Medial frontal AVM: Techniques
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Let's talk about resection of another Medial Frontal AVM. This is a 12 year old female who presented with spontaneous intracerebral hemorrhage. MRI evaluation reveals the location of the hemorrhage, in relation to the malformation on the right medial anterior frontal lobe. Coronal as well as sagittal in my images, again demonstrate the location of the malformation just above the hematoma cavity. Preoperative ateriogram was completed, which as expected, demonstrated the right medial frontal malformation, primarily fed by the anterior cerebral artery branches on the AP internal carotid artery injection. The dominant draining vein is traveling medially to join the inferior sagittal sinus. Patient underwent resection in the supine position via a right-sided parasagittal craniotomy. Here's the location of the external ventricular drain. Tuber holes were placed on each side of the parasagittal sinus and parasagittal craniotomy was elevated. Here is the location of the superior sagittal sinus. Following epidural hemostasis, the dura was opened in a curvilinear fashion based on the dural sinus. Any bleeding was controlled using sutures along the edges of the dural opening next to the superior sagittal sinus. Interhemispheric fissure was entered, additional CSF was removed via the external ventricular drain. I prefer to place a suture within the superior aspect of the faults. This suture mobilizes the superior sagittal sinus out of our working corridor. Here's the anterior medial frontal lobe, the arachnoid bands are widely dissected. Here's the arterialized vein within the inferior sagittal sinus, and the arterialized vein draining the malformation. The malformation should be just about here. Here's the arterialized vein. Small corticotomy was completed based on CTA intraoperative image guidance, and the hematoma cavity was entered. Here's the hematoma. It was evacuated. Upon further brain relaxation, now I can start looking for the malformation. This is most likely a portion of the malformation, at least. I expected the malformation to be just above the clot. Here, you can see a better view of the malformation. Here's the clot, just above it is the malformation. It's pedicle is based on the ACA branches located here. The corticotomy was extended more anteriorly, so the entire length of the malformation is in view. Here's a view of the nidus, one of the draining veins. Here is the hematoma cavity, just anterior to the malformation. So now I have isolated the malformation, both along its anterior and posterior aspects. The medial aspect is where the feeders are and will be handled during the last stages of the operation. Therefore, after hematoma evacuation, my primary goal would be disconnection of the malformation more laterally. Here's another view of the malformation feeding vessels from the ACA. Here's the bulk of the malformation. I initially spared this vessel, however, it's corkscrew appearance led me believe that it most likely feeds the AVM. This vessel was eventually sacrificed. Here is a portion of the vein that is wrapping around the nidus. Obviously it should be carefully protected during dissection. I continued to evacuate the hematoma before tackling the lateral aspect of the AVM. Now, I'm trying to disconnect the anterior aspect of the lateral AVMs connection. I expect to face some deep white matter feeders in this area. That corkscrew vessel that I previously discussed was disconnected so that the frontal lobe can be released, and so that I can reach the lateral pole of the malformation. Here is the initial attempts at disconnecting the lateral pole, as well as the inferior lateral pole. Here is the deep white matter feeder that is being disconnected. These white matter feeders can be quite resistant coagulation. The malformation has been mobilized medially. Again, the lateral pole of the malformation is difficult to reach. Dynamic retraction of the suction is used to mobilize the medial frontal lobe, so I can reach those feeding vessels coming into the AVM from the lateral side. Here is the lateral pole more posteriorly. You see the bleeding from the white matter feeders in the operative corridor toward the lateral pole is very limited, and therefore bleeding can be quite challenging to control. I continue to clear the operative field and find the exact point of bleeding. This area appears to be the bleeding point. Here's another tethering artery that was also disconnected so that I can have a better look at the area of the bleeding here. Ultimately hemostasis was secured. A more lateral trajectory to the malformation is now possible. Again, the deep white matter feeders are quite problematic, as expected. You can see a couple of them here. Now, I'm reaching the hematoma cavity again. This is a good sign that I have adequately transected and isolated the AVM nidus more laterally. Can I stay within the white matter tracts, just lateral to the nidus? Another bleeding point is being controlled. No residual AVM is apparent on the lateral side as well as inferior aspect of the cavity. This is the final attachment point along the lateral pole of the nidus. You can see that the draining vein, the inferior sagittal sinus is now quite blue. Good sign that most of the feeders have been disconnected. Now the AVM is being rolled more laterally so the medial feeders from the ACA are disconnected. It's the final attachment there. Here are the branches of the A2 within the interhemispheric fissure. The edges of the peel are coagulated and inspected to ensure that no residual AVM is apparent . Here is AVM removal. One tiny last connection, Further inspection reveals again, no residual nidus. Immaculate hemostasis is reached. Here's a suspicious segment that was also removed. If the nidus is completely removed, usually hemostasis is easily reached. Persistent bleeding usually means residual AVM nidus. Here's the postoperative angiogram, which demonstrated complete removal of the malformation without any evidence of arteriovenous shunting. Three months MRI also revealed nice removal of the malformation without any complicating features and this patient made an excellent recovery. Thank you.
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