Grand Rounds-My Pearls of Technique: A Review of Challenging Cases

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- Hello, ladies and gentlemen, and thank you for joining us again for another session of the Double NS of the Grand Rounds. We have Dr. Bill Caldwell from University of Utah back with us again. He's been a tremendous surgeon, a master surgeon, a great mentor for me and many young neurosurgeons. And he's going to talk to us about techniques of neurosurgery for a variety of complex cranial cases. I want to really thank him for his time today. And Bill, go ahead and we'll start the first case with a clip ligation of a basilar artery aneurysm.

- Great. Well, thank you very much, Aaron. It's an honor to be here once again. I've chosen these cases, each of them to demonstrate something that I've learned or something that I like to impart that I've learned over the years. This is a 57-year-old woman. Presents with a large unruptured basilar aneurysm. It had a very broad neck and our endovascular colleagues felt that it couldn't be coiled adequately. They did discuss the option of stenting across it and she wished us to proceed with a clip ligation. I'm going to use the subtemporal approach as described and popularized by Dr. Drake for this aneurysm, because it gives you such a direct view and a direct shot across the neck of the aneurysm with your clip. Broad neck, that really incorporates both of the P1 takeoffs. So linear incision just in front of the external auditory ear. And we come in subtemporally far before craniotomy and we're looking here at the third nerve, we open up the cisterns. We try to work around the third nerve, the third nerve's the key to the operation. It's a guide to the junction of the basilar with the superior cerebellar and the posterior cerebral. We have to open up the tentorium in this case to get better proximal view. We find the fourth nerve and open up the tentorium behind the fourth nerve, cauterize this, and then suture this back onto the tentorium to give us a better view. Now we're down on the basilar artery. There's the neck of the aneurysm and the proximal basilar. We'll open up the arachnoid and place a temporary clip across the proximal basilar below the superior cerebellar takeoff. Now, this is a very broad neck and I couldn't see around the other side of the neck. So we'll use adenosine cardiac arrest in this case to stop the heart temporarily, deflate the aneurysm, and to dissect around the aneurysm completely. So you can see the aneurysm is now soft with the temporary clipping and the adenosine cardiac arrest. And we'll place the definitive clip across the neck. This is a relatively easy clipping. The aneurysm ruptures the minute the clip is placed. Here you'll see it deflate. And then we remove our temporary clip. We'll do an ICG angiogram and document that both superior cerebellars and posterior cerebrals are open. So it's a quick and a very direct approach to the basilar.

- I wanted to ask a couple of questions on this topic, Bill. Obviously, a spectacular work. Number one is about use of adenosine. There's much talk about it, but some surgeons are to use it because of potential complications. How many times roughly per year do you use adenosine? Do you let your anesthesiologists manage the dosing? And how often do you use it?

- Sure.

- In terms of repeating it in single procedure.

- So it's a terrific adjunct in my mind to clipping these difficult aneurysms, especially the ones that are larger and you can't see around the neck with a narrow view, such as when you come in on a subtemporal basilar artery aneurysm. I use it roughly five or six times a year. And the way we do it is before surgery, I warn our anesthesiologist that we're going to be using it and they'll do the dose response prior to the craniotomy. And they'll figure out exactly how much dose to give and then how much cardiac arrest that we would expect. And I've had personally no complications with it. I find it a very useful technique especially for posterior circulation large aneurysms. So these are cases that traditionally, you know, 10 and 20 years ago, we would have used cardiac standstill and bypass techniques. And now with temporary clipping, better anesthesia, and adenosine cardiac arrest, we can avoid that very aggressive technique.

- So essentially the dose response occurs on the side of the anesthesiologist and then you just tell them how much, how long you want.

- Correct.

- You tell them, well I want about, you know, 60 seconds or 40 seconds and they adjust the dose. If you try to clip and if you have to repeat it, obviously you have them to sort of re-inject another dose. How about if you have entropic rupture and you really need it for an extended period of time and you don't have good proximal control, could you tell us what you do then?

