January 08, 2016
Let's discuss resection of an arteriovenous malformation, a small one on the tentorial surface of the cerebellum, and at the same time review some of the techniques for managing troublesome bleeding from the avulsed tentorial bridging veins. This is a 21-year-old female who presented with a severe headache and spontaneous cerebellar hemorrhage as demonstrated here. A catheter angiogram showed a small malformation along the tentorial surface of the cerebellum, most likely fed by the superior cerebellar artery branches. The draining vein was relatively difficult to identify, most likely related to the mass effect of the hematoma. She subsequently underwent a midline suboccipital craniotomy, primarily on the right side. However, the supracerebellar corridor was used to access the tentorial surface of the cerebellum and remove the malformation. Two stitches were placed along the posterior aspect of the tentorium to elevate the transfer sinus gently. The cerebellum was quite swollen, under significant amount of tension. And as one of the hemispheric bridging veins was being controlled, one of my colleagues was faced, was additional bleeding from this source. Often the bleeding can be quite problematic, especially in the face of cerebellar swelling. In this situation, it's best to coagulate the peduncle of the vein over the cerebellum, and then seal the bleeding from the entry point of the vein into the tentorium via thrombin soaked Gelfoam. Repeated coagulation of the vein just at the level of the tentorium often leads to additional bleeding. Since the vein is kept open at its lumen due to the stiff surface of the tentorium, therefore its lumen has to be sealed with the thrombin soaked Gelfoam. Here you can see the initial attempts to control the bleeding. However, again, non-directed control of the bleeding at the torn peduncle of the vein is often non-fruitful. You can see the bleeding at the level of the vein entering into the tentorium. Initially, a piece of Gelfoam was used, but since it was not directed right at the point of bleeding, blind compaction of hemostatic material can be non-productive. I continue to use suction to be able to identify the vein and try to coagulate its peduncle away from the tentorium or at the tentorium, but you can see the lumen of the vein is left or kept open by the stiffness of the tentorial surface. Piece of Gelfoam was used to, it can seal the opening of the vein within the tentorium. This maneuver is quite effective. Some tamponade is necessary. After the bleeding is controlled, you can see the sealing of the defect at the level of the tentorium. Here it is. I followed the surface of the tentorium, small incision within the lateral anterior tentorial surface of the cerebellum was made and the clot within the cerebellum was evacuated. The malformation is most likely slightly lateral to the clot. You can see the working space is quite narrow, because of the full cerebellum in this young patient, complicated by swelling related to the AVM and its hemorrhage. Can see some of the deep white matter feeders after removal of the clot, the cerebellum is slightly more relaxed. I continued to find the nidus and devascularize it circumferentially. Here's some of the feeders from the anterior aspect of the nidus. I can see the tentorium again on the contralateral side, through the cross-court route. Most likely there is some residual AVM laterally as expected here. Definitive hemostasis is reached after the nidus is completely disconnected. Dynamic retraction is quite beneficial in working within very small operative corridors as demonstrated here. Here are some of the feeders from the superior cerebellar artery coming in laterally. These are all coagulated and disconnected. There are numerous feeders there. Often the hematoma compresses the nidus and the angiogram can underestimate the size of the nidus. You're going around the malformation and disconnecting its feeders, until the tentorium on the ipsilateral side is more evident. Here are some of the sum of the feeders from the posterior aspect of the mesencephalon. Now, the last connection, more anteriorly is being severed, and the disconnected nidus was extracted. Here's the resection cavity. Some of the other potential feeders nearby the resection cavity are also coagulated, as long as they're not en passage vessels, you can see the edge of the tentorium. Here's the midline. It can work going from right to left. It's the posterior aspect of mesencephalon, the midline should be here. Some of the feeders that were disconnected. Here you can see one of the veins of Rosenthal. No other obvious vascular abnormalities evident. Postoperative angiogram demonstrated, complete the resection of the malformation without any further arteriovenous shunting. Thank you.
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