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Grand Rounds-Minimally Invasive Spinal Cord Tumor Resection

Jean-Pierre Mobasser and Richard G. Fessler

June 10, 2011

Transcript

- Good afternoon and welcome to another series of the AANS Operative Grand Rounds. I'm Jean-Pierre Mobasser from Goodman Campbell Brain and Spine. And today we are gonna be discussing minimally invasive spine surgery for tumor resection. With us we have Dr. Rick Fessler. Good afternoon, Rick.

- Good afternoon Jean-Pierre. How are you?

- Good, thank you. Thanks for joining us today. We appreciate you taking the time to do this with us.

- I'm very happy to.

- And let's jump right in and discuss the different types of tumors we're gonna be dealing with, both intradural and extradural. And I think you can look at the standard list of tumors that we tend to deal with in these areas. We'll move on and start with some intradural tumors, which are largely benign and resectable lesions. Obviously there are gonna be some nuances and differences between the types of tumors, both intra and extramedullary and the different types of intramedullary lesions. Do you mind discussing these different types briefly and telling us which ones tend to be easier to resect and what problems you run into with the surgery itself?

- I'd be happy to. I have not done dermoids or epidermoids yet. I think they will be difficult because they tend to be such fungating tumors that are stuck to everything around them. So I'm thinking that just as when they're open, those will be very difficult tumors to take out. And hemangioblastoma probably turns out to be an easy tumor to take out, as long as one maintains good hemostasis, because the border between the hemangioblastoma and the spinal cord tissue is very clearly distinguishable. Ependymoma maybe the harder tumors that we take out on a routine basis, because occasionally, they can be fungating out of the spinal cord itself. And at least at some point in every ependymoma, you reach a point when you can't tell for sure whether the tissue you're dealing with is ependymoma or whether it's normal spinal cord. That of course is the point where we always hopefully stop, so that we don't injure the patient. Astrocytomas, really are relatively easy as well, because we tend to be less aggressive with them, because we often can't distinguish the plane between normal tissue and tumor. So we tend to be less aggressive in taking them out and they tend to be not so hard to work on.

- And I think we're gonna talk a little bit about the principles of doing tumor surgery, both open and minimally invasive. Having in open cases, having a laminotomy or laminectomy to expose the entire tumor, and then both be rostral and caudal to the lesion itself. I think what we're gonna look at with the minimally invasive approach is, is that same exposure truly necessary. One of the nice things about a minimally invasive approach is preserving the ligament structures and potentially as fine as process and inner spinous ligaments. Rick, correct me if I'm wrong, but you've been able to protect and preserve the spinous process and the supraspinous ligaments in most of these cases you've been doing, correct?

- That's correct. So far, I haven't had to take the supraspinous ligament. In order to gain a very good dorsal exposure of the spinal cord, if you're going to do an intramedullary tumor, for example, you do drill away quite a bit of the base and unilateral side of the spinous process, and that may compromise the patient. Although we haven't seen that so far.

- And then moving into the classic open surgeries, we can see an example here with a thoracic tumor on the ventral side of the cord and see the wide exposure, the muscles retracted all the way out beyond the transfers processes, the multi-level laminectomies. And it seems like a lot of soft tissue trauma in order to achieve what's focused in the center of the picture, which is the exposure of the spinal cord in the tumor.

- So this slide really demonstrates that most of these tumors are very focal problem. I think many of the problems we've experienced in the past, haven't been related to taking out the tumor, because we've done a pretty good job on that, but they've been related to what we have to do in order to get to the point of taking out the tumor. I think now recognizing that in fact, these problems are focal, developing the appropriate retractors, visualization and instruments, we can now get to these tumors without destroying the normal anatomy that surrounds them.

- And therefore being able to avoid having to fuse, a large amount of these patients.

- Having to fuse them is it's actually very rare. I've only had the fuse one patients so far, that was a patient who had a very large cervical dumbbell neurofibroma. And in order to get the entire tumor out, we had to do a two level facetectomy. So in that patient, we did have to do a fusion and a posterior instrumentation. Those of course were done minimally invasive as well.

- And one of the pitfalls of open surgery that may require a fusion is subsequent imaging to follow the lesion, particularly if it's a young patient.