- Yeah. I mean, that's a difficult situation. I don't like to use adenosine for more than about a minute of cardiac arrest, because what we plan on is that the cardiac arrest starts and then the arrest goes on for 30 to 60 seconds and then the start-up phase. So in total, you have more than a minute by the time the cardiac arrest initiates and then by the time you get up to full perfusion, you actually have more than a minute. So that's usually the limit of what we do. Anesthesia, it gets very nervous if it's more than that period of time. The scenario that you're talking about is one that you can't always prepare for in that say you're in a tight spot, you've got a bad rupture going on. And what we'll do in those cases is we'll use an adenosine arrest if we need to, but I'll use it more in the vein of trying to get a better temporary clip on and get some relaxation, get the bleeding slowed down to get better temporary control. And there's very few places that you can't offer yourself better temporary control. And so you can use the cardiac arrest to help facilitate that.

- Thank you. Let's go ahead to the next case please.

- Sure. So the next case is a very interesting case. This was one of my partners' cases that he asked me to help him with, Richard Schmidt. And the patient came in with a subarachnoid hemorrhage, but she was managed at an outside hospital under the presumptive diagnosis of infectious aneurysms. And she had had a fusiform aneurysm in two locations. This right middle cerebral aneurysm had ruptured. And this had also increased in size and so they sent her over to us. And we proceeded with a plan exploration and possible trapping or bypass around this aneurysm. So interestingly, so we went ahead and explored it. And what we found is as billed on the angiogram, there was this very ragged section of middle cerebral artery here. And then there was a distal vessel that was quite important and was quite large and we wanted to re-vascularize. We didn't think that we could adequately treat the aneurysm by a wrapping technique. So we harvest the superficial temporal artery. And what we'll do is we'll bypass not into the artery directly at the aneurysm, but more distally. And so what we'll do is here's we'll put temporary, these are ABM temporary clips. And then we'll place it and do an arteriotomy at a recipient vessel past the first major branch point. And so we don't have to completely stop all of the flow in both branches to do the anastomosis. We place our anchor stitches. I like to do these with interrupted technique. So I don't develop any constriction at the region of the anastomosis. We perform the anastomosis back bleed and then open up and check an ICG. ICG shows the bypass is patent. Here's the recipient vessel. So now we'll go ahead and clip off and trap the aneurysm and resect the aneurysm. So we trap and then dissect out the aneurysm. Now remarkably, this is the first case I've seen of this. This was a varicella aneurysm and I've never heard of this personally causing infectious aneurysms. There was no bacteria noted, but there was varicella in the pathology specimen. We obtained hemostasis and close. We take care not to constrict the superficial temporal artery. And here you can see it feeding the middle cerebral artery. And then a formal angiogram demonstrates the clip in place. And then the external supply through the superficial temporal supplying that branch.

- Definitely a very challenging case and really great work. Let's go ahead into a next series of videos that would be more on the aneurysms. Let's go ahead and start with a craniopharyngioma, please Bill.

