Transnasal Resection of Craniopharyngioma: Principles
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The endoscopic transnasal approach offers an excellent opportunity for resection of parasellar craniopharyngiomas. This is a 62-year-old female who presented with visual dysfunction. And one MRI was diagnosed with a partially calcified parasellar mass, as you can see on the axial CT, as well as the coronal CT. On the MRI, coronal sequence with contrast, you can see the relatively multicystic predominantly solid mass with evidence of optic apparatus compression and affecting more of the left side. You can see on the sagittal image the location of the mass again in relationship to the sella and the pituitary gland which is most likely displayed posteriorly on the T2 coronal image. You can also see the heterogeneous texture of the mass with more compression on the left side. This patient subsequently underwent a transnasal approach. You can see the optico-carotid cistern, the bone over the optic nerve bilaterally. The sella is over here. We'll go ahead and start to remove bone over the tuberculum and anterior aspect of the sella. Here's again the sella. The bone over the optic nerve bilaterally, optico-carotid recess. For the extended transsphenoidal approach and specifically craniopharyngiomas, I only remove the bone along the anterior face of the sella. The bone over the entire sella is now removed as you can see in this video. So only the bone over the anterior half of the sella is excised. Bone removal extends to a level of the carotid arteries bilaterally. You can see the protuberance of the choroidal artery on the right side. The optic nerve, the recess on the right side. After the dura is excised in a cruciate fashion, typically, all I see is first the tumor. None of the neurovascular structures are evident. The opening is relatively small but it's quite adequate. Only part of the tuberculum and anterior aspect of the sella is removed. The tumors is first debulked using Pituitary Rongeurs. This debulking allows identification of the neurovascular structures and the stalk. By mobilization of the tumor, you can see the pituitary stalk is quite evident here and adherent to the capsule of the tumor. Alternatively, you can start dissecting superiorly first from the optic chiasm. However, the anatomy often dictates what's the first dissection plane that should be tackled. Here's the Liliequist membrane or the arachnoid membranes over the basilar artery and posterior fossa. I attempt dissecting the tumor capsule from the pituitary stalk. It is somewhat difficult, however, most likely doable. Again, you can see the stalk, the tumor, the adherence. The use of the angle dissectors is very important. I divert my attention to the left side. The choroidal artery is somewhat asymmetrically localized and should not be injured during the dissection. The capsule of the tumor is being mobilized away from the superior hypophyseal artery here and its branches. It's really important to preserve these vessels as they feed the chiasm. Any of their significant manipulation or injury can lead to vasospasm or compromise of these vessels and postoperative visual decline. The plane is relatively doable in terms of further expansion of the dissection planes between the arteries perforators and the tumor capsule. I'll go ahead now and dissect the tumor from underneath the left sided chiasm which was more affected based on preoperative imaging as well as the chiasm. Sharp dissection is critical to mobilize the adhesions between the tumor and the optic apparatus. More importantly, the dissection should stay within the arachnoid planes. Now we're back where we were at the beginning at the location of the pituitary stalk. Here's the left side optic nerve that is quite adherent to the tumor. Patience and gentle, careful dissection is important to mobilize the tumor away from the left sided optic nerve which was number one affected based on preoperative ophthalmological evaluation and also preoperative MRI. Here again is the choroidal artery at the tip of the arrow. The tumor is being dissected in the space between the optic nerve and choroidal artery. All the perforators, along the plane underneath the optic nerve are carefully protected. Only arachnoid membranes are manipulated. A right angle dissector is quite effective. You can see A1 originating and emerging from the ICA. Here's a very nice view of the retrochiasmatic space. Here's the superior hypophyseal artery and its branches that have been dissected from the tumor. Again, the tumor is debulked and then dissected away from the neurovascular structures. Hemostasis is quite pertinent to allow visualization of the arachnoid planes. The pavrin-soaked Gelfoam may be used on these arteries after their manipulation to relieve their spasm. Here are the last connections between the tumor along its posterior inferior aspect. Here is a more demagnified view and our small opening. Now the stalk has to be carefully dissected away from the tumor. Here is a piece of tumor on the stalk that's being mobilized away. Here's the stalk being dissected and preserved in this patient, which is ideal to protect postoperative neuroendocrine function. Here again is the pituitary stalk. Here's the last piece of the tumor from the chaism that is being descended. These are some of the small attachments to the tumor from the chiasm that are being released. Now, the tumor is ready for extraction. It's been gently removed after it's thoroughly circum dissected from the surrounding structures. Here's the anatomy after the dissection is complete. I'll go ahead and review multiple views in a moment. Ample amount of irrigation is used to clear the blood. Again, you can see the superior hypophyseal artery leading to the underneath the chiasm. You can see the pituitary stalk. Angled endoscopes are quite effective. You can see a small piece of the tumor that's remaining. That will dissected and removed as well. There's ample amount of perforators underneath the chiasm. Here's that small piece. And we'll go ahead and use suction to remove that tiny piece of tumor Here it is. 45-degree endoscope is used to carefully inspect the contralateral optic apparatus, choroidal artery wall, assuring myself that the tumor is thoroughly removed and a costal resection is accomplished. An angle suction is used to inspect the surrounding structures. You can appreciate the contralateral optic nerve, ipsilateral optic nerve, the choroidal artery, A1 hypophyseal artery. A panoramic view of the cerebrovascular structures, including the optic apparatus. See some of the perforators above the left optic nerve. And all of this was possible in a relatively small space along the anterior aspect of the pituitary gland and just resection of part of the tuberculum without unroofing the optic nerve. As there was no tumor infiltrating the optic foramen, which is typical of craniopharyngiomas. So an inlay was placed within the intradural space, an allograph piece of dural inlay. And then another piece of dura was placed over the bone and the gasket-seal method was used, as you can see here. I'm going to briefly review that technique. So after an initial inlay within the subdural space another piece of allograph was placed over the bone, and then a piece of prostheses was cut to the appropriate shape and countersunk in the defect in order to reconstruct the skull-based defect. It is important that some solid reconstruction be performed to increase the high likelihood of reconstruction and minimize the risk of postoperative CSF leakage. Valsalva maneuvers exclude presence of any obvious CSF leak. The prosthesis is nicely in placed without any risk of displacement during the postoperative period by coughing or other maneuvers by the patient. Here's the nasoseptal flap that was harvested at the beginning of the procedure that is being mobilize into and over the area of the bony reconstruction. All the edges of the nasoseptal flap should, be in contact to the surrounding mucosa and bony surfaces as much as possible. Pieces of Surgicel are used to increase the adherence of the flap, glue may be used at the end of the procedure to further increase the durability of the nasoseptal flap adherence to the skull base during the immediate postoperative period. This is a post-operative MRI which demonstrates costal resection of the craniopharyngioma. The pituitary gland and the stalk are intact. There is no evidence of the residual and this patient postoperatively really did very well without any complication and her vision significantly improved. She did not subsequently undergo radiotherapy. Thank you.
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