Grand Rounds-Microsurgical Management of Cavernous Malformations: Personal Perspectives
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- Or a mouse. As you can see, this is a brainstem cavernous malformation that's with a relatively recent bleed. And I think this sort of highlights, this is some of our animation via computer scientists. And I'm gonna start off with 2D sort of the M for you to really appreciate when we switch over to 3D. the sinus is here on the left side, it's tacked up the bone flap when across the sinus. we're separating the arachnoid adhesions from the tentorium and then creating a space. I'm a big believer in not using a rigid retraction but naturally we're retracting all the time, which we've called dynamic retraction because you're using your instruments. The advantage of that is that you're really only retracting where you need to see, and it is going on all the time. So you're relaxing, retracting, relaxing, retracting, utilizing the drainage of CSF. We're now down in the ambient cistern, we're over the top of the cerebellum. Were we able to find a laser or anything like that? No, okay. And then with image guidance, now we've switched over to 3D. We've made a small opening into the midbrain medial lemniscus, which is an incredibly well tolerated incision. Venous bleeding is not infrequent with cavernous malformations because they clearly are venous pathologies. So they really come from the venules. You could see veins with their first budding of a cavernous malformation if you look closely. So getting down to the cavernous malformation, the component of the venous anomaly is what I generally call it that's part of the Cav mal naturally you have to take the portion of the venous malformation that drains the normal surrounding brain and often can be very, very large. It has to be very much preserved. So you'll see this constant removal here. You see the little vessels utilizing attraction, and then that sweeping movement of the sucker. That sucker has a teardrop opening in it so that when you completely have moved your finger from the teardrop opening, there's no suction at all at the other end. So you're just really using it as a dissector. So constantly moving back and forth between the traction and the suction. And the other thing that I think we've learned with experience is to spend a lot of time looking at the cavity and pulling out anything at all that looks like reminiscent of cav-mal. The little white fibers that you see, because obviously the walls of the cavernous malformation is an endothelial cell so it's very, very thin. And when the blood is out of it, it makes it difficult to appreciate that it is part of the cavernous malformation. But in order to limit the recurrences, that's really what you have to do. So this is all part of going around the cavernous, the wall of the cavernous malformation to pull out the little bits and pieces. And it's amazing how often when you think you're already all done you'll find another little component. And then once we're all done, we spend time to make sure that it's dry. And here you can see on the right slide, you see the nice pathway into the midbrain over the top. This is a deep cavernous malformation. As you see here, it's a little five-year-old. You can see the presentation with some weakness. This is the setup. Do you need image guidance for this? No, not really. But the advantage of having the image guidance is that you know how far you are across the cavernous malformation, the best angle to it. Bipolars obviously are very important. I have a bias against these, they're non-stick and they're basically throw away, which means that they're always clean and always safe. And here we are going down in the Sylvian fissure and then off the Sylvian fissure directly to the cavernous malformation. Bipolar ring some of the venous component also shrinking it so that we can keep the opening to the cavernous malformation as small as possible. And you can just see breaking it off piecemeal and you see no rigid retraction here at all. And that constant sweeping motion using your sucker as a counter traction to your instrument. and here you see the cavernous malformation resected. This is one in the left, a little further back. Thank you very much. And here we're gonna do it. We're gonna open the sulcus and it really sort of emphasizes how the sulci really are beautiful ways of getting into the deep portion of the brain. So we see the surface vessels, we see a large vein down here, and then the arteries inside the sulci constantly spreading one way, the other direction. Using image guidance could see where we are and then inside the cavernous malformation, just removing it so that the center is gone and we can bring it toward the center that we've debulbed. So here is really this constant motion of bringing the cavernous malformation toward the center. These are little micro pickups, suction that has a light at the end of it. Since we have very small openings, light is always a problem because the light from the microscope and the vision from the microscope come in at two different angles. So that the deeper you go, the less light you're gonna have in the center of your aperture. But you can just see this constant separating of the brain utilizing your suction. And then finally a very good obstetrical move, and the placenta is out. And then again, bowing around the cavity, making sure that we've really gotten the dial as completely as at all possible. And you can see really the brain is nicely intact, utilizing the sulci. and even though we're very eloquent cortex, there was absolutely no deficit in this young woman. This is gonna be a telovelar craniotomy. So the cavernous malformation is off on this way, so we're gonna come off to the side. Now what's important is that the incision is low because you want to slide up underneath next between the two tonsils, but you wanna have a shallow approach. And here also you see with that approach, we see the floor of the fourth ventricle. It has some hemosiderin stain on it, but we open between the vermis and the tonsils or the cerebellar hemisphere just like