Out-of-Control AVM: Getting out of Trouble Free
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Intra-operative rupture of arteriovenous malformation can be quite problematic to manage. And let's review this video to discuss some of the nuances and etiologies. This is an 18 year-old female who presented with intractable headaches and was diagnosed with this incidental left posterior parietal arteriovenous malformation. You can see their major supplying vessels as expected from the distal MCA branches. The primary draining vein joins the superior sagittal sinus. One of the important features of this AVM to appreciate preoperatively is extension of this malformation to the level of ventricle most likely the numerous plaque cell segments that can be feeding this malformation. Before we review the video, I would like to discuss the etiologies for intraoperative brain swelling during malformation resection. One of the primary etiologies is brain swelling related to acute hemodynamic changes associated with disconnection of the malformation, which leads to abrupt changes in venous drainage patterns of the surrounding brain leading to acute brain swelling. The second etiology can be related to bleeding into the ventricle from the plaque cell feeders that are not readily visible during the section around the deep aspects of their operative field. These plaque segments, as they bleed into the ventricle lead to acute hydrocephalus and significant brain swelling. Obviously the blood fills the ventricle and also compounds the brain swelling. Let's review the details in this case, this is the left posterior parietal lobe. The primary vein joins their super sagittal sinus in this location, another arterialized draining vein is apparent. Again, this is the mid line and a normal draining vein of the adjacent cortex is also apparent. I continue to circumferential disconnection of the malformation, both along the cortices and the deep white matter tracks. Every time I temporarily occlude them affirmation, as you can see the malformation continued to swell, which means that additional feeders are present that have to be first disconnected. I continue dissection along the gliotic margins. The brain continue to more and more swollen. As you can see I'm not within the nidus. And as I got close to the ventricle, as you saw a moment ago, let's review that moment one more time here, which is I think very important. You can see as it got close to the ventricle, which is apparent just about at this point right here, this is day inlet into the ventricle. Some bleeding from the plaque cell segments was apparent but it did not appear very serious. And this is one of the pitfalls in resection of paraventricular AVMs where the bleeding is not very apparent, but actually the bleeding could be going into the ventricle causing brain swelling. Since significant bleeding was not encountered, I continued the dissection, as you can see the brain continued to swell further. Due to this acute swelling and my inability to reach the ventricle again, I felt that aggressive brain retraction to enter the ventricle was unsafe and therefore closure deemed the safest pathway. You can see the malformation almost reaching the edges of the craniotomy. Post operatively, you can see the extent of intra ventricular hemorrhage as was intraparenchymal hemorrhage. It is possible that both mechanisms, number one, brain swelling, as well as the loss of control over the plaque cell segments led to acute swelling in this patient. The patient sedation was lightened and she was somewhat very weak on the right side was, was able to move a right side slightly. An external ventricular drain was needed for the next few days to drain additional CSF. The patient continued to improve, and about 10 days after the index initial surgery, underwent additional cerebro arteriogram, which demonstrated complete thrombosis of the malformation as demonstrated in this arteriogram. She was subsequently taken to the operating room for removal of the nidus to avoid any recanalization of the nidus and as you can see upon her return, 11 days later, the brain is much more relaxed. The hematoma was evacuated. Here's the entry into the ventricle. Before the patient was taken to the operating room, hemiparesis had almost completely resolved. Post-operative CT scan after the second operation demonstrates complete removal of the hematoma. She recovered from the surgery without any neurological deficits and has done since very well and has returned to college. Thank you.
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