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Orbital Surgery and the Neurosurgeon

William Couldwell

October 18, 2021

Transcript

- Colleagues and friends, thank you for joining us for another session of the Virtual Operating Room. Our guest today is, Dr. Bill Couldwell from University of Utah Neurosurgery. He is one of our most frequent speakers, for a very good reason. He is the very rare combination of an incredible academic leadership and research personality combined with a master in neurosurgeon. Today, he's going to talk to us about surgery of orbital tumors. And how this arena is really, a very special part of neurosurgery and a very important for neurosurgeons. So, Bill, thanks for being such a great contributor to this series. I'm very much looking forward to learning from you and from your videos as always. Please, go ahead.

- Well, thank you Aaron. It's an honor to be here once again and to talk about a topic that's of great interest of mine. And I'd like to really sort of introduce the notion that neurosurgical disease that enters the orbit should be really managed with neurosurgeons. And a lot of our disease such as meningeomas, other tumors that involve the base of the skull can involve the orbit secondarily and we need to be comfortable with operating there. And so, with that introduction, I sort of think, that the orbit is the sort of area in the next frontier that skull base surgeons should really be interested in. In so far as, we went through this with the sinuses a generation ago, we've become very comfortable operating trans-facially, through the sinuses trans-orally, and we need to go trans-orally as well. So this is where I'm from, this is the foothill of the Rockies, and this is our hospital and this is our Neurosciences Center here. And if you have the opportunity to come to Southern Utah, some of the most dramatic parts in the country. So, the skull base surgery is very interesting, we serve a very large geographical area as we're sort of the hub for a tertiary and quaternary care for many states that are underserved and low population but it adds up to a large area. And I show this case, as an example of the problem we face in skull base surgery. In that, we don't have any real Level I and II evidence for management of a lot of the diseases that we take care of, a lot of the diseases is variable and it's rare. This was an adenoid cystic carcinoma in a woman from Montana who actually disregarded the fact that she went blind in her eye, in her left eye, two years prior and she came in an extremists and you can see she's trapping her ventricles here. And we removed the tumor here in the middle fossa emergently, and then did another stage to approach to remove the posterior fossa as well. So given the fact that we don't have a lot of evidence basis for what we do, the unique problems that we face in skull base surgery also include, that most difficult skull base tumors are rare, such as the one I showed you. They're variable in size, location, texture and vascularity. The approaches are multiple and also our complications are sudden and often unpredictable. And this is compared to the diseases such as heart bypass, carotid endarterectomy, et cetera, that we do in medicine that are really more textbook, more routine in so far as that they're standardized. So every one of our skull base tumors is unique and must be treated as such. So what's new and where are we going here? Well, I think we need to understand the anatomy of the area. And I really would like to just take a moment to honor Al Rhoton, who I've learned so much from during my career who left this tremendous legacy for us in the cadaver anatomical work that he did and helps our understanding of surgical anatomy so much. And when I was a young man, we understood the cavernous sinus very well but we really stopped our same depth of knowledge when the nerves entered the orbit. And it's a continuum from the cavernous sinus anteriorly to the orbit. He left this collection and Luke will go ahead and show this video. But basically when John Robertson and I were involved with the NNS, we really worked with Dr. Rhoton to be able to leave this legacy for all neurosurgery and it's a through the NNS website. And I would like to call out to Jefferson from UT Memphis, who did such a fantastic job in co-leading all this material, cleaning up the kodachrome slides and basically highlighting all the structures, making it a searchable database, and also putting up all of Dr. Rhoton's live lectures on YouTube for all to see. It's a fantastic resource and I use it routinely for talks such as this but also to review anatomy the night before a big case. So let's move on Luke and go back to the slides. So the orbit is made of seven different bones and let's just review the boney anatomy of the orbit. The frontal bone, obviously is the largest bone that's involved in the roots of the orbits. The sphenoid bone, the zygoma, the maxilla the inferior part of the orbit, the palatine and the lacrimal and the ethmoid here on the medial orbit and the lacrimal. Often the overlooked bones are the palatine and lacrimal bones which offers small surface area involvement of the orbit. It's important that when you're looking at the orbit superiorly and I think you need to recognize this, that when you're doing enter your skull base surgery is that the orbits are not flat, obviously there's ridges and bony ridges but there's also a depression at that the region of the olfactory groove here. And this is important because if you choose certain approaches to the anterior skull base, you need to be able to view down into the gully, that is the olfactory group to be able to completely remove all the tumor in its attachment. So that I prefer if I'm going to come in from above to an olfactory group meningioma, I prefer to come in a little bit laterally so that I can look down into the gully. I find that if I use the supraorbital approach, sometimes it's hard to reach down there and adequately see to remove the tumor and most inferior aspect of this area. Now, as I mentioned, we started off with our knowledge in the cavernous sinus and we were all disciples of the anatomy in this area and following the era of Cowase and Doling, we've started to be interested in moving forward into the region of the orbit and see important relationship of the nerves of the superior orbital fissure here. So obviously the fifth nerve, three divisions of the fifth nerve, V1 through the superior orbital fissure, V2 through femoral tandem rotundum V3 through femoral . And then third nerve running in the superior aspect through a cistern that runs into the cavernous sinus and then into the orbit. And then the fourth nerve, which crosses over the third nerve at the superior orbital fissure and this is an important relationship that I use all the time, is third crossing four. Right here is where it's really seen beautifully at the superior orbital fissure. So if you do open up the oculomotor cistern and follow the third nerve alongside where the calanoid was removed here you will injure the fourth nerve as it goes over the third, so the fourth comes over the third and then outside of the annulus of Zinn to the medial part of the orbit to innovate the muscle. So the third nerve continues forward and splits into two divisions and I'll show you those in the next slides. And then the fifth nerve, the most superior branch, this