Gabriel Zada, MD, a neurosurgeon at Keck Medicine of USC, discusses cranial tumor surgery, including a review of the current catalogue of minimally invasive endoscopic surgical techniques available to treat adult brain and skull base tumors.
Mm, mhm and yeah, yeah, yeah. Mm. Hi. My name is Gabriel Zadeh, professor of neurosurgery here at the Keck School of Medicine in the U. S. C. I'm the director of the U. S. C. Brain Tumor center. And for today's 24 20 lecture, I'll be discussing minimally invasive cranial tumor neurosurgery in the year 2020. So let's get started here in my disclosures. So today, what I hope to convey is the current catalogue of minimally invasive and endoscopic surgical techniques for an adult brain and skull base tumor surgery practice highlight the benefits that endoscopy and keyhole approaches can provide. We're going to review the top 20 commonly utilized endoscopic approaches that facilitate 360 degree access to the skull base and sub cortical regions. And most recently, we're going to discuss the potential benefits of blue light endoscopy to a tumor practice. It's amazing to see how far technology has come over the last century, especially with endoscopy going from candle and filament based endoscopes to Walter Dandies, Endoscope and Harold Hopkins contribution with the rigid endoscope. The benefits of angled endoscopy were discussed in the 19 seventies by some of our mentors here at USC. Dr Apuzzo, Dr. Kersey. Dr Weiss. And it's important to consider that all endoscopic and a nasal approaches, uh, to the skull Base and pituitary region were first described only two decades ago in the 19 nineties. And since then, we've seen really, um, significant evolution of these techniques. So on the left is the first video I know of of a endoscopic assisted pituitary surgery by Professor G. O in Paris. And on the right is resection of a cranial. For Ngoma be an extended approach. And it's just amazing to see how far we've come over half a century with regard to our optics and technology and how much we can do. Uh, the, uh n no nasal or sub labial speculum based procedure for removal of skull base tumors. And this minimalist march continues throughout many aspects of neurosurgery, not just a tumor or endoscopic service line. We see this in spine and a vascular radiosurgery, robotic techniques and laser induced thermal therapy techniques. So today, what I hope to cover is a lot. It's the top 20 minimally invasive endoscopic cranial approaches used particularly for a tumor practice. We're gonna cover uh, neural endoscopic techniques within the ventricles, endoscopic and a nasal techniques, keyhole approaches and port based sub cortical approaches. What's amazing is that these minimally invasive approaches provide really 360 degree access to the skull base, sub cortical regions and intra ventricular space. This is the development of our minimally invasive endoscopic cranial service line. In an adult practice over one decade, we've now crossed the 1000 case mark, and you can see our distribution there. An overwhelming majority or endoscopic nasal approaches. So let's start with the oldest and most classic endoscopic approach in the brain, which is the endoscopic third ventricle Ostuni pioneered approximately a century ago. And in adults. We use this for treatment of non communicating hydrocephalus, often aqueduct, all stenosis. This is a wonderful approach because it's channel based, and you can perform this with one tool. You don't need to handed micro dissection, even though you're in a water medium so great, uh, operation that any cranial neurosurgeon treating hydrocephalus and tumors should be familiar with. Although channel based approaches are great, uh, it becomes more challenging to perform them for actual lesions. Whether there are tumors in the ventricle or call Lloyd Cysts, and I used to do all my colleagues cysts, uh, neuro endoscopic channel approach. However, there are some challenges and limitations. You're working in a CSF or water medium, and therefore, if there's any element of bleeding that can be particularly challenging with regards to visualization and irrigation, you are confined to essentially one instrument. And some of the limitations are an inability to perform true two handed micro dissection. And here you can see the cyst being veniste rated and drained and then ultimately removed. I'm going to talk about how my practice has changed for coexists. Later on, we're gonna talk about endoscopic and a nasal approaches, and these can be categorized as direct approaches to the Cella Corsica proper or extended approaches which really provide access to the entire midline skull base. Going from the frontal Sinus all the way down to the upper cervical region, Odin toyed region and frame and Magnum, and there are even lateral approach is that traverse the trans steroid and trans maxillary spaces. We maintain the principles of true skull base surgery, which are bony removal, to expose the critical neurovascular structures that we need to see two handed micro dissection. And of