Giant Medial Sphenoid Wing Meningioma
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Let's discuss the tricks of the trade for resection of giant medial sphenoid wing meningiomas and techniques to localize and preserve neurovascular structures early during the dissection. This is a 26 year old female who presented with an incidental very large left-sided medial sphenoid wing meningioma. The tumor is pointing slightly more laterally, therefore accounting for lack of significant visual field symptoms in this patient. There is minimal amount of edema associated with his tumor. However, there's evidence of mass effect. The MC branches are likely to be at least partially encased by the tumor along the superomedial pool of the mass. Again, the tumor is essentially based over the coronoid process with some high proptosis of the coronoid process. I prefer to install a longboard during early on during the procedure, to achieve early brain relaxation. So that an extradural clinoidectomy can be completed. Extradural devascularization is therefore possible. And also the optic nerve can be generously decompressed through the clinoidectomy. Let's go ahead and just briefly demonstrate the placement of the lumbar drain before the patient is placed in the spine position. Obviously, CSF is drained more aggressively as the dura is incised, not early on to avoid any transtentorial herniation. A standard curvilinear incision was used as guided by neuro-navigation. A myocutaneous flap is reflected anteriorly. A generous frontotemporal craniotomy is completed. The hypertrophied medial spheroid wing is being resected. Again the lumbar drain can assist with some decompression, early on of the dural sac. Here is the medial portion of the lesser spheroid wing as well as the coronoid process, that are being drilled away. The base of the tumor was extradurally devascularized, after the bulwark. The roof of the optic nerve is also being resected. Early decompression of the optic nerve protects the nerve during tumor manipulation, and also provides early decompression of the nerve through transection of the falciform ligament intradurally. And Polymer irrigation is used to avoid thermal injury. And micrucurate is used to remove the thin shell upon over the dura of the optic nerve. You can see that dura of the optic nerve at the tip of the arrow. Further drilling skeletonizes the optic nerve effectively. And you can see the nerve here, thin shell of bone left over the more posterior aspect of the dura. A diamond bit is used. Now the dura over the nerve is circumferentially dissected up to the point where it enters the intracranial cavity. Here's the portion of the coronoid process that was hypertrophied. It's now being carefully dissected from the surrounding coronoidal ligaments. It has been generously hollowed out. A pituitary rongeur is used to remove the last piece of the coronoid process. Inner splitting is controlled using gelfoam. Here is the dura of the optic nerve. Next, the dura incised in a terminal fashion. You can see the tumor extruding through the Sylvian fissure. Now, the tumor is intradurally devascularized along its base. The optic nerve is found early on, if possible. Specifically in this more soft tumor, the early removal of the tumor along the dura of the skull-base allows early identification of the optic nerve and the carotid artery, and therefore their preservation. Here we can see the optic nerve, the carotid artery at the level of the skull-base. The tumor is thoroughly devascularized along the dura of the coronoid process and the lesser sphenoid wing. Here you can see the carotid artery. Tumor is relatively suckable. Here is the route of the carotid arteries being identified. Unfortunately this is not usually the case with most of the sphenoid meningiomas as they're fibrous, and such early skeletonization of the carotid artery at the level of the skull-base is not feasible. Here again is a portion of the IC at the skull-base and the optic nerve that has been carefully identified and protected. The tumor is also debulked. These structures are carefully protected, covered with a piece of Cottonoid. Next this tumor was so well hollowed-out that I could roll the tumor very easily without any significant adherence of the surrounding brain. Here you can see the distal MCA branches that are being carefully protected, and, gently dissected from the superior pole of the tumor. The arachnoid bands are being coagulated and cut. Further tumor debulking was necessary. You can see now the distal MCA branches, the carotid artery and its route, after the tumor was removed. Small feeding vessel to the tumor was also transected. Here you can see again the carotid artery, and its route, the frontal lobe, temporal lobe, the point of adherence of the tumor. Piece of preparing soak gelfoam was used to bathe the regional vessels to relieve their vasospasm. This is an important maneuver to decrease the risk of Ischemia. The affected dura, all the way to the level of the superior orbital fissure was resected, and a tumor that enters the cavernous sinus is left behind. Piece of temporalis muscle was left at the area of the clinoidectomy to avoid any risk of postoperative CSF fistula formation. The magnified view of our resection cavity. Piece of allograph dura was used to seal the dural defect. And the postoperative MRI demonstrated adequate removal of the mass without any complicating features. Thank you.
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