superior orbital branch here, and this then runs on top of the levator muscle. And here's a view. And I think it's important to recognize that most of the structures as they enter the orbit, come in laterally and go medially, so this is true for much of the nerves as I mentioned, the fourth nerve, the fifth nerve, it's true for the veins as well, the superior ophthalmic vein and the inferior ophthalmic vein start laterally and go medially. And the ophthalmic artery runs over the optic nerve in most cases and about 90% of the cases and 10% of the cases of it runs under the optic nerve but it starts laterally and goes medially. Now, when we think about approaches to the orbit, there's a myriad of approaches into the region of the orbit that have been described but I like to simplify it and this is the way that I look at it and I encourage you to consider reading this review. So if disease involves the orbit, we can usually choose two general approaches to the region of the orbit. So if it's lateral in the orbit or superior in the orbit, I usually choose a normal autonomy approach or a superior approach over the super orbital area or approach or mini and then if the disease involves in fairly, and this is just a review of all the pathology that can occur in the orbit, much of this, maybe orbital specific and much of it is disease from the neurosurgeon side, that's entering the orbit. And then if the disease is involving the inferior orbit and the medial orbit, we like to choose a more trans-facial approach. And so here you see the inferior orbit you can come through the maxillary sinus, the endoscope really helps with this or the nasal sinus or you can combine the two as I'll show you in a video very shortly. These approaches are designed to address the pathology without having to manipulate the optic nerve. So you really wanna come at the region of the pathology without interrupting the optic nerve and then obviously choose your portal between the musculature as appropriate. So there's also two ways to think about this, so I can address pathology within the orbit and then we can also use the orbit as a conduit for which to approach other lesions in the cranium, so trans orbital approaches or approaches to the orbit. So here's an orbital tumor, this is a meningeoma of the orbit. This man has proptosis and some visual loss and you can see here, the lesion is medial and inferior, so this is ideal. So why don't we go ahead and show the video Luke. This is ideal for an endonasal approach. And what we'll do here is, we'll use the maxillary sinus and the nasal cavity as a conduit to reach the area of the tumor but we will do it all through the nose and we don't need to make a separate maxillectomy in this particular case, even though we certainly can and we routinely do this for other tumors. So we'll make the nasal sinus and the maxillary sinus, a common corridor and then remove the inferior and medial part of the orbit. And the tumor removal then is simply just another neurosurgical resection. What we're going to do is there's the periorbital fat will de-bulk the center of the tumor and then using bimanual technique here, we'll go ahead and cauterize or reduce the tumor and dissect around the tumor and reduce it to its pedicle as vascular pedicle and then divide that. And you'll see us now dissect the region of the tumor and then go ahead and cauterize the pedicle. Now for an opening this large in the orbit, I don't usually do a formal reconstruction and this closure is simple. And we'll go ahead and then you can see as post op scan. I think Luke, if we just move on. You can see his post-ops can here, where we've reduced the proptosis and his vision, his optic nerve is left untouched. So Luke, why don't we show both of these videos? You can show the one on the upper left and then we'll move on. This is just the imaging. This is a classic schwannoma of the orbit, V1 schwannoma involving the orbit and causing visual loss in a young man. So this is a classic neurosurgical operation. And Luke, let's move on to the next video. A frontotemporal approach, you can see we entered the frontal sinus when we remove the mon flaps or we'll to address that but what we want to do here is you want to do it on orbitalnomy large enough, so that you can see the anatomy and you can see where the levator muscle is and you can see where the tumor is approaching and find your window into the region of the tumor. In this case, we're going medial to the levator here and carefully open up the periorbital, retract the levator away. Remember the third nerve is the innervating levator from underneath, so what we want to do is, if you can remove it from medial to lateral, that's excellent because you won't interfere with the third nerve, as I mentioned, the third nerve comes in laterally. So we won't interfere with the innervation to the levator by this approach. So we open up the schwannoma, it's partially cystic. you'll see. And this is just like doing a schwannoma in any other location in the head, we'll de-bulk the schwannoma and then we'll identify the plane between the periorbital and the periorbital fat and the tumor and then use our dissection techniques to maintain that plane, soft catenoids developed many years ago that we use as dissection planes. Aaron is now updated these with new designs and we get the tumor removed completely. We'll plug the frontal sinus. This is how I like to deal with frontal sinus violations and skull base surgery, I pack it with autologous material. Usually I've plugged a hole with muscle. and then sew a pair of cranium graft over the opening. Bone flap is replaced, and then we're done with the metaphor cranioplasty and then we'll go ahead and get a post-op image here that shows the tumor removal. Okay, Luke, let's move on. This is an interesting case that I'd like to show you. This is among a series of patients that were recently published by Sam, Mefty and I, and we've noticed a unique variant of these trigeminal schwannoma patients. And what you'll see with this patient is, she's got multifocal schwannomatosis of the trigeminal nerve. And so she's got tumor extending from the cavernous sinus all along the first division, right up to the superior orbital rim. It's partially cystic, partially solid. This wound presents with some proptosis and you can see the mass over the superior aspect of her orbit extending right back to the region of the cavernous sinus. So what we'll do in this case is, we'll choose an approach that allows us to go from the cavernous sinus, right to the superior orbital rim with one opening. And this gives us a beautiful exposure into both the cavernous sinus and to the orbit and we'll remove the orbital rim with the bone flap here, you can see that, we've already exposed the orbit. And then we'll go ahead and this is my oculoplastics partner, Dr. Patel, a wonderful colleague and friend. And what you want to do in this case, is drain the cystic schwannoma, remove the solid portion that you can, but leave the first division intact because you don't want to cause an aesthetic guy in this case. So middle fossa approach, healing the lateral wall of the cavernous sinus, exposing the schwannoma in the cavernous sinus as taught us many years ago and then we find our window into the cavernous sinus and here between V1 and four and then we'll go ahead and remove the schwannoma within the cavernous sinus. And then what