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Atherosclerotic MCA Aneurysm

October 28, 2019


This is another video describing the nuance of technique for clip ligation of highly atherosclerotic MCA aneurysms. This is a case of a 63 year-old male with an incidental right-sided MCA aneurysm. There no evidence of calcium or anything suspicious. On the CT angiogram the neck is relatively narrow, in fact, let's go ahead and review the intra-operative findings. Right-sided front temporal craniotomy was completed. The right Sylvian fissure is widely dissected. Here you can see the aneurysm relative to the distal, just underneath the anterior aspect of the superior temporal gyrus. All the arachnoid bands are carefully dissected. The aneurysm looks very atherosclerotic in this case, therefore, a very wide dissection of the aneurysm is necessary, so all the branches are carefully identified. In this case, as you can see, the atherosclerosis extends all the way to the inlet or the outlet of the M2 branches. In this case, perfect clipping along the neck can be very hazardous as intraluminal constriction of the vessels would not be easily visible extraluminally. That's because again, the presence of very stiff walls that are easily collapsed, closing the outlet of the M2 branches. As you can see, I placed the clip very distal to the neck because I knew that the walls will be collapsed and therefore, this clipping is actually a lot more effective because even though it's this distal, since the walls are so thick, the closure will lead to additional collapse of the wall, more proximal or closer to the neck of aneurysm. Doppler ultrasound or the micro Doppler device revealed good flow now within the vessels. Placement of the clip anywhere closer to the neck would lead to compromise of the flow within the M2 branches. This is an important nuance that should be kept in mind. Here you can see the ICG angiogram revealing good petency of their vessels, no obvious flow within the aneurysm neck. Here's the FLOW 800 ICG revealing adequate flow symmetrically between the M1 and M2 branches. I think the FLOW 800 is especially useful in these cases, because it can compare flow within different vessels rather than just demonstrating if there is flow or not. So it can be a little bit quantitative relatively, rather than just qualitative. Since this aneurysm is highly atherosclerotic, it's important to know the relative amount of flow between vessels to assure not only petency, but adequate flow within the distal vessels. Postoperative angiogram in this case revealed complete exclusion of the aneurysm. One more time, as you can see, even though the clip was along the more distal aspect of the aneurysm and closer to the dome, the aneurysm is completely excluded angiographically because the thick walls of the aneurysm collapse much more effectively with the clip and relatively even a few millimeters away from the clip again, because of the thick walls that are easily collapsible, thank you.

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