Transcript

- Colleagues and friends, thank you for joining us for another session of the virtual operating room. My name is Aaron Cohen. Our guest today is Dr. Doo Sik Kong from Samsung Medical Center at Seoul, South Korea. He is the director of skull base surgery there. A professor of neurosurgery, tremendous experience with the endoscopic transorbital approach, which has really been an innovative way in terms of reaching anterior and mid skull base pathologies. So he has experience with over 110 surgeries using the endoscopic transorbital approach. His lecture is spectacular. You're gonna love the videos, the innovation and the technical advancement illustrated there. So I highly recommend it. Doo Sik, I really want to thank you for letting us learn from you and I'm very excited to watch your lecture. Please go ahead.

- Yeah, thank you for your kind introduction. And it's a great honor to be a part of your world-famous Neurosurgical Atlas. And also, thank you very much for having me. And a few months ago, Dr. Ted Schwartz had a great presentation about the introduction of transorbital approaches. And today, I'm going to talk about the surgical indications and the feasibility of transorbital approaches, and I'm going to share my experience in Korea. The purpose of this presentation is that transorbital endoscopic approaches can reach the various ventral skull base lesion through the orbit. The aim of this study is to evaluate surgical anatomy by step-by-step cadaver dissections. And we are to review indications, and surgical technique, and complications. We already established the International Transorbital Working Group including Dr. Kris Moe, Dr. Ted Schwartz from United States, and Dr. Joaquim Ensenat, Alberto Di Somma from Spain, Dr. Matteo de Notaris from Italy, and I and my colleague, Dr. Chang-Ki Hong, from South Korea. We annually hold a hands-on workshop. So I hope that you join our group to learn how to start the transorbital approaches. This is a brief figure to describe the surgical corridor of treatment modalities on the skull base lesions. And transorbital surgical corridor is very similar to the anterior lateral, pterional approaches, and orbitozygomatic and supraorbital approaches. And I think minimal invasive approaches should be less destructive surgery, and also it can spare the operation time. Overall, most important thing is the surgical corridor of minimal invasive surgery should be parallel to the long axis of tumor. And also, it gives a short working distance to the lesions. And also, of course, it has good cosmetic outcome. The representative minimal invasive surgeries are endonasal and supraorbital approaches. And conventional open skull base tumor surgery is very important to access the skull base lesions, but sometimes it takes too long time. And sometimes it requires excessive retraction of temporalis muscles and too destruction to the numerous surrounding tissues. And sometimes the patient complain of the the cosmetic issues, skin or muscle depressions. For this middle fossa tumors to access these lesions, more transpituitary or posterior pituitary approaches may be required. As a minimal invasive surgery, I think the endonasal or transorbital approaches can be applied to the small sized lesions. But if you accumulating your experience about the transorbital approaches, these large tumors like these tumors can be accessed with the transorbital successfully. And then, why we have to do the transorbital approaches. We have to know the difference of the transorbital approaches compared to the supraorbital cranial tumor approaches or endonasal approaches. As a minimal invasive surgery, this is a coronal plane of the skull base. Endonasal approaches can cover the infratemporal, pterygopalatine, sinonasal tract Ans supraorbital approaches can cover the whole anterior cranial fossa lesions. I think the endonasal and supraorbital approaches must be a good excellent approaches. But still, they cannot have some limitation to reach the middle cranial fossa and cavernous sinus lesions. And then I think the transorbital may be an alternative candidate to reach the middle cranial fossa or cavernous sinus area. Compared to the transcranial approaches, after transorbital approaches, you can see the whole tumor was removed, but there was no defect of the outer bone. Only inner bone defect, sphenoidal bone defect was seen. And it has no temporalis muscle atrophy, leaves minimal scar. And you cannot see which side is operation side. It's has a very excellent outcome cosmetically. And compared to the endonasal approaches, we have to know that the transorbital approaches provide a direct view and short working distance and it does not require to cross ICA. It has the less destructive to the surrounding tissues, middle turbinate, septum, nasal septal flap, pterygopalatine fossa. As a result, transorbital approaches can spare the vidian nerve. And overall, transorbital approaches has a very minimal rate of the CSF leak. I have experience of only 3% of CSF leak. Compared to the transorbital and the endonasal, the indication is very essential. This tumor, the left side that is in the left side figure, this tumor is here. The location of ICA is