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Superior Thalamic AVM

April 29, 2016


Let's discuss resection of superior thalamic arteriovenous malformations via the transfalcine approach. This is a 32 old male who presented with intraventricular and intracerebral hemorrhage. He was known to have a thalamic AVM that was previously suboptimally treated with radiosurgery. Here's the lesion along the superior aspect of the thalamus, primarily fed from lateral and medial posterior carotid arteries, as well as small white matter feeders from the posterior communicating artery, the thalamus perforator vessels. The lateral location of the mass made it ideal for a transfalcine approach. The ipsilateral interhemispheric approach would lead to significantly retraction of the ipsilateral hemisphere. Here's the intracerebral hemorrhage associated with this malformation. Patient was placed in the lateral position. Here's additional images describing the location of the mass malformation and the large draining vein, most likely a branch of the internal cerebral vein joining the vein of Galen and transfer sinus. Some of the feeding arteries from the colloidal vessels are obviously apparent. Here's patient positioning. Midline incision for the transfalcine approach, we'll use the contralateral interhemispheric corridor to reach the ipsilateral target, and lumbar drain was installed for early CSF drainage. Here, you can see the left-sided interhemispheric approach, the falx. An incision is created within the falx in order to reach the contralateral medial hemisphere. Here's the vertical limb of the incision. Here's the horizontal limb. Therefore, a T-shaped incision is completed. More demagnified view of our operative corridor. A corticectomy is created within the medial posterior frontal area. White matter dissection leads us to the ventricle. Here's entry into the ependymal ventricle. CSF is released. No navigation was used based on CT angiogram. The white matter dissection section is widened so the entire length of the AVM is in view. Here is the malformation. Post a part of the thalamus choroid plexus. Here are the posterior and lateral colloidal vessels leading to the malformation. Here's the colloidal vessel choroid plexus, superior part of the thalamus on the contralateral side, or ipsilateral to the lesion. The falcine incision was extended so the most lateral aspect of the target is exposed. Two sutures are placed within the falcine flaps to mobilize these flaps out of our operative corridor. Another view of the posterior aspect of the AVM, the colloidal vessels are immediately coagulated to devascularize the malformation. Any of the plexal feeders are also disconnected. Next, neuro navigation is used, and the nidus of the malformation is circumferentially disconnected. Radiosurgery significantly facilitates coagulation of the deep white matter feeders, and decreases the risk of removal of these arteriovenous malformations. Essentially, radiosurgery downgrades these AVMs to a more operative stage. Small operative corridor, lateral disconnection of the malformation can be quite challenging. Here are some of the plexal feeders that are also being disconnected. Here are some of the veins on the surface of the ventricle. Those that are not involved with the malformation are carefully protected. Here are some of the white matter feeders. Again, radiosurgery thickens the wall of these vessels through endothelialization, and therefore makes them quite amenable to bipolar coagulation. Some of the bleeding from the white matter feeders and the posterior thalamus perforating vessels is readily controlled. Here's disconnection of the medial margin of the malformation. I expected drain vein to be looking medially and most posteriorly. Here's a further disconnection of the medial margin of the malformation. Necrotic margins after removal of the malformation are apparent. After most of the malformation is disconnected, the posterior draining vein is also sacrificed. Here's the malformation that was extracted, choroid plexus. Any of the plexal feeders are further coagulated and cut. Here's the draining vein on the wall of the ventricle that appears dark blue. No other obvious feeding vessel or arterialized vein is apparent. Final view of our resection cavity is provided. Here's a more demagnified view. The falcine flaps are returned in their original position. And in this case, the postoperative angiogram demonstrated reasonable removal of the malformation without any complicating features. This patient's hemiparesis worsen after the surgery, but ultimately improved. Thank you.

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