive with my surgical resection, and less aggressive with reconstruction of the orbit.

- Great, thank you.

- So this is an interesting case. This is a 66 year old gentlemen presenting with a headache, and you'll see, he's got a giant partially thrombosed, right middle cerebral artery aneurysm, that you can see here in this location. Here's the CTA, you can see calcium in the wall. And the M1 and both the M2 is coming out of it. Here's the CTA reconstruction M1 one entering, M2 is leaving. So I could not see an endovascular solution for this, so we'll perform a direct exploration of the aneurysm. Standard front or temporal exposure. And we'll first plan to expose the aneurysm, and decide how we'll manage it. On the way in we'll harvest the superficial temporal artery. And this is what we're doing here, in case we need to perform bypass. We'll use this as insurance in that eventuality. So we'll protect the superficial temporal, and then proceed with our standard opening. Frontal temporal bone flap, and expose the region of the pterion. So we're under the microscope now, and we'll perform a microsurgical dissection of the region. And I like to take a look at the aneurysm directly. So expose the optic nerve, and open up the Sylvian fissure widely here. We have proximal control with the carotid, and the M1. Now we'll completely expose the aneurysm in this case, to determine the best method of treatment. We'll open up the arachnoid. Please note that the aneurysm is large, you can see the hemosiderin standing in the wall of the aneurysm, it's partially thrombosed, We'll expose the aneurysm completely, remove the temporal veins, Sylvian veins here. Now you can see, that this aneurysm is multilobulated, and part of this filling and part of this thrombosed. So what we'll do is we'll place a temporary clip on the M1, and I couldn't clip it directly, because of the calcium in the neck. And so I'll have clipped the thrombosed part of the aneurysm. And so we're isolating the aneurysm into two components now. Put a very large clip across the giant aneurysm, and we'll perform an endarterectomy, while we maintain flow through the distal vessels. So there's no rush here, the native flow is maintained, and we'll open up and perform an endarterectomy on the aneurysm. We'll bring the ultrasonic aspirator in, and aspirate the contents of the thrombosed part of the aneurysm. Now we'll do this until we get back bleeding. We start to get back bleeding here, and you'll see me flush the aneurysm here, to make sure that we don't have any debris, going into the patent part of the aneurysm. Now will reclip the M1 for proximal control, and then go ahead with a definitive clipping of the aneurysm. Now we have a softer aneurysm to deal with, and we can identify the neck, and place a large straight clip over the neck. You have to be careful in these cases, because the aneurysm wall may be thickened with calcium, and you don't know how much you're narrowing the lumen of the bifurcation. So this is a Drake trick, you place a fenestrated clip distally, and a straight grip proximally. Multiple clips, the neck is reconstructed, one small dog ear, and we'll place the last clip. We'll perform an ICG study now, open up the vessels, and perform an ICG angiogram, that shows a patent bifurcation. And you can see the calcium, is interfering with the view of the ICG on this side. With the result, and we'll go ahead and close. We'll place a little muslim gauze, over the neck of the aneurysm to induce fibrosis, scarring around the aneurysm.

- One detail that I wanted to just echo here was the importance of not being perfect, in clipping these MC aneurysms and the enemy of good truly is very bad. And that's, if you really wanna make the neck perfect intraluminal space would be very much narrowed. And so you almost have to leave some very generous atrium to avoid stenosing the M2s.

- So I just wanted to emphasize the clip placement there. And when I mentioned this was a Drake trick, so the idea is, if you place an extra long clip, a large curve clip, over the entire neck, the closing force of the clip, is greatest closest to you. And the clip may not close on the far side at the ends of the clip. So what you do, is you place a fenestrated clip, that puts higher closing force on the far side. And then you put another clip next to it, on the proximal side, a straight clip. So that way you have optimal closing force, over the entire broad neck of the aneurysm. And that's a well-known trick, and it's a great use on these large aneurysms, where you've got room to swing, both clips like that. And again, I just wanted to emphasize, you wanna be very careful on these ones, because you may look like you reconstructed the neck very well with your clipping, but you may be making too narrow lumen within the aneurysm and the bifurcation because the neck may be thickened, and it usually is with calcium in these lesions. So that's why it's important to do the ICG angiogram study on the table, to make sure that you've left an adequate pate lumen in the bifurcation.

