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Atherosclerotic MCA Aneurysm: Tricks of the Trade

December 05, 2018


There are certain tricks that would facilitate clip ligation of atherosclerotic aneurysms, and more specifically, MCA aneurysms. Let's go ahead and review such tricks. This is a 52 year-old male who presented with an incidental MCA aneurysm. You can see the location of the aneurysm, relatively long M1, and definitely, presence of calcium and atherosclerosis at the base of the aneurysm. Right frontotemporal craniotomy. The Sylvian fissure was widely dissected. As many of the superficial Sylvian veins as possible were saved. The inside-to-outside technique was used. You can see the exposure of the aneurysm, the frontal branch, the neck of the aneurism at the arrow. Here's the temporal branch. It is very important that the neck of the aneurysm is circumferentially dissected. Here's the temporal branch. Here's the M1 that I'm dissecting now to secure proximal control. Here's the M1. You can see the use of dynamic retraction. Perforator at the distal M1, temporary clip was deployed. The circumferential base of the aneurism is being inspected, and you can see presence of calcium and atherosclerosis. And working around the entire circumference of the neck of the aneurysm. Calcium extends to the base and potentially the origin of M2 trunks. First, I attempted a slightly curved clip but you can see the clip is sliding toward the bifurcation and stenosing the bifurcation. I attempted to change the angle of the clip application and tried to place the clip slightly distal to the neck and toward the dome. And the clip is not closing. So, I used a tandem clipping technique to keep the clips distal to the neck. And you can see, I did not receive adequate flow within the distal vessels. That means there is stenosis within the origin of the trunks. Went ahead and removed the more proximal clip. Again, did not hear adequate signal within the M2 trunks. This time I used a fenestrated clip to use the enhanced distal closing pressure of the fenestrated clip to see if I can clip more distally along the neck. Usually the distal part of the aneurysm to the tip of the clip would collapse. As you can see, this construct appeared to work well. There is filling of the distal vessels. As you can see, the clips are very distal to the neck of the aneurysm, but as the aneurysm neck collapses, there will be closure of the neck as well. For this way, the openings to the trunks remain patent. The distal closure pressure of the fenestrated clip is an advantage here, to keep the aneurysm collapsed and avoid any further a slippage of the clip toward the neck of the aneurysm. Here's the final product. You can see the dynamic retraction preserves the frontal and temporal opercula. Let's go ahead and a review post-operative angiogram, which demonstrated nice clipping, and no residual aneurism. Patency of the parent and branching vessels, no evidence of ischemia on CT scan, and this patient made an excellent recovery. Again, the important point is that extraluminal inspection. In other words, inspection during the surgery under microscope may significantly underestimate the amount of intraluminal stenosis cost on the branching vessels. In this case, the M2 branches. Therefore one has to be very careful to place the clip more distally as necessary to remain the openings to the M2 branches patent. As you can see, there is no residual neck, even though the clips were applied much more distally than usual. And that's because the presence of the calcium and atherosclerosis intraluminally will collapse, then it could be aneurysm. And if the clips are just distal enough, the neck would be collapsed without necessarily collapsing the MC bifurcation. Thank you.

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