- So this is a craniopharyngioma that presented as an episode of confusion in a professional pilot. And he had episodes of memory loss and confusion. An MRI was performed, which demonstrates this intraventricular lesion. Now the critical issue in this case is this is a partially cystic partially solid tumor. We anticipated it was going to be a craniopharyngioma. Notice that the pituitary stock is in its native position. This is an important surgical nuance and technique because some people would suggest me be coming in transnasally on this, but this is within the third ventricle. So if you have to choose an approach here in my mind, where you get into the ventricle as your primary approach. So we'll do this instead of coming in bifrontally, we'll do this frontotemporarily. And the reason for that is that we avoid having to deal with the olfactory tract. And you'll see we'll have a beautiful view at opening into the third ventricle. So right frontotemporal approach, I'm dissecting out the optic nerves and the optic chiasm here. We open up the Sylvian fissure to give us more room and expose the region of the lamina terminalis. So we open up the lamina terminalis and we come upon the tumor. And you'll see here that the tumor, this is the cyst wall of the tumor. We drain the cyst and we tease the tumor out from inside the third ventricle, carefully carefully with some traction and some dissection. Here's the cyst wall coming out. And then you'll see the solid part of the tumor within the cyst wall. Here's the solid part of the tumor. We'll gently dissect around the perimeter of the tumor, making sure that we remove the tumor from the wall of the third ventricle. After removal, we obtain hemostasis and we inspect all the walls. We can also use an endoscope, angled endoscope, to make sure that we've removed everything. You have a nice clean wall here. So the whole reason for choosing this approach is to preserve pituitary function. And if you look on the postop scan, the tumor's gone. But also importantly, you can see the pituitary stock is in its native position. So we haven't disrupted the floor of the third ventricle or the pituitary stock.

- I think you very well raised the issue of the endoscopic transnasal approach for large intraventricular tumors. I think, which is very long and the ability to perform microsurgical techniques at that may be limited and this seems to be a great approach. In this particular patient, Bill, was there any worsening visual fields after surgery or a lot stable?

- No, he was stable after surgery. And interestingly, he had diabetes insipidus for a short period of time after surgery but it resolved and he has normal pituitary function. Whereas, if I came in transnasally, we would have to traverse the floor of the third ventricle and we would definitely disrupt pituitary function in that particular tumor doing that. So that's why I chose coming through the lamina terminalis in this case.

- Thank you.

- So this is a impressive case with very significant proptosis. One of the worst cases of proptosis that I've personally seen from an intraosseous meningioma. She's a woman from Eastern Europe who had been denied treatment in her home country. She had this massive intraosseous tumor with a proptosis. She still had vision in her eye. She came in actually herniated and she came in very sick with acute neurological deterioration. And you can see from the mass effect from the intraosseous meningioma plus the edema around the tumor that she's actually has temporal lobe herniation here. And the temporal horn is over here near the midline. So we took her to the operating room emergently to perform a decompression and a removal of this tumor. We didn't have time to consider embolization preoperatively. Here's her proptosis on the operating table. You can see how profound it is. And we'll perform a standard frontotemporal craniotomy in this case. And expose the region of the tumor. Now, the tumor is in the bone and the soft tissue component is extending into the cranial cavity and into the orbit. So all this region here is tumor. And so we'll come around the periphery of the tumor and then remove this with a drill. Very vascular. We have to manage this. It takes several hours of drilling to remove all this tumor. It's a little bit like archeology, we're drilling out, we're trying to find normal structures within the massive bone here. We'll drill the bone around the orbit. Here's the lateral orbit, superior orbit, and we'll drill out the clinoid. Decompress the optic nerve here and remove the anterior clinoid. We'll drill beneath, here's V2 and the foramen rotundum exposed. We'll drill around that and we'll remove all the affected bone. The next step is we remove the intracranial portion of the tumor. Relatively small amount of soft tissue component that was attached to the frontal lobe here and the temporal lobe. We'll dissect this free and remove the dura and the soft tissue component. Now the next step is to remove the tumor involving the orbit directly. This is important to be able to get the eye to reduce. She has profound proptosis and you want to have the eye reduce. So what we're going to do is we're going to remove all the tumor that's involving the periorbita right down to the periorbital fat. We'll be careful of Muller's nerve here to help with lid elevation. And then dissect the tumor off of the periorbital fat all the way back to the orbital apex here. At the end, we have to close. We need to close all the openings into the sinuses. Here, we're putting a dural graft in here and then muscle plugs into the areas that we entered, the frontal sinus and the ethmoids and into the pterygopalatine fossa. We placed fascia graft, fat graft, and here's our postop scan. You can see the decompression that we've achieved. We've removed all the bony part of the tumor and the soft tissue component. So we bring her back in two weeks and we've had a custom cranioplasty made for her. And we'll fix this in place using titanium mini plates. And close. And finally, this is the reduction that we achieved. This is two weeks later. You can see her eyes reduced beautifully. So the take home messages that the skull-based surgeon needs to be an orbital surgeon as well.

