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Dysplastic MCA Aneurysm

January 19, 2016


Clip ligation of dysplastic MC aneurysms can be quite challenging in contingency plans such as revascularization of bypass procedure should be available if necessary. Clip ligation of these aneurysms does place the branching vessels at significant risk due to the presence of calcification or other abnormalities within the vessel that can place the lumen of the branching parent vessel at risk during deployment of the clip. This is a 22-year-old male who presented with an eight millimeter, incidental, unruptured dysplastic, MC aneurism after workup for headaches. As you can see on the 3D reconstruction of the cerebral angiogram, the entire bifurcation is somewhat unusual. One of the larger M2 trunks has this very dysmorphic aneurism incorporated into its branching patterns. Although calcification is not very clear on the CT angiogram, let's go ahead and reveal the intraoperative findings. The left sided frontotemporal craniotomy was completed. The Sylvian fissure was widely dissected. You can see the fissure was quite adherent as expected in this very young patient. Subsequently, the aneurism was exposed. You can see the M1, this very dysplastic aneurism that appears somewhat almost fusiform with multiple lobes and another lobe located actually here. Multiple clips are obviously necessary for reconstruction of the parent branching vessels. I first investigated the flow within the surrounding vessels via micro-Doppler ultrasonography. Next, I placed a straight fenestrated clip to close part of the aneurysm. You can see a lot of whitening at the sac, which can signify the position of calcium in these areas. You can see the vessels are all patent. After placement of the first clip, I was really worried that although extraluminally, all the vessels appear patent, evidence of calcium within the walls could compromise the vessel intraluminally upon application of the clip. You can see another dome of the aneurysm, again, somewhat calcified. You can see some residual neck. A second straight fenestrated clip was placed across and just proximal to the first clip to exclude as much of the aneurysm as possible. I was relatively happy with this construct. However, flow was not very clearly identified there. I placed the curve clip to close off the second aneurism and you can see on the ICG angiography, a large branch of the MCA that was close to my two clips is now filling. I was planning on revascularizing this branch. Before proceeding with that plan, an intraoperative angiogram was performed, which revealed great collateral support for that MCA branch that was lost during clip application since the flow appear to be very adequate and bypass did not seem necessary and I felt I have achieved adequate exclusion of the aneurysms based on my intraoperative findings. You can see the first component of the aneurysm was completely excluded on postoperative 3D angiogram. However, there was a slight residual aneurism around the other M2 branch that I left behind to avoid any loss of this important branch with placement of the second clip. This patient did very well after surgery and this slight residual aneurysm has remained stable at five years followup. These dysplastic congenital aneurysms are again quite difficult to exclude with clip ligation and at the same time preserve their branching parent vessels. Revascularization procedures as contingency plans should be available during application of a clip and suboptimal clip application may also be necessary to avoid undesirable sequelae. Thank you.

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