very important thing. Compared to the endonasal approaches, I think endoscopic transorbital approach may be better to avoid crossing the ICA. But right side, see the right side figure, this figure was provided by Dr. Mark Hughes from Scotland, and this trigeminal schwannoma cases, which approach is better? I think in these cases the ICA is shifted more laterally. It's very rare cases. But anyway, if the ICA is located laterally compared to the transorbital, endonasal approach is preferred approach here. And four years ago, we compared our experience of the endonasal versus transorbital outcome for trigeminal schwannoma cases. This analysis, the 13 cases of endonasal, 12 cases of transorbital approaches for trigeminal schwannoma. Let's see, for the middle fossa tumor and dumbbell type of the trigeminal schwannoma cases, we had an excellent outcome of the transorbital approaches compared to the endonasal approaches. Of course, principle group or any , you may have a comparable outcome of the endoscopic endonasal approaches. But in our series, still, transorbital approach has superior outcome to the endonasal approaches. But extracranial part of schwannoma cases, of course, endonasal approaches was be better than the transorbital approaches. And let's compare to the supraorbital approaches. This is the figure from the Neurosurgical Atlas. And through the supraorbital craniotomy, you can see the the very inner structures around the parasellar areas. But still, the cavernous sinus portion and medial temporal portion is very deep and requires the oblique areas. But when we remove the greater sphenoid wing, we can see is very various medial temporal area, cavernous portions directly. So we have to know the difference of the supraorbital and transorbital approaches. And this is a swimming posture. And above the water is the supraorbital approaches and under the water is the transorbital approaches. The level of the water may be the the orbital rim. If you take out the orbital rim, you can attempt the supraorbital and transorbital approaches at the same time. If you preserve the orbital rim, you have to select which approach is better to access the skull base lesions. And therefore, we have to know the difference of supraorbital, and transorbital, and endonasal approaches. And then we have to apply the optimal approaches to access the skull base lesions. I have experienced of 115 cases of transorbital approaches. Meningioma cases was the most common cases, followed by schwannoma, and other tumors. Let's see the surgical details. While set up is almost the same as the endonasal approaches, then we have to know the correlations between scar and skin thickness. We are not plastic surgeons, but we have to know the these findings. Skin thickness is correlated to the severe scaring. If the facial thickness varies, and superior eyelid is very thin, but forehead and cheeks are very thick, and also, there is an ethnic difference, we have to know that. So the higher the incisions, the higher the chance of the scar. We performed the supraorbital supra-eyebrow incision for this patient, there was no scar. But sometimes we face some patients and even with the infra-eyebrow incisions, because according to the individual difference that there is some dense scars or some skin depressions. But for the transorbital approaches, there was no know the the dense scar because of the thin skin thickness. We have to know the higher the incisions, the higher scar. To do the transorbital approaches, we first incise the skin or on the superior eyelid, then we divide the oblique rectus muscles. Then we need to preserve the orbital septum. If you invade the orbital septum, the levator palpebrae muscles injuries and then the patient may have a permanent ptosis. Then we have to expose the periosteum over the lateral orbital rim. It's a very is simple technique. Then we can palpate the hard bone and reach the lateral orbital rim. Then along the lateral orbital rim superiorly, we incise the periosteum, then elevate the periosteum along the periorbita. Then we can elevate the periorbita from the lateral orbital wall, so-called greater sphenoid wing. We can identify the superior orbital fissure. This is the figures from the literature. And we drill the greater sphenoid wing middle cranial fossa dura, but the exposed superior orbital fissure is here. But actually, I don't agree with this figure. If you open the middle cranial fossa dura, it's not enough space. And then I think we have to drill the base of the greater sphenoid wing, it's very important. It's like we have to drill the base of the sphenoid sinus during the endonasal surgery. It's very important to drill the base part of the greater sphenoid wing. And also, we have to drill the lesser sphenoid wing. Finally, we have to drill the sagittal crest, so-called composing of the lateral boney surface of the superior orbital fissure. Then we can expose the fully temporal dura, periorbita and meningo-orbital band here. It's very important thing. If you perform the intradural dissections, we can face the multiple cranial lobe within the cavernous sinus V1, three, four nerves here. Let's see the boundary of bone removal. This is the orbit. If we