- Thank you.

- So this is an interesting case, and I chose this case to demonstrate a principle that I've tried to use in these rare type cases over the years. But this is a 28 year old female with galactorrhea. She has elevator prolactin level, the remainder of her hormones are normal, and she's got an enhancing lesion, involving the hypothalamus and pituitary stock. It's in the inferior third ventricle and the hypothalamus. And so what we'll do here is we'll biopsy the lesion. But we're gonna do it in a very specific fashion, in order to try and preserve pituitary function. So standard endonasal approach, extended transsphenoidal opening, here, you can see we're opening up above the diaphragms Maselli. So we're in the tuberculum region here, rented the inter cavernous sinus, circular sinus there we've identified and cauterized, and we're in the suprasellar cistern. Now I'm gonna come in just from one side, just on the right side here, and open up into the hypothalamus on the right side. Now, if you stay unilateral, and you leave the pituitary stock intact, there's a good chance that you may not hurt the pituitary function. And that's what I'm trying to do here. So I'm removing the tumor from just one side only, 'cause all we wanna do is biopsy it. We then pack the nose as usual, fat packing. And then I use this surgeon cell sling technique, to hold the fat in the sphenpoid sinus, so we don't have to put any foreign body in and close. This is our post op scan, can see fat in the sphenoid sinus, the lesion has been partially removed. The biopsy here, turned out to be DNET, and we ended up just following this patient. And I followed her now for two years, and she's had perfect pituitary function, with normal maintained menstrual periods. And you can get surprised, actually we thought this was going to be like a lymphoma. It ended up being endoplastic neuropathy of the tumor, and we ended up just observing this patient. So I think it's important, that if you're gonna do a biopsy, you try not to hurt the pituitary function when you perform the biopsy.

- Thank you, let's go ahead and go to your last case, which is a retrosigmoid CPA tumor.

- So this case is a very interesting case of a young woman. She's a athlete, and she noticed problems with her balance over the last two or three weeks. She's had some difficulty swallowing, and our MRI shows a very large tumor, involving the posterior fossa, and the tentorium and the petrous region. And we felt this was likely a large vestibular schwannoma, or a petroclival meningioma. She's positioned the lateral position, we'll perform a retro sigmoid approach here. With appropriate cranium nerve monitoring, seven and eight. Here's our incision that we use and the plan bone opening adjacent to the transverse in the sigmoid sinus. Under the microscope, we're opening up the cistern over the region of the tumor. This is seven and eight right here, and we identify the posterior aspect of the tumor. We'll first drill out the IAC, to see the relationship of the tumor, with the seventh and the eighth nerves. So we'll take a dural flap down, and drill the region of the IAC, to expose the extent of the tumor. We make sure the tumor is completely separate, from the nerves in this area. It is, this tumor does not appear to be emanating from these nerves. And we then move on and we identify the fifth nerve in this case. And then we proceed with opening the tumor, and debulking the tumor. We use the ultrasound to remove the center of the tumor, it's very vascular. And identify the attachment of the tumor, which appears to be at the petro tentorial junction, just by the fourth nerve, entrance point. Very vascular, this tumor turned out to be hemangiopericytoma. We continue our extra tumoral dissection, debulking of the tumor, and then dissecting it from the surrounding brainstem, and cranial nerves. Removing the capsule here and the tumor. Now, it was very interesting in this case, because the fourth nerve was engulfed in the tumor, that there was enough room that when we removed the tumor, we identified both ends of the 4th nerve, and we remove the remaining part of the tumor here. This is the attachment of the tumor, and there's the cut end of the 4th nerve. And we identify more distal part of the 4th nerve, and I'll do an anastomosis of the 4th nerve, and end-to-end anastomosis of the 4th nerve. Luckily we had enough room in the nerve, to be able to just perform a primary repair. Now I know suture, two sutures interrupted, and the nerve is repaired. The closure we saw in the dural graft, and medpor cranioplasty and then close the skin. And here's her post op scan, and she's done very well.

