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Medial Sphenoid Wing Meningioma: Techniques

January 22, 2016


Medial Sphenoid Wing Meningiomas can encase or engulf numerous neurovascular structures, including the MC branches, the internal quad artery and the optic nerve. let's review some of the tenants that would improve the safety of the resection. This is a 32 year old male who presented with a large left-sided Medial Sphenoid Wing Meningioma during world cup for a minor head trauma. This asymptomatic tumor as you can see is encasing a part of the internal carotid artery. Obviously the MC branches are draped over the superior pole of the tumor. The optic canal was not significantly invaded by this tumor. However, the encasement of the internal carotid artery can pose certain tech challenges for its gross total resection. Also a CT scan did not show any significant evidence of hyperostosis. A Left front temporal craniotomy was completed, patient was placed in the supine position. Let's review some of the details of head positioning and head turn. The patient's head is turned about 30 degrees. You can see the left front temporal craniotomies completed. The bone work is continued over the roof of the orbit. So an unobstructed operative traject is provided to the area of the optic nerve. Therefore the rim of bone over the frontal part of the craniotomy is drilled aggressive, flushed and parallel to the roof of the orbit. In addition, the lesser sphenoid wing is drilled until the superior orbital fissure is identified. You can see the location of the superior orbital fissure. The speed of the video is slightly increased during this part of the exposure. Here again you can see the superior orbital fissure an orbital zygomatic craniotomy is usually unnecessarily. Here you can see the initial exposure was performed and the immediate neurovascular structures were identified. The tumor was devascularized at its base. It was debunked and the tumor capsule was mobilized. Again as you can see in this video using a normal operative speed, sharp dissection is used to mobilize the MC branches away from the superior pole of the tumor Aggressive manipulation of these vessels should be avoided. I use ample amount of prepared soaked gel full cotton to bathe these vessels periodically and avoid their vasospasm. Here you can see the M one MC bifurcation tumor is very adherent. So the perforating vessels should be very carefully protected. At some point the tumor cannot be significantly mobilized. And therefore I cut the tumor in half preferably parallel to the estimated access of the internal carotid artery. Here's part of the M one being sharply dissected from the capsule of the tumor respecting arachnoid membranes. Here's the papaverine soaked gel foam or the smaller perforating vessels. Now that the tumor along the anterior skull base is mobilized you can see the optic nerve. So I work essentially on the superior and the inferior pole of the tumor identify the M one superiorly and the internal carotid artery at the level of the skull base, and then connect the two structures to create the line that mimics the route of the internal carotid artery along the medial pore of the tumor here is the optic nerve. Now that I know the location of the internal carotid artery at the skull base and the optic nerve, I cut the tumor in half over the presumed route of the internal carotid artery. This division of the tumor significantly facilitates resection of the tumor without undue traction on the surrounding neurovascular structures. You can see the internal carotid artery is exposed in the middle of the tumor. The anterior half is easily removed and subsequently the posterior half is also resected over the anterior and medial temporal lobe. Therefore the maneuver of finding the M one is purely and the IC at the lower skull base, and then dissecting the tumor carefully in the middle parallel to the presumed route of the ICA is quite a effective maneuver to dissect a tumor without significant risk of injury to the surrounding neurovascular structures. Postoperative MRI in this patient demonstrates good resection of the mass without any untoward side effect. Thank you.

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