drill the greater sphenoid wing here, then we can enter the temporal side. If we drill the lesser sphenoid wing, then we can open the frontal side. Finally, if we drill the anterior clinoid process, and we can access the clinoidal meningioma here. Sometimes the meningioma develop the hypertrophy of the greater sphenoid wing. It's very hard born making. When we drill the greater sphenoid wing, this part is removed. We can obtain a wider working space and surgery is much more comfortable to remove the tumor. And interdural dissection is very important. Peel off the temporal dura from the lateral membrane of the cavernous sinus. We can expose Meckel's cave tumor or cavernous sinus lesions here. How to get indication of transorbital approaches? Actually, transorbital approaches surgical corridor is from anterior to the posterior part. And then cranial optical lesion may be the first indication of transorbital approaches. As you accumulate the experience of transorbital approaches, we can reach middle cranial fossa, such as trigeminal schwannoma, and then we can extend to the posterior fossa involving tumor. The major indication of transorbital approach is middle cranial fossa lesions, including spheno-orbital meningioma, trigeminal schwannoma, or intracoronal orbital apex lesions. This year, Alberto Di Somma published data and he shows the the level of difficulty in transorbital surgeries. He classified the transorbital surgery into the five step, from the easy and beginning step to the very difficult cases. And then, this step one is extracoronal, extradural lesions, and step two is spheno-orbital meningioma, followed by trigeminal schwannoma, anterior clinoid meningioma, or selective amygdalohippocampectomy. Finally, petroclival meningioma may be the most difficult lesions for transorbital approaches. According to these level of difficulties, I will show my cases. First one is level one, middle fossa extradural approaches. This case was orbital wall fracture. This boy had a lateral gaze limitations here immediately after head trauma. We diagnosed it as entrapment of lateral rectus muscle into the fractured bony fragment. We performed transorbital approaches. This is the trauma eye. Incise the skin along the superior eyelid. This surgery was done by my oculoplastic colleague. Then we opened the oblique rectus muscles, then we expose the the greater sphenoid wing. We identified some abnormal finding. This was not the sphenoid deficient. Some maybe soft tissue. So maybe the lateral rectus muscles would enter to the fractured fragment of the bony portions. Then we just drill out the greater sphenoid wing here, here. You can find the soft tissue masses within the intracranial part. Then we reposition the lateral rectus muscle into the orbit area. It's very simple technique. Then we repositioned the lateral rectus muscles, placed the fascia lata, then finished surgery. After operation, sorry, after operation, there was no limitation of lateral gaze. And then you can see the postop cosmetic outcome. And this is another case. This is a level two, the spheno-orbital meningioma. I have experienced of 54 cases of spheno-orbital meningioma cases. Spheno-orbital meningioma is mainly sometimes involve the greater sphenoid wing, involving the anterior temporal lobe, or involving orbit, or infiltrating to the temporalis muscles. And then we analyzed our outcome. And I think that the best indication of spheno-orbital meningioma is the globular type. Not infiltrating, not showing the infra type patterns, not invading the extraocular muscles area. This patient complained of the prothesis and paresthesia on the face. We performed the transorbital approach for this lesions, we placed the Silastic sheet. Silastic sheet is very useful technique to protect the periorbita. At the same time, it can the help to retract the orbit more medially. Then we remove the lateral orbital rim to reach the lateral margin of the the tumor. We expose the frontal and temporal side here. This is the dura part of the tumor. We removed it. Then this is nominal, temporal, paraclinoid and Sylvian vein here. We removed it. At this step, we don't have to use the rigid retractor because already, the greater sphenoid wing was removed. Then we obtained the wide working space. For closure, we use the three fat graft on-lay graft, or fascia lata, or AlloDerm graft. And lateral rim repositioned with the titanium plate. After operation, you can see the total removal of the tumor. Then there was no cosmetic issues on the patient. How to reconstruct after removal of the meningioma? I favor the free fat grafting for the meningioma cases or wide dural opening cases. And nowadays, AlloDerm graft is okay, no more fascia lata, or no more fascia graft was done. But the fat graft can be done in-lay, or on-lay, or both. When we put the fat graft and then we don't have to perform the lumbar drainage. To avoid enophthalmos and then the PDS placement is optional. PDS is the very, for oculoplastic surgeons prefer the material, it's like the absorbable Medpor sheet and it can prevent the post-op or avoid the post-op enophthalmos. And 6-0 Rapide absorbable sutures for skin closure is a very good for the cosmetic outcome. The level