[Music] so you say okay we know we want to do a posterior faucet decompression what are the things on the menu that we need to decide if we're going to do or not do so the first question is really are we going to open a dura because every posterior fossa decompression includes bone removal c1 laminectomy but then you can start to deviate do you just thin the dura and then you're done or do you move on to opening the dura so there's obviously literature to try to answer some of these questions the questions are not definitively answered yet but we're getting more and more data as time goes on so this is just a couple of examples one single center study one meta-analysis and what they basically found was that if you have a syrinx the cyrix is more likely to respond more quickly and probably more completely so it's more likely to resolve or get very small if you open the dura and do a duroplasty that doesn't mean the symptoms are necessarily going to respond better it just means the pictures are going to look better and that's an important distinction sometimes that really matters sometimes it probably doesn't and so that's where some of the the tougher questions are so in both of these papers they basically said if you've got a syrinx we'd probably lean towards doing a duroplasty in the meta analysis the paper on the right what they said is if you don't have a syrinx we would probably lean towards not doing a duroplasty in order to avoid the risk of csf leak or other complications that can happen when you open the dura because a dura is like a big water balloon it's under some pressure you create a weak spot in it by opening it and sewing it shut and you can have complications as a result of that the paper on the left which is from seattle found that there weren't really that much in the way of complications so they didn't worry about it too much but the meta-analysis from multiple different sites showed that there could be complications and so those are best avoided if you can avoid them these are a couple of other papers that look at similar questions the one on the left is an older meta-analysis but i think that it did a really nice job i think of sort of laying the groundwork for decision making for a number of years and what they they found was that if you do a duraplasty you're more likely to solve the patient's symptoms to solve their problems so you probably don't need to reopen very often however if you don't do the duroplasty you're less likely to have complications so that increased rate of solving the problem also comes with basically an equivalently increased rate of complications that can require you to go back in to do something to solve that problem so it's a little bit of you know choose choose what you want do you want to have to go back to operate because the symptoms aren't better so you got to redo the surgery or do you want to have to go back to operate to treat a complication because you have a csf leak or something around that and that's really you know both of those occurred in somewhere in the like 10 to 12 percent range so you really had very similar numbers and you were just sort of deciding which way you wanted to go and importantly the clinical improvement of the patients was more or less the same regardless of which approach you used up front so there was clearly an issue this was early on there's clearly an issue in terms of defining well who's more likely to have a problem if you do a dural opening so who can you avoid it in or who do you really need to take that risk in because they're not going to get better if you don't open the dura and we really didn't have answers to any of those types of questions when this paper came out this again was a meta-analysis of the data from 2008 we're starting to get some of that information now so where some of that information is coming from is park reeves which i mentioned before so the paper on the right was basically their initial effort looking to see what correlates with searing size and in that paper what they basically showed is that that age and that if you have a duroplasty you're more likely again to have a rapid decrease in the size of your steerings that doesn't necessarily mean that you're clinically going to do better and what they said is we just need to wait for a randomized trial and lo and behold they were finishing a randomized trial at the time so we just finished this study last year um and now we're just doing the follow-up and then you know we'll write it up and um and we'll see what the data shows so we don't have the answer to who is most likely to do okay if you don't open the duro versus who do you need to open the dura for but those data are hopefully coming along in the next couple years i think we have to do one year follow up on each patient before we can analyze the data there so let's just say you decide okay i'm going to open the dura what do i do after that do i just open it and look in there and then sew in my patch or do i open it and do some kind of additional maneuvers so some intra-dural activity and historically there have been a number of things that people have done they've done things like put a stent from the posterior fossa to the subarachnoid space they put stents directly into syrinxes they have tried to plug up the central canal thinking that syrinx came down from the fourth ventricle into the central canal people have gotten away from almost all of those things as first line therapy we still sometimes will use a stent from the fourth ventricle to the sub right node space as like third line therapy but one thing that people still do and i still do fairly routinely is explore to make sure you see good fluid flow coming across the obex so what you want to know is that csf is able to make it from the intraventricular space in the fourth ventricle out into the cervical subarachnoid space and wash back and forth across the foramen magnum and so all you really need to do in order to verify that is separate the tonsils and look and see and the reason that this paper is important and this is a paper that came out of alabama is they found that in 12 of their kids when they looked there was actually a thin veil of arachnoid that was blocking the fluid from getting out so even if you just open the dura