Spinal CSF Leak Foundation in conversation with Dr. Andrew Callen
Dr. Callen took some time to discuss with us his most recent publication, “A Causative Role for Remote Dural Puncture and Resultant Arachnoid Bleb in New Daily Persistent Headache,” a remarkable new paper on the case of a woman with an iatrogenic spinal CSF leak whose symptoms didn’t show up for 12 years after her inadvertent dural puncture.
Dr. Callen’s case report concludes: “We report a case of remote-onset dural puncture headache, recognized only by the presence of a subcentimeter bleb on MRM. This patient was initially diagnosed with NDPH, which as codified by the International Classification of Headache Disorders, 3rd edition (ICHD-3), is a headache in which head pain has a distinct and clearly-remembered onset, becoming continuous and unremitting within 24 hours, and not better explained by another diagnosis. As a diagnosis of exclusion, in this case, NDPH was no longer accurate once the arachnoid bleb was identified and its causal role appreciated. Future research should investigate the strength of the association between previous exposure to remote dural puncture—both intended and unintended—and later development of NDPH, and also explore reclassification of remote-onset dural puncture headache as a distinct clinical entity.”
Dr. Callen is on the medical advisory board of the Spinal CSF Leak Foundation and is an Assistant Professor of Neuroradiology at the University of Colorado Anschutz, where he is also the director of the CU CSF Leak Program.
Transcript:
Andi Buchanan
Hello and welcome. I’m Andi Buchanan, executive Director of the Spinal CSF Leak Foundation, and with me today is Dr. Andrew Callen, neuroradiologist, assistant professor of radiology, and director of the CSF leak program at the University of Colorado School of Medicine. Dr. Callen is with us today to talk about his recently published paper, a case report titled, “A Causative Role for Remote Dural Puncture and Resultant Arachnoid Bleb in New Daily Persistent Headache.” Dr. Callan, welcome.
Dr. Andrew Callen
Hi Andi. Thanks for having me.
Andi Buchanan
Thanks so much for being here. Before we dive into this remarkable case, can you just define a few terms in that title? What is a remote dural puncture and what is an arachnoid bleb?
Dr. Andrew Callen
Sure. So, you know, the typical way we think about post-dural puncture headache, and I think the majority of the community thinks about post-dural puncture headache, is in this sort of acute or very subacute period.
The international classification of headache disorders defines a post-dural puncture headache as occurring within five days after a dural puncture, either a dural puncture that was intended, like a spinal tap, a lumbar puncture to take off fluid, or an accidental dural puncture, as in the case of an epidural during labor, for example.
So, a remote dural puncture is referring to a puncture that occurred much more than five days ago. In this case that we talked about, it was several years prior to that. And that’s important because it goes against the sort of traditional thinking in that regard. The dural bleb, or pseudomeningocele, reflects a certain type of injury to the dura, which is not necessarily just a hole that we would think of in other types of leaks where there’s a hole in the dura and the fluid is just coming out, but rather there’s a hole in the dura or a weakness in the dura where the inner layer of the meninges—the arachnoid layer—is protruding out through the that hole, and we don’t know exactly how leakage or the symptoms of intracranial hypotension manifest as a result of this type of injury. What we think based on our intraoperative experience and intraprocedural experience is that there may be an intermittent leakage that occurs around the base of this.
As that arachnoid membrane herniates through, it may act as a ball valve mechanism, intermittently leaking, intermittently not leaking, which makes it very challenging to see on a myelogram, for example. But intraoperatively, when this was repaired, and during our procedure when we tried to patch it, we saw evidence that there was some communication between the intradural space and the extradural or epidural space.
Andi Buchanan
Part of what makes this case so remarkable to me is that, if I understand it correctly, this patient did not come to you and say, “Many years ago I had an epidural in childbirth and I’ve had symptoms of a spinal CSF leak ever since.” She came to you with a mystery: symptoms that had started five or six years ago and had no apparent reason that showed up on imaging for them to be happening. And that long ago labor epidural wasn’t even part of the story. So what made you think to look at that spot?