- Great result in a very challenging case. The next case is about vestibular schwannoma, especially the large ones. That can be one of the most challenging skull-based cases. So I'm very interested in your technique.

- Sure. So this is an elderly woman that presented with declining mental status and confusion. And she had a very large vestibular schwannoma and hydrocephalus. So we'll choose a retrosigmoid approach in this case. I prefer it for the very large ones, because it gives you a good panoramic view of the relationship of the tumor with the brainstem. So we'll do this in the lateral position. We pull the arm down out of the way to give us room here. Have her well-taped so that we can rotate her during surgery, which is important to look into the auditory canal, et cetera. Here's our incision. Here's the asterion. And we'll go ahead and proceed with opening, simple opening. Identify the lateral sinus. Open the dura. She has a fairly tight posterior fossa as you'd expect. Take some time and drain some CSF. And then come down on the region of the tumor. Now, the first thing we'll do in this case is drill out the canal. And this is Dr. Clough Shelton, my otology partner, who loves to do all the acoustic tumors with us, terrific colleague and an otolaryngologist. And he is going to drill the canal. We have an understanding that we do all acoustic tumors together with otology in our department and we choose the best approach for the patient. So we identify the fifth or the seventh nerve here. Vestibular nerves have been cut and here's the seventh nerve in the canal. So now we'll go ahead and proceed with coring the tumor. Big tumor, so we cut a window into it. And we'll go ahead and use an ultrasonic aspirator and remove the tumor. Now, the technique that I use is this sweeping technique where we take fine cottonoids and sweep the arachnoid down from the side of the tumor and identify the brainstem. And carefully dissect the perimeter of the tumor from the brainstem. So here's the nerve. I presume that this was part of the eighth nerve. So here we'll sweep down with our cottonoids and sweep the arachnoid down. We stimulate the nerve. And it doesn't stimulate the eighth nerve and we'll cut that. And then we'll look for seven at the base of the skull. So there's seven in the canal and now we can work and dissect the tumor off of seven from both directions. We'll remove the redundant capsule. Here's the seventh nerve that we've identified at the brainstem. And we'll carefully dissect that under direct vision from the region of the tumor. So we can work at it from both sides, the lateral side and the medial side. This is part of the vestibular nerve attached to the seventh nerve here. There's the seventh nerve. Vestibular nerve attached to it and we'll dissect the remaining seventh nerve off of the tumor. Seventh nerve stimulated well at the end of this case. And she was left with a House-Brackmann three after surgery. Close with Alloderm, Medpor cranioplasty and then close the scalp and muscle layers. Here's your post-op scan. Her hydrocephalus improved after surgery.

- Yeah. What's the rate of facial nerve preservation anatomically in these big tumors? What would you consider good?

