Peritorcular and Parafalcine Meningioma
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Peritorcular Meningiomas are exceedingly rare. This video reviews technical nuances for resection of such meningiomas. This is a 42 year old female who presented with visual dysfunction. You can see the large meningioma on the CT scan with enhanced images. This patient could not undergo MRI evaluation due to presence of a foreign body. The lesion is primarily affecting the right side of the torcular. Sagittal image also defines the location of the mass relative to the inian. An arteriogram was performed. Their venous phase reveals complete occlusion of a portion of the superior sagittal sinus, and more specifically, part of the posterior third of the sinus. The torcular is essentially occluded. There are some transosseous venous channels that could be quite challenging during performance of the craniotomy. And we'll try to limit our bony opening over the torcular in order to avoid venous bleeding. One has to remember some of these venous channels are compensatory and are actually critical for drainage of the surrounding areas and should be preserved as much as possible. On the other hand, the of vein of trolard is overdeveloped or expanded to account for the loss of the superior sagittal sinus by the tumor. Let's go ahead and review the operative events. Let's start with patient positioning. Most colleagues use a horseshoe scalp flap, or section of such tumors, a long linear scalp incision can be also adequate. I personally recommend the use of the more expanded horse shoe incision in this case. You can see the location of the torcular, as marked on the scalp. Let's go ahead and review some additional images describing the incision, this case, the location of the superior nuclear line, and the head turn for performance of this operation. After completion of incision, you can see the extent of bony exposure. A burr hole was placed using intra-operative CT navigation, over the super sagittal sinus where the tumor extended most anteriorly. Next additional burr holes are placed just above the transfer sinus and torcular, hoping that we can preserve some of those transosseous venous channels that are important for venous drainage of this area. The dura was quite adherent. The number three pen felt had to be used aggressively in order to mobilize the dura from the inner aspect of the calvarium. You can see the burr holes. Of note, a lumbar drain was placed at the beginning of the procedure for cerebral relaxation. However, a very small amount of CSF was drained. To avoid any risk of tress tentorial herniation in the presence of such a large tumor with significant mass effect. The bone over the area of the torcular, or just above the torcular was drilled using the M3 bit. And the footplate was carefully used in this area to avoid any injury to these transosseous venous channels. Nonetheless, some bleeding was encountered, especially epidurally. Mostly venous bleeding, and this venous bleeding was immediately controlled using gel foam powder soaked in thrombin. Now that the bone is removed more aggressive drainage of CSF was attempted to reach some brain relaxation and avoid brain herniation during opening of the dura. Here, you can see a portion of the transfer sinus that was exposed during our elevation of the bone flap. Ample amount of gel foam soaked in thrombin was used to achieve hemostasis. You can see there are some enlarged and well-developed venous channels within the dura that were not appreciated initially on the preoperative angiogram. After epidural hemostasis is secured. The surface of the dura is heavily coagulated to provide some devascularization. This is interoperative flouricine angiography. Again, revealing complete occlusion of this portion of the posterior superior sagittal sinus. Next the dura is open in a stellate fashion, just over the tumor. And I'll go ahead and debulk as much of the tumor as possible before I manipulate the portion of the tumor that is facing the brain. Here's the part of the super sagittal sinus where some venous bleeding encountered, and it was tied off. We felt this was the area where the tumor initially extended more anteriorly along the super sagittal sinus. Some of the tumors is debulked. You can see that posterior part of the falx at a tip of my arrow. Additional tumor debulking continues. Parts of the tumor are relatively soft. The other parts are relatively calcified and somewhat fibrous. Here's again, peaceful removal of the tumor. So further relaxation and manipulation of the capsule is possible. Various methods were used for debulking the tumor, including pituitary rongeur suction as well as ultrasonic aspirator. One has to note that interim is located just about here at the level of the transfer sinus. So tumor removal has to extend all the way to the level of the tentorium. Now that most of the tumor has been debulked, at least on the right side, where the majority of tumor is present. I'll go ahead and carefully peel-off the capsule away from the brain. The tumor significantly invaded the pia and therefore carotenoid patties were used to protect the prime hemal of the brain from the force of the suction device. Part of the tumor over the tentorium is being gently mobilized. I'll go ahead and leave that part of the tumor that is invading the transfer sinus alone for now. And again, continue to de-vascularize the tumor from the surface of the tentorium. This part of the tumor was quite fibrous. Some aggressive venous bleeding from the area of the falx was encountered, most likely an enlarged venous channel. And this venous bleeding was controlled. As you can see, using where clips. And this bleeding is primarily within the falx and arterial junction. This is readily controlled. We'll continue to remove the tumor from the falx, from the tentorium, from the surrounding brain. You can see how the pia has been invaded by this tumor, but ultimately we were able to remove the majority of the tumor on right side. Here's the last piece of the tumor on this side that is being evacuated. Here's the portion of the dura that is affected by tumor is being excised. And this is part of tumor on the left side of the falx that is also being removed. Here's the part of the tumor that is affecting the transfer sinus. Now more anteriorly, I'm able to remove the tumor from the tentorium. This part of the tumor that is invading the torcular is left behind so that I'm not interfering with any of those venous channels. Here, you can see an attempt to remove the tumor within the transfer sinus, especially the part that is occluded and a portion of the tumor within the sinus was removed without significant venous bleeding. Here is the use of their ultrasonic aspirator to remove the portion of the tumor within the transfer sinus on the right side. Here's the final result. Essentially, all the tumor is removed besides small part of the tumor that was affecting the torcular and those transosseous, transdural venous channels. Now, more superiorly and anteriorly, part of this super sagittal sinus that is affected by the tumor was resected. I can see these large parasagittal veins were carefully protected where they drained into the superior sagittal sinus. The remaining dura was approximated, tack up stitches were placed along the edges of the craniotomy to avoid or minimize the risk of post operative epidural fluid collections. And this is the post operative CT scan, which reveals reasonable resection of this tumor. Thank you.
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