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Atherosclerotic MCA Aneurysm: Pitfalls in Fluorescence Imaging

January 01, 2015


This video describes the pitfalls in the use of intraoperative fluorescence for cerebral aneurysms, and more specifically regarding atherosclerotic MCA aneurysms. This is a 62 year old female who presented with a 1.5 centimeter left sided, unruptured MCA aneurysm. You can see the broad base morphology of the neck and relationship of the neck to the M2 trunks. Patient subsequently underwent a frontotemporal craniotomy. The Sylvian fissure was dissected, using the standard technique. In other words, the inside to outside method. The superficial arachnoid bands were first dissected and the M2 branches were found and followed to the neck of the aneurysm. Here's the fake arachnoid band along the anterior limb of the Sylvian fissure, or the sphenoidal segment of the fissure. Getting closer to the aneurysm. Arachnoid bands are sharply dissected. Here you can see the aneurysm, the M2 trunk, we'll continue to dissect around the circumference of the neck until the M1, and the other M2 trunk is also identified. Here you can see the neck of the aneurism, M1, M2, M2, a very broad base neck, temporary clip was used. So the neck of aneurysm can be circumferentially dissected. With deflation of the aneurysm, I'm able to see behind the neck, and assure no resistance for passage of the clip lights. The perforating vessels are also carefully dissected and protected, so they're kept out of harm's way. I initially placed a straight clip. You can see the clip, slided toward the bifurcation, and caused its occlusion. So, a curved clip was attempted, appears to be better for preservation of the inlets of the M2 branches. You can see ICG angiogram demonstrating no filling of the aneurysm. However, micro-Doppler ultrasound inspection revealed some flow within the aneurysm, despite the negative ICG findings. Therefore I placed additional clip, to close the distal neck more accurately. Here's another clip to close the proximal neck, more robustly. Despite these efforts, puncture of the aneurysm revealed slight filling of the dome. Therefore the fenestrated clip was advanced further across the distal end of the neck, an additional straight clip was also added. You can see the aneurysm is no longer filling. As stated a straight clip was also added to this construct. You can see the postoperative angiogram demonstrated complete exclusion of the aneurysm with patency of the branching vessels. There was no evidence of Ischemia, and this patient made an excellent recovery. Overall, this video demonstrates the importance of confirmation of aneurysm occlusion, after performance of an ICG angiogram. There could be several factors leading to negative or false negative ICG angiogram findings. One of which could be related to the fact that the aneurysm is filling very slowly and therefore there is not enough contrast available immediately for the aneurysm to enhance under the fluorescence module. Second, the wall of the sac can be quite thick and therefore, enough emission signal may not be created for the camera to detect the filling of the aneurysm. How many of these aneurysms would eventually thrombose despite minimal filling of the sac is unknown. Nonetheless, overall, the aneurysm complete occlusion should be confirmed with the puncture of the aneurysm. If the aneurysm is atherosclerotic, or if there's any question on micro-Doppler ultrasonography, that the sac could be filling. Thank you.

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