and sewed it back shut you still wouldn't have solved the problem in those kids and interestingly it was about 10 or 12 percent of kids who had an uh dural sparing right so they didn't open the dura operation who failed and had to go back for another surgery so the question is are those the kids who correlated with the ones who had arachnoid veils in the fourth ventricle so you got to open that up and see it and take care of it and so this is you know just my personal opinion is if you're going to open the dura look in there make sure that there's good csf flow in and out of there so that you know you've solved that problem and then if you want you can heat the tonsils from the outside a little bit and shrink them up to make that space bigger hopefully to make it less likely that you're going to have some kind of scar formation or something that is going to close that space up again but that's again another choice so my feeling is if you're going to open the dura at least take a look and make sure you've got good fluid flow coming out of there so you said okay we're opening the dura we're going to make sure there's good fluid flow now what are we going to do we're going to close the dura right and so generally speaking people don't do a primary dural closure you know they don't just sew the dura back shut again because the whole object of the surgery is to establish more space there so you need to try and sew in a patch or something to increase the space so okay i'm going to sew in a patch well what kind of patch am i going to use you know am i going to am i just going to like take my shirt and sew it in there like of course not right so you got to think about what kind of patch so you've got broadly two categories you've got autographed so the patient's own tissue and you've got everything else so allograft and allograft can come from a number of sources it can be animal tissue that's been processed it can be purely synthetic things so people have looked at success rates using all these different materials to try to figure out what's the best thing to use because there's obviously pros and cons of anything so this is another park briefs paper that we just published this year and basically what it showed is that the total complication rates using either autographed so a patient's own tissue most commonly that's pericranium so you make an additional incision just above your surgical incision and take a piece of pericranium bring it down sew it in so comparing that to using anything else the overall complication rate was equivalent however there was a significant difference in terms of pseudomonical so collection of fluid under the skin and chemical meningitis that's basically an inflammatory process where the body has a response to whatever tissue you put in there so it's not surprising that when you take a patient's own tissue and you just move it around their body is not going to have a problem with that but when you bring in something off the shelf that's a total foreign body and you sew it in there some people's bodies are not going to take too well to that and they're going to have a big inflammatory response it turns out that inflammatory response can be really miserable it can prolong time in the hospital it can sometimes require additional surgeries and it can just make the process kind of awful so chemical meningitis pseudomeningoceles those are things that if you can avoid them it's definitely worth avoiding so in my practice we only use pericranial autograph unless for some reason we can't and it's largely because of that specific thing so that was one of the findings of this paper then they uh we also took a look at different non-autographs so there's bovine pericardium as i mentioned there's just sort of a collagen graft and these are different brands basically of of uh off-the-shelf grafts there's purely synthetic things and what was found there was that the bovine pericardiographs were actually pretty good they didn't cause a lot of issues with regard to pseudomonas seals csf leaks chemical meningitis but when you got into some of those other things that's really where you started to see those problems happen so that's really useful because it gives us guidance as to what are we going to put in the patient to you know to create that patch that's going to minimize the risk if they're going to have some kind of complication or difficulty so this gets into kind of that last thing about what operation are you going to do so atul gowel is a very well known really well respected neurosurgeon in india and he does a lot of complex craniocervical work he does a lot of upper cervical fusions and he posited in 2015 that actually all chiaris are in fact just the body's response to some kind of occult instability at c1 c2 and therefore every patient with a chiari should not have a posterior phos decompression but instead should have a c12 fusion so for people who aren't totally familiar with that that's a great operation when you need it but first of all you're fusing two bones together you decrease range of motion a little bit you're putting the vertebral arteries at risk you're putting the spinal cord at risk because you're passing screws right next to them so in in my hands while that's a great operation i feel that it's a little bit higher risk operation than a posterior faucet decompression and you're taking away somebody's range of motion so uh to me you know i feel like it's it's a safer better long-term option to use a posterior phosphate decompression if you can and there was a very sort of uh exuberant response from the pediatric neurosurgery community to this concept basically saying we don't think this is the case we do not think it's appropriate to do c12 fusions on every kid who has a chiari we think it's unsafe and we're not doing it so while i thought it was important to mention the fact that there are alternative you know perspectives and ideas on how to treat chiari by and large the majority of the pediatric neurosurgery community treats them with some form of posterior faucet decompression at this stage of the game [Music] hey everyone ryan rad here from neurosurgerytraining.org if you like that video subscribe and donate to keep our content available for medical students across the world