you then can do is, you can basically trace out the first division along its entire course from the cavernous sinus to the orbital rim. So we'll open up the periorbita and fall along the first division. And you can see this is seated with nodules of tumor and in a multifocal fashion, all the way along the nerve. So it's a schwannomatosis but a very specific type of schwannomatosis involving only the trigeminal nerve in this cases. And we've seen a number of these patients and we don't understand the genetic background of this disease but there's a nodule tumor that will remove. And then closure, we'll close the periorbital as best we can. And then of course we've been extra dural so we don't have any dural closure. Got into the final sinus again here, so we closed that and replaced the bone flap. And then you'll see on the closure, the reduction of the mass that we've been able to achieve with the closure or with the tumor removal and she had resolution of her proptosis. She was a little more numb in V1 but then quickly recovered afterwards. So thanks very much, Luke, let's move on. I'd like to talk a little bit about spheno- orbital meningioma. The problem that we face obviously is this hyperostosis. And this is a very common scenario of which most experienced neurosurgeons have witnessed, where a middle fossa meningioma is removed. A patient has proptosis that may progress despite there's no soft tissue within the middle fossa floor and this is hyperostosis bone, that's tumor in the bone involving this bridge. And this is a very dramatic case of a woman with terrible proptosis from Eastern Europe, the most dramatic case that I've seen but you can remeasure the proptosis index by using this measurement from the edge of the globe to the orbital apex and then measure it against this normal counterpart. And, oh, what you're really dealing with here is, a tumor involving soft tissue, it's involving the periorbita and it's involving the bone of the orbit. And so I've adopted a very much more radical approach over the last 15 or 20 years and what we do is, we drill up all the involved bone of the superior orbital area and the lateral orbital wall. And so you wanna remove all the involved bone, now, luckily the superior orbital ridge and the orbital rim is usually not involved, so cosmetically it's easy. You just work right up to that area and remove all the involved bone of the orbit. So all the involved bone is removed to enable reduction of the proptosis. And so here you have a case in point, this is a man from Las Vegas that I took care of who had a middle fossa meningioma. You can see how much hyperostosis is involved right here. And in all of this is high prostetic bone that needs to be removed, including the middle fossa here. And so what we'll do is, this is his post-op scan and you see now reduction and removal of that involved bone. I'm gonna ask Luke to go ahead and show this video of this a very dramatic case, which I think emphasizes the important points that I'd like to bring up when we remove these tumors. And I try to remove all of the tumor. I think it's important that we recognize that if we're going to help the patients with proptosis reduction, we need to really think about removing the tumor completely. So tumor in the orbit, extracranial as well here and in the middle fossa, it's got tumor in all three places. She was actually very sick when she came to us because she had a trap ventricle here, you can see the lateral ventricles trapped and she's starting to herniate. So we operate on her urgently and frontotemporal approach, extended proptosis that she has, she could still see out of the eye, it was still functional eye although she had double vision and she had some visual loss in that eye. So what you wanna do here is really expose the area, remove all the tumor extracranial and intercranial and interorbital. So orbital rim exposing here and all this is tumor in the bone and walling the muscle here. So we'll plan to remove the bone and you can see how thick the bone is all through here. This is our chief resident operating and it takes a long time to drill all this bone. I liken this to archeology, you're really trying to dig through an unknown depths to find the important structures. And you can see here that the periorbita is all involved with tumor as well, right? So we know that our job is not finished by just removing the bone of the orbit. Here's the optic nerve that we decompressed and we'll remove the clinoid here and then ultimately you end up with a complete boney removal of the lateral wall and the superior orbit, it's all involved tumor, the middle fossa and I'm now removing the middle fossa component of the tumor and the funnel fossa component of the tumor. This was a very invasive and aggressive tumor, there's a lot of edema. So, with the edema in the brain that the node is breached and that you may get parasitization of the peel supply by the tumor, which is what I'm separating there. And then remove the tumor and its dural involvement completely right up to the region of the orbit. And then we'll start on the orbit and this is the important point. I start behind the orbital rim, right? And I find the normal plane of the tumor involvement with the orbit. So open up the periorbita and then dissect along the plane and remember that the periorbital fat is your friend, it's a buffer to the important structures like the optic nerve, the ophthalmic artery. And so you're gonna take this back, all the way back to the region of the annulus of Zinn. Remember the annulus of Zinn is where the muscles attach, it's an anchor point of the muscles. And in this particular case and in most of the cases, the muscles are not involved with the tumor and you can go ahead and remove the tumor aggressively. So we'll use a AlloDerm patch here to close the dura. I'm into the ethmoid sinus, so we'll go ahead and plug the hole there with muscle and fibrin glue, the same thing with the frontal sinus here, we'll plug the muscle and fibrin glue where we entered the frontal sinus and then we do not formally reconstruct the orbit, I'll put some fat and fascia between the orbital structures and the dural closure. And then two weeks later, we'll bring her back and I just wanna find out, look at the optic nerve here. It's like a road course. And the reason for that is because she's been so well decompressed now, the eye is reduced dramatically. So we'll go ahead and put a custom cranioplasty in because all that tumor, the bone was involved with the tumor that we removed. And then, we'll look at the eye here on closure and I'll show you the amount of reduction that we've achieved with this resection. So, now you can see on the left pre-operatively and on the right how much reduction of the proptosis that we've achieved. So you'll say, we'll 'cause anaphylaxis in some of these cases. Luke, let's move on back to the slides. And we published this initially several years ago but I have a series of close to a hundred patients now. And I think the important point that I'd like to make is, that if you look at the proptosis in these patients, if you look at our preoperatively, the amount of proptosis that they've had and postoperatively, we've never achieved enough thalamus. So this is a different animal in my mind, these patients with these big spheno-orbital tumors that they don't over-correct. I think if you take a normal orbit and decompress the