- Well, we always try to preserve the facial nerve. I think it's not always possible in some cases. We'll make that decision intraoperatively. In this case, it was very attenuated and very thin, but we were able to preserve it fine. But I find it very hard to predict whether we'll be able to preserve the facial nerve in a big tumor such as this. And I have seen it incorporated into the tumor such that it can't be preserved without leaving some tumor there. And you'll have to make that decision at the time of surgery. But I always tell the patients we'll do everything we can to preserve the facial nerve. And in a case such as this, I would have been prepared to leave a little bit of tumor on the nerve if it couldn't be preserved at all. But if it dissects off easily and readily, we don't plan on doing any subtotal resections. We remove the tumor because the facial nerve will get better. So this is an extensive case of a right trigeminal schwannoma that involves the region of the pterygopalatine fossa and the cavernous sinus and back into the posterior fossa. This is a 37-year-old male that presents with right facial numbness. So we'll plan a tri-fossa exposure in this case. So a frontotemporal exposure in combination with a posterior fossa exposure and a temporal approach. This is the incisions that we use. This is the case. You can see the extensive tumor involved in the region of the cavernous sinus extending through the foramen rotundum into the pterygopalatine fossa. And then posteriorly back into the region of the temporal bone and surrounding and encasing the carotid artery. Here's the CT scan showing the bone erosion. Pterygopalatine fossa and the middle fossa in this case and the middle ear involvement. So we'll start with the posterior fossa component. Clough Shelton, our otology colleague, will perform a transtemporal approach. Mastoidectomy is performed. And he'll proceed with closing off the external auditory canal. The middle fossa will be obliterated. The middle ear will be obliterate. So here's the middle ear. Removing the region of the middle ear contents. This is the tumor within the middle ear. We'll dissect out the region of this tumor in the temporal bone and identify the carotid artery in the temporal bone. The carotid artery is identified adjacent to the jugular bulb and we remove the tumor from this region and dissect it free of the carotid and the jugular bulb. After we finished the temporal exposure, we'll proceed with our craniotomy. We perform a frontotemporal craniotomy extending back to the region of the posterior fossa. Standard extradural technique middle fossa exposure. We drill up to posterior orbit in this case and then peel up the lateral wall of the cavernous sinus. We expose the tumor as it extends through the foramen rotundum. We use the ultrasonic aspirator. Here's the second division of the trigeminal nerve right alongside here. And this is all tumor that I'm removing from the region of the pterygopalatine fossa. I'd like to point out that you could work very far anteriorly through the middle fossa floor here. And an anterior transfacial approach is not necessary in this case because you can remove all the tumor up to the region of the maxillary sinus from your corridor here through the middle fossa floor. So we've removed the pterygoid fossa component and now we'll remove the cavernous sinus component. Here's V3 extending through foramen ovale. We drill the floor and we find, adjacent to V3, a window to the tumor. And again, proceed with debulking the tumor, and then dissecting the tumor free of the nerves in the cavernous sinus. Here's V3 we're lifting up. And remove the tumor underneath the trigeminal nerve. Now we identify the carotid at this point, both distally and proximally. So we've identified the carotid within the region of the cavernous sinus and the petrous temporal bone. We drill out all around this last piece of tumor in the petrous bone and dissect off the tumor off the carotid directly. Here I'm dissecting the tumor off the carotid directly. This is the tumor within the petrous bone. We remove that and here you now have a skeletonized carotid extending from the cavernous sinus down to the jugular bulb. We close by obliterating the area completely with fat, cranioplasty with Medpor, re-plate the bone and close the scalp. And he was left with a worsening sensation in his face, but no double vision and his facial nerve is intact.

- Great work, Bill. Some surgeons may argue that why not decompress something, a portion of tumor through the subtemporal approach extradurally and then for a small amount of residual tumor or through the bulb and the ear just do radiosurgery. What are your thoughts regarding that approach?

- Well, my personal feelings about this are is if a tumor can be removed safely, he's 37 years of age, he's had a complete resection and it requires no additional therapy. I don't personally like to radiate young people with benign disease as a general rule. Because I've seen problems, if the tumor recurs, it's more of a surgical challenge because the tissue planes are much more difficult to dissect after radiation. As well as I'm always concerned about a small but definite risk of inducing other genetic changes within the tumor. So if I can avoid it, I prefer in younger people to do an aggressive surgical resection on these skull-based tumors. However, I wouldn't sacrifice cranial nerve function at trying to achieve that. But in this particular case, I felt it was justified to do an aggressive surgical approach.

- Bill, as always, I want to thank you for your valuable time and your amazing videos, and obviously your expert surgical technique. Look forward to having you with us in for another session in the future.

- Thank you, Aaron. It's an honor, again, to contribute to the Double NS Grand Rounds.

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