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PCoA Aneurysm Causing 3rd Nerve Palsy

February 04, 2015


This is another video for clip ligation of PCoA aneurysms presenting with symptomatic mass effect and third nerve palsy. This is a 57-year old female who presented with acute right-sided ptosis. You can see the location of the aneurysm on the right side is relatively sausage shaped. It's apparent on the sagittal image as well. She underwent a right frontotemporal craniotomy for clip ligation of this aneurysm. You can see the incision, the minimal turn of head. Here's the exposure, the optic nerve, the carotid artery, the clinoid process, the origin of the aneurysm. You can see that decline of process and its dura is covering the proximal neck of the aneurysm. Intradural clinoidectomy is indicated. The dura over the clinoid process is dissected and the portion of the bone that is covering the aneurysm is drilled away. The flap of the dura is placed over the artery and the neck of the aneurysm to protect these structures during drilling. An ultrasonic device for the bone was used in this case. Continuation of the drilling method just over the posterior wall of the carotid artery is necessary so the proximal in the neck of the aneurysm can be found and hopefully, proximal vascular control over the ICA is also secured. Here's the flap with the dura over the ICA. Bony removal is continued methodically. Here you can see a portion of bony removal is completed, the proximal neck of the aneurysm is apparent. However, further bony removal is needed to complete proximal control over the ICA. Bleeding from the bone was controlled using bone wax. Next, the flap of the dura is removed so additional space is secured. Here's the proximal ICA, the proximal and distal neck of the sausage shaped aneurysm. Here's the distal neck. The neck is readily apparent. Dissection allows careful inspection of the neck of the aneurysm, so the clip blades can be applied under direct vision. Further sharp dissection around the superior neck of the aneurysm. The interior carotid artery is protected. A proximal IC at the level of the skull base is partially atherosclerotic, however, appears collapsible using a temporary clip. Here you can see the origin of the PCoA. I would have missed this origin on this adequate exposure and dissection at the level of the neck of aneurysm was performed. Here you can see the neck of PCoA aneurysm incorporating the origin of the posterior communicating artery. Therefore, the clip has to be placed slightly more distally along the aneurysm to protect the inlet to the PCoA. Further boney removal allowed further exposure of the aneurysm neck so that the blades can be inserted distal to the origin of the PCoA. There's barely enough space available right now. Here's further dissection over the shoulder of the PCoA to ensure adequate space for insertion of the clip blades. A relatively unusual configuration for the PCoA to originate so distal along the neck of the aneurysm. Here's a good circumferential exposure of the neck. A definitive clip is placed across the neck preserving the origin of the PCoA, the blades are passed as parallel to the long axis of the ICA as possible. To ensure more definitive clipping, I repositioning this clip after further dissection over the shoulder of the PCoA was performed. Here's placement of the clip. The aneurysm appears collapsed. The third nerve is also evident. Since the dome of the aneurysm was very adherent to the nerve, I did not persist on further dissection so that the injury to the nerve is minimized. Post operative angiogram demonstrated complete exclusion of the aneurysm in this patient, third nerve palsy resolved within three months after surgery. Thank you.

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