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Petrosal AVM: Intraoperative Fluorescence

April 21, 2016


This is a nice example of a petrosal arteriovenous malformation, a small one that had ruptured. This is a 57 year-old male who presented with a spontaneous cerebellar ICH. You can see the location of the hemorrhage relatively deep associated with an abnormal tangle of vessels on the CT angiogram. Here again is the location of the hematoma, and the malformation facing the petrosal surface of the cerebellum. Angiogram was completed. You can see the location of the malformation primarily fed from the superior cerebellar, as well as the anterior inferior cerebellar artery feeding vessels. The draining vein travels laterally, and joins the transfer sinus. He subsequently underwent a retromastoid craniotomy, here's the exposure tentorium, dural of the petrous bone and the cerebellum, mobilization of the cerebellum allowed identification of the important neurovascular structures within this cerebellar pontine angle cisterns. My first goal was to identify the neurovascular structures as well as the draining vein. I suspect that the draining vein is located here, moving towards the transfer sinus. Another draining vein deeper was not expected although there is a normal vein closer to the fifth cranial nerve. An ICG angiogram was completed. FLOW 800 evaluation in this case revealed the draining vein to be the one located here as expected. Again, the FLOW 800 assisted with careful identification of the correct draining vein. So here's a normal vein, arterialized vein, and the malformation is located along the petrosal surface of the cerebellum. Here's the further inspection of the normal vein. Here's the seven and eighth cranial nerves. Some of the feeding vessels to the malformation from the ICA are apparent. Small cord ecotomy within the petrosal surface of the cerebellum was conducted. I wanted to reach the hematoma. First identified some of the deep white matter feeders to the AVM. You can see fixed retractors are not used. Dynamic retraction is utilized. Some bleeding was encountered from the deep, white matter feeders. These feeders were controlled in a timely fashion. I redirected my attention more posterially to avoid these feeding vessels and reached the hematoma cavity. Here's again, circumferential disconnection of the malformation, working along its apex, disconnecting all the ICA branches. Here's a more demagnified view. The draining vein was carefully protected, as you can see here at the tip of my arrow. Here's the hematoma cavity. The blood clot is being evacuated. Now moving toward the superior part of the malformation, trying to disconnect some of the superior cerebellar artery feeding vessels. Malformation appears to be relatively well disconnected. However, there are still some feeding vessels coming from the anterior surface of the malformation. Here's disconnecting some of the ICA feeding vessels. Additional feeding vessels from the inferior pole of the malformation are being coagulated and sacrificed. I always keep the area of the cerebral pontine fissure in mind to avoid any injury to the brain stem during my dissection. Here's another feeding vessels from ICA, it's been coagulated and cut. This feeding vessel had to be more coagulated before it was cut. An additional feeding vessel toward the malformation. I felt at this juncture that most of the feeding vessels are disconnected. The draining vein appeared more dark. The intraoperative ICG angiogram was repeated. A FLOW 800 evaluation was analyzed, which revealed continued arterialization of the draining vein, therefore, I must have missed some of the superior cerebral artery feeding vessels that have to be disconnected before the nidus is delivered. So I redirected my attention along the more superior aspect of the draining vein, I worked around the vein to disconnect some of the residual feeding vessels from the SCA. Here's the tentorium, the arachnoid band, fourth cranial nerve is most likely there at the tip of the arrow. Then I continued to disconnect the malformation circumferentially, additional feeding vessels at the depth of the malformation are disconnected. Here are some of the superior cerebellar artery branches just on the lateral surface of the brain stem. These feeding vessels on the surface of the brain stem are disconnected in an epipure fashion. Here you can see that the nidus is essentially only connected by the draining vein. Here's the draining vein, appears collapsed. A final ICG angiogram on FLOW 800 analysis revealed no further flow within the draining vein, as you can see here, it's essentially dark in this area. Now the vein is coagulated and cut, and the malformation is ultimately extracted. More demagnified view of our operative cavity, additional hematoma was removed. No residual AVM is apparent. Seven and eighth cranial nerve, fifth cranial nerve, and other demagnified view of our operative cavity using dynamic retraction, and postoperative angiogram confirmed complete exclusion of the malformation. And this patient made an excellent recovery and his gait improved after surgery. Thank you.

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