three is trigeminal schwannoma. I have experience of 27 cases trigeminal schwannoma cases. As you know, the trigeminal schwannoma is very complex tumors. And according to the study, we applied modified Samii classifications, trigeminal schwannoma can be developed from the cisternal segment of the posterior fossa along the Meckel's cave and can divide into the three types of three branches of the orbit, mandibular and maxillary branches. And intracranial part of the trigeminal schwannoma can be classified into three type. Predominantly middle fossa type, mainly posterior fossa type, or middle and posterior dumbbell type of tumor. Intracranial tumors can be classified into the V1, V2, V3 type. This patient complained of the parasthesia on the left side. You can see the tumor mass involving the middle and posterior fossa type. We call the dumbbell type of the tumor. For these tumors, to access these tumors, the tumor involving middle and posterior fossa, and then we select the transorbital approach to access these lesions. Because the tumor is located middle and posteriorly bilaterally, both. We incise the skin around the superior eyelid. Then we dissect the soft tissue. Then identify the lateral orbital rim, incise the periosteum, and carefully elevate the periorbita from the greater sphenoid wing. And then we started to drill the greater sphenoid wing. At this stage, we need to use the rigid retractor. Every 10 minutes interval, we need to release the rigid retractor to avoid the pupil dilatations or the BP, blood pressure changes. And then when we do the left sphenoid wing, at this step, we obtain a wide working space. We don't have to use the retractor. Just we can retract the orbit with suction, it will be okay. Then we expose the temporal dura and periorbita. This was the Silastic sheet. Then I tried to peel off the temporal dura from the periorbita. Then we have, I look for the clarity line. Then this was the lateral membrane of the cavernous sinus. Then this was the meningo-orbital band. Then we cut the meningo-orbital band here. This was the meningo-orbital band. This was the anterior clinoid process. This was maybe lesser sphenoid wing was removed. Then we opened the lateral membrane of cavernous sinus along the the V1 pathway. This was the V1 pathway. Then we identified the tumor capsules, debulked the tumor with the Sonopet or ring-thread here. After debulking of the tumors, we identify the margin of the tumor. We can find that some trigeminal fascicles. And as much as possible, we have to preserve the trigeminal fascicles. Then we debulk the tumor. This is the final step. This is the porus trigeminus outlet to the posterior fossa. You can see there's some cisternal segment. Maybe this is a cisternal segment of the trigeminal nerve. We have to very carefully dissect the tumors from this segment. Then this was the anterior surface of brainstem. Then finally we totally removed the tumor. Within the Meckel's cave, there was no tumor. With the DuraGen, we closed the porus trigeminus, and then we put the AlloDerm graft in with the TachoSil, we closed it. At this stage, we don't use the fat graft materials. And then we close it. After operation, you can see the total removal of the tumor. There was no problem. This is a post-op MR images in post-op patient portal. Post-op second day, but the there was no cosmetic issues. This is another case of trigeminal schwannoma cases. Mainly involving in the posterior and middle fossa tumor. The tumor was very cystic. We performed the transorbital approaches. We performed the same surgical procedures. From there, we elevate the periorbita and expose the greater sphenoid wing. Drill the greater sphenoid wing from the lateral to medial side. The greater sphenoid wing has a triangular shape. We successfully removed the greater sphenoid wing. We can obtain the wide space. Then this was the meningo-orbital band. We coagulate the meningo-orbital band and cutting the band. Then we can fully expose the lateral membrane of the cavernous sinus. Then we peel-off technique. Then I try to look for the lateral membrane of the cavernous sinus here. This was the tumor mass. This was the dura propria of the temporal lobe. And this was the periorbita. And then gradually exposing the lateral membrane of the cavernous sinus. And open the tumor capsules. Tumor capsule was very cystic tumor. They easily removed and then stuck off the tumor, grabbing. This was the porus trigeminus that posterior compartment and within the capsule, we removed the tumor here. Then this was the space within the Meckel's cave and cavernous sinus. There was no tumor, then we close it. It's almost the same closing technique was applied. After operation, gross total resection of the tumor was performed. There was no post-op cosmetic problems. This is another case of cystic tumor mass type A middle fossa tumor. We performed the the transorbital. After removal of the tumor, we identified some fascicles trigeminal nerve. Here. This was the middle fossa portions of the tumor. Then I removed the part and this was the trigeminal nerve from the cisternal segment. This was the posterior fossa. And the porus trigeminus was closed with the DuraGen. For inlet, we