Parietal AVM: The Risks of Residual AVM
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This video describes the principles for a section of a Lateral Parietooccipital Arteriovenous Malformation. This is an 18 year-old female who presented with a severe headache, and a minor spontaneous intracerebral hemorrhage. Angiogram demonstrated a relatively compact arteriovenous malformation in the left lateral parietal region, primarily fed by two large pedicels, and drained by a large draining vein toward the superior sagittal sinus. Patient underwent partial embolization off her AVM. For her operation, she was placed in the lateral position. A linear incision was used for exposure of the AVM, intraoperative neuronavigation was employed. For a completion of the craniotomy, you can see the arterialized vein apparent on the surface of the brain as compared to a normal-appearing dark vein. Microsurgical techniques were used to dissect the sulci, so that proximal control over the raw arch pedicels can be obtained. The borders of the AVM, were defined using navigation and the areas of the cortex over the border of the AVM, were coagulated and disconnected. All the large vessels within the sulci were carefully protected, and their identity was clearly found before they were completely disconnected. Here you can see a vessel that appears to enter the AVM. I'll still keep this vessel intact until the later stages of the operation, where I can pursue the vessel closer to the area of the nidus. Some of the finer vessels are sacrificed. The draining vein is protected during isolation of the nidus. Here's another large artery within the sulcus. I'm just at the level of the nidus, disconnecting the white matter. You can see the nidus of the malformation that is being disconnected from the surrounding gliotic margins. A retractor may be used to hold the AVM away from the plane of dissection. Here again, you can see the embolic material that can be used as a navigation tool, to superimpose the intraoperative findings on the preoperative images. Micro scissors are used to disconnect the feeding vessels. More of the embolization material is apparent; some of them may be transected. Here's the gliotic margin on the malformation. It is important to maintain this scoliotic margin, to assure myself that the nidus is not violated. Premature violation on the nidus can lead to torrential bleeding. Here you can see the gliotic margin well demonstrated embolic material. The nidus of the malformation. A very nice demonstration of maintaining the plane of dissection. The deep white matter feeders are always problematic, and patience is required for their control. They do not own robust walls. Bipolar forceps may not work on controlling them. And one has to pursue these slightly into the normal white matter, in order to secure a portion of their lumen that contains more normal collagen; slightly away from the nidus of the malformation. You see this vessel was initially thought to end directly into the nidus, now it appears to be an emphasized vessel. The branches that ended up directly into the nidus were coagulated and cut. It's important to maintain the patency of emphasized vessels. Specially if they're such a large size. Again, another view of the gliotic margin of the malformation. The white matter feeders were not apparent here, improving the efficiency of our dissection. I maintain the plane of dissection just around the depth of the nidus. Here's another deep draining vein, that was left intact until the end of dissection. Since most of the AVM was circumferentially disconnected. This draining vein was also sacrificed and disconnected. The AVM has been gently mobilized outside of the operative cavity. Here's further inspection, to make sure all the nidus is completely removed. I'm very satisfied with the extent of resection in this case. Again, you can see that the emphasized vessel was protected, and the entire malformation was removed uneventfully. Again, this video summarizes that basic principles for removal of super tentorial arteriovenous malformations. Thank you.
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