orbit and open up the periorbital, you will definitely get thalamus with these ones we have not seen that. And so I'm very aggressive. I don't do any formal reconstruction. I did have one complication where the patient had hydrocephalus postoperatively and the frontal lobe was pushing down on the globe and causing proptosis again but after shunting the patient I reduced nicely. Now, the other thing I just wanted to point out is this is, something that Anna Osbourne taught me in that when tumors grow next to sinus, meningiomas, when they grow next to sinuses, they can cause blistering of the sinuses, we call this pneumosinus dilatans and you see this most dramatically with these tuberculum celly tumors. And so what you see here is, you see the tumor growing adjacent to the tuberculum here and what it's doing is, it's increasing the area of tuberculin for you and it's actually helping with the consideration of approach through an endonasal approach. And the same thing happens when the tumors grow next to the funnel science and so we had a classification system that we've published some years ago on this but this is just an example of how this pneumosinus dilatans actually facilitates your approach. You see the same thing with tumors and Luke, we'll go ahead and play this video involving the frontal sinus and you'll have to deal with the pneumosinus dilatans because this may be a separate mass upon the sinus itself. This is an interesting case, a 20 year old fellow with right-side proptosis and you can see the size of the frontal sinus here. So this itself is causing mass effect in addition to some tumor involving the medial orbital area. The tumor was not that large but it's causing proptosis. And so we'll do a bifrontal approach here and then remove the region of the tumor involving the periorbita and also the orbit itself. And this tumor was actually quite invasive. He's a young man, he's got double vision already. And so what we'll do is, we'll remove the tumor completely, including part of the musculature of the eyes as well. So here's the soft tissue inter-hemi spherically I'm removing or remove the dura overlying the orbit involved orbit and then drill out the sinus. There's the medial orbit on the right side and there's the frontal sinus. And I'm drilling out all of the sinus that's causing mass effect on the orbit itself. Get down to the normal periorbita, the time, drill the bone, remove the tumor involving the orbit. There's the anterior ethmoidal opening into the orbit there and you can see this is where the anterior ethmoidal branch comes in and the posterior ethmoidal. And then Dr. Patel will now do an orbital approach to remove the tumor involving the medial rectus. These patients have double vision already, so we'd like to go for a tumor control operation here and we'll remove the tumor completely. And you could see the muscles being removed, a piece of the muscles being removed with the tumor that's invading the muscle. Luke, let's move on. So orbital meningiomas, I do an aggressive removal of all bone and soft tissue. Remove intraconal tumor if not attached to the muscles and consider removing the tumor involving muscle in younger patients and you can get significant proptosis improvement. So I've adopted that very aggressive approach and we're just publishing a long-term followup on a lot of patients right now. And it looks like the recurrence rate is less when we choose an aggressive approach to remove the tumor. So more to follow. So where are we at? So this is an interesting history in so far as the evolution of the frontotemporal approach, is an approach we use daily for most neurosurgeons that are busy with cranial surgery. And the first use of the term, pterional, was by Hamby in 1964 but it was Yasargil's frontotemporal approaches to circulation aneurysms and the upper basal artery that really popularized the approach in the sixties. And we realized that when we did these cancer surgeries, so if you take out this squamous cell involving the maxillary sinus and the inferior orbit here, that if you're planning to remove the contents of the orbit in this case, because the inferior rectus was involved that you get an amazing exposure of the anterior cavernous sinus and you can see the anterior loop for the carotid right there. And the brain was not touched, there was no brain retraction and you get a beautiful view. So with that introduction and these operations are very well tolerated, the orbital approach to the cavernous sinus is actually one of the shortest approaches, it's shorter than our frontotemporal approach. It's about four centimeters, it's not the shortest, the shortest is through the maxillary sinus but we developed this approach about 10 years ago and the whole idea is, it's a way to get to through the pterional approach to the anterior temporal area and the cavernous sinus through the orbital wall. So we're doing a trans orbital approach to the cranial cavity. And if you use this to the region of the cavernous sinus, it's a very short approach, it's very quick, it's all extra dural. And the idea is that it's cosmetically acceptable. There's no interruption of the temporalis. There's no brain retraction and it's entirely extradural. So I'd like to just show you this video, Luke while we play this, and this just shows the approach very well. This is a cavernous sinus lesion in a 65 year old woman. She presented with ophthalmoplegia. She had leukemia two years previously, was treated bone marrow transplant. And the lesion was in the cavernous sinus on the left side and the oncologist did not know whether this was a occurrence of her leukemia or whether this was another tumor but this demonstrates the approach. It takes us about 40 minutes to do the approach. It's very simple. And I use a lateral canthal incision to do this and I fork it up into the fisher and then expose the periosteum of the orbital rim. And what we're going to do here is free up the lateral orbital area. I'm using a C1 here, so I remove less bone or you can use an oscillating saw but remove a small window about 15 millimeters of the bone of the orbital rim and how we go from the zygomatic bone, where it meets the lateral orbital rim superiorly about 15 millimeters. We'll go ahead and fit our plates, so we get perfect apposition afterwards. And then you expose the lateral orbital the wall and what you wanna do here is thin the lateral orbital wall and follow the lateral orbital posteriorly through the region of the pterygium and then find the anterior dura of the temporal lobe. And so now I'm just going extra durally peeling up the temporal lobe dura exposing the tumor within the cavernous sinus. And you could see it's firm, it's clearly not a leukemia. This is firm tumor and this turned out to be a weird sort of unicorn Epstein-Barr virus associated muscle tumor of the orbit and the cavernous sinus. And then we'll go ahead and then we're entirely extra dural so there's no dural closure here, we close the soft tissue and then place the subcuticular suture over the region, and close the skin in this area. Very quick, simple approach. I send the patients home the next day and this is an eye protector we put in. Thanks Luke, can we move on? So you can do this for other tumors. We'll use it for tumors that involve the cavernous sinus, where we want to decompress the cavernous sinus, say for meningioma, we wanna decompress the optic nerve. This