placed the AlloDerm graft materials. Then placed the PDS to avoid enophthalmos. We close it. Post-op, we can find the gross total resections. And at this step, maybe four years ago, we saw that the middle cranial fossa was a very good indications of transorbital approaches. But middle and dumbbell type of of tumors, I was not sure, I was not confident to the transorbital approach may not be a good indication of the dumbbell type of tumor. But nowadays, the dumbbell type tumor is also very good indications of transorbital approaches. So we performed multicenter studies to accumulate our case series. And Korean Society of Endoscopic Neurosurgery groups and for recent five years, we collected 50 cases of the trigeminal schwannoma, four underwent transorbital approaches. Four total institutions participate in these studies. And 50 patients, and then we collected data. And middle fossa type tumor was 17 and we exclude the posterior fossa tumors. We didn't transorbital approaches for mainly predominant posterior fossa tumors. And then 20 cases of dumbbell type. 30 cases of the extracranial type of the trigeminal schwannoma cases. The median follow-up was 21.9 months. And you can see the middle fossa tumor, we had a very great excellent outcome of the gross or near total resections. And dumbbell type tumor still shows the 90% of gross total or near total resections. But still, extracranial type of the tumor, especially V3 origin tumor, has some limitations for transorbital approaches. And for this V1 one origin tumor, the tumor involving the V1 and extending to the cavernous portions, we perform the transorbital approaches. We opened the periorbita, remove the tumor. Then finally we remove the cavernous sinus portions here. And then immediately after, the patient, immediately after the operations, the patient complain of the complete ptosis, but gradually improved the ptosis. And this case is a very unique case. This tumor involved in the V3 origin tumor embedding into the infratemporal fossa. And we performed the operations transorbitally. And then successfully removed the tumor without the endonasal approaches. This was the post-op patient portal. This was the video for her. The tumor mass involving the infratemporal fossa and involving the middle cranial fossa tumors, maybe V3 origin tumors extending to the middle fossa tumor. We performed inferior transconjunctival approaches combined with lateral canthotomy to access the more inferior part of the temporal fossa. Then this was the inferior orbital fissure. But the other procedure is almost the same. Greater sphenoid wing was drilled. And this is temporal part, temporal dura. You can see the opening of sphenoid recess. Maybe this was the V2 area. Using enough drilling of the base of the temporal fossa is very important to expose the more base part of the tumor. And opening the meningo-orbital band, then peel-off technique. I exposed the anteromedial and anterolateral triangle. You can see the space between the V2 and V3 area. The tumor was accessed with the anterior lateral triangle. And then here, tumor was very highly suckable. And then using the Sonopet, we debulked the tumor. Then angled endoscope and angle the instrument, and then we successfully remove the tumors totally. Here. And this is the space involved in the infratemporal fossa area. Maybe this was the V2 area. And then with only the transorbital rim, we successfully remove the tumor. And at this step, in this case, we put the fat graft, but nowadays, no more fat graft was done after removal of the tumors. Whole tumor was removed. Let's talk about the reconstruction techniques after schwannoma cases. I favor the DuraGen to close the porus trigeminus and also AlloDerm graft, or fascia lata graft for inlet cavernous sinus. In these tumors, we don't have to use the fat graft because we didn't open the dura. Just open the Meckel's cave, just open the porus trigeminus. So I think there is no, a very minimal chance of the CSF leak from the cavernous sinus or porus trigeminus. And PDS placement is also optional for the avoidance of the enophthalmos. And 6-0 Rapide absorbable suture for skin closure. The level three is also the intraconal orbital apex lesions. We have to select the endonasal approaches or transorbital approaches may be better for accessing the orbital tumor. This patient complained of the proptosis on the left side. The tumor is located mainly in inferior lateral portion of the optic nerve here. So maybe endonasal approach is possible approaches. But I think tumor is located in the lateral part of the optic nerve, transorbital approach is may be preferred technique. We perform the skin incisions, open the periosteum. It's almost the same one. Then identify the supraorbital fissure. Then after drilling of the greater sphenoid wing, we opened the periorbita then identified the tumor capsules. It's very important to remove the greater sphenoid wing even with the orbital tumor to obtain the working space. This is the distal nerve of the tumor and we cut the this tumor. Then we've finished it. We performed a complete removal of the tumor. After operation, we can find the total removal of the tumor within the orbit area. There was no ptosis. This