course, reconstruction is a critical aspect. So let's start by discussing the most basic endoscopic and a nasal approach for pituitary lesions confined essentially to the seller. This is resection of a Cushing's disease, a C th secreting micro adenoma, the extra capsule or approach. You can see the beautiful views we get with the endoscope and careful dissection of the tumor away from the normal pituitary gland. When you remove a micro adenoma with this technique, it has a higher chance of achieving hormonal remission, especially for Cushing's disease. And here you can see how we get around the capsule to remove this tumor. We've now done direct E. A s in over 400 patients, and 86% of these are for pituitary tumors, followed closely by Rocky Cliffs cysts. We do these with a single surgeon approach a direct approach to the cellar with a median O. R. Time of under two hours, median hospital stay of two days, gross total resection in 58% of pituitary tumors and hormonal remission, and over 80% of functional pituitary tumors with a very low complication rate of one. I see a injury without neurological sequelae. Postoperative CSF leak rate of 4% and new Hypo pituitary is, um and 3% of cases when you start leaving the area of the cell a heuristic a proper and start doing extended endoscopic procedures, you really need to make sure all your instruments are ready to go, So these are much more involved in intricate procedures. Here we're seeing removal of a tuberculosis ella meningioma via trans tubercular, um, and transplant them route. So, uh, reconstruction becomes critical, and obviously you're working around critical neurovascular structures, so you have to have all your ducks lined up in a row here. Now we're dissecting the meningioma away from the optic chi as, um, and you'll soon see the com complex, uh, knowing that we have removed this tumor in its entirety and improve the patient's vision. Starting with the most interior and extended endoscopic and a nasal approaches is the transcript reform approach, which approximates the level of the of the olfactory groove and can get you all the way to the frontal Sinus. So here we are, developing a medical flap, and my NDP colleague, Dr Ravell is exposing the frontal Sinuses we're now thinning out the bone of the phobia at my palace surrounding this olfactory neuroblastoma removing the Crista Galli. And now we're performing unblock resection of the portion of the tumor invading the frontal lobes and gyrus rectus, cauterizing the vasculature that's feeding this tumor and dissecting away from the olfactory tracts and bulbs. And now we've achieved a complete resection, and we're focusing on our reconstruction, which is done with cash, a lotta and a pentacle nasal septal flap in addition to a lumbar drain for 48 hours, with 10 cc's an hour of typical drainage starting to work more posterior along the skull base is a classic approach, which is the transplant and trans tubercular approach, which gets you great access to the super seller region. This is a an approach that's classic for tuberculosis element, NGO Mazz and cranial for NGO HMAS in particular get this beautiful anatomy, getting you back to the optic nerves and chi as, um, the carotid arteries, the superior hypotheses all arteries and, of course, the infant nebula and pituitary stock, as well as the com complex. Although we rarely use extended approaches for giant for pituitary tumors, occasionally for giant pituitary adenoma as we will in my practice. Extended approaches are used in about 16% of pituitary tumors. These are some indications when you have the tumor spilling over the tuberculosis sell into the anterior cranial fossa, or lateral extension, into the ocular motor system. This patient presented with profound vision, loss and rights, third nerve palsy. So we performed a trans tubercular approach to assure that we could dissect this away from the optic nerves and chi as, um and third nerve. I usually start with opening just the seller to really get an understanding of what the consistency of the tumor is like and then expose the super seller region. Here we are dissecting the tumor away from the optic eye ASM with careful two handed micro dissection and now dissecting away from the carotid artery. You can see the A com complex at the top of the screen, and although these are pituitary tumors, they can be very invasive and adherent to the surrounding neurovascular structures. Here's our reconstruction, in this case with Allied ERM and using a gasket seal technique and a pentacle nasal septal flap over that a complete resection was achieved with dramatic improvement of vision and preservation of the normal pituitary gland. Another classic indication for the transfer curriculum Transplant. Um, approach is, uh, for cranial for Ngoma, even a giant cranial for Ngoma with retro seller extension all the way back to the A pre Ponting cistern can be removed this way. So we've removed the tubercular and planum you're now seeing the optic eye. ASM Careful two handed dissection away from the basilar apex, third nerve focus