is a man who is losing vision of the cavernous sinus meningioma. He's got a small tumor that's causing compression of the optic canal here. And what we'll do is, let's just show them this very quickly, Luke I'm removing the anticarnary process and I've drilled the canal in this case, through this approach and then you can go ahead and see the decompression and we've lifted up the wall of the cavernous sinus as well. No formal closure of the dura in this case, we'll go ahead and then use surgery foam and replace the bone flap and then close. Thanks Luke. And this is what his scan looks like post-operatively, you can see what we've removed, we've decompressed the lateral orbit here. We've removed the process in this location and drilled out the canal. And if you look, these incision is very well acceptable cosmetically and this is about six months after surgery and there's no wasting of the temporalis muscle here at all. So we're actually writing up this series right now. We've done a number of different cases. I just wanna show a more recent case where... Yeah, let's show this one, Luke, this just demonstrates a point that Sam L. Mefty is actually espoused for many years, that some of these patients instead of just shunting them to radiation, we should consider operating on them. So this is a young girl with a progressive third nerve palsy. And you can see here that she's got a lesion off her cavernous sinus in super orbital fissure in the region of the third nerve at the oculomotor cistern and going in through the superior orbital fissure. And I thought that we should probably take a look at this and explore this because she was progressive and people were willing to just write off the third nerve and decide that that was the fake and they would just radiate the patient. And I want you to consider this case because I think in some cases it does merit exploration. So pterional approach, as I've shown you and then we'll go in and explore the region of the cavernous sinus and superior orbital fissure in this case. So come through the terrarium, lifting up the temporalis muscle, exposing the dura of the temporal lobe and then coming in again and then now exposing the region of the cavernous sinus and the superior orbital fissure. Now, when we explore this, you'll see that I'm looking for the lesion. And I find the lesion, which is a firm nugget adjacent between three and four just near the superior orbital fissure and so I'm coming around it and it's completely discreet. It's not infiltrative at all, it's discreet. And this is the point that all these tumors are not infiltrative in the cavernous sinus and it may merit exploration in a lot of cases. So here I'm coming around, I'm dissecting the tumor from the lesion of the cavernous sinus and then we'll go ahead and debulk the tumor and then remove it completely, you can see the fourth nerve to the right there. So it's easy to obtain hemostasis here. It's all venous bleeding, it's not a problem. And then we'll go ahead and then close. Luke, let's move on. So I'd like to move on and talk about tumors in the orbit right now. And I wanna share this with you. So this is an important anatomical relationship, this region at the orbital apex in the annulus of Zinn. So the annular tendon or the annulus of Zinn encompasses the area of the optic canal here, where we have the optic nerve and the ophthalmic artery running through. And then also the lesion of the medial superior orbital fissure. So the annular tendon encompasses this region of the medial superior orbital fissure and you have the third nerve, the sixth nerve and some branches of five running through the annular tendon here. And you'll see this on the video. There's actually a notch here that you can see that marks where annular tendon inserts in this area, right here. So I'm gonna show you a case of a 20 year old woman, who has right eye progressive painless visual loss. And she had a biopsy of the optic nerve because it looked like a tumor that was inconclusive and then the second one was a conclusive for a low grade optic nerve glioma. And so she progressively went blind and you can see the enhancement of the nerve here. You can see where she was biopsied before, there's a lot of post operative surgical scar. So she has no vision now. And we're going to remove the optic glioma from the globe back to the region of the chiasm to prevent progression of the disease into the chiasm. It's important here because these are low grade tumors and they can threaten vision in the contralateral eye and in the chiasm. And so we're gonna do a curative resection of this low grade glioma by removing the tumor and we'll do it in one stage. Traditionally, this is done in two stages approach with an approach from the front by the orbital surgeon, usually ophthalmic surgeon and the second one from the back to cut the nerve, just to enter to the chiasm. So what we're doing here is, we're drilling out the lateral orbital wall, you saw me open up the meningo orbital band. I'm drilling the superior orbit now and the lateral orbit will unroof the optic canal. And you have to completely expose the optic nerve all along its course here. So we'll drill the lateral orbit, there's the superior orbit and medial orbit, will remove the orbital roof completely so that we can expose the region of the nerve all the way up to the globe. We identify the object strut, drill the object strut and release the anterior clinoid process which is here removed. And then you can see the anatomy here, the carotid, the optic nerve, the optic strut and the ophthalmic artery. Now we'll open the dura, I like to open a T- shape fashion along the sphenoid or the fissure and then across the frontal base and the temporal base. Now we'll expose the ipsilateral optic nerve, this is right side obviously in the contralateral artery. And I'll cut the optic nerve just interior to the chiasm about two millimeters to respect . And then we'll open up the falciform ligament along its medial side. Now, this is important because I'm exposing here the annulus of Zinn and we're going to open up the annulus of Zinn medial to the lavetor and the superior rectus attachment. So there's the levator, there's the fifth nerve, the frontal branch of the fifth nerve. Careful not to injure that when we open up a periorbita. Now the whole idea here is, to follow the tumor out from the intracranial space to the globe. And you gotta be careful of the fourth nerve, which is going over the annulus of Zinn but it's still in your way, you're gonna have to be careful that work around it. So then you use your self retaining retractors to hold the periorbital fat, it's a beautiful way of doing this. And what we'll do then, is we'll march out along the optic nerve superiorly right up to the region of the globe. We'll expose the nasociliary nerve which is a branch of V1 that runs right over top of the nerve anterior that we're for is and you identify the post your globe here. And then we'll go ahead and transect the tumor and the nerve at the globe. Now, what you wanna do then is, lift up the transmitted nerve, this is what I'm doing now and then work your way back and we have to dissect it from the annulus of Zinn now and this just there's fascial attachments within the annulus of Zinn and this is what I'm doing is that I'm exposing and opening up the annulus and removing the tumor from the region of the annulus of Zinn taking