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AVM within Eloquent Cortices: Intranidal Resection Technique

August 13, 2019


Here's an interesting video describing resection of arteriovenous malformations, within eloquent cortices and more specifically, the angular gyrus or language cortex. I'm going to describe the intranidal resection technique, which would allow the most amount of cerebral sparing in this eloquent cortices. This is a 52 year-old female who presented with this malformation. She had previously suffered from a small intraventricular hemorrhage related to this malformation. The MRI demonstrates the location of the malformation, very much heading toward the ventricle. Most likely there's going to be choroidal feeders here that can be difficult to manage. The deep white matter feeders. You can see based on functional MRI, the location of the language, very intimately associated with a malformation on the dominant side. The contrast enhanced axial image also demonstrates a relatively sausage shape, shape of this malformation and its complex configuration. Let's go ahead and look at the CT angiogram. Again, you can see the malformation heading toward the ventricle. The CT angiogram demonstrates that this malformation is actually bigger than what you see on the MRI as expected. This CT angiogram was used for navigation during surgery. Let's review the angiogram, which will be the gold standard study here. The malformation now is even bigger as expected. The true size of the malformation is more clear. The feeding arteries are from the MCA branches as expected. One important detail is that these branches have to be very carefully protected as these distal MCA branches that go to the AVM could also have en passage arteries that feed the eloquent cortex and these en passage vessels have to be very strictly protected for malformations in this functional cortex. The draining vein is, one is the vein of Labbé. There's another draining vein on the cortex traveling toward the parietal area. And you can see another draining vein, that's traveling more anteriorly. Again, you can see the draining veins, the size of the malformation. On the coronal view, again, you can see the relative large size of the malformation. You can see the enlarged and hypertrophied MCA branch and en passage character. It is very intimately associated with a malformation and one has to be very careful to protect this vessel and it's en passage branches during resection. Here's patient positioning. The patient is in a semi-lateral position. In a supine sort of semi-lateral position. And you can see the horse shoe incision there. The location of the malformation, above the ear. After completion of the craniotomy, you can see the malformation is clearly identified. Let's hold the video and review the anatomy. The surface anatomy again, demonstrates that MCA branch, that is so critical to spear and it's en passage arteries. Again, this is inferior, superior, posterior and anterior. You can see the other feeding vessels. Here's the malformation at the surface. And, I wanted to be sure if this is truly the nidus or actually artery to artery connection, and necessarily may not require a section. Therefore I started with ICG and a flow 800 evaluation to assess the flow within the malformation. Here, you can see a very fast flow within the malformation based on fluorescence angiography. Flow 800 demonstrates the draining vein. This arterialized vein in orange. You can see another one more in backwards, the MCA branch. And here you can see the malformation. Started with resection here so that I do not tackle any part of the cortex. I felt that that strategy would initially protect as much of the cerebral tissue as possible. So I went ahead with skeletonizing the MCA branch and coagulating and disconnecting the feeding vessels that unquestionably go to the malformation. Then I entered the malformation and tried to stay right at the surface of the malformation. Again, preserving as much of the cerebral tissue as possible. I did expect that I'm going to run into some bleeding, as you will see in a moment. However, again, just staying right on the brain. Right on the surface of that malformation and at times getting into it and moving out of it. Protecting the draining veins. Here, you can see some bleeding. Again, this is part of malformation that's underneath the critical MCA branch that I'm trying to coagulate. Obviously coagulation the malformation without injuring the MCA. As bleeding became more perfuse, I went ahead and moved outside the AVM, just on the periphery of it, malformation. When I've disconnected some of the malformation along its posterior aspect. It can, because I'm so close to the nidus, and at times, into it, I have certain tolerance for bleeding and using the suction effectively. I know that the operative field is not going to be completely dry. However, uncontrollable bleeding has to be avoided. Again removing the malformation piecemeal. Avoiding any intrusion to the white matter or cortex as much as possible. Here is within the nidus of the malformation. Again, mobilizing this section of the nidus as I work around it. And removing part of the nidus in order to create space and avoid traction on this cerebral tissue. You can see some of the deep white matter feeders and part of the nidus, continue to stay right at the edge of the malformation. Cut pieces of the nidus and protect white matter. Again, working in a very small corridor, a small corticotomy. Getting close to the bottom of the malformation. Now I'm moving part of the malformation more posteriorly. I see white matter here. I know that I'm good in terms of being on the surface of the malformation there. Again, this is a little bit inferior. Right on the surface of the white matter. You can see I'm working from inside the nidus to outside protecting the brain Here, cutting out another piece of the malformation from inside-out That piece was removed. Let's go ahead and get some hemostasis. Here's deep, white matter feeder. I tried to remove small amount of brain around it until I find the section of its wall that's coagulable, more away from the malformation. Here's some hemostasis. Let's go ahead and repeat the ICG to assess if the veins are still arterialized. Here's the flow 800 image. You can see this vein is still arterialized there is a section of the AVM left here. And again, part of this vein is arterialized most likely confirming that this part, is all supporting the nidus. So I'm going to just work underneath these vessels and undermine this tissue here to remove this malformation and use the same strategy here. So this is a staged resection using flow 800 guidance. Here you consider moving that anterior part by undermining this part of the brain, protecting as much of the cortex as possible. Here's another piece of the malformation that was removed. Again, working now posteriorly, and again, undermining the MCA branch and removing the residual malformation. You can see the final product. Let's go ahead and do another ICG and flow 800. This time you can see that maybe there's just small residual here of the malformation filled by the MCA branch. Obviously all its distal branches have to be protected. You can see an arterialized vein here that requires this section to be removed for AV shunting to be excluded. Here is changing the rotation of the operative field. Here, now is that, distal MCA branch and here's part of the malformation right beneath it. We'll go ahead and remove this part and control the bleeding from the deep white matter feeders. Here's the final product for MCA branch it's distal territory is well fed, and here's the malformation completely removed without touching any of the normal brain tissue. Here's another final ICG run. There's no arterialized vein or a AVM nidus apparent. You can see there's flow within the MCA and its distal branches. It's relatively slow, but it's happening. And again, this part of the brain is still being fed by the MCA branch, but more slowly. So, as you can see, there's no arterialized vein here. There's none here either. And this part of the brain that was overlying the malformation still being fed, and most likely will be spared by the technique of undermining this cortex and removing the last piece of the malformation. Here's the final product. Good hemostasis. Here's the post operative angiogram demonstrating preservation of the MCA branch and it's distal territory en passage vessels. You can see the resection cavity relatively small sparing of the surrounding brain. Here's the coronal view off the post-operative angiogram. And the three month MRI also demonstrated preservation of the cortex as much as possible. Here is a sagittal view. You can see a very small corticotomy that allowed us to remove the malformation from inside-out and in a staged fashion, piecemeal. And this patient had an excellent recovery course. She woke up from surgery with some language difficulty as expected, but within two months from the surgery, she was essentially 95% back to normal. Her language remained intact and she was able to return to her previous activity and her career. So this video again shows a very unusual way of resection of a malformation from inside-out, from the inside the nidus in order to be able to protect as much of the brain as possible. For lesions or AVM's that are very much within the functional cortices. Thank you.

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