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Hippocampal AVM

July 29, 2016


Here is the case of a posterior hippocampal, or posterior medial temporal arteriovenous malformation. This is a lady who presented with spontaneous intracranial hemorrhage. You can see the location of the hematoma along the basal posterior left temporal lobe. The malformation is situated along the posterior part of the hippocampus medial temporal lobe. Most of the feeders are expected to originate from the posterior circulation, distal branches of the PCA, as well as branches of the basal MCA branches. Let's go ahead and further review the angiogram images. In this case, there's a large dominant branch of the PCA feeding this malformation. The draining system is essentially localized more medially ultimately reaching the vein of Galen. Here is another phase of the angiogram, again, demonstrating the predominant PCA branches feeding the artery in this malformation. Patient underwent evacuation of the hematoma resection of arteriovenous malformation. You can see the location of the head. A limited linear incision wouldn't be more than adequate for removal of the malformation. Here you can see a craniotomy, the dura is open in a cruciate fashion. Gliotic changes within the pier again, overlying the hematoma. Small quart economy completed just over the hematoma, and the hematoma cavity is entered and evacuated. As the hematoma is evacuated, I expect the malformation to be situated just medial to it. The drainage system again is medial to the malformation, and will not be exposed early on during the operation. The hematoma is generously evacuated, now the malformation is evident along the medial aspect of the hematoma cavity. I'll go ahead and move around the malformation, here's the choroid plexus intimately related to the malformation. Out of the medial to it is a large branch of the PCA feeding the malformation. Another branch of the PCA is evident medial to the malformation, this one is exposed early on. The hematoma essentially is circumferentially has disconnected the malformation and has done the job of the surgeon. Here you can see while trying to do some sharp dissection, I inadvertently injured one of the large feeding vessels. Again, this event emphasized the importance of patient microdissection to make sure all the feeding vessels are carefully identified early on before they are coagulated and cut. Here's more white matter to suction. Here you can see the injury to one of the dominant branches to the malformation. In this situation it's best to ask for another suction to clear the field while the bleeding point is identified, coagulated and controlled. Bleeding is quite a risk, overwhelming the suction. My assistant is helping out with clearing the field to some point, or some degrees, so I can find the bleeding point. Make sure it's coaguluted and controlled. One has to remain in control, and not lose his or her composure. Now, that that dominant feeding vessel to the malformation is controlled, I continue my circumferential disconnection of the malformation until the tentoriums I identified I expect to see some of the basal temporal lobe distal branches of the MC that will be feeding this malformation. Obviously those vessels have to be controlled and excluded. Again, continuing to work around the malformation you can see the tentorium was exposed, now work medial to the malformation. Obviously the draining vein that is situated more medially and posteriorly is preserved. I continue to disconnect the malformation circumferentially. Here's some of the more basal feeding vessels here at the tentorium, the edge of the tentorium, or the insucturia. Here is a feeding vessel from the PCA, Let's coagulate it again carefully and then transect it. A relatively sizable segment of the vessel should be coagulated, so that the vessel can be cut without further bleeding. Obviously the fourth nerve which is situated along the edge of the tentorium has to be protected, aggressive coagulation should be minimized to avoid postoperative trochlear palsy. Now, I continue circumferential disconnection of the malformation, or subpelli. Additional feeding vessels from the posterior circulation are identified, coagulated and cut. As you can see the disconnection continue circumferentially, now the malformation is being mobilized more laterally as some of the feeding vessels more posteriorly that could be hidden just behind the malformation are identified and disconnected. Again, after the malformation is disconnected, the draining vein that is traveling posteriorly is coagulated and cut. Ultimately the malformation can be delivered. Here are some of the connections to their choroid plexus. There are a number of choroidal vessels, and more specifically their posterior choroidal arteries that are feeding the malformation through the ventricle. Here you can see another dominant branch of the posterior choroidal artery that is feeding malformation through the ventricle. Here's the draining vein that is moving more medially joining the vein of Galen. This is the predominant drainage system of the malformation, It is being coagulated and cut. Only after the malformation has been circumferentially disconnected from its feeding vessels. This should be the last connection of this malformation to the surrounding structures. Adequate hemostasis is secured. Postoperative imaging in this case demonstrated complete exclusion of the malformation. The dominant PCA vessel that was feeding the malformation was disconnected and this patient did not suffer from any severe ischemia postoperatively. Thank you.

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