Welcome back listeners to another episode of the Colorectal Quiz. I'm Shimon Jacobs, colorectal surgery fellow at Children's National in Washington DC. Doctor Fisher's out today, but I'm here with our host, Doctor Levitt, who's gonna introduce our special guests. The topic today is on the tethered spinal cord, and with us is Doctor John. Serros, who's a professor and vice chief of neurosurgery at Children's National Hospital in Washington DC, and Christina Ho, one of our pediatric urologists and reconstructive partners who is a co-lead of the spina bifida program here. Welcome to both of you. Thank you for joining. Thank you for having for having us. Before our case presentation, let's review spinal anomalies in the setting of anorectal malformations. Babies with an anorectal malformation have a high association of a spinal problem, something to the tune of 25%. They all need to be screened in the newborn period with a spinal ultrasound. Is a spinal ultrasound a good screen, or does the patient need a follow-up MRI? One of the problems is after about 3 or 4, maybe 5 months of age, The, the lamina get big enough, they get broad enough that the ultrasound wave can't make it through. That was Doctor John Maceros, our guest neurosurgeon. So, if you can do an ultrasound and the conus is in a normal position, done. Um, if the conus is clearly low. Don't do an MRI right then. Send them to us. We'll image the kid after 3 months of age when the image quality, the resolution of an MRI is better and will be of surgical quality. First of all, Kus, what, what are, what are we talking about here? Yes. The conus medulais, that is the very, very end of the spinal cord where just below the conus medullarris is where the phylum terminale takes off and there's no further neural tissue, that's why you can cut it. Awesome spinal anatomy review. And what does it mean to have a tethered cord? What's different from a normal spinal cord? In, in a normal child, in a normal person, the spinal cord, which lives inside the dura, inside the fecal sac, is attached and is attached to the brain, um, is fairly free. And as we grow, the spinal cord goes up with us. So a tethered cord is when the cord is low because during development, it's become either attached or it's become fixed in its position, and of course, all that tension with growth is felt at the bottom of the cord. Studies were done a long time ago. To see if you can pull on the spinal cord and affect the cervical spinal cord. Well, you can't because the spinal cord is attached to the dura by little dentate ligaments. So all of that tension is at the bottom of the cord, and the bottom of the cord is where all the nerve roots come out that go to the lower extremities into the bowel and bladder. The reason we think that happens incidentally is because it gets so taut, it gets so Distorted from being pulled on that the little micro vessels, particularly the little arterials in the end of the cord, get occluded and, or at least get stenosed, and there is local ischemia and an ischemic cord leads to nonfunctioning nerve roots, particularly the lower sacral nerve roots which go to the bowel and bladder are super sensitive to this. So to round out our discussion on screening a newborn with an anorectal malformation, what if the ultrasound shows the conus terminating in an intermediate area? The in-between stuff is a little bit difficult when they're at the L2-3 disc, as you pointed out, or at the upper part of L3. You know, the conus doesn't find its final resting spot until about 4 months of age. So if you do an ultrasound in a, in a 1 month old, and the conus is mid-L3, it may go up to a normal level. So I wouldn't go running off getting an MRI on that kid. I'd rather, I'd rather you just send him to us. We'll repeat the ultrasound probably at 3 or 4 months of age until the very, very last minute that we can do an ultrasound. And if it still looks like it might be tethered, we'll do an MRI. Barring symptoms, we'll probably follow that child. If they have symptoms, we consider untethering that child. OK, so Doctor Masos you're saying developed symptoms. So what are the neurologic and orthopedic manifestations that we might see? And Doctor Ho, what are the neurologic symptoms that might be associated with the tethered cord? Especially for, um, for babies, it can be hard to, um, exhibit some of the urinary symptoms that older children may have of a tethered cord. In general, a lot of the urologic manifestations can include things that, um, can happen to any child at any age, like recurrent UTIs, especially. febrile, you know, bladder stones, sometimes blood in the urine, um, but a lot of the things like inability to potty train or urinary incontinence that isn't figured out until they're much older. So, you know, it's very hard in a baby to pick up subtle neurologic issues. It's almost impossible. So, you may not know anything until the kid gets up on their feet. Now, of course, they may not get up on their feet, but if they have that big of a problem, they probably have further down there's orthopedic stuff. They probably have something obvious. They have a, you know, one leg's shorter than the other, one's foot's smaller than the other. They're not moving one leg. Well, um, they have a hip dislocation. They have something. In a kid who's not