a Sylvian fissure. And you just keep opening and opening until you have nice exposure. And again, no rigid retraction, taking a piece of gel foam. And this patient is obviously prone and putting it up toward the top of the fourth ventricle to prevent any CSF from going or blood from going up the aqueduct. And then opening off the midline, this is really off to the lateral side, just where the foramen of Luschka is, identifying the cavernous malformation and then removing it piecemeal. Again with the light at suction that really gives us the ability to see so that we can differentiate cavernous malformation from the surrounding brainstem. You see that constant pushing with the sucker and just keeping going around. These are very small pituitary like instruments, very small opening, obviously, if you can see how that small sucker takes up so much of the room. And you see, whoops, sorry. And you see the light from the suction really sort of illuminating that area that is most important for you to be able to see. And it's not infrequent that it's really quite difficult to make sure that it is not just the raw brain that you're looking at, as opposed to part of the cavernous malformation. And here you see the opening and here you see the post-op where the cavernous malformation was. This one gets a little bit deeper. This is in the thalamus. You can see here its relationship to the third ventricle sitting right here. This is the position that we liked the patient in. The head will be turned so that this here is horizontal. There is no reason for the patient to be vertical because your eyes are horizontal and your hands are horizontal. So you're gonna get your best coordinating efforts by having the patient horizontal to the floor of the bed. Going in between through the corpus callosum, between the two arteries entering the third ventricle, I mean the lateral ventricle, and here you see the choroid plexus. If it's in the way we can drink it some, and then opening the choroidal fissure and getting right down into the third ventricle. Now most textbooks really tell you to open the choroidal fissure between the choroid plexus and the fornix. I like to open it lateral to the choroid plexus, because then you can use the choroid plexus the buttress, the fornix, which is obviously one of those key structures that we wanna not hurt in any way in order to minimize the risk to memory. So by just utilizing these, we're now down in the third ventricle, moving around until we can see the cavernous malformation, you can see our approach here all the way down. And again, we need that light. We mobilize that cavernous malformation and then remove it piecemeal. That constant movement you see is because the microscope is obviously being used with a mouthpiece and I constantly move it around to get the best focal length and the best angle, visual angle to the pathology. See no retractors, you're just using gravity on the ipsilateral hemisphere. And then you're moving the cavernous malformation through that exposure. And then spending again, a lot of time inside that cavity under high magnification, you can see all the hemosiderin. To get rid of the cav-mal, here's the choroid plexus. And here's the opening and the corpus callosum. Always taking the bone across the midline. So you can actually pull the sagittal sinus across and you can see the empty cavity. This is a midline approach again, and here you see a cavernous malformation that's really sitting in the aqueduct underneath the quatre genital plate. Again, the patient is horizontal, that's fornix on top opening between the arteries the A3's, looking into the third ventricle, and then opening the third ventricle again, the midline is off to the top. We're opening the choroidal fissure. And then we get all the way down to the posterior portion of the third ventricle. You can see our line of approach here. And then we see the cavernous malformation sitting really right, and the post, your third ventricle at the mouth of the aqueduct. And then again with these tiny little instruments, we remove the cavernous malformation. Sometimes I'll brace my foot against the operating table to pull it out as hard as I can. Just making sure you're not all asleep. I've used Ventriculostomies a lot beforehand. Now I sort of decide whether it's dry or not. If it's completely dry and I'm not worried, then I'll have a ventriculostomy at the bedside, but not leave it in. Initially, I always add it in. And feel free to interrupt at any point in time, I heard that Linda, I've got you identified, troublemaker. And here you can see this is where it was, nicely removed. Patient tolerated this really just remarkably well. This is left interhemispheric so this is now very deep sitting right here. Again, this is the sort of position, the pedis horizontal. Here we've opened the contralateral, I mean the lamina just so that we can get CSF out. We're looking at choroid plexus here. That's the foramen right here. And we're gonna go right through that to expose the cavernous malformation. It's just sticking right out at us. Sometimes those that really look particularly difficult, turn out to be much easier. Fornix will be up here. Oh, this is just really the lateral wall of the third ventricle, but working through the foramen of Monro rather than opening the choroidal Fisher. And sometimes it's rather difficult to predict which one you're gonna need. And here it comes in pieces. And you really see how pristine the rest of the surface of the third ventricle is. This is getting down to the hypothalamus. We were worried about the hypothalamus so we kept our opening small. Constant counter pressure with our sucker. You see there as we pick it up and mobilize the wall of the cavernous malformation. You can see that constant motion and you can see why you need the light in there because it's very far down through a small corridor, depending on your focal length, your light and your visual access can be separated by as much as six degrees. And you can see when the light isn't there, how dark it is just with the microscope light in itself. And that's why you really need to keep