January 29, 2016
Large arteriovenous malformations with diffuse niduses present daunting challenges in their resection. Let's review the intraoperative events in this patient. This is a 42-year-old male who presented with seizures and was diagnosed with this unruptured left frontal large arteriovenous malformation. Angiogram more adequately defined the angioarchitecture of this malformation, which was primarily fed from the enlarged anterior cerebral artery branches. You can see the large draining veins. This is primarily a paramedian or medial frontal arteriovenous malformation. Definitely a high-flow arteriovenous malformation. Partial embolization was attempted. You can see part of the lateral aspect of the malformation has been embolized. Nonetheless, the nidus of the aneurysm remains large and relatively diffuse, especially along its poster aspect. The large primary draining vein is heading posteriorly to join the superior sagittal sinus. Patient underwent a left frontal craniotomy with generous exposure of the cortex and the surrounding normal plane. Here's further views of this relatively diffuse malformation with many feeding vessels. By coronal incision, exposed adequate part of the anterior frontal bone. Large bone flap was elevated with two burr holes over the superior sagittal sinus. Two sutures were placed along the superior falx to mobilize the superior sagittal sinus out of our working zone. We protected the large poster draining vein. Intraoperative angiogram using fluorescein revealed the angioarchitecture of the malformation. As you can see in this video, most of what I see on the lateral frontal surface is draining vein rather than arterial feeders. This prompted me to aggressively devascularize the malformation from the ACA branches along the interhemispheric fissure. I should have probably been more aggressive in disconnecting these dominant feeding vessels before the AVM was disconnected along its lateral cortical surface. The reason for this statement is that later in the video you will see that the AVM continues to remain very tense, despite adequate cortical disconnection along its more superficial surface. Here's disconnection of one of the large feeding vessels to the malformations from the ACA. Now the AVM is being disconnected more superficially. Obviously some of the smaller veins are being affected. Here's the large draining vein that was identified early and protected. The deep white matter feeders were quite problematic, and as expected, especially along the posterior border of the tumor. Hemostasis was obtained using clips and bipolar coagulation. Couple of unfortunate events occurred during this procedure. You can see the AVM is being disconnected more anteriorly. Here's a draining vein along the more anterior border of the malformation. I'll go ahead and perform another intraoperative fluorescein fluorescent angiogram to investigate which veins could be potentially disconnected first so I can work around the depth of the nidus. You can see the posterior veins are especially working vigorously. The anterior vein is somewhat less functional. As I was working along the posterior aspect of the arteriovenous malformation, aggressive bleeding from the draining vein was encountered. This meant that, unfortunately, the AVM nidus now can potentially be at risk of rupture because the primary draining vein is being compromised without complete disconnection of the feeding vessels to the malformation. I went within the interhemispheric fissure and tried to disconnect the feeding vessels efficiently. However, significant bleeding from one of the feeding vessels was encountered. And now you can see also torrential bleeding from the lumen of the ACA. Obviously this is a very difficult situation. I would like to preserve the lumen of the ACA, and at the same time disconnect the malformation since its primary draining vein is compromised. I placed a tentative clip over the bleeding point, knowing that I'm potentially compromising the lumen of the ACA. This tentative clip will stop the bleeding so that tentative temporary clips can be placed eventually so I can reposition my final clip. Here you can see that the bleeding is quite vigorous from the lumen of the ACA. Temporary clip more proximally did not help. I placed the clip right at the bleeding point. The ACA is relatively of a large diameter here, because of the presence of the malformation. Micro-Doppler ultrasonography reveals compromise of the ACA. I'll go ahead and release the malformation and reposition the clip in a moment. The segment of the ACA is being excluded using temporary clips. The permanent clip will be repositioned so that the lumen of the ACA remains patent. Here's the final status of the resection cavity with the malformation removed. Postoperative angiogram revealed adequate removal of the interior segment of the malformation, but there was slight residual malformation more posteriorly, leading to a draining vein. This part of the malformation was subsequently also removed. You can see a subsequent intraoperative angiogram revealed complete exclusion of the malformation. Here is the final status of the resection cavity and postoperative MRI and angiogram reveal adequate results. There is no evidence of arteriovenous shunting, and the MRI does not demonstrate any evidence of ischemia in the ACA distribution. This patient recovered from his surgery and has not had any further seizures since his operation. Thank you.
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