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PCoA Aneurysm: Neck Tear and the Cotton-Clipping Technique

December 11, 2015


Let's talk about clip ligation of multilobulated posterior communicating artery aneurysms. In this specific case an intraoperative rupture at the level of the neck occurred, which required, the cotton clipping technique. Therefore, this technique will be reviewed in detail as well. This is a 50 year old female who presented with an incidental posterior communicating artery aneurysm, on the left side. You can see on the 3D reconstruction cerebral arteriogram this aneurysm is quite complex. It's multilobulated with at least two superiorly and inferiorly pointing labials and one smaller labial posteriorly. As expected it's intimately associated with the posterior communicating artery, which is quite large and potentially a fatal form of this artery. This patient subsequently underwent a left frontotemporal craniotomy. The lateral aspect of the pterion and sphenoid wing were drilled away generously. You can see the extent of the exposure. The sphenoidal segment `of the Sylvian fissure was opened. The anterior aspect of the internal carotid artery was exposed. You can see the proximal neck of the aneurysm, the mobilization of the arachnoid membranes at the tip of the arrow. More medially, you can appreciate the posterior choroid process Here's the anterior choroid process. Proximal control is secured through this maneuver Fix retractors or avoided dynamic retraction is used. Here is the membrane of Liliequist over the interpeduncular cisterns Here is just proximal to the neck of the aneurysm is the very large posterior communicating artery. The arachnoid membranes are dissected parallel to the PCoA And here is the space between the artery in the proximal neck. So let's go ahead and dissect the distal neck. Here where things got more difficult. You can see the potential space between the superior pointing labial and the posterior wall of the carotid artery. However, this potential space was relatively small and this dome of the aneurysm was significantly adhering to the posterior ICA wall. This configuration makes surgery quite difficult as the amount of working space for the clip on the distal part of the neck is limited. A temporary clip decompressed the sack of aneurysm. I continued dissection along the distal neck to create additional space. You can see that in fact, the superior pointing dome is adhering to one of the branches of the anterior choroidal artery. Here is the dominant posterior communicating artery. And further dissection along this plane. The distal aspect of one of the blades will be seeing right next to the posterior communicating artery. Here's that potential space. I continue to work that space. Although additional working space is available is inadequate. The dorm is quite thin. I attempted a straight clip. However the clip lace would not fit through this limited space along the distal neck. Additional dissection is necessary to create more flexible working angles for the distal blade. Here's the inter choroidal artery incorporated to the very thin dome of the aneurysm prohibiting any additional dissection. This is the best I thought I could do safely. Here is this very complex multilobulated aneurysm with very thin walls, exceptionally unusual. This patient had another small aneurysm over the ophthalmic artery contralaterally. Before I proceed with funnel clip application on the left side, I exposed the contralateral ophthalmic artery aneurysm, which was quite small and measured the safety of clip application wall for the contralateral aneurysm. Here's the ipsilateral optic nerve. Contralateral optic nerve mobilization of the subfrontal lobe in order to identify the space just contralateral to the contralateral optic nerve. Here's the aneurysm dome. The arachnoid membranes are dissected Proximal control seems to be unlikely in dislocation concerning the optic nerve overlying the internal carotid artery. Here is more sharp dissection exposing as much of the region, widely as possible. The aneurysm dome is more in view. Sharp dissection is the best dissection to avoid intra-operative rupture. Here's the dome completely dissected The anatomy of the region is now much more clear. Peforating vessel is present there. Now I'm attempting to decompress the nerve more thoroughly. I did not feel clipping of the contralateral ophthalmic artery aneurysm was safe. I redirected my attention to the ipsilateral posterior communicating artery aneurysm. Here is again this anterior choroidal artery branch, very much adhering to the thin dome of the aneurysm. Sharp dissection was employed under temporary occlusion of the ICA This blunt tip probe instrument was my last attempt to create additional space between the thin dome of the aneurysm in the posterior wall of the carotid artery. The limited space probe inhibited any sharp dissection and adequate visualizations around the tips of the scissors. There's definitely now more space available for the clip plates to maneuver themselves. Here is the third nerve. Straight clip was used. Obviously the approximal blade has to be just over the PCoA. As you can see here, that's the origin of PCoA. The blades are being rotated counter-clockwise to spare the origin of the PCoA. The space to work through is quite limited. The blades are slightly sharp at their tips. Every attention has to be paid to avoid any injury to the neck of the aneurysm, as much as possible. The distal tip of the proximal blade required further rotation to prevent any compromise of the PCoA. And I continue to rotate the blades to achieve a reasonable clip deployment. No matter how much I'm rotating the blades. I am not reaching the desired configuration to preserve the PCoA. The next step was further exploration. This is the PCoA again. One has to remember that the clip blades are somewhat sharp and as you will see momentarily, even gentle manipulation of the dome along the distal neck of the aneurysm led to an intraoperative rupture, as you can see, which is very unfortunate. And neck injury is suspected. As I attempted to place a clip the bleeding is more torrential. We've continued to preserve our composure attempt additional clip placement. Here's another clip, although slightly blindly decreased the bleeding. However the PCoA is also compromised. The clip is repositioned in the face of bleeding. I rotate the clip lights to preserve the PCoA as much as possible. The third nerve is protected. However, as you can see, the tip of the blades have compromised the PCoA, that's quite dominant in this patient and has to be preserved. This tentative clip, a low dissection of the interchoroidal artery from the superior dome of aneurysm. The clip is repositioned. While preserving the PCoA. Here you can see the location of the PCoA during this maneuver. Additional injury to the neck of the aneurysm was inflicted. Partly related to the very thin wall of the dome in the region. Here is the PCoA that is being preserved Here You can see the tear at the neck of the aneurysm. You see within the lumen of the aneurysm very close to the neck. This critical situation with the neck tear threatens the vitality of internal carotid artery. Therefore, a small piece of cotton was used to cover the defect within the aneurysm. And a second clip was used to bolster and keep the cotton in place. The initial clip was removed, but additional bleeding was encountered. This phenomenon leads me to believe that the location of the cotton is not appropriate as additional repositioning are necessary for the second clip to achieve closure of the tear at the neck. Here is further dissection of the PCoA. Further inspection of the neck, making sure the anatomy is appropriately understood for placement of the final tandem clip to close the tear within the neck of the aneurysm. Here is the second clip after the cotton has been placed more closely toward the neck removal the first clip this time does not lead to further bleeding. assuring me that the tear has been are properly managed. However, there is a residual dog ear from the aneurysm, that has to be addressed. This is relatively easy to handle via a bane edit small straight clip. The dog ear was excluded. The tip of a second clip stopped just at the level of the PCoA. The third nerve looks very healthy. This clip was repositioned just to exclude the aneurysm completely intraoperative micro Doppler ultrasonography revealed exclusion of the aneurysm and health of the branching and parent vessels. Post-operative angiogram demonstrate complete exclusion of the aneurysm and preservation of the internal carotid artery and the poster communicating artery. As you can see here without any residual aneurysm. This patient awoke from the anesthesia without any complicating features. Thank you.

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