- And that's had a huge impact on our ability to follow these patients. Of course, titanium has helped us along because our imaging quality with titanium instrumentation is much better than it was with our previous stainless steel instrumentation. Cobalt chromium is falling somewhere in between, but still the imaging characteristics that you get with cobalt chromium are not great. So if we can avoid instrumenting these patients, where we're far ahead and being able to image their spinal cord down the road to look for recurrent.

- I think some other benefits that we need to discuss are reduced pain and blood loss and a shorter recovery time with a minimally invasive approach, which you've all seen papers discussing this in minimally invasive lumbar fusions in addition to tumor surgery.

- The issue with tumors, patients can be charged the day after surgery or two days after surgery. So it's had a huge impact on the rapidity of their recovery.

- Let's look at this lesion that you're showing here, and this is upper cervical lesion at the C3 level. And you can see on the left-hand side, the sagittal and below it the axial image showing an enhancing lesion ventral to the spinal cord that does not appear to be durally based.

- That's correct. In this individual, the tumor turned out to be an ependymoma. When you look at the sagittal image, you tend to think, my goodness, this really can't be done minimally invasive. And even in an open approach, this is going to be a very difficult procedure. But when you look at the axial image, you can see that in fact, the tumor is very far off to the side. And when you release the dentate ligaments, the spinal cord is gonna slide over even more. So most of the tumor actually is going to be exposed through a unilateral approach. And then by debulking the tumor slightly, we should be able to take it out, lateral to the spinal cord without manipulating the spinal cord very much at all.

- And your CAT scan really shows the bony window you created in that hemilaminectomy, which really matches the MRI axial image of where the tumor was.

- And the tumor came out very nicely.

- The post-operative image on the right side of the screen looks very nice. We then can turn to a different part of the spine and the lumbar spine at cauda equina at the end of the phylum. And look at this lesion here, both on sagittal and axial view, which shows an enhancing lesion at the level of the cone is consistent within ependymoma. Obviously, we're now not having to worry as much about the spinal cord, although we still monitor for these cases as well, correct?

- That's correct. I use both motor and some sensory for all of my cases.

- Do you think it would be safe to say that neuromonitoring for spinal cord tumor resection is pretty much a standard, nationally?

- At least for the intradural extramedullary tumors. I know very many accomplished neurosurgeon that do not monitor their intramedullary spinal cord tumors because, usually their dissection is going to cause some alteration of those responses and they feel that as a result of that, it really gives them no further information.

- Sure. So let's take a look at a video of this case.

- So at this point, in this case, we've already done our incision, our dilation through the fascia and muscles, the hemilaminotomy, and now we've opened the dura and are beginning to tace the dura back. Essentially these techniques are exactly the same, minimally invasive as they are open.

- And it looks like you're now sectioning the connection, is that on the rostral or caudal and that you started with?

- This is on the caudal end. In this particular case, this was a very early case that I did. And as you can see, I debulked the tumor before I pulled it down and cut the rostral end. For caudal end ependymoma, I don't recommend doing that and I no longer do that. But I think my technical skills were less advanced when I did this tumor than they are now. And at this point I would take these tumors out intact.

- And your reasoning is to prevent spread of possible cells within the CSF?

- Correct.

- Okay. Well, it looks like you're able to get a very nice resection and here it looks like we're getting it above the lesion and coagulating and cutting the phylum at that level. Correct?

- Correct. And then the entire lesion came out.

- And that has a very nice subsequent image of the nerve roots at this point. So now we're gonna get to the dural closure issue. And do you obviously like to try for a primary closure as much as possible?

- In most cases we do a complete primary closure. The only time that's not true is if we resect the dura, for example, in the case of an meningioma. And in those cases, we will put a graft in.

- And I assume as you guys have been doing this for a while, that technology, the instruments you now use to do these surgeries is improved over the years.

- Yes, and this very early video, you can see that we're using standard instruments. The only difference is that these are thoracic surgery and the scopic instruments, so they're much longer than our typical instruments. What we use now though, is a modified Peapod pituitary. Peapod pituitary is a short up biting pituitary. What we did to that was modify it so that it will hold a needle rather than bite and it can lock. So that angle turns out to give you the perfect angle to show you a stitch. We then tie the knot outside of the patient and push it down into the wound with a knot pusher.

- And are you now using a bayonet knot pusher or just a regular knot pusher?

