Slides
Transcript
Thank you all. It’s good to be here with friends again.
I’m going to talk about the basics of epidural patching, something all the experts in the room are very familiar with, and some of the patients are kind of expert in. But I know we have some patients here who have not had a patch yet and some that are interested in learning more about it. So it’s going to be kind of a basic talk, and we’ll talk about just what the purpose is and what it is so that you guys can understand it.
Disclosures are there. I always put up this QR code – it’s the Google Drive folder where I share articles but also contact information compiled primarily by Duke and about other physicians interested in seeing people with CSF leak, and we hope more resources will be there soon.
So they’ve dissected the bones off, and you see the dura here and also blown up here, the spinal cord underneath, and the little nerve rootlets coming off to coalesce to form the individual nerve roots. It’s in this space that the spinal fluid would be, and it’s the dura here that we’re worried about becoming incompetent in some way and leaking, leading to a CSF leak.
This is what it looks like on an axial image or an axial dissection. The spinal cord is here, again, the nerve roots coming out. This is the dura, and it’s this space in here that would be filled with CSF. And just one more dissection here. So, this is a section of the dura and the cord peeled off, where you can see the spinal cord and just how thin, but it still has some substance to it, the dura.
If you do a section across someone, the vertebral column is here. You can see the intervertebral discs. And so, number four here – this would be the ligamentum flavum that a needle would have to pass through to get into the epidural space here, which is labeled as number four, with the dorsal dura being three, the spinal cord being five, and the CSF subarachnoid space being number six.
When we’re doing an epidural patch, what we’re trying to do is put a needle in the epidural space, not penetrate the dura, and inject some kind of sealant into the epidural space. When we’re doing epidural anesthesia, we inject local anesthetic, but when we’re doing a blood patch, we’re injecting blood or fibrin glue in this space with the idea that we will cover up the defect.
It’s clear that, in fact, sealing the defect is not the only way that an epidural patch can help people. We have people who have presented to Stanford with large subdural hematomas, bad brain sag, bad CSF leak. We’ve patched them. They’ve gotten 95% better, back to hanging out with their friends and drinking margaritas, but that last 5% of symptoms prompted us to do repeat imaging. And even though they had gone from being totally unable to be upright with large subdural hematomas to 95% recovered, they still had a very large hole in the dura when Dr. Schievink explored them.
So, if they still had this giant hole in their dura, how is it exactly that the patches I was doing got her from being kind of in danger of dying from a leak to 95% better without sealing the hole? I think there is more to this that we don’t understand, that we will come to understand in the years ahead. But there it is.
So, let’s talk about the basics. The week before the patch, I tell patients to stop NSAIDs – that’s things like ibuprofen and naproxen – because they impair platelet function. It’s not a strict contraindication, but it does impair platelet function. And if you’re on other medications that we don’t think of as blood thinners that have subtle antiplatelet effects – like SSRIs or antidepressants – the combined action of an SSRI and an NSAID can actually make your platelets quite nonfunctional.
We tell people to stop GLP-1 agonists – things like Ozempic and Mounjaro – they clearly cause decreased gastric emptying. You’re more like a full stomach, and so when sedated, you’re much more likely to vomit and/or aspirate. And so, we ask people to stop.
It turns out many people who wind up coming to us have generalized pain complaints. They’ve often seen pain doctors. Some are started on low-dose naltrexone – that’ll interfere with the sedation. We ask patients to stop blood-thinning medications. There are specific recommendations for that, and we have them pick up medications for after the patch. Which, in our setting, includes a prescription for oxycodone and acetaminophen for three or four days. Zofran. We give people Phenergan suppositories as well. Changing someone’s CSF pressure can be very nauseating to people and sometimes so nauseating that it’s hard to keep a pill down, so I like to have patients have a suppository for nausea as well. I think that, actually, for reasons I don’t have a good explanation of, many patients have reported to me that when they get rebound high pressure after being patched and they have nausea with that, the Phenergan seems to work better for them than the Zofran often.
I do not give people a prescription for something for rebound, like Topiramate or Acetazolamide, unless they tell me they’ve been patched before and had significant high pressure, in which case I will give them one of those agents. I currently prefer Topiramate for treating as an initial treatment for rebound high pressure. It causes less metabolic disturbance, and I’ve seen people get in trouble with their electrolytes too often with the Acetazolamide for it to be my first choice – not to mention the kidney stones.
Then, the week before, arranging your logistics. The day of the patch, I have a pre-patch checklist. Do you have any reason to think you might have an infection? One of the cases that’s documented out there of a post-epidural blood patch epidural abscess was someone who, in fact, they had drawn blood on before the patch. They were able to go back and test it, and she had staph aureus bacteremia, and she had bacteria in her blood before her patch. She just had some bad dental disease, and if you have bacteria in your blood, that’s going to go into the patch.
So, it’s important to ask about an infection. I ask people, is there any reason you might think your blood might not clot normally? You’d be surprised the things that people will say. “Oh, you know, my mom has a bleeding disorder,” or something like that – things that you’d like to know before you do your patch. Any new shortness of breath – never a good thing. An allergy to x-ray contrast or antibiotics, which they’re likely to get exposed to.
I’ve been doing 6 OR days a month where I patch a month. I do 8 patches a day. That’s 48 patches a month. I do, on average, 600 patches a year. On average, I put two and a half needles in per patch. That’s about 1,500 epidural needles a year. 8 years – 10,000 needles.