is another case, the recurrent schwannoma mass. The patient had the right side complete, I'm sorry, right side vision loss. And tumor mass located the medial side of the optic nerve. Usually, I favor the endonasal approaches may be better, but sometimes the endonasal approaches requires right angled and acute angled endoscope. Very difficult to manipulate the tumor for anterior located tumor. Instead of that, the surgical corridor of the transorbital approaches may be better for these lesions. To do so, we selected easier approaches, transcaruncular or precaruncular transconjunctival approaches. This is the caruncle. This is the caruncle. With the assistance of our oculoplastic surgeons, we performed precaruncular incisions with the monopolar coagulations. And then if we enter this space and extend into the transconjunctival incision, then we can easily locate the medial part of the orbit area. Then she exposing the medial rectus muscle, then open the periorbita. Then we identified the tumor mass located the medial part of the tumor. This was the recurrent tumor. The cystic changes and then remove the tumor. The tumor removal process is the almost same as microscopic surgery. Then we removed it. Okay, postoperatively the patient had some strabismus, and then he underwent the correction surgery in one year. Here, after correction surgery. And we successfully removed the tumor And next is that challenging indications of transorbital approaches. I think the petrous apex and temporal parenchymal lesions or infratemporal fossa lesions may be possible indication of transorbital approaches. These indications are level four major temporal lobe lesions For recurrent meningioma cases, this was the three, I performed the transorbital approaches. And then this was, because this patient had the recurrent tumor and had the widen temporal horn enlargement, then I identified the temporal horn open here. Through this hole, I entered the endoscope and then I found that fantastic view. This was amygdala hippocampus complex, temporal horn, choroid plexus. This is temporal horn. I thought that we can perform the selective amygdalohippocampectomy in near futures. And then, one patient had visited my outpatient clinic. She had a recurrent seizure attack. MR imaging diagnosed her as a DNT. And then we performed the medial temporal lobectomy preserving the lateral cortex of the tumor here. Transorbital approach is the same procedures. And then exposing the greater sphenoid wing. And then we open the temporal dura, exposing the anterior surface of the temporal lobe, maybe under the navigation guidance, and then we suck out the tumors involving the medial temporal lo here. Then this is the temporal horn. You can find the choroid plexus. Then maybe this was the hippocampus. Then we remove the medial temporal lobe. You can see that this is cistern space, maybe the ambient cistern, here, bigger part. Then, and this part is a continuance of temporal horn. Then we finish the operation. Coagulations, then we close it. And then for wide dura opening cases, I put the fat graft. After operation, the medial temporal lobe was successfully removed. And then we could preserve the lateral temporal cortex. And post-op follow-up of the visual occlusion field, there was no field defect. And then I thought that we can avoid the various lobe injuries after the operations. This is another case of the anterior clinoidectomy, level four. This is very difficult cases. And then through the transorbitally, we can identify the optic canal, and superior orbital fissure, and also optic strut, and anterior clinoid process can be found. This patient complained of the rapidly progressive visual disturbance for less than two years. It's very small sized the tumor, I'm sorry, very small size tumors invading the optic canals. And then we perform the transorbital approach. Open the lateral orbitotomy. Then take out the lateral orbital rim, drill the lesser sphenoid wing. This was the optic canal, ACP and superior orbital fissure. We drill open the extradural optic nerve. And then, using the Sonopet, we make the bone as egg shell like. And then successfully remove the anterior clinoid process. Then you can see the extra dura part of the optic canal. Maybe this is the proximal ring. This was the distal ring of the dura. After cutting the distal ring and then we identified the tumor. Then this was the ophthalmic artery and ascending distal ICA, then we close it. And we successfully remove the tumors within the optic canal. This is another case of the anterior clinoidectomy with transorbitally. This case was a recurrent meningioma cases. We opened the eyelid, then opened the periosteum and elevate the periorbita. This was the inferior fissure. Drill the greater sphenoid wing and opened the superolateral orbitotomy. For meningioma cases, I always perform the lateral orbital rim removal. Then this was a temporal dura and then sagittal crest. And meningo-orbital band was coagulated and incised. You can see the anterior clinoid process here. The base of the anterior process. After exposing the meningo-orbital band, we identified the optic canal here and anterior clinoid process is here. Carefully, as we remove the anterior