Transcript
Question: It is clear from both of your presentations that we are now understanding that most lateral leaks are not ruptured diverticula but actually tears of the dura near the nerve root sleeve with arachnoid herniations which can look like a diverticulum. In that context, is it ever possible for meningeal diverticula to actually rupture or leak, or does that just not happen?
Answer:
Dr. Madhavan: I think this is certainly something that I learned a lot about from Wouter and from Jürgen too, and I think that is accurate. I think most of these leaks probably are primary lateral dural tears and the arachnoid herniation is a secondary thing. I would say I have seen a small number of cases where I thought that it was a primary meningeal diverticulum that tore or ruptured somehow. In general, I think those cases are far less common. And I think the ones I’ve seen them in tended to be people who had some sort of connective tissue disorder. I think one of them was a Marfan patient, for example. But it’s interesting. Right. It’s interesting that you don’t get more of these times where there’s a primary meningeal diverticulum that ruptures. I mean, it may be because those turn into CSF-venous fistulas instead or something like that. But in general, I felt like they’re quite rare. So I don’t know if Wouter has the same experience.
Dr. Schievink: Yeah. No, I totally agree with you. So we see it once in a while, but it’s a kind of unusual occurrence. And I learned that from Dr. Beck when he had his meeting in Bern many many years ago, where he taught me that what I thought were ruptured diverticula actually were primary dural tears. So I’m really grateful to him for that because the treatment, as you can imagine, is a little bit different as far as surgery is concerned.
Question: Considering what you said about them more often being primary lateral tears, would you say that they’re more likely to be caused by trauma than other types of leaks? Are they more often associated with those connective tissue disorders that you mentioned, and if so, why do you think that is?
Answer:
Dr. Schievink: Yeah. Well, I think definitely the lateral dural tears, when we see them, they are more often people, and even teenagers, definitely those in their 20s or 30s. Occasionally, I have one patient, a man from Washington State who is in his 80s, who has a lateral tear, but the vast majority are young people in their 20s, 30s, or 40s, and those are the ones where we find the fibrillin-2 mutation.
Dr. Madhavan: Yeah. Regarding the trauma part, I’ve had a few patients who will get these from major trauma, like a nerve root avulsion too. But I think those are very different, right? Like as Wouter mentioned, the ones who get these spontaneously, they seem to have some intrinsic connective tissue weakness and manifest relatively early in life.
Dr. Schievink: Yeah. And definitely the traumatic ones are almost always in the cervical spine, not so much in the thoracic spine.
Question: Gotcha. Thank you. Can you both help us to understand a little better — us being the patient community — the difference in terminology between pseudomeningoceles, diverticula, outpouchings, cysts, and so on? Can MRI alone distinguish between these?
Answer:
Dr. Madhavan: I guess regarding the MRI part, I don’t think you can always distinguish them with MRI. I think they can often look very similar, and that’s part of the reason I think a lot of these lateral tears were initially incorrectly recognized or mischaracterized. And the terminology, maybe Dr. Schievink is a little bit more apt to answer that. But I do think pseudomeningocele I generally wouldn’t consider to have all three layers of the dura, the meningocele, maybe more so. Bleb is more of a morphologic term. Cyst, I’ve kind of come to think of similar to diverticulum in this realm. But yeah, Wouter might have more insight.
Dr. Schievink: Well, I mean, you know, you’re the radiologist. But in general, when people talk about bleb, right, we used to call that a pseudomeningocele. So to me still, what we call a bleb, that’s the same as a small pseudomeningocele.
Moderator: Understood. So it sounds like a pseudomeningocele still involves arachnoid, but the level where it would be called a bleb is where it’s much smaller. Correct?
Dr. Schievink: Yes. I think that’s a good way of describing it.
Moderator: Okay. Well, thank you very much.
Question: Once these lateral leaks are repaired, I think this question is mostly directed towards Dr. Schievink, but Dr. Madhavan, I’d love to hear your perspective, too. What are the chances that a patient would re-leak at that same spot or at a different spot in their spine? Why does it seem that most lateral leaks are reported to happen in the lower thoracic spine? And can patients with a lateral leak have pain at the site of the leak in addition to the typical symptoms?
Answer:
Dr. Schievink: All right, those are different questions. I do think occasionally people tell me, “Oh, I know where my leak is, right? Because it’s in my spine, and I can tell you it’s on the left or the right side.” That’s more or less convincing. But what’s really convincing is a patient who tells me, “Oh, before I got my headaches, I got this terrible pain around my flank, around my chest, and it happens to correspond exactly where the lateral leak is.” I think those patients are really good examples of leaks causing localized spine pain symptoms.
As far as what are we going to do with leaks, what is the chance of a recurrent leak? In general, when we looked at this a couple of years ago, I think about 6 or 7% of patients with lateral leaks had more than one leak. Those were both patients who had lateral leaks occurring at the same time but also patients who underwent treatment for a lateral leak that was fixed and then they developed another lateral leak years later. So I generally tell those people the good thing is we don’t know what would cause that to happen again, so there are no restrictions to what you can do. And I think the risk profile is pretty positive for the patient in that the recurrence risk is probably less than 1% per year for a spontaneous lateral leak. I mean, I don’t know what you think, Ajay, but that’s what I usually tell them.
