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Anterior Cranial Base Chondrosarcomas

December 02, 2015


Hello, ladies and gentlemen, my name is Aaron Cohen. I would like to discuss techniquoniosis for resection of anterior cranial base tumors, extending to the nasal cavity using the case of a sixty two year old female who presented with bilateral visual decline and was noted on MRI to have a relatively large heterogeneously enhancing mass within the nasal cavity, extending into the anterior cranial base. As you can see, the floor of the anterior fossa is being eroded and this tumor is partially calcified. There was also evidence of bilateral optic nerve compression within their foramina along the skull base. This patient subsequently underwent a bilateral, bifrontal craniotomy. Let's go ahead and review the patient positioning in this case. The patient was placed in a skull clamp and a bicoronal incision was fashioned. The incision was made and a pericranial flap was elevated to assist with reconstruction of the skull base, at the end of our resection. You can see that we're gonna go ahead and extend our scalp undermining more posteriorly, to be able to harvest a large piece of pericranium all the way as far as we can go posteriorly. This is beyond our initial skin incision. You can see the coronal suture there. The pericranial flap is being elevated, even the piece over the temporalis muscle is elevated to be later used for closure of the involved dura. We're going ahead and divide the pericranium along the edges of the superior temporal line. I am making a burr hole along the midline. You can see the dura overlying the superior sagittal sinus. The burr hole is being expanded. I have to note that a lumbar drain was placed at the beginning of the procedure to assist with brain relaxation. You can see using the burr hole, two osteotomies are made and the last osteotomy parallel to the floor of the anterior fossa is made using a B1 drill bit without a foot plate. This allows an osteotomy just along the base of the cranial fossa, and the frontal sinuses are obviously entered. The edges of the dura are tucked away. The dura is gently stripped away from the anterior aspect of the cranial fossa. The mucosa of the frontal sinuses are removed, and I use a bone wax that is mixed with bacitracin powder to fill the frontal sinuses to prevent any postoperative rhinorrhea. I'm now cutting the dural attachments at the level of the cribriform form plate. You can see the tumor along the base of the anterior fossa eroding through the bone. Using pituitary rongeurs, I push this to remove as much as tumor as possible. Here you can see the brain and the involved piece of dura that is being excised. Here in the more posterior aspect of resection, you can see the olfactory nerve within the suction and a piece of the dura that is involved is being removed. Here's a more de magnified view, we'll continue to remove more of the tumor posteriorly. This tumor was noted to be a chondrosarcoma on final analysis. You can see the carotid artery within its bony encasing, and also the optic nerve covered by dura. Further tumor removal allowed us to expose the right optic nerve and the carotid artery within the bone. You can appreciate, again, the optic nerve here, covered by the dura as well as the carotid artery covered by the bone. Here's the carotid artery covered by the bone. And here is additional removal of the bone within the nasal cavity. Here is another view of the optic nerve and carotid artery. We'll go ahead and use a piece of pericranium over the temporalis muscle and close in a watertight fashion, the area of the dura that was affected by the tumor. We will next use an endoscope through the nose to remove the areas that are affected by the tumor using angle scopes, a loaded, a gross, total removal of the tumor. The cranial closure is performed using the large piece of pericranium that is being torn posteriorly, and the posterior edge of the pericranium is being sewn to the most posterior aspect of the dura. This will prevent it, the displacement of the pericranial graft. Split thickness bone from the cranial bone flap is being used to further reconstruct the floor of the anterior fossa. You can see the postoperative MRI, which reveals gross total resection of the tumor with adequate reconstruction of the floor of the anterior cranial base. The patient's lumbar drain was continued approximately three days after surgery, following which it was removed. The patient's vision improved after surgery, and there were no complications such as CSF leakage. Thank you for your attention.

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