clinoid process, then we opened the temporal dura, remove the tumor portions. Here, this was the Sylvian fissure. I opened the distal ring of the optic canal. Then finally, remove the tumor mass compressing the optic nerve at the intracanalicular portion of the optic nerve. And fully decompressed it, finished. You can find the total removal, I'm sorry. And then sometimes we perform the multiple surgery combined with the endonasal and transorbital approaches. And some these tumors, oculomotor schwannoma cases, we performed the endonasal and at the same time also transorbital approaches here. After transposing the pituitary gland and we remove the sellar portion, parasellar portion of the tumor. Then using the transorbitally, and we remove the cavernous sinus portions, located the ICA, lateral part of the ICA. Then we successfully removed the tumor. This case, the girl had recurrent optic glioma refractory to the chemotherapy. And then she lost her left regions and ocular pain. And then tumor is growing and more medially, medially, and involved in the optic chiasm. So I selected the endonasal and transorbital approaches for gross total resections to cut the optic nerve to avoid the extension to the more medial, the more optic chiasm environment. Then this was the endonasal approach. We opened the optic nerve. Optic chiasm is here. You see the enlarged optic nerve. And then we coagulate. It must be very unpleasant seeing this. But we have to, I decide to remove the tumor and then cut the optic nerve. And I identify the margin of the optic nerve is clear. Then we perform the medial transcaruncular, precaruncular approaches to access the medial orbital tumor. Then exposing the periorbita. Open here. This was a intraorbital tumor, intraconal tumor. Then we removed it. And this was the tumor capsule. You can see the enlarged optic nerve here. Being enveloped by the tumor and we cut it. Post-operatively, some tumors might be left. But most of the tumor was removed. And another level four indication is maybe cavernous sinus lesions. And then we identify the multiple cranial lobes through the transorbital approaches. From the cardio dissections, we can identify the three and four, or V1 nerve. This patient had the chordoma case. We performed the endonasal approaches. But unfortunately, we found that some tumors behind ICA within the cavernous sinus are left. I performed a multi-layer technique for reconstructions. I was not sure to reopen the reconstruction. And then, right then, I selected the transorbital approach for the remaining tumor. Here. We performed the transorbital approach. Then opened the cavernous sinus. This was fourth nerve, V1 nerve. This is the right side and this is the infratrochlear triangles, so-called Parkinson triangle. You can find some tumor capsules within this space. It's very careful to remove this part because this part is behind the portion of the ICA and some branches maybe rise from the ICA. We have to very careful to remove this part. And then, so I try to remove the tumors with the ring-thread. Gentle removal is very important. But this is was from the profuse cavernous sinus bleedings, the vision was not clear. After operations, this was the pre-operation, and postoperatively, you can find almost the tumor was removed through the Parkinson triangle. And level five is the most difficult cases of transorbital approaches. Maybe petrous apex lesions such as petroclival, meningioma, or epidermoid, or the meningocele. And Alberto Di Somma shows the feasibility of the transorbital approach accessing to the petrous apex area. And we classify the petrous apex lesions according to the relationship of the petrous ICA. And then, sometimes transorbital approaches may be helpful. This boy had a recurrent meningitis. MR imaging shows bilateral meningoceles and maybe the right side was the main region of the recurrent meningitis. Here, perfused contrast leakage was found. We performed transorbital approaches. Placed the Silastic sheet, take out the lateral orbital rim, then open the greater sphenoid wing here, temporal dura, periorbita. The meningo-orbital band is here. This was foramen rotundum this was the right side eye. Then this was the foramen ovale and foramen spinosum. You can find some rupture of the middle meningeal artery. Then we extended to the more lateral side to access the carotid triangle. You can find the GSPN. Then maybe this must be on petrous ICA. I was not sure, but this was the meningocele. Meningocele was enlarged cases. Then we safely identified the meningoceles. We injected the fluorescein and then green color was seen from the posterior fossa area. This was the green color. And then meningoceles communicating with the posterior fossa. Then we close it with the fat graft material. Then we close it. After operations, there was no leakage of the CSF leak. And then there was no problems of the recurrent meningitis on that boy. But we have to talk about the complications of the transorbital approaches. And compared to the endonasal and transcranial approaches, patients' discomfort is very minimal for the transorbital approaches. The patient does not complain about the postop headache because of no retraction of the