Frontal Paramedian AVM: Intraoperative Rupture
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Deep white matter feeders can be somewhat problematic during a section of arteriovenous malformations, let's review some of the techniques for avoiding complications. This is a 16 year old female who presented with an unraptured paramedian right arteriovenous malformation. You can clearly see the location of the malformation relatively it's diffused nature leading toward the ventricle. One can suspect numerous deep, white matter feeders associated with this somewhat diffuse arteriovenous malformation. Angiogram also demonstrates the angio-architecture of this malformation leading to their superior sagittal sinus primarily fed from the ACA and MCA branches. This patient underwent over embolization of her malformation. Most of the larger pedicels were embolized. It's been my experience that over embolization of these larger pedicels leads to hypertrophy of the deep white matter feeders that may not be easily visible on the angiogram. The initials steps of the operation involved disconnecting the malformation while preserving the larger draining veins. Here's the sup frontal dissection along the Entera basal frontal lobe disconnecting the peel feeding vessels as the AVM was more circumferential disconnected. One of the less functional veins was disconnected so that the malformation can be more easily mobilized, and the deeper part of the malformation toward the ventricle can be disconnected. Here again is continuation of a dissection along the basal frontal lobe, more medially, here's the dissection along the medial portion of the malformation. The draining veins are protected. Here's further dissection along the white matter. Again, more medially. This draining vein appeared relatively collapsed and its temporary occlusion did not lead to any engorge of the malformation and therefore it was disconnected. The primary draining vein which was traveling more immediately was obviously protected. I continued white matter dissection. However, you can see, I ran into significant bleeding at the apex of the malformation. In this situations it's best to follow these deep white matter feeders, slightly away from the malformation so that their relatively more normal wall is found and coagulated. The closer these deep white matter feeders are to the malformation, the more dysfunctional their walls are, and the more difficult they are to control. Packing is not advised as brain swelling offering ensues. I continue to follow these deep white matter feeders toward the ventricle. Again, persistence is a virtue in this case, these deep white matter feeders can definitely test our patience and stamina, one has to definitely stay out of the nitus to avoid any bleeding from the nitus, as I continue to remove the malformation further bleeding was encountered. Again, staying away from the apex of the malformation is important. Sometimes the plexus and ependymal feeders to the malformation, that can be quite vigorous in these cases. Again, one has to persistently follow these vessel toward the ventricle, find them and coagulate them immediately before they retract and lead to torrential intraventricular hemorrhage and severe brain swelling. The brain remained relatively relaxed as I allowed the blood to drain toward the resection cavity, I avoided blind packing of the bleeding area. Continue to coagulate these vessels. Here you can see another one popping, collagen is relatively missing from the wall of these deep white matter feeders, and therefore these vessels are not responsive to bipolar electrocoagulation. I continue dissection slightly away from the malformation of finding these deep white matter feeders and controlling them. Some bleeding should be tolerated. A very dry operative field is often unachievable until the malformation is completely removed, therefore the final solution is complete. Remove all the malformation to reach adequate hemostasis. The malformation appears more collapsed now, the veins are darker as you can see, I continue my circumferential dissection as long as the brain is relaxed, and the bleeding is relatively under control. Some bleeding was encountered as you can see, suspecting the fact that some of the deep white matter feeders are still loose. I continued coagulation and disconnection of the malformation until the entire malformation was removed. The brain appeared somewhat edematous, but not very swollen. This finding is not unusual for large AVMs following adequate hemostasis. The case was closed and this patient recovered from her surgery uneventfully. Thank you.
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