care of not to injure the nasociliary nerve and the fourth nerve. And there's your specimen from the chiasm to the globe. One step removal. So we reapproximate the annulus so that she'll have normal movement of her eyes and have the muscles anchored properly. We'll reapproximate the periorbital. And in this case, in contrast to a meningioma, I will reconstruct the orbit, in this case I'll use a preformed oval implant that you just bend to the desired shape. And we again enter the frontal sinus, so we'll go ahead and take care of that. And then after we close you'll see the scan that shows a complete resection of the optic nerve as expected. So I think this is sort of a major way of looking at this is an extension of the neurosurgical disease right up to the region of the globe and you can do it from a neurosurgical perspective in one stage. Thanks Luke, let's move on. And then finally, I just want you to think about this sort of periorbital or meningioma as a disease progression that we should really take more responsibility for and I use this as a case in point. This is in a really unfortunate young woman who had a WHO grade one meningioma resected from the middle fossa here in 2004 and then she had progression of her disease and you can see here, she's still got a lot of disease in her bone. And then she progressed into the orbit with the residual growing into the orbit and had multiple surgeries that were partial resections. Finally, she lost vision in her eye and they put a prosthetic globe in but now she's got tumor extending completely through the orbit incasing the carotid in the cavernous sinus and involving all this area and it's down into her face here as well to the region of the nasal pharynx, the oral pharynx and the maxillary sinus as well. So this has happened over many years, is kind of a slow train wreck and she's got a terrible recurrence and we'll go ahead and do an ontological resection of this tumor. Now it's important on these cases, she obviously got a nonfunctional eye on the right side. We're going to have to deal with the carotid artery within the cavernous sinus and to do that, I will do a balloon occlusion test. So the next video shows the at the procedure but basically what we'll do is, we'll do a thigh free flap for closure. And we'll also get a saphenous vein graft for reconstructing the carotid if we needed but we did a balloon occlusion test and she passed the balloon occlusion test so we don't need to bypass this patient. So frontotemporal approach, I'm opening up the orbit, this is all filled with tumor we'll move the prosthetic globe and then remove the tumor within the orbit itself. Now the main blood supply to this tumor is coming from the ophthalmic artery. So you just go back to the apex of the orbit and you cauterize the ophthalmic artery and then you're able to completely remove the tumor within the orbit itself. And now the orbit is clear and then we'll go now and remove the tumor down in the face. And this is simple, there's nothing too hard down here. There's the maxillary artery that is usually involved with the tumor that you'll have to find branches and take but the removal of the tumor within the deep face is fairly simple, you just keep following it down from your frontotemporal approach. In these cases, it's involving here is the sum of the fat in deep face. And I'm taking the tumor out from this region. And then you'll see I'm drilling the pterygoids here and into the maxillary area. Then we'll go ahead and remove the intradural part which is the tougher part. These patients have been radiated multiple times and you can see parasitization here of the tumor from the intracranial vessels. This is the M1, M2 branches on the right side and what I'm doing here is I'm dissecting these branches off of the tumor and you find each one and cauterize it separately and preserve the M1 branch. And then go ahead and continue coming around the tumor and we'll do an oncological resection here, there's the optic nerve and the carotid artery on the right side. And we'll go ahead and prepare to ligate the carotid. And so there's the optic nerve and we'll plan to ligate the carotid below the ophthalmia or the takeoff. And she tarted this fine, we do evoked potential monitoring obviously during the case and then she's doing fine. So we'll tie off the ICA and the neck and then you can come around the cavernous sinus itself in a stepwise fashion and do an exoneration of the cavernous sinus. So cutting the carotid here definitively, now that it's been tied off in the neck. And then we'll do a standard cavernous sinus resection and it's just a matter of coming around the tumor in all its margins, drilling through the temporal bone and getting into the posterior fossa here, drilling across the posteriors bone and then cutting the fifth nerve at the root entry zone and the fourth nerve, we're cutting the fifth nerve root there. And then come immediately into the region of the stellar and then removing the tumor completely from this area. This is the most important part of the resection, removing the mass and then coming below and making sure that we're moving up completely. And you'll see what we'll do is, we'll drill out the involved bone of the posterius bone and remove all the soft tissue and that may be involved with tumor as well. So there's the remaining posterius bone here and I'll drill this further to make sure that we have moved all the bone that's involved in this area. So let's show the last video, please Luke there on that slide. And then ultimately reconstruction. I use fascia, usually fascia lata to close the dura since they're taking a thigh flap in this case and then with our ENT colleagues, we'll sew in a vascularized flap to fill in the space of thigh free flap in this case. And this gives you a vascular pedicle of which to connect to the region of the extra artery. You'll just see the anastomosis being done here, creating a plasti and then sewing the free flap. And then a direct anastomosis to the external carotid artery. Thanks very much, Luke let's move on. And this is her postop scan. I'll put an EVD in which I didn't show for CSF diversion and to try and avoid a CSF leak. And then she spent I think two weeks in the hospital but ultimately did fine and she went home. And so I really believe that we need to take a real interest in orbital surgery, this is within our wheelhouse. It's an important frontier. It's really important to know the anatomy. And we include this now in our skull base courses that we do here with our trainees and when we do skull base courses for external people as well, it's an important frontier and it's easy for us to do. It's a very forgiving area to operate and we should just know the anatomy and not feel intimidated by dealing with this. And I think we need to take more responsibility for the disease completely. And think about that last case that I showed you where this person had subtotal resections all along multiple times and multiple radiation treatments and have we done the best for the patient? And I'm not sure but I'm thinking about this, that we need to better calculate the morbidity of radiation in the total management of the disease and consider that more effectively because the complications of the radiation occur down the line, they're amortized over many years, whereas in surgery, we take all our risk upfront. So with that, I say, thank you very much.

