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Petroclival Chondrosarcoma: Reaching Retrocarotid Space

April 29, 2016

Transcript

The endonasal transclival approach is an excellent corridor for resection of petrosphenoclival chondrosarcomas. This is a 32-year-old female who presented with an incidental lesion for workup of her headaches. And on MRI evaluation, you can see the relatively homogeneously enhancing mass within the petroclival junction encasing the internal carotid artery. Importantly, the tumor extends to the level of the cavernous sinus along the internal carotid artery. This is a classic presentation and location for a chondrosarcoma in this region. The endonasal approach offers very direct and flexible working angles for removal of this tumor using angled endoscopes and dissecting instruments. Here is again another view using the CT scan. The minimally erosive borders of the chondrosarcoma. Again, characteristic of this tumor and relatively infiltrative nature of this tumor toward the cavernous sinus. Here is the area of the paraclival carotid artery. Here is the sphenoid sinus and the floor of the sella. You can see the junction of the petrous bone and the clivus. Again, the appropriate location for a chondrosarcoma. If we go back to the CT scan that we reviewed a moment ago, you can see the extent of the tumor within the clivus and the petrous temporal bone. And again, involvement of both structures characteristic of the location of a chondrosarcoma off of the midline. So you can see some discoloration around the carotid and paraclival area, signifying the location of the tumor. CT neuronavigation is also used intraoperatively. CT angiogram can actually be more effective so that the route of the internal carotid artery is carefully identified. Here, You can see some of the tumor over the internal carotid artery that is being removed. The artery is actually located just a little bit more laterally. The first important principle is early identification of the vessel for its protection. And also adequate drilling of the affected bone for maximal resection of the tumor. Ring curettes are specially important to mobilize this very gelatinous tumor. Again, the gelatinous texture and extradural location of chondromas and chondrosarcomas make the endonasal approach ideal for the removal. I'll go ahead and do additional clivectomy. Next, the location of the internal carotid artery is estimated and the bone over the artery is removed using Kerrison rongeurs. You can see the cross quarter approach is used from the left nostril toward the right side. Here again is removal of the tumor. Just medial to the internal carotid artery, you can see the pulsation of the carotid artery. Next, bony removal over the artery is continued. This part of the bone appears relatively unaffected. Now that the floor of the artery is removed. Again, the rongeurs are used to follow the route of the artery parallel to its axis rather than perpendicular to it to avoid any inadvertent injury to the wall of the vessel. You can see some of the paraclival and periatrial venous plexus. You can see that I used a Kerrison rongeurs and their footplate just parallel to the route of the artery to avoid inadvertent inclusion of the artery into the footplate. The artery is followed until it enters the cavernous sinus. Here, you can see some of the tumor in the paraclival and periarterial area. Drilling continues. Now that the location of the petrous carotid is identified, hemostasis is obtained using Floseal and gentle tamponade. Here you can see the floor of the sella and area of the cavernous sinus. You can see the dura over the lateral clivus. I continue to remove the bone over the internal carotid artery until, again, it turns and enters into the cavernous sinus. Skeletonization of the artery is quite important for adequate tumor removal. The tumor is primarily around the carotid artery and just underneath it within this operative view. Here's part of the bone removal over the posterior aspect of the floor of the sella. The bone is thinned out and then removed using curettes and Kerrison rongeurs. As estimated based on preoperative imagings, some of the tumor had invaded the cavernous sinus. So I follow the tumor into the cavernous sinus. Here's the turn of the internal carotid artery being encased by the venous cavernous sinus. Here's additional bone removal over the posterior floor of the sella. It's important that all the affected bone is resected as safely as possible. Venous bleeding can be readily controlled. Bleeding should not limit removal of the affected bone. As you can see, the bone is very soft over the area of the clivus infiltrated by the tumor. And this part of the bone is being resected. The dura is protected as much as possible to avoid the risk of a CSF fistula. We're nearing the midline of the clivus, the bone appears more normal now. Here, you can see again the dura of the clivus. The diamond drill is quite safe. CT navigation also guides the extent of bony removal. You can see the discolored tumor that has been resected more inferiorly. I used the curette to feel the tumor end. Again when the normal cortical tumor is encountered, I'm more satisfied with the extent of my bony resection in the region. Again, neuronavigation is being used continuously to confirm our location. Here, you can see the dura that remains intact. No transdural infiltration of the tumor is noted. This is an important part of the operation where the tumor just behind the internal carotid artery is being removed. One has to use these right-angled large blunt ring curettes to remove the tumor in the retroclival as well as the retrocarotid space. 45-degree endoscopes identify again the boundaries of the resection and the dura in the temporal lobe area. Here, you can see the tumor is aggressively removed in the region. This is an area that is relatively unreachable via the transcranial routes. You can see the generous skeletonization of the internal carotid artery. Angle suctions are also used when necessary. I'm relatively satisfied with the extent of bony removal. A piece of fat is placed within the resection cavity. The nasoseptal flap which was prepared at the beginning of the operation is mobilized to cover the area of the surgery thoroughly. Its edges are approximated appropriately. A piece of Surgicel is used to buttress a nasoseptal flap. The postoperative imaging studies demonstrate gross total resection of the mass without any complicating features. Thank you.

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