- I think that is relatively insignificant. If you're doing the tumor resection on the dural closure under a microscope, then a bayoneted instrument will be advantageous. If you're merely doing it with loupe magnification, it probably doesn't matter.

- And this postoperative MRI looks very nice. It shows a very nice resection of the lesion with the expansion of the canal, is that just a little fluid collection in the epidural space in the laminotomy defect, or is that some sort of fibrin glue product?

- That's just a fluid collection. This is a very early postoperative MRI. And that's just a little fluid that's leftover from the surgery itself.

- Do you ever use fibrin glue products along your suture line?

- I often will. I generally will put down a layer of dura Jen over the suture line. And if there's any question of whether I've got a tight dural closure or not, then I will use some fibrin glue as well. If I'm comfortable with the closure, however, then I don't use that.

- Here's another lumbar lesion, and intradural extramedullary lesion, again, both the sagittal and the axial MRI showing an enhancing lesion within the canal. Again, appears to be pushing all the neuro elements, ventrally and laterally.

- That of course, makes it a little bit easier. And those are great cases to begin with. If you don't have to work your way through an entire mass of nerve roots and the tumor presents itself to you very early, it'll make the case much easier for you.

- And here we see the beginning of this case with the dilation technique, through the pair of spinal muscles, using fluoroscopy to localize the area, have you changed your tractors over the year?

- I have. In our early cases, the only retractor that was available was the xtube. And that was adequate to do a tumor that did not extend more than two segments. But many tumors in fact, do extend more than two segments. So we've actually gone to retractors such as the quadrant retractor, and there are a variety of them available now. They will allow you a little bit longer cephalad and caudad retraction, and they also have a separate medial lateral retractor. And they actually will retract the soft tissues better than just as standard tubular retractor. And as a result of that, there's less soft tissue to remove at the bottom of your retractor before you get to the bone.

- And in looking at this intraoperative picture of that particular lesion, what strikes me is what a good view of the lesion there is and how it seems that there's not significant blood loss or tissues exposed around it, how we're solely focused over the lesion itself.

- I think that's correct. There's very little blood loss, average blood loss where a case like this, even with a three or a four level hemilaminotomy will be 200cc or less. All of the surrounding tissues remain essentially normal, but you get essentially an identical exposure of the tumor that you do with an open procedure.

- Postoperatively, the MRI again looks very nice. Do you wanna comment on the skin incision and location of the skin incision?

- Yeah, this slide nicely points out one of my learning lessons. When I started doing these tumors, it was my assumption that I would have to take a relatively lateral approach in order to get an adequate exposure of the tumor itself. It turns out that by bringing my incision to a centimeter and a half off midline, rather than five centimeters, I'm able to take off the base of the spinous process and contralateral lamina much more effectively and consequently get a much better exposure of the intradural content. So, I no longer recommend a far lateral incision, I would do this at a centimeter and a half rather than five centimeters.

- Okay. And what size tubular retractor were you using when you're using a fixed tube?

- It was the xtube. So it's 25 millimeters on top and it'll expand to 40 millimeters on the bottom.

- And obviously we can use different depths based on patient size, correct?

- Correct. And you can give to the top or the bottom of a longer tumor merely by winding the tube up or winding the tube down.

- Okay. Here we have what looks to be a more difficult lesion, a thoracic mass that appears to be durally based in this mid thoracic spine and appears to be very ventral.

- That's correct. And when it immediately becomes a concern, because you don't wanna manipulate the spinal cord in these cases, but I don't think one would manipulate the spinal cord anymore and in minimally invasive approach than one would in an open approach. And of course the keys to resecting these tumors are to get an adequate exposure above and below the tumor to perform a partial facetectomy or panniculectomy in order to be able to work laterally to the tumor, to section the dentate ligament so that the spinal cord will move slightly out of your way, and you won't have to retract on it against the traction of the dentate ligament. And that should debulk the tumor, so that you can move it out from underneath the spinal cord, without manipulating the spinal cord itself.

- It strikes me that there's certainly, gonna be a learning curve to these. And it seems like starting with a lumbar tumor without spinal cord involvement and getting comfortable doing these would be preferable to starting with something like this.

- Absolutely, not only is the risk higher up here, but by starting in the lumbar spine, you have a larger area to work with as well. The working space in thoracic spine is significantly smaller than it is in the lumbar spine.