Dr. Madhavan: Yeah, I haven’t seen too many lateral leaks recur at the same level. The only thing I say is I think it’s really important to have a skilled surgeon who knows what they’re dealing with, and I think having a good myelogram can help, because the only times I’ve seen it recur is when it wasn’t correctly localized or it wasn’t recognized at the time of surgery. I think that’s the most important thing, but I think the recurrence rate is pretty low.
Moderator: Thank you. That’s very interesting to hear about the secondary site leaks as recurrence, too.
Question: We now have a question from the audience. This is regarding SLECs, which you both mentioned. Would patients with arachnoid outpouching leaks more often than not have no SLEC on their spine MRI considering what you’ve presented today?
Answer:
Dr. Madhavan: I think more often they do have a SLEC. So the cases I showed were probably more exceptions to the rule. Probably, and I don’t have perfect data on this, but probably more than 80% of the lateral leaks I’ve seen have had some sort of epidural collection. One thing I will say, it’s not always necessarily a SLEC, like a well-defined collection. Sometimes, I think one other speaker showed the dinosaur tail sign, and sometimes you’ll see more subtle findings than that that just indicate a small amount of epidural CSF leakage. But there are cases where I even retrospectively don’t see anything on the MRI other than just the arachnoid outpouching, and there’s no epidural fluid.
Dr Schievink :Well, I think, I mean, obviously I agree with Ajay, but I actually feel the opposite way, because he and I and basically everybody else who are CSF leak aficionados on this panel, we get the patients, we get to see the people who are diagnosed with the leak. And I actually think that a lot of patients have a leak, but they undergo many different tests, like we have shown, and it doesn’t show up on regular imaging, and we never see them. So I actually think that the vast majority of people are just not diagnosed.
Dr. Madhavan: Yeah, that is true, and that might skew what we see on MRI.
Dr. Schievink: Even your really great MRI might not show it.
Dr. Madhavan: The only thing I’ll say too on that is I think the fat suppression is the biggest thing. I don’t know if you agree with that, Wouter. Probably the most common thing that I think causes these to get missed is that they’ll do an MRI without fat suppression, and I think it’s very easy to miss subtle epidural fluid on that type of scan.
Moderator: All right. Thank you both. We know we’re at the cutting edge of the treatment when we have disagreement from our foremost experts.
Question: You mentioned the fat suppression sequences. I’m curious what your recommended set of sequences would be for a patient who is seeking treatment perhaps at an outside center where they don’t have as much experience with CSF leaks as yourselves.
Answer:
Dr. Madhavan: I think the main things are you want both sagittal and axial images with fat suppression. And beyond that, and that would be T2-weighted images, predominantly what we want for CSF leak evaluation. T1-weighted images don’t show CSF as well, so they’re not as important, but they’re helpful if you have the time to do them sometimes. But I think if you get a good sagittal and axial T2-weighted image with fat suppression. And then the other one that oftentimes gets cited is there are these specialized 3D high-resolution sequences, and they come with different names. The trade names are like CISS, FIESTA, or different ones that GE and Siemens have, and those can be very useful too. Those will show oftentimes small amounts of CSF leakage. Not every institution will have those available, but I think they’re super helpful when they do.
Moderator: Thank you.
Question: For Dr. Schievink – we have a question from the audience. Some patients experience further leaking from the devices such as clips and sutures and have concern that the clips are abrading or adding trauma to the ruptured area, or repaired area, pardon me. What are your thoughts based on what you see in practice on whether this is actually occurring or what other factors are contributing to this?
Answer:
Dr. Schievink: I mean, clearly there’s no perfect technology to repair leaks, even with surgery. We’ve been trying to use sutures. In the US there’s only a single type of suture where the diameter of the needle is smaller than the diameter of the thread, and that’s a type of suture that I’ve used for at least 10 years. But even in that circumstance, people still definitely can leak from the hole that you make from the suture, from the needle. So that is a problem, definitely much more common with any other type of suture material. And there’s no question that even after surgery, which a lot of us believe is the most secure and definitive way of securing a leak, people can still at least have symptoms of a leak and even radiographically can still have clear evidence of a leak.
Moderator: Thank you.
Question: You mentioned that you consider, or some consider, that surgery is the most definitive treatment to offer. We have another question from the audience regarding that topic, specifically with treatment protocols and flows from blood patching to surgery. If a patient has had blood patches targeted at suspicious outpouchings and they have had relief but also experienced recurrence of symptoms, what criteria would you use to determine whether to pursue another blood patch, repeat imaging, or surgery?
Answer:
Dr. Schievink: Look, I think that’s a really great question, but there are just so many variables in that. It depends on the clinical scenario. How good is the story for a CSF leak? What are the imaging findings? I mean, how good was the myelogram? How good was the surgery? How good was the non-surgical type of treatment? That just depends on so many different variables. I mean, it’s difficult to give a kind of shotgun type of answer to that question.
