December 14, 2015
Giant bilateral parafalcine meningiomas came resected through a unilateral para transfalcine craniotomy. Let's review the techniques here. This is a 68 year old female who presented with memory difficulty and subtle bilateral lower extremity weakness. And on MRI evaluation, was diagnosed with a relatively large posterior funnel, parafalcine meningiomas with significant evidence of mass effect on the corpus callosum. You can see on CT angiogram, the displacement of the calcium marginal artery laterally on the right side, and the pericallosal arteries inferiorly. The steps for resection of this large tumor involved number one, exposure or de-dressing of the tumor through a right-sided unilateral interhemispheric craniotomy. Number two, devascularization of the tumor by transection of the connection of the falx through the superior, anterior, and posterior poles of the tumor. And number three, aggressive debulking of the tumor, and number four, dissection of the thinned out capsule from the critical neurovascular structures, including bilateral calcium marginal and pericallosal arteries. This patient underwent placement of a lumbar drain for early CSF decompression as the basal cisterns were not accessible during the stages of this operation. The patient was placed in a supine position after placement of a lumbar drain. A right-sided linear incision over the center of the tumor was mapped using neuronavigation. This is the sagittal sinus incision, extends slightly toward the left side. So, the superior sagittal sinus can be unroofed during the craniotomy. Following completion of the craniotomy, the dura is open in a fashion and reflect toward the left side. The interhemispheric quarter is entered, and all the arachnoid bands are widely dissected. Here is the tumor. The falx is carefully coagulated, heavily coagulated, and then transected until the medial frontal lobe on the left side is identified. Next, I follow the contours of the tumor and disconnect the poles of the tumor from the falx. Here is the more posterior aspect of our dissection, where the falx is transected after its coagulation, and the periphery of the tumor is pursued. The falx is quite hypervascular in these cases. Here's the tumor on the left side, the capsule of which is being coagulated. I continue around the posterior pole of the tumor until the inferior sagittal sinus is identified and transected. And here is that last posterior attachment to the inferior aspect of the falx. Now that the tumor is devascularized, I use a ultrasonic aspirator to debulk the tumor as aggressively as possible. The initial effective devascularization significantly facilitates debulking of the tumor and its dissection, as the bleeding is relatively minimal. And I do not have to intermittently stop or frequently interrupt my dissection to achieve hemostasis. Now, I'm removing a tumor on the left side since I'm working transfalcine. Now, I'm working on the posterior pole of the tumor. Further debulking is conducted contralaterally toward the left side. The lumbar drain provides significant decompression of the brain. I have drained about 50 CSF gradually after the dura was opened, even though this tumor was very large and associated with mass effect. Gradual drainage of CSF is very safe. Here is one of the vessels that came in view a moment ago. There are numerous veins usually on the capsule of the tumor that have to be carefully isolated and coagulated at its bleeding point, inadvertent or indiscriminate use of bipolar coagulation is avoided, as the pericallosal and callosomarginal vessels can be injured. irrigation clears the upper field. There's evidence of PL invasion at the anterior aspect of the cingulate gyrus. A piece of Cottonoid is used to maintain the dissection planes, and protect the supple planes from the forceful action of the suction. Also, as the tumor is being mobilized away from the brain, these pieces of Cottonoid are used to wipe the brain away from the capsule. Here's the vessel. You can see that I find the exact site of bleeding, and following coagulation, the vein is transected. Here is one of the calcium marginal arteries on the right side. Here's one of the veins on the capsule of the tumor that has been coagulated and cut. This is part of the cingulate gyrus on the right side that is quite adherent to the inferior pole of the tumor. Again, you can see the maneuver of using the Cottonoid patty to wipe the brain away from the capsule of the tumor that is being mobilized away from the cortex. The tumor's surface is also shrunken using coagulation. I continue the steps of using the Cottonoid pledgets to mobilize the brain away from the tumor capsule. You can see how important brain decompression is to facilitate these steps of dissection. You can see the vein that is skeletonized before its and then sharply transected. This important