- How many lumbar cases did you do before you tackled a lesion such as this?

- Probably 10 to 15.

- Okay. And that's coming from somebody with an expertise in both spine tumor surgery and minimally invasive surgery.

- And that brings up a very important point. The learning curve for minimally invasive surgery is significant. And of course the learning curve for spinal cord surgery is significant. So I think one wants to be comfortable at least with one of the two to a large extent before you attempt to do minimally invasive spinal cord tumors, that as you either want to be a very accomplished minimally invasive spinal surgeon, or you want to be a very accomplished spinal cord tumor surgeon before you start combining the two technologies.

- I would agree with that completely. Do you feel that these procedures are good at the tertiary center type of procedures? Or do you think this is something that someone in the community could do if they had comfort with both of those areas?

- I suspect that most spinal cord tumors are done at tertiary referral centers. And I'm pretty sure that particularly, minimally invasive spinal cord tumors will be that way. Certainly for intradural tumors, some of the intramedullary extradural tumors aren't that hard to take out. And I think a very accomplished tumor surgeon or a minimally invasive spine surgeon could do that in the community setting.

- Well, let's look at a video of this case and why don't you walk us through the opening and exposure here.

- Again, we've done our incision, which is a three centimeters long. We've done our dilation, taken off the residual soft tissue and then done a hemilaminectomy and drilled off the ventral surface of the spinous process and contralateral lamina. I find hemostasis of the lateral gutter is the same in a minimally invasive approach, as it is in an open approach. My particular technique is to fill the lateral gutter with SURGIFOAM and then pack it with SURGICEL. And by doing that, I get very nice seamless stages of the lateral gutter, even after you open your dura and you start draining CSF. Tacking the dura back then to the sides of the canal to your soft tissue should be essentially the same as it is in an open procedure. And by doing so, again, you can see here how we tie our knot outside the body and push it down with a knot pusher. You can see that we're exposing the lateral side of the tumor already. The next thing I'm doing in this particular case then, is releasing the dentate ligament. And when that's released, you can actually see the tumor becomes much more visible.

- I tend to like the fact that most of the spinal cord is protected and covered by the dura rather than being exposed as it normally would be in an open case.

- I think that will provide us some protection. Because if with a relatively large tumor and located completely ventral to the spinal cord, we need to debulk it. And I began that by bipolar ring insertion along the dura, and then doing essentially a suction de-bulking with a ultrasonic device.

- Do you have some particular tips with the ultrasonic devices for working through at such a small channel?

- Most of the ultrasonic device makers now have a minimally invasive attachment, so that you can do it through a tube.

- So, obviously planning these surgeries is critical and making sure that the equipment that you need is gonna be ready before starting a case like this.

- That's true. And lasers can be very helpful for this too now. And they have some very easy to use handheld lasers now that you can use to debulk these tumors before you take them out.

- And at this point it looks like you're able to rotate this portion of the tumor out safely. And it looks like you basically devascularized and removed it from the dura.

- Exactly. And then in this particular patient, this patient was relatively elderly and I didn't feel that resecting the dura would give her any more longevity to the tumor not growing, then she would have in living a normal life. So I did not resect the dura, and I'm really bipolar at the insertion site to try and kill all those tumor cells.

- If this were a 25 year old individual, would you change your surgical plan at all?

- I would try and resect the dura and to reconstruct it. My technique to do that would, it'd be hard to get stitches on the contralateral side. So, I would most likely lay my dural graft on the contralateral side without stitches, and then stitch it to the interlateral side and try and get a tight dura closure, fix it laterally.

- Would you lumbar drain the patient in a situation like that?

- Yes I would.

- And here we're going through the closure. And you can see your needle driver with a nice curve tip, which seems to add the ability to reach that particular angle.

- It makes it much easier. I will say though, that closing the dura is probably more difficult than taking the tumor out.

- I would tend to agree with that. Well, this looks very nice. At this point, did you put a dural graft over this suture line?

- I believe we did. It was either a dura gel or a gel foam cover and then pull the tube out and did a fascial closure with zero Vicryl stitches, three OF subcuticular stitch, and then close the skin with Dermabond.

- And I think as we've always discussed in minimally invasive techniques, having those muscles fold back over the wound, rather than have that dead space makes a big difference when it comes to pseudomeningocele and continued dural leaks.