- Excellent lecture, Bill, really unparalleled expertise demonstrated in this video for interorbital surgery. I also agree the last case is really the take home message. It's a fine line. Are you an aggressive surgeon? Too aggressive a surgeon right up front? Or are you not doing the right operation? And therefore delay a much, much bigger risk to the patient and place the patient at a much higher risk later as it happened. And I think that's something that we all have to be very aware of, that if you don't take care of the lesion right up front very well surgically and don't have the expertise that patients should be referred to institutions where such expertise exists rather than try to do a glorified biopsy because if these tumors are not managed well, by the time they go too far, the risk of surgery tremendously increases. And I think I would say orbital surgery, is sort of an orphan surgery because neurosurgeons have sort of put in the back of their mind, that oculoplastic surgeons have sort of, don't have the complete expertise there and sort of there's a big void for these patients. And it's a big opportunity to be able to help many of these patients who need help and be able to extend their quality of life in addition to lengths of their life. So as always in this region, the anatomy is if the key and obviously be able to have a multidisciplinary team of good surgeons who have an interest that you'll get along with and be able to provide the patient with excellent care. So as always Bill, I wanna thank you again for being such an incredible mentor for so many people, including myself and your incredible contributions to neurosurgery on many levels, thank you.

- Thanks Aaron, it's really been an honor to be involved. And I would just emphasize one thing that you said, it's important to have a great working relationship with your great EMC colleagues and your ophthalmologists and you can learn so much from talking with all your colleagues and working with your colleagues on such cases. And I've been blessed in my career so many times with great colleagues that I've learned so much from because we're all looking at it from a different direction and be open-minded. And I think that we need to improve the care because I think there's sort of these no fly zones that we have in neurosurgery, an orbit has been one and we're not offering the best care if we can't really use that as a continuum of care with our ophthalmological colleagues to provide the best care in that area. And that last case, I think exemplifies that. And I think we need to think globally and develop some kind of a risk score for the risk of surgery and radiation and what, when is most appropriate time to have radiation instead of more surgery? Because I think really that's the big question.

