Peri-atrial AVM: Transfalcine Approach
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The posterior interhemispheric transfalcine transprecuneus approach is quite effective for resection of atrial or trigonal arteriovenous malformations. This is a 28-year-old female who presented with sudden onset headache and left-sided visual field cut, and on preoperative imaging, was noted to have a right-sided atrial arteriovenous malformation, primarily fed from the branches of the posterior superior artery through draining veins joining the vein of Galen. You can see the angioarchitecture of the malformation, which is relatively non-compact. There is a hematoma residing just along the more superior pole of the arteriovenous malformation. This hematoma reaches the medial aspect of the hemisphere and the area of the precuneus. I felt that the transfalcine transprecuneus approach will lead to least amount of transgression of the unaffected brain. The ipsilateral interhemispheric approach would require significant retraction of the ipsilateral hemisphere to reach the lateral pole of the malformation. This case is one of my early cases where I attempted the posterior interhemispheric transfalcine approach. I placed the non-affected hemisphere up, or in the non-dependent position, therefore avoiding the advantages of the gravity retraction. I later found out that that use of gravity retraction and mobilization on the unaffected hemisphere is quite important. And after this case I have always placed the non-affected hemisphere in the dependent position. This is the normal unaffected left hemisphere. You can see the incision within the falx. These are the two falcine flaps. Two pieces of Telfa were used over the brain to protect the peel surface of the hemisphere. The view of the Opera microscope was changed about 180 degrees. You can see the transfalcine corridor through the precuneus toward the atrium of the lateral ventricle, where the AVM is located. Again, the unaffected hemisphere was placed in the non-dependent position. A lumbar drain was used. Neuronavigation was employed. You can see the incision crosses the midline. Here's the location of the craniotomy and its size. You can see the outline of the superior sagittal sinus. The dura was open in curvilinear fashion over the non-affected hemisphere and a transfalcine approach toward the affected hemisphere was employed. A pair of sagittal bridging veins were untethered to expand the interhemispheric corridor. Lumbar CSF drainage allowed a very relaxed brain. Two sutures were placed over the superior aspect of the falx to mobilize the superior sagittal sinus and expand the operative corridor further. Here's the second retention suture within the falx and its effect where the traction on the suture has been implemented. A T-shaped incision is created within the falx. The first incision is parallel to the superior sagittal sinus. Next step, precuneus is entered and the AVM is identified within the atrium. You can see the arterialized veins are identified within the atrium hemispheric space relatively early. Over the splenium you can see some of the deep white matter feeders to the malformation. Plexal feeding vessels to the nidus are also disconnected early via this route. Here you can see some of the deeper feeding vessels. Here is the splenium. Some of the feeding vessels from the splenium to the nidus are also disconnected. Here's the hematoma cavity. The nidus is circumferentially disconnected. Obviously the hematoma cavity assists with the circumferential dissection. Here's a normal vein, which is the vein of Galen. The arterialized vein is located more laterally as you can see here. Here's another view of the arterialized vein. Again, the splenium is situated at the tip of the arrow. Unlike the transcortical approach, the transfalcine approach readily allows anatomical orientation via the surrounding neurovascular structures. Deep white matter feeders are carefully disconnected. You can see some of the arterialized veins are turning dark and now can be also disconnected, allowing extraction of the nidus. Here's the nidus that's being removed. Postoperative angiogram demonstrated complete exclusion of the arteriovenous malformation and this patient recovered from her surgery without any complications. Thank you.
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