Dr. Andrew Callen
Yeah, it was a very challenging case, as most, I think, of the people we see are. It’s nothing that’s really that straightforward, or cut and dry. And if it is, they sometimes don’t make it to see us. But I think there’s a couple things that were confounding in that case.
Number one, as you mentioned, the fact that the injury was so remote. Number two, in this particular patient, they had a number of perineural cysts up and down their spine, large irregular perineural cysts, and this is something that we always pay attention to when we’re looking for other sites of potential CSF leak or venous fistula that are spontaneous. And so that was a distractor in this case as well.
But, whenever I have a new patient come to me, we have all their imaging. Sometimes they’ve had workups elsewhere with diagnostic tests. I just try to start from scratch look at things from the very beginning as if there had been no workup yet performed, and on the very first MRI that this patient had—before any intervention, before any diagnostic intervention looking for a new CSF leak, but well after the labor epidural—there was this dorsal dural bleb there in the lumbar spine. And I first double checked to make sure that this wasn’t after a puncture from one of her, the myelograms— [that it hadn’t] developed after her symptoms had started and [was] therefore unrelated— and once that was confirmed, I became very suspicious that this could potentially be related. And so that what led me to go back and talk to her again and say, “Did you ever have anything in the past in terms of an epidural, another needle?” et cetera. And she said, “Yeah, many years ago when my kid was born, I had a labor epidural, developed a headache the day after, which went away on its own, and then I was fine, headache-free.” And so then a light went off and I said wait a second. Maybe this is what’s the culprit lesion all along, as opposed to a spontaneous leak elsewhere in the spine that that neither we nor other institutions were able to find up until that point.
Andi Buchanan
Yeah. That is really fascinating that this indication was missed on that early MRI and I guess because of these confounding perineural cysts and other things that could have been suspicious for leak. So was there anything specific about that in the MRI that grabbed your attention? Anything that could be generalized for maybe other clinicians looking at imaging and reviewing for suspicious areas?
Dr. Andrew Callen
Yeah, it’s a really important question. I think that this finding, as you can see in the figure, in the paper, is very subtle. It’s tiny. I think it was just one to two millimeters on the mri, and without the appropriate protocols— the appropriate sort of thin slice, heavily fat saturated, heavily T2 weighted, these technical terms we use to describe the type of MRI that we obtain in our patients who were suspecting CSF leak— it could be easily missed or skipped over in a routine MRI of the lumbar spine, so to speak.
And even if you obtain that 3D, that, you know, the correct protocol exactly as you’re supposed to, it’s a very tiny finding, and I scrutinize these dural contours very carefully to see if there’s any sort of irregularity. And a lot of times there could be a little bit of artifact or there could be a physiologic, a structure like a vein, which could mimic this.
But in a patient with enough pretest probability with as debilitating symptoms as she had and with an otherwise negative workup, these things just jump to my attention even more and more. So what I would say to answer your question is, make sure that you’re doing the right protocols, that you have your thin slice imaging of the lumbar spine, and usually your sort of normal degenerative spine MRI won’t include those. And then just, maybe have the images re-reviewed by somebody who’s paying particular attention to these types of findings as opposed to the typical findings which are described in a radiology report, like degenerative disease, disc disease, looking at the spinal cord, et cetera, which are important, but less important for this type of situation.
Andi Buchanan
It seems there’s this notion that iatrogenic leaks are more easily addressed than spontaneous leaks since you theoretically know where the location is and all of that. Do you think that plays a role in why these have maybe been overlooked or historically dismissed as a potential cause for symptoms?
Dr. Andrew Callen
Yeah, absolutely. I think that people definitely dismiss the post-dural puncture headache. I think that there’s some irony there, because people who are working in this space know that these are the most, some of the most challenging leaks to fix or to improve the people’s quality of life.