Moderator: Of course, Dr. Madhavan, I’d be interested to hear your thoughts too as a neuroradiologist.
Dr. Madhavan: Yeah. No, I agree with all that. I think the key factors would be how definitive are you about where the leak was. I think if you have a good myelogram showing exactly where it was and you’re fairly confident in that, that would make me lean more towards surgery, just because then you know you’re sending them to a surgeon with a good localization. If it’s more questionable, then that might be more amenable to blood patch. But like Dr. Schievink said, there are so many factors at play that ultimately it almost always comes down to a discussion with the patient about the two options and the benefits and disadvantages of both.
Question: Are there any particular new technologies related to repairing CSF leaks that you are excited about, specifically as it relates to these lateral dural tears? This could be intraoperative repair techniques or even new technologies for percutaneous treatment.
Answer:
Dr. Madhavan: Just starting, I guess, with patching. Dr. Callen and Dr. Mamlouk have both been doing a lot of work with injecting blood and fibrin into epidural collections, and I can’t remember from their paper whether that was done with any lateral leaks, but I think that that’s something that has caught my eye and is very interesting to me. I’d like to see where that goes in the future.
Dr. Schievink: Yeah, look, I mean, I wouldn’t want to comment on the success of our interventional neuroradiologists who have pioneered glue injection since 2003. I think for the future, if we could identify what really is behind the causation of these leaks, whether it’s a fistula, lateral leak, ventral leak, that’s really going to be what’s going to be important. But it’s going to take a while. For us to identify these Fibrillin-2 mutations, that essentially took us 10 years. That only happens in one out of four people who have a specific type of leak, and we don’t really have a good treatment to prevent that from happening again.
As far as surgery is concerned, there certainly are different types of sealants that have come on the market that we are exploring at this time, and I’m somewhat positive about the outcomes of those different treatments. Like I said, the different suture materials that are on the market have been around for a long, long time. But otherwise, certainly as far as different types of leaks, we’ve been very happy about the prospect of doing minimally invasive endoscopic surgeries through a tiny little tube, seven or eight millimeters. The results are not as good as the conventional surgery, we’re talking about 80 versus 95 percent, but certainly the recovery of those surgeries is much, much easier for the patient, so we certainly are excited about that.
Moderator: Thank you.
Question: With all this talk about different techniques of repair, one question that we commonly receive and have received live today is whether these attempts at repair can complicate further attempts at repair, such that blood patching maybe it causes scarring that complicates surgery, maybe surgery causes scarring or adhesive arachnoiditis. Can you speak to some of the complications that may or may not contribute to further challenges in care?
Answer:
Dr. Schievink: Sure. Yeah. So I think blood patches, yes, they can cause some scarring. Very little problems with doing surgery. If you do surgery, for example, for different types of leaks, we haven’t really discussed that, but for these ventral leaks, nowadays in November 2025, if somebody has had an intradural approach to a ventral leak where you open the dural sac, even in the very best of circumstances there’s going to be a little bit of scarring. So if somebody has that type of approach, whether it’s done here at our institution or somewhere else, and they still are leaking, then I generally recommend doing an endoscopic extradural approach, and vice versa. So if somebody has had an endoscopic extradural approach to their leak, whether it’s here or somewhere else, and they have failed that surgery, then I recommend the other approach.
Moderator: Dr. Madhavan, does it complicate imaging?
Dr. Madhavan: Imaging usually not too much, and that’s one of the nice things about both blood patches and fibrin is they don’t cause really any issues for myelography at least. For further treatment, for epidural blood patching, I will say the scarring can sometimes be an issue. You’ll kind of notice that the epidural space is harder to inject blood into, but usually we’re still able to repeat blood patches without too much problem. It just makes it a little bit more technically challenging.
Moderator: Thank you very much.
Question: We have time for one more question. Let me look through the list here. You both mentioned lateral tears and meningeal diverticula being associated with CSF to venous fistulas. What is the incidence of that that you suspect?
Answer:
Dr. Schievink: Well, look, I’d say 90% of CSF-venous fistulas arise from a meningeal diverticulum, and very rarely you can have a lateral leak. Maybe 1 or 2% have a lateral leak, and then in addition to that lateral leak they also have a CSF to venous fistula. In those patients, fixing the lateral leak will almost always suffice and also get rid of the CSF-venous fistula.
Dr. Madhavan: Yeah, that’s been my experience too. I think the association between these arachnoid outpouchings and CSF-venous fistulas, it’s not super common. It’s maybe about 10-20% of those that I see. But again, the nice thing, like Dr. Schievink said, is that you fix them both in one shot when you fix the lateral dural tear. The only thing that I’ve become very cautious of is you don’t want to let someone just try to fix the fistula in most cases, because if the lateral tear isn’t recognized, someone may try to do an embolization or something else, and really the primary problem in most of those patients is the lateral dural tear.
Moderator: Well, Dr. Schievink, Dr. Madhavan, thank you so much for both talking today, presenting your information, and for all that you do for our patients.