Clip ligation of distal PICA aneurysms can be at times challenging since these aneurysms can be atherosclerotic, in addition, the anatomy can be at times confusing. Let's go ahead and review this video on a 64 year old male who presented with subarachnoid hemorrhage, CT angiogram demonstrated evidence of an aneurysm along the area of the foramen magnum. You can see a view of the aneurysm right along the posterior aspect of the lore and brainstem around the lip or posterior lip of the foramen magnum, This patient subsequently went through an angiogram to assess their morphology of the aneurysm more adequately, you can see, again, this is relatively fusiform aneurysm, or it carries or harbors a wide neck or potentially partially fusiform along the distal aspect of the left PICA. Patient underwent a suboccipital craniotomy into prone position, here's the Indian, here's the C1. You can see this small craniotomy or a craniectomy that's often necessary and more than adequate to expose the area of aneurysm. Intense amount of clot was encountered, all the blood was evacuated until the poster brainstem and the tonsil were found in a very thick clot. Here's the left tonsil, right tonsil PICA, we'll go ahead and dissect the PICA until the aneurysm is encountered. Here's the all backs, The left tonsil is elevated. Here you can see the aneurysm with fibrous clot around it. We'll continue dissection so that the incoming and outgoing vessels are found. One has to be very careful as their vascular loops can be very confusing and lead one to mistake the actual outgoing, or the distal PICA relative to the aneurysm as the proximal PICA. Here appears it appears this is actually the proximal PICA with a loop and this is the distal PICA. We'll continue to clean off the aneurysm, again you can see a more the magnified part of the surgery and the extent of craniectomy. One may estimate that this is actually proximal PICA, and this is distilled PICA but in fact, there is a vascular loop here which will make this distal PICA, and this one, the proximal PICA. Because of some confusion in the anatomy, you can see that the temporary clip was placed on the distal PICA. Here you can see the loop going toward the fourth ventricle. Nonetheless, there were some decompression of the aneurysm and a clip was placed across the neck, just like other atherosclerotic aneurysms clip placement can not be perfect as the presence of atherosclerosis will lead to significant intraluminal stenosis that's not apparent extraluminal. So as you can see here, the anatomy is now more apparent. The patency of the vessels is not also confirmed due to presence of atherosclerosis. I'll go ahead and remove the clip. Temporary clip now was placed correctly on the proximal PICA, no further flow within the distal PICA is now apparent. Aneurysm appears a lot more relaxed and I can place the clip more effectively as the aneurysm is more relaxed and also place the clip slightly more distal along the neck so that the patency of the PICA lumen at the level of the neck is secured. I had to readjust a clip so some of the dog-ear that was apparent a moment ago is no longer present. You can see a nice construct now, good flow within the PICA, the aneurysm is completely excluded, there is no obvious residual neck. Post-operative CT scan revealed no evidence of ischemia. Post-operative angiogram confirmed nice exclusion of the aneurysm without any complicating features, and this patient made an excellent recovery. Again, two points are important here, as mentioned at the beginning of the video, that's careful understanding of the anatomy and presence of vascular loops, and in addition, avoiding perfect clip placement as the presence of atherosclerosis can be quite stenotic intraluminal that may not be visualizable extraluminal. Obviously it's often better to leave a little bit of neck behind, and assure good flow within the vessel. Thank you.
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