and p com arteries After we've removed the tumor from this area will look more superior early and removed the tumor from the third ventricle, which is what you're seeing here in the mammal. Everybody's. We were able to achieve a complete resection of this giant Adam Antenna Metis cranial for Ngoma, and there's a view of the third ventricle. Well, then fill the dead space with fat and proceed with our rural reconstruction with fashion Lotte and a pentacle nasal septal flap. In addition to a temporary lumbar drain, MRI showed complete resection and another example of a tuberculosis element. Ngoma. I'm very selective about these. I still often believe in a good old fashioned craniotomy for meningioma, as I'll show you an example of one of my favorite cases, which is an eyebrow craniotomy. And I'm, uh, typically 50 50 with very careful selection about patients for end of nasal versus craniotomy for skull Basement NGO Mazz. Here's my colleague Dr Roble, preparing a PETA Khaled Nasal septal flap, tucking it into the nasopharynx exposure of the spine oId Sinus and removal of the bomber thinning of the seller region and super seller region. In this case, the tuberculosis Ella. Careful removal of the bone with carrots and rangers away from the carotid arteries and medial optical optical created recesses cauterizing the dura two D vascular rise the tumor early with bipolar Kateri using a Doppler two really identify the location of the corroded arteries and then opening the midline super seller Dura over the tumor, cauterizing the superior, cavernous into the cavernous Sinus and then de bulking the tumor, finally dissecting it away from the optic eye. ASM and Infinite Gulum, which is what you're seeing here. We're now looking over the top of the tumor, and you're seeing the optic eye ASM and were able to dissect this tumor away from these critical structures. You'll see the infant nebula, um, come into view and were able to achieve a complete resection of this tumor with dramatic improvement in vision. Moving, uh, more in fairly and post eerily along the skull base is the Clive Davis, and exposure to the Clovis was very difficult even 20 years ago. This is a textbook from some world experts in neurosurgery in the early nineties, and they used to call these approaches to no man's land. That's because there was not a good way to get to the Clavius, the Clive. This is a difficult area which is bounded by the carotid arteries and six nerves and obviously, houses the brain stem and basilar artery. Chordoma is the classic example. This is a 17 year old, a young man who was a basketball player who presented with Diplo Pia and 1/6 nerve palsy with intra dural extension of the chordoma with compression of the brain stem. This is how they used to do this operation via trans basil approach, lifting up the frontal lobes very morbid procedure to access the skull base. Or they used to just do a craniofacial approach, as you can see on the right, both very morbid approaches, the endoscope has offered a dramatically improved exposure of the Clavel region and exposure to the posterior fossa when needed. Here we are fitting out the bone over the crowded arteries, two skeletonized them and cavernous Sinuses, locating the carotid arteries with the Doppler removing the cavernous Sinus component of the Chordoma and then going to the posterior fossa region. So we've now removed the dura. We're dissecting the tumor away from the basilar artery and these very small ponting perforating vessels that feed the ponds and brain stem here. So in a young person like this, the first opportunity to remove this tumor is the most critical. And here you see the tumor being removed from the brain stem achieving homeostasis fat packing of the dead space rotation of a pentacle nasal septal flap, and a near complete reception was achieved with some residual in the right cabinet Sinus. He then went on to have proton beam therapy, but here he is graduating from high school six weeks post op. So when Endo nasal approaches are not ideal, another wonderful, minimally invasive option for anti R skull based pathology is a super orbital approach, often done via an eyebrow or eyelid incision. So one of my favorite approaches in neurosurgery because it's so elegant it was developed for a variety of indications. Vascular pathology by Pernet Skis Group initially, but a really wonderful approach for anterior skull, basement Ngoma or other tumors, uh, as well as frontal Sinus pathology. So for some planum olfactory tubercular meningioma, as I prefer this approach, the reconstruction is not as critical and patients recover very well. So here's a right eyebrow approach. I like to use low profile Lone Star retractors here, replacing a burr hole at the McCarty Keyhole, rotating a super orbital bone flap about three by two centimeters. We've drilled out the under surface of the of the orbital rim tacked up the dura, and now we're removing tumor. We've debunked it, and we're dissecting it away from its the tubercular selar region. You're seeing the chi as, um and right optic