You do that enough, and you’re going to see some complications. I have had one patient have a saddle pulmonary embolus after the patch. It was 30 days later. She was spending a lot of time flat before the patch, but I’m sure the patch didn’t help. And it turned out she was both on oral contraceptives and had Factor V Leiden – a hereditary condition that predisposes to clots. She did fine, but now I ask everyone, you know, have you or anyone in your family ever had a blood clot? Are you a smoker? Hormonal contraceptives? And for those patients, I don’t have them stay flat for 72 hours. They’re flat for 24 hours. Any last-minute questions for me?
The day of the patch, the nurse checks you in at Stanford. They ask about suicidal thoughts. I don’t know if Deb’s going to talk about this – about three-quarters of our patients have had suicidal thoughts not too infrequently and not in the distant past. And so we do a suicidal screen to make sure that you’re not feeling like you might hurt yourself today, which would not be altogether beyond the pale. The nurse will place an IV, and at Stanford, what we do is we have the nurse identify the best antecubital vein in the arm, looking at both arms, and then they leave that one alone – that’s for me. They go to the other side, and they have to go find a vein somewhere on the bad arm, so I get to greedily take the best vein, and they have to look for the scraps on the other arm. We do a pregnancy test or a waiver. It’s not good to get pregnant if you think you’re going to need radiation and invasive things to find and fix your leak.
In the room – so the blood patch, I think, really is a three-part procedure. You have three objectives. You want to reliably obtain an unlimited quantity of sterile blood – I think this is often overlooked at the expense and because of the kind of more invasiveness of safely accessing the epidural space. I think that usually when epidural patches go awry, it’s often what I see from people who come from other centers – it’s because they really didn’t get enough blood, and I think that’s a real issue. And I’ll talk a little bit more about that in the next slide. So, what we want to do is reliably obtain an unlimited quantity of sterile blood, so the amount of blood is limited only by what the patient can take. I don’t want the amount of blood to be limited by how much I can get out of this small vein in the hand.
We want to safely access the epidural space, and then we want to facilitate giving the patient the maximum tolerated dose of blood or fibrin. And I think sedation’s a little bit helpful for that. People can take an extra 10 cc’s of blood when they’re comfortable. So, the most common way – and the way I was taught to do an epidural blood patch – is to place the needle. And that can be done either at the bedside by an anesthesiologist or by the experts in this room, typically image-guided, either fluoroscopically or under CT guidance. And then once the needles are in the back, you draw the blood. That’s the way I was taught, that’s the way I think it’s done in 95% of the country.
The issues with this are if the blood is hard to get, your options are really limited. Once the needles are in the back, it’s very hard to move the patient, it’s hard to reposition the arms, it’s hard to look for a vein somewhere else. If you’re doing it under CT guidance or fluoroscopy, they’re face down – all the best veins are facing the bed. I really think that there is a better way to do this. So, I mean, I started off doing it this way. I also think that when you’re hunting for a vein when someone’s already got the needle in their back, and you’re trying to maybe reposition their arm, and a nurse is getting under there and trying to prep the arm, it is a hazard for maintaining strict sterility.
My preferred way is to obtain reliable access to the blood first, and reliable access means it can’t be a small vein. It has to be a good size vein. I want a 16 gauge either in the antecubital or an arterial line in the hand. And if you get that access to the vein first, so that you can draw the blood once the needles are in, sterility is easier to maintain. It’s easier to make sure you get all the blood you want. This is what it looks like. We prep out the whole arm with a surgical prep so that the arm is not kind of sterile. It’s not just wiped down with an alcohol swab. Sterile. That’s the IV going in. This was before, when I still used to use 18s. You can draw from an 18, 20 minutes later, maybe 75% of the time, but when you have a 16, you can draw all the time. We attach it to sterile tubing, and then what you’re going to see is that sterile tubing is hooked up to a sterile IV that has primed that tubing, and we have an extra stopcock there at the end. You see the cover on that stopcock is going to stay covered the whole time, so even if I contaminate my hands at some point, under that cover is going to still be sterile. With a no-touch technique, we’ll be able to get sterile blood from this, even if me or the fellow or someone else has broken sterility.
We do treat people pre-procedurally with Benadryl. This protects against allergy to contrast, antibiotics, fibrin sealant. It also – people may not realize – Benadryl has an anti-nausea effect through its anti-muscarinic and anti-histaminic central nervous system effects. It has an anti-vagal effect, and it protects from extrapyramidal symptoms if you’re going to give an anti-dopaminergic nausea med. We also give Ondansetron and Cephazolin. There’s no data proving that Cephazolin reduces the risk of infections, but it’s certainly not a good contrast media – excuse me, not a good growth media. When you’ve put it in the blood, it’s going to make it harder for something to grow in that blood.
We place our needles into the epidural space. The epidural space looks like this. That’s the dura there. This is a T2 non-fat-suppressed MRI to make the epidural fat light up, and so the epidural fat is right there, and you can see it on the axial here in that little triangle there. This is the CSF. And so, when we’re coming in with our needle, we’re really trying to hit the apex of that triangle so that the distance to the dura is really far. If we come in further laterally, we’re very close to the dura when we enter that epidural space. So, we want the margin of error being in the middle.
The other thing that I would say that I wanted to pass on to the experts in this room is that when we’re doing our loss of resistance, when we’re passing through the ligamentum flavum here, we do put local anesthetic down the needle into the ligamentum flavum, which fills that hub with local. So if I’m doing this with the trainee, and they’re doing their loss of resistance, I know when they’re in because the loss of resistance syringe is filled with air, and I’m going to see that local disappear when they get into the space.
And so, that’s the basics. We do sometimes do transforaminals to get blood in the front of the epidural space. We draw out the blood from the syringe from the IV that we placed. You can see that that syringe was attached to the covered stopcock with a no-touch technique, so then we can draw up sterile blood again, even if somebody has broken contamination. We put the blood it – it looks like this. Those are the basics of epidural patching. Thank you.