- We just haven't had a problem with pseudomeningoceles at all.

- So, let's move on and we can discuss the intramedullary lesions. Obviously this seems to, again, raise the bar slightly higher than what we've been discussing before.

- I think one would want to be a very accomplished spinal cord tumor surgeon and minimally invasive surgeon before you attempt to any intramedullary tumor.

- Can you talk to me a little bit about achieving midline myelotomy through sorta hemilaminectomy approach?

- Yes, that's where it's becomes particularly important to make your incision a centimeter and a half off midline rather than five centimeters off midline for example. By doing it a centimeter and a half off midline, you can drill off very aggressively the base of the spinous process, a little bit of the spinous process itself and the contralateral lamina, so that essentially you can come down on the midline of the dura, and that is critical to being able to safely do intramedullary spinal cord tumor surgery.

- Okay, well, let's look at this lesion right here. We have a sagittal and an axial MRI showing what appears to be a intramedullary ependymoma. When you're planning for a case like this, are there any specifics or certainties that you need to address before going to the operating room?

- Well, in the thoracic spine, of course, you have to be able to correctly localize your level. And in minimally invasive surgery, that's even more important than open surgery, because you've got no leeway. You're coming down on a focal point and you better know where that is, and you better know how to get there reliably, before you ever make an incision. Now, I learned through years of doing thoracic disc surgery, that by being rigid in one preoperative workup and in one's intra-operative imaging, you can do that reliably. For example, I do not accept an MRI that will not show the lesion and either see C2 or the sacrum in the same cut. You've got to come from one end or the other and you've gotta have them in the same cut. And I prefer the sacrum because it's very difficult to image through the shoulder. The other thing I want to know, is I want to know that there are in fact, five lumbar vertebrae, and I want to know how many ribs the patient has, because that obviously will alter your level, one way or the other. When I have all of those things, I then will count in the operating room, knowing exactly where I have to go. I will count multiple times and I will have everyone in the operating room, including my scrub nurse and the people walking around agree that our count is correct, and that we are at the correct level. By being that rigid, I've been able to avoid operating at the wrong level in the thoracic spine.

- I think what you just stated is such a critical part of what we do nowadays, particularly in this day and age, where patients come with CDs from outlying facilities. It's hard to know how the radiologist has determined the level. Did he count from above, from below? We are routinely seeing patients that are sent from somewhere else, and when we reimage them, if we need to reimage them, the counting is actually different than what the outside facility has come up with.

- I find that very frequently.

- So, I think your point about having C2 or the sacrum in the view of looking at the lesion is a wonderful idea and something that I need to change in my practice. I've been averse to making patients go through multiple MRIs and trying to reduce costs and trying to be understanding of where they come from. But I think that all that can lead to is a potential disaster for you and the patient.

- I believe that's correct. This is one of the instances where I've really maintained extreme rigidity.

- What do you do if the insurance company denies doing it? Is that something you do a peer to peer conversation with to explain your rationale?

- Yeah, absolutely.

- So let's look at this thoracic ependymoma and obviously we've been through how we localize this, and here's a few interoperative pictures showing the myelotomy. Any particulars in the myelotomy or in this case that you found difficult?

- In this particular case, the midline veins showed me the midline sockets very nicely. That isn't always the case. As you know, when you get an expense or lesion in the spinal cord itself, you very often lose the definition between the dorsal column. And that of course can be critical. And it's particularly critical in minimally invasive surgery because you are coming down slightly off midline. So you've got to be very careful about where you make your incisions and try and use all the clues that are available to make sure you are in midline, so that you don't cut through one of the dorsal column. In this case, it was fairly obvious. And this was a beautiful case to begin with. This was my first intramedullary case. And it was nice because it was very small, very defined, and it had a fifth of both above and below it. So, I was able to define both the cephalad and the caudal borders of the tumor very nicely before I bisected into it. In this particular tumor, there was one spot laterally on the contralateral side, where you begin to lose the border between tumor and normal tissue, and that's where we ended our resection.

- Well, the inferior image shows what appears to be a very nice resection cavity.

- This turned out to be a very gratifying case. Not only technically, because we were able to get in there very nicely to find the tumor well and resected in total, but a year after surgery, that patient sent me a picture of himself when he was finishing his first iron man, since having had the surgery.

