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Small Periventricular AVMs: Important Nuances for Complete Removal

October 28, 2019


This is a nice video describing techniques for resection of small periventricular AVMs, and, more specifically, those AVMs that are so small, that interoperable localization, at times can be difficult. This is a young patient who presented with an intracerebral hemorrhage and intraventricular hemorrhage. CT angiogram demonstrates a large hemorrhage in the right frontal area, extending into the frontal horn associated with a draining vein. At the tip of my arrow, you can see the small malformation associated with this hemorrhage located here and a draining vein. The draining vein again enters the ventricle. Localization of this malformation can be difficult within the blood clot, but most likely the malformation is just lateral and slightly posterior to the clot. Let's go ahead and see what we find intraoperatively. Patient underwent a right frontal craniotomy. The dura was opened. You can see small corticotomy performed. The blood clot was entered, and let's go ahead and go under the microscope. Initially, we see rather fibronous material. It's not obvious where the AVM is. Let's go ahead and find the gliotic margins, and, just here, you can see an abnormal vessel, most likely associated with the AVM. In any of these small AVMs, intraoperative findings are very important, and one has to be very careful to investigate the entire clot cavity wall to be able to identify the AVM. Neuronavigation may not be adequate. Here you can see I'm using the spring action of the bipolars in order to find the true gliotic wall of the cavity and isolate the malformation. I continue this strategy until rather straightforward, clean gliotic margins are encountered. You can see this mass, which is very suspicious, to be the AVM. Obviously, due to the clot, the size of the AVM can be underestimated. I'll go ahead and work around until very clean walls are found, as you can see, at the tip of the arrow. Here's the gliotic margin. Here you can see the clot and, most likely, AVM intermixed. Again, I continue circumferential dissection until clear margins are apparent. The suspicious mass of tissue was removed and, especially in young patients with increased risk of AVM recurrence or growth, I'll continue to aggressively go around the cavity, find the frontal horn and make sure there is absolutely no question about clear resection margins. Any abnormal vessels are coagulated and disconnected. Patience is a virtue, to make sure that the malformation is removed. Obviously, finding the appendoma, making sure all the suspicious tissue into the ventricle are removed. Here you can see the wall is very carefully inspected. No obvious abnormal tissue is apparent. The ventricle was encountered and no obvious evidence of AVM into the ventricle was noted. Here's the final product and intraoperative angiogram demonstrated complete removal of the malformation without any early AV shunting. Here's a postoperative CT that demonstrated complete AVM and clot removal, and this patient made an excellent recovery. So, this video, again, emphasizes the nuance of technique for resection of small AVMs that may not be apparent on neuronavigation and careful inspection of the resection walls, intraoperatively, would be critical and entry into the ventricle and complete inspection of the ventricular wall would also be important to assure complete exclusion of the malformation. Thank you.

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