maneuver prevents bleeding of the veins within the operative blind side of the surgeon. Now that the capsule is more discernible, the depth of dissection away from the neurovascular structures is more understood by the surgeon, and more aggressive tumor debulking along the margins of the capsule are conducted. The suction device holds the capsule away from the brain while the aspirator continues to evacuate the tumor. It is relatively easy to become aggressive with the aspirator and cut through the capsule inadvertently, and injure the neurovascular structures. Here's the anterior pole of tumor that is being dissected from the corpus callosum. While this portion is being mobilized, the corpus callosum comes in view. The pericallosal arteries should be nearby. The bulk of the tumor still providing some resistance. Therefore, the aspirator is used to further debulk the tumor after the depth of dissection from the edge of the tumor capsule is more completely understood. Further debulking allows mobilization and rolling of the capsule more posteriorly, the steps of dissection, understanding the depth of the capsule, and then debulking the tumor further, and then rolling the tumor more posteriorly. Continue until the pericallosal arteries are in view. These steps are pursued along the anterior and posterior poles of the tumor until the entire segments of the pericallosal arteries are identified. Here's one of the more proximal segments of the calcium marginal artery is dissected. One of the pericallosal arteries was in view. Here's the distal part of the right pericallosal artery, just over the corpus callosum. Seems somewhat adherent to the inferior pole of the tumor. Now, the tumor is being mobilized along its posterior pole until the contralateral pericallosal artery is identified. The veins can be quite annoying. However, patient dissection can keep them under control. Here's the left pericallosal artery, this is the right pericallosal artery. The pericallosal artery is dissected from distal to proximal direction at the posterior pole of the tumor. I'm hoping that I can dissect both of these arteries thoroughly. This is most likely that right pericallosal artery. Here's one of the feeding perforating vessels from the pericallosal artery to the tumor. I continue sharp dissection and debulking. The tumor has to be really significantly shrunken so one can look around the corners of the tumor and conduct microsurgery. Venous bleeding can be easily controlled using a piece of Cottonoid in gentle tamponade, rather than aggressive coagulation to avoid inadvertent injury to the surrounding neurovascular structures. Here's one of the branches that was inadvertently avulsed. In this situation, to leave this branch patent, I use a piece of cotton and leave the cotton on the vessel. This usually can save the branch without its injury and compromise. This piece of cotton is soaked in thrombin, however, all the vessels that are manipulated are bathed in papaverine using a piece of gel foam soaked in papaverine. Now that we're getting to the final steps of dissection, this last piece is quite adherent to the left pericallosal artery. This piece is being substantially decreased in size so I can look around and see if complete removal of this fragment is possible, or a portion of this tumor should be left behind to protect the vessels. I continue to measure the depth of the capsule relative to the vessel, so the aspirator would not injure any of the pericallosal arteries. Here is the pericallosal artery that is quite at disjuncture. I'll continue to dissect the vessel using a combination of sharp and gentle blunt dissection techniques to find the planes available. This area was amenable to sharp dissection. High magnification is quite useful. However, at some point, I have to use a more blunt dissector to gently look for dissection planes, as you can see here, after the dissection plane is found, sharp microdissection techniques can be used to release the artery against or away from the tumor capsule. One of the branches seems quite adherent to the tumor capsule. Just about now, I feel that cortical resection is most likely too risky, concerning the age of the patient and the benign nature of this tumor. A very small fragment can be left behind to protect these vessels or avoid their significant manipulation that can lead to distal ischemia. Here's the final attempt to dissect the tumor, but these vessels are significantly involved with a tumor capsule, this is the left pericallosal artery. I decided to leave this small piece of the tumor behind. This is the post-operative MRI, which revealed reasonable resection of the tumor without any complicating features or distal cerebral ischemia. This patient memory function improved, and her lower extremities strength returned to normal. Thank you.
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