- But I think that really goes back to the fact that a path of risk resistance is not always the best pathway.

- Right.

- And because this is not your wheelhouse doesn't mean you have to radiate just because there is low. In fact radiation, when it does hurt people, it's a significant risk.

- Yeah.

- Go ahead.

- Yeah and it adds significantly to the morbidity down the line when you do have to take the bull by the horns and try to remove the tumor completely.

- Yeah, I agree with you. And one thing that you very well mentioned Bill is that avoiding dogma and being open to learning from your colleagues and ENT, as we do for acoustics and oncoplastic, ophthalmologists, plastic surgeons, unfortunately, neurosurgeons have traditionally not been having a good track record there. And I think you have to understand the neurosurgeons are only part of the team. And at times may not be the biggest part of the team, so we have to put the ego behind the operating room door and just come in with a very open mind and learn about how they do things because the potential is huge.

- Right.

- And just because you did something that way in residency, doesn't have to always be done that way. And I wish there was a pill or there was some treatment we could give to our colleagues sometimes to realize how critical that component is. But I think that's, as I've always said, the hearts of innovation in neurosurgery and techniques and the heart of technical excellence and passion for it resides and being able to avoid dogma, push the limits, be safe, learn from others and be self reflective in terms of how you can do better at every level and having your colleagues from other specialties and extremely component of that. So again, Bill, thank you, a huge amount of learning for me and others and sincerely appreciate it, again being with us today.

- Thanks very much Aaron. It's always an honor, thank you.

- Thank you.

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