January 13, 2016
Atherosclerotic MCA aneurysms can pose a number of different challenges in their clip ligation. Let's review some of these challenges in this video. This is a 60 year-old male who presented with an incidental 10 millimeter right-sided MCA aneurysm, as demonstrated on this catheter arteriogram with a relative complex morphology and a broad base. He subsequently underwent a pterional craniotomy for clip ligation of his right sided MCA aneurysm. You could see numerous Sylvian veins. I typically conduct the dissection between the veins as there's usually no significant connection between the veins. However the veins reseek contributaries from the surrounding opercula. Through our forceps, gently tear the arachnoid bands while protecting the thin-walled veins. I really do like this technique which is efficient and at the same time, very safe. After the thick superficial arachnoid bands are dissected, I cover the brain to protect the brain against the heat of the microscope. Dissection is deepened and the Sylvian fissure is opened in the inside to outside technique. This means that the first step of the section is conducted deep into the surface of the insula, and the M2 branches are identified, and then the dissection is conducted from inside to outside. One of the veins had to be sacrificed here to be able to mobilize the frontal lobe. Sharp dissection is the best technique to preserve the pial banks. The anterior aspect of the Sylvian fissure can be quite adherent, requiring patience on the behalf of the operator. Generous dissection and splitting of the fissure, obvious the need for the use of fixed retractors. Here, you can see the dissection is conducted from inside to outside technique along the sphenoidal segment of the fissure. Here's the M1 branch around the alignment insula. The arachnoid bands allow mobilization of the frontal lobe away from the transsylvian trajectory. Here is one of the veins draining into this fennel parietal sinus. Dissection, again, is continued along the entry aspect of the fissure to allow gravity to mobilize the frontal and temporal lobes. The spring action of the bipolar can be effective here against that dominant Sylvian vein that is not sacrificed, but mobilized away from the frontal lobe. Here's the medial aspect of this lesser sphenoidal joining the clinoid process. Here is the vein draining into this sphenoparietal sinus. All the important veins are protected as much as possible. Here's the optic nerve. So the fissure is dissected aggressively. The M1 and M2 branches are exposed so the vascular anatomy can be protected during deployment of the clip. No fixed retraction is used. Here's the neck of the aneurysm, you can see the atherosclerosis, and potentially some calcification at the neck of the aneurysm. As the aneurysm is identified and its location is more discernible, the fissure may have to be dissected more posteriorly. The angle of the microscope is directed from superior to inferior direction to minimize the use of retraction of the superior temporal gyrus. You can see the atherosclerosis, you can see the funnel trunk, the temporal trunk is hidden underneath the aneurysm. A temporary clip is placed and here you can see the origin of the temporal trunk around the atherosclerotic neck of the aneurysm. Papaverine soaked Gelfoam may be used to relieve the spasm in the smaller branches of the frontal trunk, it is along the posterior aspect of the neck. You can see the use of gentle dynamics retraction to guide the dissection. This lobe of aneurysm is relatively bulbous, interfering with adequate visualization of the neck, gentle bipolar coagulation, and aneurysmorrhaphy along the midsection of the aneurysm dome can be effective to facilitate precise clip deployment. I'm concerned that the initial clip could potentially slide and occlude the temporal branch. I first gauge the flow within the branches before the clip is applied using Doppler ultrasonography. Here's the piece of papaverine soaked Gelfoam bathing the smaller vessels that appear to be in spasm. Temporary clip is reapplied, so I can deflate the aneurysm and be able to fashion a good clip. Here's that bipolar coagulation along the midsection of the aneurysm to facilitate clip application. A straight clip is applied. The clip appears to be sliding toward the temporal trunk. You can see that the clip is compromising part of the origin of the M2, because of the evidence of atherosclerosis and mild calcification at the level of the neck. Ultrasonography confirms lack of flow within the temporal trunk. I'll go ahead and remove this clip after more of the aneurysm dome is exposed so that I can mobilize the clip away from the neck. I'm still concerned that this atherosclerosis can be problematic. Enforcing my clip proximally, the flow is restored within the M2 branch. I create more space around the neck of the aneurysm and hope that I can place the clip more distally. Additional aneurysmorrhaphy is conducted. I avoid coagulation of the neck to prevent its weakness. Now the aneurysm is more manageable and does not appear as bulbous. Here's the clip placed more distally across the neck. However, it continues to slide more proximally toward the neck of the aneurysm, compromising the M2. I try put a second clip distally and there remove the proximal clip. Despite this measure, the clip continues to slide toward the M2 origin. Since this maneuver was ineffective, I continue to try to gather the bulbous aneurysm, hoping that the clip would sit a little bit more distal to the neck. Again, the clip continues to slide. Tried to put a second clip distal to the first one and move the proximal one, this maneuver appeared to be effective, but still I'm not satisfied with the inlet into the temporal trunk. I allow some reperfusion, assure myself that most of the M2 branches are patent. Still there is some compromise of the temporal trunk. We have to rethink our clip application. I use now a fenestrated clip next so that I can use the additional closing pressure at the tip of the blades of the fenestrated clip. This is again another attempt at using the tandem clip configuration, hoping that I can achieve anything better, which was again unsuccessful. Here is the application of the fenestrated clip with additional closing pressure at its end. This appears to be more effective. The clip is no longer sliding toward the neck of the aneurysm. The inlet is free. I repositioned the clip so I'm happy with the drainage into the temporal M2. A second straight clip is used to close the opening across the fenestration. Now the temporal trunk appears patent. Intraoperative fluorescence angiography using fluorescein and ICG confirms patency of the temporal and frontal trunks with complete exclusion of the aneurysm. I'm satisfied with the result. Since there is some shortcomings with the use of fluorescence with atherosclerotic aneurysms, I would puncture the aneurysm after its complete clip ligation. I had to reposition the fenestrated clip because it appeared slightly short. Now it appears all the way across the distal neck. The temporal trunk remains patent and free. Here's the final product. You can see that avoidance of fixed retraction leads to a healthy brain at the end of the operation, all the veins also remain healthy. Closure is conduct in standard fashion. Adequate hemostasis is achieved. Watertight closure of the dura is not necessary. Postoperative angiogram demonstrated small amount of residual neck, which was necessary to avoid compromise of the temporal trunk since this area was affected by calcium and significant atherosclerosis. This patient recovered from his surgery without any untoward effect. Thank you.
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