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Calcified Foramen Magnum Meningioma: Challenges in Complication Avoidance

December 04, 2015


Calcified foramen magnum meningioma can be quite daunting due to their adherence, to the surrounding neurovascular structures, which increases risk of their resection. This video describes the case of a 42 year old male with two previous unsuccessful attempts at outside institutions for resection of his highly calcified meningioma originating from the juggler tubercle. He continued to worsen neurologically due to progressive brainstem compression. You can see on the actual T2 MRI evidence of significant brain stem pressure, evidence of a highly calcified mass around the area of the juggler tubercle extending into the craniocervical junction. They axial CT scan confirms the highly calcified and bony like tissue of this tumor. The previous two attempts at outside institutions were ineffective due to severe fibrous and heart texture of the tumor that prevented any easy decompression and mobilization of the mass away from the brain stem. The patient was placed in a latter position. The previous lazy S incision was used. This is a cerebellum that is lifted gently using the fixer tractors. This is the juggler tubercle and the tumor and the dural overlying the superior pole of the tumor. You can see, I was able to decompress only a very small portion of the tumor using bipolar cautery and suction. Now the dural over this part of the tumor is being coagulated and cut. The texture of the tumor is very much similar to bone. Here sneaking underneath the cerebellum to find some of the cranial nerves just superior to the anterior pole of the tumor. You can appreciate this significant fibrous and bony character of the mass. Here's the cerebellum that's being mobilized from some of the posterior aspect of the tumor. Ultrasonic aspirator was also ineffective in this tumor. Here's the more the magnified view of the cerebellum the bony opening along the lateral suboccipital area and the tumor here. I went ahead and use a bovie cautery to move some of the overlying soft tissues and previous scar over the tumor which was essentially consistent with a piece of bone, For me to be able to decompress the brain stem, I have to debulk the tumor and this debulking would require drilling of the heart of the tumor, which is pretty much made of bone. Here is stripping away some of the soft tissue from the posterior aspect of the tumor. Next, I used a drill to decompress the tumor. This bone was so firm that a cutting burr had to be used to more effectively and efficiently remove the bone. Soft tissue capsule was kept between the area of bony trailing and the brain stem to protect the brain stem. Now I'm working more at the periphery of the hard part of the tumor in the middle. As you can see here, this is the soft capsule or a relatively soft capsule that was kept intact to protect surrounding neurovascular structures. Here's the cutting bird I was required to drill the ivory like bone within the middle of the tumor. Monopolar cautery was necessary to achieve hemostasis. Here is the relatively thin shell of bone that is left that is being also drilled away. Kerrison was used to remove this thin shell of bone anteriorly. Here's a soft tissue mass covering the brainstem. Various curettes were used to remove the relatively softer part of the tumor before the most outer layer of the tumor, next to the brain stem is micro surgically handled. I continue to create additional space so the capsule of the tumor can be mobilized laterally. This is essentially meningioma of their jugular tubercle. Therefore the vertebral artery in the lower cranial nerves will be closely involved along the medial and anterior aspect of the tumor capsule. I'm able to accomplish some decompression here. Here's the more lateral aspect of the tumor that is being drilled away. And here is the capsule of the tumor that is mobilized laterally. You can see it's quite adherent. Part of this adherence, is most likely related to the previous surgeries in this area that created scar tissue and therefore made the dissection more riskier. I continued short dissection as much as possible and stayed over the capsule tumor to be able to minimize the injuries to the soft tissues. This is still the latter part of the cerebellum. Now we're getting close to the brain stem. You can see some of the C1 nerve roots at the level of the brain stem. I used a round knife to be able to stay just over the capsule of the tumor at the same time mobilize the neurovascular structures. here is a cottonoid patty, maintaining the dissection planes within the scarred area between the capsule of the tumor and the latter aspect of the brain stem. The tumor still is quite difficult to mobilize. I use ultrasonic aspirator and other instruments to be able to dissect the tumor and further decompress it. In this area, you can see that this is the capsule of the tumor just about in the midsection of the tumor and micro-Doppler ultrasonography device was used to palpate and map the location of vertebral artery. At this location, the doppler excluded approximate presence of the vertebral artery and I continued with my sharpest section. Unfortunately, as you can see here, the vertebral artery was inadvertently cut, which is very unfortunate. Due to a significant disruption of the artery, I had to proceed with coagulation and obliteration of this vessel, which is quite concerning. However I felt that this artery was compromised very proximally and therefore the contralateral flow from its counterpart from the other side should be able to nourish the necessary distal territories also supplied by this vertebral artery. So I continue sharp microdissection and work around the areas that are scarred and you can see that some of these vessels that seem to enter the tumor and therefore had to be sacrificed for the capsule of the tumor to be able to mobilize away from the brain stem. I continued pursuing the capsule of the tumor very carefully to be able to protect that neural structures as much as possible. Here, you can see a more distal part of the vertebral artery over the capsular tumor. Now working more superiorly where there is Virgin territory, you can appreciate the PICA a moment ago that was preserved. Here's the capsule of the tumor that is being further debulk using micro scissors. A relatively good Decompression has been achieved, more superiorly. and this fibrous capsule of the tumor is being dissected. The C1 nerve roots were incorporated in the tumor had to be sacrificed. Here's that branch of PICA there that came into view a moment ago. Here you can see PICA, the capsule again is being dissected away in the virgin areas relatively easily using fine angle curettes. The brain stem seems to be much happier in this area and well decompressed. This was the area of the initial drilling of the bone, and I'll continue to mobilize the capsular tumor away from the brain stem. This is the distal vertebral artery, leaving the tumor, joining its contralateral counterpart. This is vertebral basil junction, this is the brain stem. You can see the good portion of the tumor has been mobilized away from the brain stem. Here again is the more inferior section of the tumor that is being dissected away from the brain stem. This is the portion of the vertebral artery that was inadvertently sacrificed. This vessel is now being freed away from the capsule so the capsule can be removed. Ventral dural was visible, further additional pieces of tumor are removed. and here you can see a generous decompression in the ventral dural along the cranial cervical junction. So here's the view good decompression was achieved. and the only area of further decompression that was performed was at the level of the craniocervical junction. This patient unfortunately suffered from a brainstem stroke and a medullary stroke, most likely related to the sacrifice of the vertebral artery. However, you can see the amount of bony removal that was necessary to achieve the brainstem decompression. The patient awoken from anesthesia with hemiplegia, significant swallowing difficulty required a peg and a trach and has been debilitated from the result of this surgery unfortunately, this video is a good teaching video regarding adherence of these highly calcified tumors, specially in the face of previous surgery as special precautions that have to be taken to preserve the vertebral artery, even if it's necessary to achieve a relatively conservative decompression in the face of preserving all the neurovascular structures in this very vital territory. Thank you.

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