- I don't think you can have a much better outcome than that. Let's move on to this next example. Now, we're moving a little bit away from spinal cord tumors at this point. However, I think we're showing the utility and the versatility of minimally invasive approaches and what else we can do.

- Tethered cord is a very nice operation for minimally invasive surgery, sorta for two reasons. One reason is because many of the tethered cords we do are in children, and doing a large dissection on them is probably unnecessary and will affect their back strength in the longterm for the rest of their life. Also, they have a very short distance between their skin and their spinal canal. So I recommend using not the long tubes with an endoscope, but the short tubes with a microscope, so that you're technically, it's a little bit easier. The skin incision in small, the muscle dissection is negligible. The dural incision can be relatively limited. And with electrical stimulation, you can then be sure that you're just cutting the tether itself and not any of the nerve roots around it. One other nice thing in adults is that, as we all know in adult patients, the symptoms can be very fleeting and somewhat difficult to relate to whether they're being caught by the tethered cord or not. In those patients, if we're going to do a major dissection of their muscles, their ligaments and their spinal elements, when their symptoms come back, we don't know whether we failed to release their tether, whether the symptoms aren't related to the tether or whether they're related to our detection of all of their tissue. So by at least eliminating one of those, it makes your decision process and their subsequent management a little bit easier.

- Absolutely. Another utilization that you've shown is the post-traumatic syrinx and a particular patient that you had, who was 27 years old, who underwent a C6-7 fracture with an incomplete spinal cord injury, who then presented with increasing pain and spasticity in this scan.

- Yeah, this patient had, as you can see a relatively focal, but moderately large syrinx. She originally had a C6-7 spinal cord injury and in imaging of the rest of her spinal cord had no other pathologies other than the previous injury, which showed atrophy at that level. And then this particular syrinx. This turns out to be a relatively advantageous approach for these patients, because when you think about it, in a post-traumatic syringolmyelia patients, they are paralyzed. They do not have muscular strength to help with the biomechanics of their spine. They are totally dependent upon the integrity of the spinal column itself. So if we have to do a bilateral procedure, dissecting off the muscles and the ligaments, particularly inner spinous ligaments to do a laminectomy, only to put in a syrinx re-acclimate shot, then the chance of that patient becoming unstable in the future are moderately high. If we can avoid that by doing a mere hemilaminectomy, not taking off any of those ligaments or detecting the muscle, then I think their chances of becoming unstable in the future are much improved.

- I think that's an excellent point. And what I also like is something that we have yet to discuss, is the use of ultrasound inter-operatively for intramedullary lesions or syrinx.

- Most of the companies now have ultrasonic probes, which are small enough to fit down the endoscopic tubes or the other retractors that we use. One thing you have to be careful of, is that some of them have sacrificed quality of image to be able to do that. So you have to be sure that the probe you're using will give you a reasonable image of the pathology you're looking at.

- And I think it's nice that you have a sorta system that you utilize to make sure that you have everything properly done in order and prepared before an operation. I think sometimes if you don't have a rigid way of planning these things, you may forget things such as ordering the ultrasound preoperatively, so that it's there when you need it. Then that can either delay the case, or you make the decision to proceed without it.

- And it can make the case harder. One of the lessons I've learned over the years is that you want to have a very set routine for the peripheral of your surgery. And by that, I mean, everything that you're going to use, the surgical instruments, the devices you're going to implant, the additional tools you're going to use such as microscopes, ultrasound, lasers, things of that nature. And you want to make sure that the people around you, know how to use them, so that you can focus on the operation rather than the peripheral. If you have to focus on the peripheral, it's much easier to make a mistake in the operation itself. So you wanna make those, so that you don't have to think about them at all, and you can focus on the operation itself.

- And I think that's a very valuable piece of information for the younger surgeons, developing their practice or the residents who are right now focused on learning how to do the operations. These are the things that are gonna make a big difference when it comes to complications, errors, and decisions that could have been done preoperatively that you then end up regretting post-operatively.

- And those are preventable errors.

- So in this syrinx, we can see the myelotomy that you made. And at this point you utilized a catheter to keep the space open and draining.

- I just use a ventricular catheter that we use for shunting. I cut a little bit bigger holes in it, and I suture it to the PO and I run it from the syrinx itself to the subarachnoid space.