- So here if you actually significantly improved, and that's great. Taking that extra effort to reconstruct that 4th nerve. This a very challenging tumor. The amount of bleeding can be absolute torrential, especially in posterior fossa, and very much a problematic situation. I assume you tried to devascularize it as much as you can at its base to facilitate the removal of the rest of the tumor, is that correct Will?

- Correct, I mean, once we realized that it was a meningeal based tumor, I didn't know interoperatively, whether this was just a very vascular meningioma, or hemangiopericytoma, but we concentrated directly on the attachment at the petrotentorial junction. And I'd like to go after that early on in the case to devascularize the tumor, makes the removal of the remaining part of the tumor, much easier.

- If you don't mind, I'm gonna share one video for you for the matter of time, we'll just keep it to one. And it's a fourth ventricular ependymoma. And I wanna get your opinion, how you deal with these 4th ventricular tumors that are very adherent to floor of the posterior brainstem. This is a young patient, you can appreciate a very large tumor, very adherent here to the wall, the fourth ventricle. I use the latter position because I can operate while I am sitting down. And here's opening, I open the dura in a linear fashion, because you can close it in a watertight fashion later, and it's the easiest that way. These meningiomas often have theaters directly from PICA, and you really have to coagulate the feeders one by one. Otherwise you can cause injury to the mother vessel. And after you coagulate these feeders, you really very nicely isolate the tumor, and you come inferior to it. And you see they're very attached to the inferior cerebellar peduncles. And you have to leave a sheet of the tumor by using the ultrasonic aspirator. And you can really come very close to the brain stem by leaving a very tiny sheet. In the midline they come off very easily off of the floor of the fourth ventricle offset, so you can do a very radical resection. After the second step of midline removal that you can see here. You can come on top of the tumor, and remove the superior portion of the tumor and clean out a whole fourth ventricle. And then laterally remove tumor just until you leave a very tiny sheet of the tumor. You can even coagulate the residual tumor, and come up with a very nice resection. Here you can see that very tiny sheet of the tumor, ultimately being coagulated, and then move to the foramina of Luschka. You are able to deliver the tumor adherent to the distal portion of PICA. As you can see here, bilaterally. And here you can see on the left side of the patient, the tumor is being delivered through the foramen, and then moved to the left side, and remove the tumor off of the lower cranial nerves. As you're looking through the Luschka, through the fourth ventricle. Here, you can see the lower cranial nerves, the tumor being dissected, and here's the ultimate result, with a near total resection of a very challenging adherent tumor and a post op MRI looks like a gross total resection of the mass. And the patients do extremely well without any deficits in their swallowing or any complicating features. And my question for you Will in this case is that, well, how would you do this differently, and what are the pros of your technique particularly?

- So that was a great result Aaron, I think that I would have done this exactly as you did. You came in telovelar with your approach I see, which is excellent. You don't have to divide the cerebellum at all, with that approach. And the key is, and this is where experience comes in. Is that how aggressive to be, when you're shaving that tumor off, at the floor of the fourth, either on the peduncles, as you had there on the floor itself. And you learn to be very gentle in that area. And I think it's impossible to get an extra tumoral resection in those areas, because you'll hurt the patient with the floor of the fourth. You have to have very much respect for the floor of the fourth ventricle, because it's easy to injure the patient cause cranial nerve deficits. And so I think that was just a nice demonstration of how aggressive to be, because if you are too aggressive, you'll end up inducing deficit. And so, I think it's an important lesson to learn, and it's important to have mentorship and to have some experience with dealing with the tumor in that location. So a critical teaching point, so.

- Thank you, Will. I wanna thank you again as always, for being a great supporter of AANS Operative Grand Rounds, being a great mentor for many young neurosurgeons, and we truly appreciate again your mentorship.

- Great, thank you, Aaron. It's always an honor to be here.

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