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Distal MCA aneurysm: Aneurysm Trapping

January 14, 2016


This is an interesting case example of a distal MCA aneurysm in management strategies for aneurysmal trapping. This is an 18 year-old male who presented with an incidental 15 millimeter distal M4/M5 aneurysm. The MRI evaluation demonstrates the location of the aneurysm sac. Cerebral arteriogram discloses the fusiform nature of the aneurism and its very distal location. Retrograde collaterals are quite robust in this area and aneurysmal trapping should be relatively safe. Intraoperative fluorescence angiography can also assist with evaluation of retrograde in this distal cerebral territories. You can see the mapping of a superficial temporal artery just in case revascularization is necessary, and retrograde flow is deemed not robust enough. Intraoperatively, the location of the aneurysm and the linear incision over it is also shown in this area. So I was prepared to perform revascularization if necessary. Let's find out the intraoperative findings. Here, you can see the craniotomy over the posterior incision. This is the dominant feeding vessel to the aneurysm. There are also a distal draining artery and most likely another deeper artery associated with this fusiform aneurysm. The predominant feeding vessel was isolated and a temporary clip was placed across this artery and intraoperative fluorescence angiography was completed. The findings are quite interesting. You can see that the parts of the brain or the cortices that are feeling retrograde or evident early through perfusion of the fluorescein and the areas that will fill through retrograde collaterals fill in a delayed fashion. Obviously these findings are expected. However, fluorescein angiography proved itself as a useful tool to confirm these findings. Let's go ahead and see how robust the retrograde flow is in these areas. You can see the perfusion appears to be quite robust. Therefore revascularization is most likely unnecessary and the aneurysm can be trapped and disconnected. You can see the venous drainage of the fluorescein angiography. ICG was not as effective as you can see, however, the flow was noted to be relatively slow in the other feeding vessels. The resolution of fluorescein angiography was superior. Next, the dominant feeding vessel was disconnected and clipped also coagulated. Here's a permanent clip to avoid any risk of postoperative bleeding. The aneurism was micro surgically and circumferentially dissected. The arachnoid knife is quite effective in these circumstances to allow clear visualization along and around the blades. Now that the aneurysm is isolated, we can go ahead and disconnect it from the surrounding vessels. Here is one draining vessel, distal to the aneurysm. Here's the partially thrombosed aneurysm as expected. Another associated vessel is also felt. The aneurism is circumferentially disconnected. Larger vessels, are first clip ligated. You can see the thrombus in the aneurysm sac. The aneurysm was open just to see the inside of the aneurysm, very thrombotic, partially atherosclerotic aneurysm. Obviously the sac was removed. You can see the location of the clips for the larger vessels. The dura was approximated around the clips without displacing them. Post operative angiography demonstrated complete exclusion of the aneurysm and evidence of retrograde flow back to the area of the aneurysm. This patient also did not suffer from any post operative deficit. Thank you.

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