walking yet, they may have reflex issues, asymmetric reflexes, asymmetric movement. In a toddler, maybe they walk late. If they're delayed in walking because of an asymmetry in their lower extremity function, that would be concerning. You know, the one dominant leg may be allowing them to walk and the bad leg is what's keeping them from walking normally. You know, kids shouldn't complain of back pain, but if you have a 4 year old who complains of back pain, that's concerning. I wanna, um, one thing I'm always curious about, which I think is important for the pediatricians that might be listening to this, is they find various manifestations of the lower back. Tell us when a pediatrician is supposed to refer a patient for at least for an MRI and then to call you. Well, typically, at least in, in our area, they send the kid first and then they, you know, particularly if they're concerned about sedating a baby for an MRI. If you're in the stay current app, click on the first image to view the physical findings of the lower back in 4 infants that you can follow as Doctor Maceros describes them. The first kid there has two little midline abnormalities. One is a little retic meningocele at the very top, and the other is a little dimple just below it, but midline cutaneous manifestations of, of a tethered cord above the gluteal cleft. Kid, uh, on the top row on the right has a little residual tail. Uh, the kid, uh, lower left, has a midline lipoma with a little appendage coming off the right side, and the other, the last kid has a big hemangioma. All these kids have the classic, you know, I didn't, I didn't need an MRI to tell me that these kids had tethered cords. The MRI tells us, um, tells me the, the anatomy and the structure, but I knew they had tethered cords. What is unclear to many pediatricians is the quote unquote sacral dimple. So there's a lot of kids and adults who have dimples within, within the gluteal cleft. Those kids seldom have a tethered cord. As a matter of fact, most of them do not. They have very low coccygeal dimples. They have ultrasounds or MRIs that show a little tract that goes caudal towards the tip of the coccyx, not rostral towards the cord. And have no cord tethering. So we've built a great foundation on this topic and we're ready to discuss the urologic implications with our case presented by Doctor Christina Ho. This particular patient was a 12 month old baby boy with an anorectal malformation and a bladder neck fistula, and he actually underwent his colostomy and then a PSARP locally when he was 4 months of age. Um, of note, right after his PSARP, he did have an episode of urinary retention, which is always something that we, in particular at the urologist take note of. Um, and then when he came here to seek his, um, evaluation, we did an examined anesthesia and also a cystoscopy. And the most notable thing on his cystoscopy is that he had, um, evidence of the significant bladder tubeculation which can be kind of a red flag for us sometimes. Um, as part of his workup, he always, they always get a spinal MRI and his spinal MRI showed this elongated abnormal caudal location of the conus, um, which extended down to the L4, and so this prompted us to order urodynamics for him. This patient seems like they got good care, good operation, however, they still have urologic issues, and the spinal MRI shows, what does this mean? L4. To illustrate this point, Doctor Merceros will guide us through an MRI of a patient with a similar problem. Look at image 2 in the stay current app. So this image is a girl, I think she's 13 or 14, with an interectal malformation. As she's gotten older, has had incontinence. So the very top two arrows are pointing at the disc between T12 and L1, the first bone in lumbar spine, and the next arrow points at the disc between L2 and L3. Or that's sort of the limits to which the normal cord should be. This girl, if you follow the spinal cord down as it tapers off to the third arrow, that's where her cord ends, between L4 and L5 at the L4-5 disc space. That is like way too low. So, uh, the. The 4th arrow down is pointing at fat in the phylum. You can see that little white string. So, uh, if you notice in her skin, um, there's a bunch of white that's fat in the skin, that's normal. You should not have fat inside the spinal canal. That's not normal. Now, it doesn't necessarily mean it's bad. There are normal people, normal children, normal spinal cords with fat in the phylum. That doesn't necessarily denote a tethered cord. But children who have tethered cords have a higher incidence of having fat in the phylum. And if you just look at this girl, uh, you can sort of see that that spinal cord looks like it's just strung over the back of her spine. It looks like somebody's tugging on it, almost like a rubber band. Clear. tethered, she's radiographically tethered. She's clinically tethered, and because of this, we untethered her. What actually is tethering the cord in this child? The actual checklist of things spinal cord, conus, phylum, with the exception of a little fat in the phylum are normal. The problem is that the phylum is not stretching. It's thick. It's non-flexible. It's very noncompliant, and because of that, the surgery for this is actually fairly straightforward. Is it stuck in, we, no, it's not. It's not. It's stuck