temporalis muscles, no outer bone defect. The patient had no postop headache. It's very minimal chance of the CSF leak compared to the endonasal approaches. In terms of the time to return to normal physical life, it's very nice. So early ambulation is possible, early discharge is possible. And also, the cosmetic issues is relatively good compared to the transcranial approaches. I have experience of three cases of CSF leak. But these three cases are from within first 10 or 11 cases of transorbital approaches. But after inserting the fat graft materials and there was no problems of the CSF leak, and also we don't have to do the lumbar drainages. But transorbital protein is requires learning curve. And first cases, may be a long time of surgery. And then long time surgery is closely associated with the wound infections, the burn, or allergy, or periorbita swelling. And then we may have experienced the temporary ptosis after transorbital approaches, but most cases are improved. And permanent ptosis is all caused by the oculomotor schwannoma removal. And then seven cases complained of the temporary ocular dysfunctions, such as diplopia. But most all patients improved gradually. And one case of enophthalmos after head trauma. And seven patients complain of keratitis after removal of the V1 origin trigeminal schwannoma cases. And for the pseudomeningocele cases after removal of the meningioma, this patient shows the swelling of the eye. And we perform the lumbar drainage and completely removed. And this patient had also the same swelling after removal of the meningioma. And we performed a slight compressing the eye. And then naturally, spontaneously improved. And we sometimes may experience the complete or temporary ptosis of the lesions. And fortunately, all patients relieved from the complete ptosis here. And periorbital swellings, or on-lay infections, or the chemical injury, the hitting injury should be avoided because all these complications are closely associated with the long time surgeries. So for beginners, we have to be very careful that developing the wound infections, the chemical pressure sore, or chemical injury. In conclusions, I think the optimal surgical approaches should be selected according to the surgical corridor should be parallel to the long axis of the tumor. And the optimal surgical approach provide a short working distance, and leaves the minimal scar, has the less disruptive surgery. And transorbital approach is also the endoscopic surgery. So we have to, first, familiar with endonasal endoscopic surgery and to how to manipulate the instrument and then we have to very carefully accumulate our endoscopic surgery. And also, the cadaver dissection is very important. And then cadaver dissections will flatten the learning curve. Thank you for listening. Thank you, audience.

- Great work, very enjoyable to watch. Really enjoyed it. I think it's a nice sort of evolution of neurosurgical technique going to the next level. I really agree that the cadaver dissection in the lab is important. Also, another question that I have is these pathologies to be exactly at the location that are a perfect fit for this approach are relatively rare. So how can one develop experience and accumulate enough cases to go from one stage to another of learning?

- Yes, great questions. And actually, this case is not rare for accumulating our experience. So according to the level of difficulties, extraconal, extradural lesion is very easy. We can do it. And then, once we're familiar with opening the transorbital approaches, we can apply this approach to the more deeper portions, more deep skull base lesions, such as trigeminal schwannoma or sphenoid orbital meningioma cases. I think that trauma cases, or fractured cases, CSF leak cases may be good indications for the beginners. But maybe the incidence of the spheno-orbital meningioma is much more common. And then maybe you may try to, the first case is the spheno-orbital meningioma cases maybe.

- And finally, do you use an oculoplastic surgeon anymore? Or I assume for beginning cases, you want to do that. For later cases, you do your exposure yourself.

- Yes, I collaborated with oculoplastic surgeons for 10 cases, first 10 cases of transorbital approaches. But now she, because she's so busy woman, busy doctor, and so nowadays after accumulating my experience, I'm doing by myself.

- Okay. Really enjoyed it very much. A beautiful case series, very innovative. Definitely has a nice place in neurosurgery for well-selected cases. One doesn't wanna push the limit too much on one approach. And remember, that it's all about having the pathology dictate the approach, rather than the surgeon, based on their experience, forcing the approach. So I think this is really a nice tool in the armamentarium of a neurosurgeon for approaching middle fossa and paraclinoid areas especially. It's a nice armamentarium for the endoscopic endonasal surgeons who are very familiar through the endonasal surgery and endoscopic surgery. So I want to thank you for your time, really enjoyed it, learned a lot. And hope to have you with us again in the future.

- Thank you, thank you very much.

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