Here is a very proximal vertebral artery aneurism that is essentially at the same location as a PICA aneurysm. This is a 36 year-old female who presented with spontaneous subarachnoid hemorrhage, as well as fourth ventricular hemorrhage. Cerebral arteriogram demonstrated a three to four millimeter aneurysm arising from the V4 segment of the vertebral artery, associated with the tonsillar artery. The tonsillar artery is arising from the neck of the aneurysm. Importantly, the PICA and the ICA are arising from the same artery, from the basilar trunk. This aneurysm is essentially located where the PICA aneurysm would be located. And we're going to approach it as such. The patient was placed in a lateral position. A hockey stick incision was used. A left lateral suboccipital craniotomy was completed. Sigmoid laminate is located here. Sigmoid sinus is located there. Cranial cervical junction is located at the tip of the arrow. The dura is incised toward the cisterna magna. The arachnoid bands, or the cisterna magna are opened, and subarachnoid clot is evacuated. We know this aneurysm is very proximal, and is located on the vertebral artery, just after the vertebral artery enters the dura. So here's the vertebral artery. Most likely, here is the location of the aneurysm. There's very little space on the vertebral artery to secure proximal control. Here's the 11th cranial nerve. I'm dissecting around the vertebral artery, just at the level of the dura, to secure proximal control. Again, here is the accessory nerve. Here's the location of the aneurysm. I also dissected this top part of the vertebral artery, just in case distal control, and aneurysmal trapping is necessary. I'll go ahead and use sharp dissection to dissect the origin of the tonsillar branch. Again, here's the location of the aneurism, the tonsillar branch. I have to dissect around the neck of the aneurism, circumferentially. Here's looking along the lateral aspect of the neck. Here, you can see the aneurysm is multilobulated, with the dome of the aneurysm located here. You wanna be able to see around this circumference of the aneurysm neck, before the clip blades are deployed. Again, here is the tonsillar branch. I'll make sure there is no other branches originating around the neck of the aneurysm. Therefore, I'm going to dissect the neck of aneurysm. Here, you can see a second branch that is now in view. Here's the medial neck of the aneurysm. I continue to use the bolted probe to find the most distal part of the neck. The neck of the aneurysm is much more visible now. Papaverine-soaked gel foam may be used to relieve this spasm on these tonsillar branches due to their significant manipulation. Sharp dissection is also used to mobilize the nerve. Now you can see that the origin of the tonsillar branch is much more readily visible. Here's the origin of the tonsillar branch, the neck of the aneurysm, all the fibrinous material has been dissected, so that the pathoanatomy of the neck of the aneurysm is clearly visible. Here's a fenestrated clip, so that the nerve is included in the fenestration. Temporary clip is removed. Here's the original of the tonsillar branch, speared by the clip blades. You can see the second branch is also healthy, not incorporated in the clip blades. Intraoperative fluorescence angiography reveals patency of both perforating branches, with exclusion of the aneurysm. Again, papaverine-soaked gel foam is used to relieve the vasospasm on the smaller vessels. Here's the funnel operative corridor. I went ahead and evacuated a clot within the fourth ventricle, and restored CSF pathways to decrease the risk of postoperative VP shunting, and the need for such shunting. You can see CSF is flowing through the fourth ventricle now. And the postoperative angiogram demonstrated complete exclusion of the aneurysm, with the patency of the tonsillar branches, and this patient made an excellent recovery. Thank you.
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