January 19, 2016
There are at least two important principles involved in resection of lateral sphenoid wing meningiomas. The first principle has to focus on control of the bleeding from the high prostatic and high pro-vascular bone around the area of the pterion. And the second principle, we'll discuss the importance of maximum resection of the affected bone and the dural in the area of the lateral sphenoid wing. This is a 56-year-old male who presented with a seizure and NMR evaluation was noted to suffer from a large left-sided lateral sphenoid meningioma extending to the middle aspect of the sphenoid wing You can see the location of the meningioma. The bone is not very high prosthetic at the level of the middle sphenoid wing. You can see the homogeneous enhancement pattern of this tumor with this small dural tail. There's definitely some mass effect exerted by the tumor and potentially some MCA branching vessel, just medial to the tumor, adherent to the corresponding pole of the tumor. This patient underwent the left frontotemporal craniotomy, you can see the location of the tumor. marked based on neuronavigation, a curvilinear incision was used with adequate extension toward the contralateral mid pupillary line. So the skull flap is reflected anteriorly adequately. This skull flap was reflected in a separate layer from the temporalis muscle. In this case, I cut the temporalis muscle in an unusual fashion to be able to reflect this smaller component, more anteriorly along with the fat pad. Therefore the initial transection within the muscle, was performed rather in the middle of it. This leaves a smaller bulk of the muscle anteriorly obstructing my view toward the pterion. The first principle that I discussed a moment ago was control of the bleeding from the high prosthetic bone. The lateral aspect of the pterion was noted to be high prosthetic in this case. Instead of lifting the bone flap via a single or two burr holes, I place multiple burr holes around the area of the high prosthetic and hypervascular bone. I control the bleeding via each burr hole before placing the second one. This maneuver allows me to control bleeding from the hypervascular bone in steps, rather than facing torrential bleeding from a large surface of the bone. Here's the first burr hole, here second burr hole is being placed Bone wax is used through each burr hole to control the bleeding from the high prosthetic bone. The burr holes are then connected to each other. Next, after the high prosthetic portion of the bone is managed, a bone flap is elevated. You can see the bleeding from the middle meningeal artery and the area of the high prosthetic bone. Additional affected bone can be removed using large rongeurs. The tumor was subsequently vascularized extradurally. The affected bone was thoroughly removed. You can see the location of our dissection as anteriorly as possible around the area of the pterion the lateral aspect of this sphenoid wing was also drilled away. Let's go ahead and open the dural. Make sure all the affected dural is removed. The devascularized tumor is disconnected from the dural and the base of the tumor is further disconnected along the medial aspect of the sphenoid. When you can see the tumors thoroughly devascularized until the optic nerve is carefully identified. This relatively necrotic tumor, can be now generously debulked. Again, the steps are exposure ,devascularization, de-bulking and then dissection in that order. As you can see the step of dissection here. Next, I mobilize the tumor away from the brain and use cottonoid patties to maintain the dissection planes. This maneuver is continued around the circumference of the tumor and you can see how they're cottonoid patties, wipe the brain away from the mobilized tumor, creating this configuration. The MCA branches are obviously carefully protected as they're expected along the posterior and medial pole of the tumor capsule. Larger pieces of tumor can now be removed. You can see a vessel within the tumor that is bleeding at this juncture. Here again, the base of the tumor is further devascularized, aggressive debulking is necessary. Hemostasis obtained in the affected piece of dural all the way to the level of the superior orbital fissure is removed. Obviously a portion of the dural that is affected by the tumor over and medial to their superior orbital fissure cannot be resected aggressive coagulation of the dural over the cavernous sinus should be avoided so that the cranial nerves are not placed at risk. Piece of allograft dura may be used to cover the dural defect, postoperative MRI demonstrates adequate resection of the tumor. Thank you.
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