And then on the flip side, I think a lot of doctors in the community will say, “Oh, that’s the easiest because there’s a puncture. You do a blood patch and then they’re better.” And we just know that’s not the case. I think there’s also a bias of people looking at imaging and post-dural puncture headache folks, because the traditional thinking is that this imaging is always negative, it’s always negative no matter what, whether you have myelogram, an MRI of their spine, an MRI of their brain, it’s always gonna be negative. It’s that—you go into looking at a study thinking this is negative, and I’m just confirming my bias by just making sure that I’m not seeing anything obvious.
But I think that while that may be true in a lot of the cases, it’s not true in all of them. And there’s a couple of of examples of subtle things that you can see in folks with post-dural puncture headache which can be localizing and can lead to a targeted treatment. And so it’s important to go into that with an open mind, into those studies with an open mind, but also work against this notion that this is an easily fixed straightforward disease, which it’s absolutely not.
And we’re learning more and more that in the chronic period, post-dural puncture headache is incredibly debilitating and causes a lot of suffering.
Andi Buchanan
It seems like there have been several papers recently published about arachnoid blebs and the treatment thereof. What do we know about these right now, and what do you think the future holds for these kinds of cases?
Dr. Andrew Callen
I think that in our experience, we have tried patching these and sometimes we’ve had good success, but a lot of times I think that they probably end up needing surgery. I think that’s probably where we’re going to end up seeing this go. Obviously we try to avoid surgery whenever possible, but whether it’s just that sort of mechanism, that ball valve mechanism of the meninges herniating through that sort of blocks off the area of leakage and prevents our patches from working, or whether it’s just the fact that it’s been there for so long that the sort of, the patch isn’t going to fully seal this leak, I’m unsure. I think it’s still reasonable to always try when you have a localizing finding like a bleb, it’s reasonable to try patching, because it’s low risk and there’s a chance that you’re going to help them and help them avoid surgery.
But I think that it’s really important to discuss these cases with our surgical colleagues, our neurosurgeons, and get them involved and get their opinions because a lot of cases, particularly the ones in the lumbar spine, are amenable to a minimally invasive approach, which is relatively low risk compared to a lot of the other leaks that we ask them to fix. So, something that’s dorsal, on the back part of the spine that doesn’t require a big decompression or a big surgery can be done in a relatively noninvasive manner. And when it’s definitive and curative is really probably the best treatment for these lesions, so I think it’s a question of identifying them, of trying to treat them if they’re safe, but also having a good surgical consultation. And I try to get my patients a surgical consultation even before I patch them, or even if we think we could close it when I think there’s a good chance they’re going to need surgery. I think just meeting with the surgeon, understanding what that’s going to look like, understanding what that road might look like for them, even if they don’t end up going down it can be helpful.
Andi Buchanan
So, in the title of your paper, I noticed you referenced New Daily Persistent Headache, and I wondered why is that diagnosis mentioned rather than spinal CSF leak?
Dr. Andrew Callen
So, in our patient, this was the diagnosis that was as ascribed to her. It was not— she was not given a diagnosis of a formal diagnosis of CSF leak, and she had a new unremitting headache that was not accounted for by another diagnosis. And despite the orthostatic nature of her headache, her sort of negative brain MRI, so to speak, and other sort of absent clinical features and lack of anything fruitful on her prior invasive workup led that to be the diagnosis. And the new daily persistent headache is a catch-all diagnosis for the, “we can’t find anything else” and there’s a new headache that doesn’t fit into another category.
And so it’s not something we typically think of as being associated with intracranial hypotension or CSF leak because then they would have the correct diagnosis. But I suspect that there’s a lot of people out there, and perhaps women in particular, who’ve had an epidural anesthesia perhaps in the past and now have newly new daily persistent headache that may be attributable to spinal CSF leak that we’re not catching. I don’t know what that number is, but certainly in this case, it’s an example of that.