nerve. Careful, two handed micro dissection away from these structures, and now we're looking cross court at the contra lateral left optic nerve where we're removing this tumor away from these structures. Here's the reconstruction, and these patients tend to heal very well. Ah, other approaches to the pineal region are also facilitated by the endoscope. There are many ways to approach the pioneer region. Here are some examples I'm going to focus on one of the most common, which is the super cerebellum infra tutorial approach which we do fully endoscopic Lee. Now the Venus anatomy is very critical to understand and you're bounded superior early by the territory. Um, initially, these veins can often be removed. Replace a small craniotomy immediately, immediately below the level of the torque yola, which gives us this great access to the pineal region. I don't do cases in sitting position anymore. It's challenging in terms of setup and ergonomically. So. I do these endoscopic cases in full Concorde position, which is more comfortable for the surgeon as well. Here's an example of a patient with a panel Saitama, who presented with symptoms consistent with normal pressure hydrocephalus. And here we are, inserting the endoscope below the territory. Um, you can see the vein of Galen. There were now dissecting the super cerebellum veins here. Here's our initial exposure of the tumor, and we're working around the tumor, dissecting it away from the text. Um, and there's the initial glimpse of the posterior third ventricle. We get a gush of CSF knowing that we've decompressed the CSF pathways and careful two handed micro dissection away from the text. Um, you can see the Corey plexus of the third ventricle and the final residual tumor being removed. A beautiful view of the third ventricle unobstructed. Knowing that we've helped this patient gross total resection achieved no need for a shunt and her symptoms improved. Let's move on to discuss, uh, endoscopic assisted surgery in the posterior fossa, whether it's the CPI angle or the fourth ventricle. And we've been using the endoscope in the fourth ventricle lately to inspect the aqueduct. But the endoscope also lends itself to resection, especially of epidermal tumors of the C. P. Angle can be used for trigeminal neurologist surgery as well. This is a microscopic view. The retro sigmoid approach removal of an epidermal, a tumor. You can see removal away from the cranial nerves, but at some point your reception becomes limited with the microscope. So we'll put in a 30 degree endoscope, which allows us to look around corners more closely at the interface with the brain stem. And because epidermis can often be removed with a combination of suction, curettage were able to remove additional tumor with with this workflow, or even if it's just for inspection and diagnostic purposes, to assure that we've achieved a maximum safe reception. We're also using the endoscope in the fourth ventricle, where, after removal of 1/4 ventricular tumor, we will insert the endoscope via the median aperture, or for a man of Majendie and, uh, and we'll start with a classic microscopic approach. As you can see here, this was for a glioma neural tumor of the fourth ventricle. We'll do a standard T mobile, our approach and maximum safe reception. At some point, this becomes limited, and and it can be difficult to look at the roof of the third ventricle near the super medullary vellum or all the way up to the aqueduct. That's where insertion of an angled endoscope can really help. So you'll see our limitation here with the reception of this tumor but facilitation of a better view with an angled endoscope. So here's the endoscopic approach. You're looking all the way up at the aqueduct and the roof of the fourth ventricle, where we can respect additional tumor here when I see the aqueduct unobstructed. I know I've helped this patient with regards to hydrocephalus, and, uh, this will improve the chance that they will not need CSF diversion. Here's another example after resection of 1/4 ventricular Medalla Blast Oma. We're looking all the way up at the aqueduct here assuring that it's not plugged removing any blood clots there, and we're making sure that CSF can flow through there. So I'd like to talk about the really the final frontier minimally invasive cranial surgery, which is, uh, still evolving and less than a decade old, which are port, port based or channel based approaches to sub cortical and intra ventricular tumors. There's a variety of approaches that can be used for this. This is really the final frontier in many ways because we're still understanding the intricacy of the sub cortical space, the complexity of all the white matter and fast sickles and and this has been helped by advanced neuro imaging with diffusion track ta graffiti that we now use. This was the problem. Getting to sub cortical and intra ventricular tumors was the collateral damage induced by retraction for many hours Now, with port based approaches and circumferential retraction were able to access a variety of lesions in the sub cortical space. This has really changed the landscape for treating interest cerebral hemorrhages, especially in the basal ganglia region. And there are many clinical trials going on to assess the potential benefit. Although many surgeons who perform this will tell you on an anecdotal level that many patients benefit from early evacuation of these clots. So after evacuation you can see the port being backed out and collapse of the sub cortical white matter. In my practice, I use these selectively for a variety of tumors metastases, gliomas, uh, an intra ventricular pathology being the most common. This does not change how you perform standard tumor surgery, so we still use all the same adjuncts we would use for open cases, which include cortical sub cortical mapping, five al fluorescence, euro navigation and a variety of, uh, advanced neuroimaging techniques. This is a patient with a metastases from colon cancer. What you don't appreciate sometimes is the amount of surrounding flair and oedema which may make these patients suboptimal candidates for radio surgery. There is level one evidence to suggest that reception of a single symptomatic brain metastases, coupled with radiation, offers better survival outcomes as well. So for a case like this, we would perform a standard parietal occipital approach through a sulk ASUs to access this tumor. Here we are dissecting the sulk ast The dural opening in this case is about 13 millimeters in with We always use a transcultural approach with Venus preservation when possible. Here's our trajectory with no navigation, We're now docking the port in this case which is a brain path port, and we've accessed the tumor here. Obviously, tissue acquisition is very critical. So we're sending tissue samples off here and then proceeding with tumor resection away from the surrounding white matter were able to achieve a gross total resection. And of course, this will be followed up with Steri attacked IQ radiosurgery. This patient's symptoms improved and although he was in his seventies, he went home post op. Day two, you can see preservation of the sulky US and Venus anatomy. I mentioned earlier Colloids cyst surgery and how I used to do these with neuro endoscopic approaches. I will now do these with port based approaches so we'll perform a small craniotomy here 13 millimeter Dural opening Dissecting out the sulky is here, using a pork based approach to target the lateral ventricle and this classic exposure of the framing of Monroe on the right side. In this case, and now we're able to perform two handed micro dissection of the cyst in an air medium away from critical structures, which include the for Nick's internal cerebral veins and any thalamic structures as well. I feel that this is a safer approach for Colloids Cysts, and this is now my go to again. We're able to achieve complete cyst resection with no need for CSF diversion. And when the pork comes out, I would like you to pay attention to the sulky is here how quickly that is preserved and comes back together and again. Gross total resection patients done very well. Another approach that we are using the ports for a cavernous angio MMA is whether they're, uh, intra prank camel or intra ventricular or exotic into the ventricle, we will do an excess Coptic converting to an endoscopic approach, which we call E. So this was a young man with a large hemorrhagic, cavernous hemangioma. You can see the trajectory we took along the long axis of the lesion, going from right to left to avoid the dominant sided left for Nick's. In this case, there's our planned incision again, 13 millimeter dural opening with a small craniotomy suckle dissection. We're now advancing the port into the lateral ventricle. An initial exposure of the cabinets. Ngoma, we're getting around the capsule here. We're starting with reception of the right lateral ventricular component. We can now toggle the port from lateral to medial and get better at a better view of the deeper contra lateral side and dissecting this away from the contra lateral, thalamus and hypothalamus. Once we feel we've achieved a complete resection, cavernous hemangioma is are very critical to assure that you get the whole thing out. So now we're working on the contra lateral side, but our workflow is to go from excess Coptic to endoscopic, so you'll see advancement of the endoscope into the cavity, where we'll use an angled endoscope to look around to make sure that we've removed this entire cavernous hemangioma to prevent recurrence. So here's insertion of the 30 degree endoscope into the cavity. We're looking around, and there's no residual. This patient did have transient short term memory deficits that improved dramatically over the next couple weeks. Complete resection was achieved. Here's our homeostasis and removal of the port. Another case where I think the port has really lent itself is for inter ventricular meningioma, as these should be carefully selected. This was a young woman with growth of the tumor and headaches. So another wonderful approach for a port where we'll use a