- And this is a post-operative MRI showing the syrinx cavity completely decompressed with just a residual area. It looks very nice.

- This patient ultimately has done very well. This procedure was done probably eight years ago. She's lucky, she hasn't had any recurrence of her. I recently saw a new MRI on her and she has continued to do quite well.

- I see your approach from the right side on the axial image. Does it really make any difference whether you approach right or left or is that more of a surgeon comfort?

- Yeah, and it made no difference in this case. Often I will approach from the patient's left side because I'm right-handed. So if I'm going to be doing laminectomy, that for example would make it a little bit easier. But ultimately if there is a side that you have to approach from, then I approached from that side. In this case, of course, it didn't make any difference.

- And nice that you're able to avoid her tattoo I guess.

- I didn't wanna disturb her butterfly.

- Very good. This is an interesting little lesion. Something that we probably aren't gonna see a lot of, but probably would be a very good starting case.

- This is a great case. In fact, this is the only time I personally seen this. It was an epidural hemangioma. The nice thing about this is, you're going into the spinal canal, but you don't have to go intradural. So this would be a great case to start on. It's unlikely one's gonna see a lot of these, but not likely this will be the case you start.

- Sure. Well, let's move on to another utilization, which is trauma. And in this case, a gunshot wound with lead toxicity and somebody who was interested in getting involved in a protocol that required further imaging. Was this an intradural or an extradural bullet fragment?

- This was intradural. Although it turns out that it had already completely scarred over the bullets. So when we took it out, there was no CSF leak. This was a patient who was quadriplegic from the gunshot wound, but wanted to be a candidate for stem cell trials of spinal cord injury. Of course, for that you have to be able to get MRI and with a bullet in your canal, you can't get an MRI. So because we could do this essentially as an outpatient, that's your minimally invasive technique, we went in and we took the bullet out for him, and he then became a candidate in stem cell trials.

- Rick, it looks on this image, if your tube had been any smaller, the bullet fragment wouldn't have fit up it.

- We just barely made it.

- All right. Very nice. So I think we've discussed this briefly, but clearly the benefits of these procedures, hospital length of stay, narcotic use, recovery time, blood loss, all of these things add up to benefits to a patient in the long run and the short run.

- And we've seen that for spinal cord tumors, just as we've seen it for most other procedures that we've done. Many of these can be done as an overnight hospital stay or for a two night hospital stay. We generally get them up walking around the day after surgery, rather than keeping them in bed for two or three days. So the risk of DVT and pulmonary embolize is essentially at least reduced, if not eliminated. There've been many benefits of doing these through minimal invasive techniques.

- Do you run into problems with patients that come to you for second opinions, who have been told they're gonna be in the hospital for a week after an operation like this?

- Yeah, that's a thing I have to be very delicate with. If, for example, another surgeon in your community has sent them to you for a second opinion, and you honestly tell them that you can do it through minimally invasive surgery, and they'll be in hospital one night rather than seven and have much less pain and blood loss, et cetera. Generally, the patient will say, well, I want you to do it. And so you can run into problems with your colleagues very quickly.

- Sure. Sure. I think at this point, we've sort of been through the types of patients and discussed inclusion criteria along the way. Are there any patients that you would exclude as far as intradural intramedullary or extramedullary lesions from a minimally invasive approach?

- At this point, I'm limiting myself for intramedullary tumors to three levels or less. Beyond that, I think the exposure that you need gets to the point where the minimally invasive technique, probably isn't adding very much to the benefit of the patient. Maybe we'll get to the point where that's not true, but I think that's where we are right now. I'm not sure about redo. So far, I haven't had to do redo intradural tumors, whether intramedullary or extramedullary, so I'm not sure about them. Those are my limitations at this point.

- Now that you've mentioned, redos, you'll probably have one show up next week.

- Probably.

- And discussing some of the pitfalls. I think that these are all things that we could all come across when we first start doing this; Pseudomeningocele, dural leak, incomplete resection. I think localizing issues we covered in detail. And I think that's one of the most critical aspects of doing these types of operations, both open and minimally invasive. And then making sure you have the proper instruments to make this as easy on yourself as possible.