And it’s something to be aware of. When a patient has that diagnosis, it means we don’t really know what’s going on, because if we did, we would have a more specific diagnosis. And so that should raise your eyebrows a bit and get you thinking, maybe we need to revisit some other concepts depending on the character of the patient’s headache and if there’s a significant orthostatic character, and maybe we need to revisit whether or not this could be a spinal CSF leak.
Andi Buchanan
What options are there for iatrogenic leak patients whose leak isn’t spotted on imaging, but for whom patching has failed?
Dr. Andrew Callen
So, it’s so tough. This is one of the, the sobering conversations I have with patients in clinic and in consultation all the time is, on the one hand, the patching hasn’t worked, hasn’t been working. On the other hand, our diagnostic testing hasn’t been showing anything. And do we want to keep subjecting you to more punctures with another myelogram, even if we use techniques to minimize the risk of that? And really the best tool at our disposal right now is just trying patching again and not being dismayed if you’re having several patches, not feeling like just one patch didn’t work, so therefore no patches will work. We can try different techniques in terms of where we put the patch. Do we try to put it in the front, the ventral epidural space, in the case that there may have been a through and through puncture where the clinician maybe just didn’t puncture the back of the dura, but also punctured the front of the dura?
Can we try up and down the spine in other areas? Can we use fibrin sealant, fibrin glue in addition to blood? We try all these things and if we if we’re getting to the several patch point and none of these are working at all, not even in the smallest amount, then maybe we have to think about, are we missing a different diagnosis here?
But I have seen patients with chronic post-dural puncture headache who eventually will respond either fully or partially or enough that it improves their quality of life at least. So they can function to some degree. But I’d say my main message would be to not give up after just one or two patches and say, this isn’t working.
And also to be very careful about visiting another myelogram or things like this, as tempting as it may be, that maybe we’re missing something else that we could find. The chance that you’re going to find something is weighed against the chance of giving this person yet another hole in their dura that we know already causes them so much suffering. So it’s a very tough question.
Andi Buchanan
Given what we know about the risks of dural puncture, how important is it for the future of spinal CSF leak diagnosis to involve non-invasive imaging?
Dr. Andrew Callen
Yeah, I think incredibly important. I want all of my patients to have this sort of spine protocol before they come see me. Because if there’s any chance that I could target a therapy or suggest a localization without a myelogram, that’s the best that’s the best option in my opinion. If we can avoid. The test that, I always tell people, this is the catch-22 of my job, is I’m trying to find and seal your leak, and I have to put a hole in your dura in order to do it.
And it just, it pains me to have to do that, but, if we can ever avoid it, I think that’s fantastic. And continuing to work not only on increasing the resolution and ability to visualize abnormalities of the dura and leaks on our imaging, but also using advanced imaging techniques.
There’s been some interesting promising data and just over the past couple years, looking at different CSF flow patterns with different types of MRI sequences and how they may reflect an underlying leak. Just really having an open mind as to whether any of these noninvasive strategies may reduce the needs to puncture someone’s dura to perform a, to look for a leak.
Andi Buchanan
Is there anything else you’d like to add about this case report that we didn’t cover in this conversation?
Dr. Andrew Callen
No, I think you hit all the points really nicely. I think that for, both from the clinician side, having an open mind about how long a post-dural puncture headache can affect somebody, how debilitating it can be from the radiologist’s perspective, saying, I need to really scrutinize those tiny little findings, which may seem insignificant because they could be very significant.
And then from the surgical community, understanding that these are, this is within their wheelhouse, something that they can fix. Hopefully all those pieces together help our patient community in terms of getting the appropriate diagnosis and treatment.
Andi Buchanan
Thank you so much for your time today. I really appreciate it. And thank you so much for all you do to accelerate research and help spinal CSF leak patients.
Dr. Andrew Callen
You’re so welcome. Thanks for having me.
Further reading: