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Frontal AVM: Principles for Resection

December 11, 2015

Transcript

This video reviews basic principles for resection of a left frontal arteriovenous malformation. This is a young patient who presented with a generalized seizure, and, on imaging, was found to have a left posterior frontal lesion with suspicion of an arteriovenous malformation. This suspicion is more confirmed on the sagittal T2MRI, and on cerebral catheter angiography was noted to have a nidus with arteriovenous shunting. The feeders are most likely from the MCA, and the draining vein is on the lateral cortical surface of the frontal lobe. The 3D angiogram better demonstrates a relatively small arteriovenous malformation, but potentially diffuse nidus. This seizure could be associated with acute thrombosis of the draining vein. You can see there is some evidence of edema around the malformation, which signifies the potential occurrence of edema associated with acute thrombosis of the previous unknown arteriovenous malformation. He subsequently underwent resection using a linear incision over the left frontal area. Neuronavigation was used to map the location of the incision. A linear incision can be quite effective in exposing a small nidus, such as this one. Obviously, the head is fixed in a skull clamp. The patient is in supine position, and the head is turned as much as possible toward the right side. Here is the completion of the left frontal craniotomy. The dura open in a curved linear fashion. Immediately, the thrombotic vein is evident. There is evidence of discoloration and edema. This is the arterialized vein. You can see it's more red compared to the regular cortical veins that are darker. The initial steps involve subarachnoid dissection, and opening of the , where the feeding arteries could be hiding. The draining vein is also the dissected carefully, especially for subcortical AVMs, to identify the location of the nidus with minimal white matter dissection. Here is some of the feeding vessels toward the malformation, which is primarily on this side, at the tip of the arrow. Now the vein is more evident. Some of the feeding vessels around the vein are coagulated and cut. It's quite typical for very significant feeding vessels to be apparent in the region around the draining vein. After subarachnoid dissection, an identification of some of the feeders, the parenchymal stage involves coagulation on the peeled surface. Neuronavigation guides this step of the operation. The AVM is skeletonized along its parenchymal surfaces. The draining vein is carefully protected. The dissection is deepened within the parenchyma. Around the nidus, you can see some of the feeding vessels that are coagulated and cut. It's important for the emphasized vessels to be protected. Here is some of the deeper feeders, including the white matter feeders that are being coagulated and transected. We continue, peel the section around the nidus of the malformation. The old blood is consistent with previous history of small hemorrhages. This thrombosed vein most likely explains the reason for the generalized seizure and the edema that brought the AVM to clinical attention. The gliotic surface around the AVM is quite apparent. Now, the parenchymal dissection continues for the inferior pole of the tumor to be mobilized away from the white matter. Additional feeding vessels are identified and cut. Now that all the feeding vessels are sacrificed circumferentially around the AVM, the draining vein is coagulated and cut. You can see the draining vein is darker now. The darkness of the vein is quite apparent at this segment, slightly away from the malformation. Here is the final steps for coagulation of the vein and its sacrifice. And here's the disconnection of the AVM and its delivery. You can see the draining vein is quite dark now. The AVM is inspected. You can see the partial thrombosis within the nidus. Inspection of the resection cavity assures no other residual malformation or feeding vessels. Here you can see the final product, that the draining vein is quite dark, very much the same as another normal vein on the surface of the brain. There is no residual malformation. The gliotic surface was also resected in this non-eloquent cortex to enhance the chance of postoperative seizure freedom. Post-operative cerebral arteriogram reveals no AV shunting. However, there is some non-specific stasis within the feeding vessels. You can see that, although there is some stasis, there's no early draining vein. This is not unusual in the case of pediatric AVMs. A repeat angiography six months after the operation demonstrates disappearance of these findings, and this patient has done very well from surgery without any evidence of recurrent seizures. Thank you.

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