looking, because very often there'll be a cav-mal that's hidden behind a layer of what looks like just hemosiderin type brain. So he's spreading the tissue apart to make sure that we've gotten it all. So here's where we opened the septum pellucid just to get rid of the septum pellucid and falling into our vision. That's where the cav-mal was and it's gone. Retrosig approach. This is a cavernous malformation sitting here. Depending on the stiffness of the patient's neck, obviously most of the time, we'd like the patient just supine, maybe park bench. Opening the arachnoid planes, going between the lower cranial nerves and seven and eight, and then opening lateral into the brainstem. We don't wanna be opening anterior because that's where we have our motor fibers. You see sixth cranial nerve down below, off to the side, and then just wiping the brainstem away, the thin little layer away from the cavernous malformation and removing the cavernous malformation in pieces. No retraction required, no retractor, despite the fact that patient is not in the sitting position. And you see some of the acute blood that was there, the hematoma, and then we spend a lot of time again cleaning it out. And that's the cavity. And here you see the entry, remarkably the weakness was not worse. So how do we get to a lesion like this here? This is a perfect example of the big problem naturally is to go to the very lateral portion of this meningioma. And the question is, how do you get there with the minimal amount of retraction? In this case, what we do is really go contralateral, opening the fornix. So we're on the right side, the right hemisphere is down. Opening the fornix, the meningioma is on the other side of this. And then we're bringing that into the space we've created rather than retracting the left hemisphere to get to the lateral edge. So we're using gravity not only to retract the ipsilateral hemisphere, but also the contralateral tumor. So it comes into our field, some ultrasonic aspiration creating space to bring in the remainder of the tumor. Cutting some more of the fornix now that we have visualization. We obviously wanted to make sure that we didn't impair all the anterior cerebral arteries. And you can see a very nice layer between the brain and the tumor. Again, gently separating it with retractors and your suction bringing it into our field of view, and then using the ultrasonic aspirator to remove the bulk of the tumor. No retractor required. We're just using gravity itself to help us with the visualization. And then again, with these nonstick bipolar separating the tissues and then bringing out the portion of the tumor that we didn't remove ultrasonically, keeping the veins intact. And when we liked the patient we close them back up. And the post-op, notice no trauma at all to the hemisphere. This is an anesthesiologist who was symptomatic from this lesion which looked like a cyst but it had a fluid level. And really it was a pineal cytoma, a long marking but only a short opening. And here you're looking at the top of the head is here. This is the tentorium. This is the midline coming down, separating the cerebellum and it's cetaceans from the tentorium coming down to where the pineal gland is. And you can see that it's a rather thick layer of arachnoid, which is not unusual whenever you have pathology down here. It would be very rare that I would take the precentral cerebellar vein. So that makes that space a little tighter. That means you leaving the precentral cerebellar vein there, you're going laterally. This is the basal vein of Rosenthal off to the side. Underneath the tentorium you can see some occipital veins. So we're going between precentral cerebellar vein here, vein of Rosenthal, right to where the pineal area is. And here's the cyst itself and you'll see very quickly that it's also a tumor. Opening it, you get an appreciation for the hemosiderin stain and the hemosiderin fluid that comes out of the cyst component of the lesion. And you can really open this space very widely and then separating the tumor and the cyst from the surrounding structures. And through this small window, you can really do this very readily. If for some reason you feel constrained on this side, then you can go over to the other side and do the same thing. But usually for these relatively small lesions, this can be mobilized pretty readily. And again, here you see the mass itself being removed. And again, you see that even though the patient is either park bench or prone, you really don't need any rigid retraction. Key is to be able to pull the sinus superiorly because you have enough bony exposure above the sinus. And those millimeters make a very big difference. This is how do we preserve hearing with the acoustic neuroma here you see the lesion, it's a cystic one. Cystic tumors tend to be more aggressive. Opening the porus, going to the brain stem, identifying where eight takes off, opening the tumor itself in line with the axis of the eighth nerve, separating out tumor on the inside just so that you've got some room on the inside so we can collapse. Then the secret really comes right here, and that is identifying that thin little layer that separates the tumor wall. And if we can identify that layer, then here you can see this is seven and eight. This is part of the vestibular nerve. That's the portion we're gonna sacrifice. I still like to keep it intact as much as possible because it gives me the anatomical landmark and it protects the rest of the eighth nerve. Seventh nerve naturally is completely protected anteriorly. And then separating the tumor, here we see a beautiful eighth with seven underneath the . No change in the evokes during this time, a little bit of tumor off to the side until we really have it emptied except for the very top. And there we have to be very careful that our instrument doesn't really injure the eighth nerve higher up until it's really completely clean. No retractor in place. And that's the eighth nerve. And here you can see there's suction, and there was really no change in hearing in this particular...
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