pride occipital approach. These are usually in the atrium of the ventricles. So here's the meningioma, and we'll do standard meningioma de bulking, extra capsule dissection and careful dissection away from the core. I'd plexus and feeding arteries. I'm gonna wrap up this lecture about discussing sub cortical glioblastoma and what we've been doing for this. So this is a patient with a very difficult, dominant sided basil ganglia, region glioblastoma. This is one of the earlier ones I did with this workflow. What we're lacking here is optical fluorescence with five la. I'm gonna show you how we've been able to change that. But here's the necrotic portion of this tumor. Well, often use this in combination with sub sub cortical mapping. And here we are removing this tumor. What you'll see on the post op film on the right is I left a small area of residual on a little satellite nodule there that I was not able to see. But we did get greater than 95% of volumetric resection. Patient remained intact and went on to have radiation and chemotherapy. So how have we changed this? Well, our goal has been to get five a l A blue light delivery into the capsule. This was supported by some work from Dr Berger's group at U. C s F with a blue lighted suction device. We've had access to a blue light endoscope, which has really changed our practice over this year. We now perform all biopsies of suspected gliomas. A very small port based approach will use an 11 millimeter diameter port with a blue light endoscope. We do not use a microscope or extra scope, and this dictates what tissue we select for biopsy. We've had 100% diagnostic biopsy rate without waiting for pathological confirmation. So this is our new workflow. It's done via a minute, you craniotomy. And as I mentioned 11 millimeter diameter borehole the next way we've used this is converting from an excess Coptic to endoscopic blue light technique. This is for deep seated, sub cortical high grade gliomas, not for the ones that come to the surface. So here is a patient where we started with a port based approach via pride, occipital sulk. Assists were de bulking the obvious component. And now we've inserted the blue light endoscope. We get this avid fluorescence that you do not see with the microscope in the depth of the cavity, and we resect the tumor capsule under direct blue light visualization toggle ng from white light to blue light. As you see here, this has been a new paradigm for us that we think has offered improved visualization of fluorescent tissue and an ability to achieve a higher reception rate, which we know is associated with potentially better survival in high grade glioma patients. We'll continue this workflow and inspection of the walls until there's no additional fluorescence. If we're in an eloquent region, we will use sub cortical mapping in conjunction with this. So here's another example of a very complex, dominant sided left frontal glioblastoma. In this case, we'll compare microscopy and endoscopy with endoscopy on the left microscopy on the right. You can see significantly more avid fluorescent with the endoscope. We've now done our mapping, and we've resected the cortical component. Here is the microscope without a lot of fluorescence identified, we're now sending tissue off. We're continuing with the superficial component. And here's a head to head comparison of the endoscope on the left, to the microscope on the right, where we get much more avid fluorescence were now respecting tissue under direct blue light endoscopy and toggle ng to sub cortical motor mapping to assure that we don't cause any motor deficits. Going back to our blue light endoscopy, inspecting the walls with an angled endoscope until we have no more fluorescence and we get 100% gross. Total resection. Volumetric Lee patient had a transient sm a syndrome, and then it was intact after that. So what I want to convey to the viewers is versatility of using the microscope, endoscope and excess scope. These are all powerful tools that tumor surgeon who performs minimally invasive surgery should be able to use interchangeably to offer the most tailored and best opportunity for patients to undergo maximally safe tumor resection with minimally invasive approaches. In conclusion, I hope I have conveyed to you that there is a variety and an entire catalog of minimally invasive keyhole and endoscopic approaches that provide 360 degree access to the skull base, sub cortical region and ventricular compartments. Angled endoscopy allows one to visualize anatomical regions that are not offered by microscopy. Port based approaches provide circumferential retraction and access to sub cortical intra ventricular lesions and blue light endoscopy may offer a benefit in the reception of deep seated high grade gliomas. Maintaining versatility of all these techniques, I think is critical to tumor surgeons performing these approaches. I'd like to thank all the following people the U. S Department of Neurosurgery and Jim Sullivan with incision video. Thank you. And I hope you've enjoyed this and mhm mhm.