- Particularly the latter is very important. Having the right instruments really does make a big difference. I think beyond that, to do tumors, you want to be very experienced. You don't want to get yourself in a situation where you're frustrated and not getting the job done, potentially injuring the patient. And that that's a factor of being very comfortable with spinal cord tumor resection and with minimally invasive techniques.

- Well, Rick, you kind of inspired me when we were putting this together. I had a patient come through my office, who I thought would be a candidate for a minimally invasive approach. So I'm gonna show you a case that I did after you sort of inspired me to go down this route. I also included both of our disclosures here for everyone to see. Sorry, I didn't include that at the beginning of the presentation. This is a 35 year old obese female who had a one-year history of left buttocks pain and also inguinal or groin pain as well. Some mild dysesthesia in the left buttocks and groin region. And then this MRI. And you can see on the sagittal and axial views, there's a lesion at the S2 level, going out the foramen on that left-hand side, which seemed to correlate with her symptoms. When you look at this Rick, is there any thoughts that come to mind, I figured this was a pretty good starting case.

- It's a great starting case. One of the things we haven't talked about, but which is relevant to this particular case, is that minimally invasive technique converts surgery on obese patients into a normal case rather than a case requiring an massively large incision, just to deal with all the depth of the fat that you have to deal with before you can get down to the lesion itself. So, minimally invasive surgery in obese patients is a huge benefit.

- And I think another benefit in this area, is we're getting near the gluteal cleft and she's a big woman. So it would have been a very large inch incision extending, not quite down near the perianal region, but close enough that I would have been worried about an infection.

- Absolutely.

- So, in this case, this is our positioning of the patient. For us, we tend to use navigation rather than a fluoroscopy just for localization. It also helps in surgery where I can put the probe down into the wound and look and make sure I've covered all the quadrants that I want to. This shows us using a fixed tube with a navigated dilator in order to do this. This shows the navigated dilator, both when we were localizing the skin incision. So the tip of it is near the skin incision with the projection, so that I can make up that my tubular port is really lined right up over the lesion where I want it to be.

- That's very nice exposure. I think image guidance is going to play a continuously important role in minimally invasive surgery. And as the tools available and the software becomes more and more user-friendly, I think it's going to become a standard part of our technique.

- And for this case, I did this with one of my partners and we utilize a microscope so that we would both have the ability to obviously work and see together. Let's go to the movie, and let's find this. And here you can see, after we had ducted the tape over the sacrum, just utilizing the drill to drill the very thin wall of sacrum that was left, and then the Kerrison in order to expand it out. And we could see that there was a small layer of what was likely dura covering this, although it had been so expanded that it was essentially thinned out. And we opened this up and could immediately see tumor within the space. In this case, we tend to open up in a cruciate fashion, which made closure a little bit more difficult, but there wasn't much tissue at the end to close when we were done.

- In the sacrum, that's very often the case. The dura is very thin and once opened, it's very difficult to close.

- And so you can see that utilizing a series of instruments, up angled micro pituitaries, reversing angled curates. We worked on removing the majority of this lesion and tried to look and see if there was some preserved fibers in this area that we could avoid. And we tended to find an area of nerves that we left running that had been compressed in fairly and ventrally along the surgical area. Here, I'm reaching up towards midline and sort of working underneath the corner, almost like a pituitary operation really, to pull that tumor down into the opening. And then with the long ball hook, you can see that we're following, that's out in the direction of the frame and just making sure that we had removed all the tissue from that area. So, this is what we were left with at the end. And you can see a fairly dry cavity with a little bit of neuro fibers in the superior portion of the view. And we could then put our dilator down there to make sure that we had all the space covered. And here's our dural substitute that we laid down into this area, along with some fibrin glue to cover the tissue as we pulled the retractor out.

- A very nice case, excellent application of minimal invasive technique.

- And this just shows the ending picture of that incision. So, what could have been a very large incision, in a large woman extending near her gluteal cleft ended up being a small incision up higher and avoiding those issues. Well, I think that concludes our talk today. Rick, I'd really like to thank you for sharing your knowledge with us on these topics. And I think they're gonna be a lot of residents and younger surgeons looking at this over the coming months. And I think this is gonna be an excellent introduction to them in spinal cord tumors, minimally invasive techniques, and the combination of both.

- Thanks Jean-Pierre. It's been my pleasure to participate.

- Thank you very much. I appreciate it.

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