at the very end of the at the very end of the fecal sac, but so is it in all of us. In this girl, it is just noncompliant. There are other kids with interectal malformations and tethered cords who actually has a spinal cord lipoma, lipomyelloningocele. Click to image 3 to follow two MRIs of separate patients with lipomyello meningoceles. The images on the left and the right are two different kids, but they have very similar lipomas. The one on the left is a lipoma at the end of the cord. The cord's down at S2, and the lipoma is within the spinal canal, which is stuck to her dura. The one on the right is attached to a lipoma that literally goes right through the fascia of her back to her skin. OK, so let's get back to our case of the 12 month old boy with urinary retention after his PAP and now with an MRI suspicious for a tethered cord. Doctor Ho, how should we continue his evaluation? For this particular patient who was 12 months old, you know, up to this point, the only thing in his history that had been a little concerning was he had this episode of urinary retention seemed to resolve, um, and it did happen postoperatively. And then on cystoscopy, there were bladder trabeculations. Which is always a red flag. Like I mentioned that maybe there are some changes to the detrusor muscle that could be neurogenic and cause urodynamics, kind of the gold standard for what we use to diagnose neurogenic bladder, especially when we cannot rely on clinical symptoms. Check out image 4 showing the tracing of the urodynamics study by phase to follow as Dr. Ho describes the findings. This, I thought was just a really nice uro. Dynamic tracing and classic for what we often see for neurogenic bladders from tether cords. It is basically a way to look at different bladder parameters including the storage capacity, compliance, pressures within the bladder, um, and looking at pelvic floor activity during both filling and voiding phases. Uh, for this child, he started leaking at around 14 ccs, so we would say that the functional bladder capacity was incredibly diminished. For his age, it should be around 60 cc. And I was only 14. Um, on top of that, he also had significant detrusor overactivity and also detrusor sphincter dyskinesia, which are two very compelling symptoms and signs of neurogenic bladder as well. On top of that, there was, uh, certainly incomplete emptying. So even though he started leaking fairly early on, as the infusion continued, he was never able to really sustain a detrusor contraction and completely empty his bladder. So according to our definition of he would be considered as having like a hostile bladder, um, which is secondary to a neurogenic cause. The indications for surgery are, can they be purely anatomic? And then what are the clinical indications for, so that's our tendency is to untether them, untether them when they're babies, because there's evidence that somewhere around 80% of these kids will eventually become symptomatic, and in order to avoid, particularly a missed symptom, we tend to untether them upfront. An ectal malformation or not, bladder dysfunction or not. So L4, L4 is tethered, L3, L3 is tethered. So now you're, we're now we're starting to get into uh a bit of a nebulous area. So unless they're below the 2-3 disc, mid L3 or lower, I don't consider them tethered radiographically. It's not a radiographically obvious tether, so you're at the L2-3 gray zone. Yeah. What do you need to hear from us that might push you? To detether, like I tell you, if it's, if it's, if it's at L23, I won't do it, regardless of what you tell me. But I would say that if it is below the L23 disk space, if it's below the upper end plate of L3. Anything that you tell me that's of concern, I would push the family to say, listen, you really need to consider untethering him. We do know that the higher the type of malformation, the more likely there will be an associated spinal and sacral problem. Without a spinal problem, you can have these things too, but unfortunately, those usually represent an iatrogenic injury to the bladder neck, when you have bladder dysfunction with a normal spine. If you can have this type of problem after an operation without a tethered cord. And you have this type of problem after an operation with the tethered cord, it doesn't necessarily mean it's the tethered cord, right? So, that's very hard to parse out. If Christina said, yeah, you know what, this kid has urodynamic studies concerning for a real neurogenic problem, uh, and it's sectioning asylum, I'll tell you, that's, in a little baby, that's a 45 minute operation. The relative risks are pretty close to zero, and the potential benefits are huge. I think Christina can speak to this, but if you have any, any dysfunction, weakness, numbness. You know, prolonged pain and bladder dysfunction for a long period of time, you're probably not gonna get that back. You may prevent it from worsening, but you're probably not gonna get it back. One of the biggest benefits to tethered cord repair, especially in infants, it does prevent their bladder dysfunction from. Worsening, um, especially in those older children, it may not necessarily undo kind of what has been done already. The, the goal is to prevent that bladder dysfunction from worsening because, of course, we're concerned that that could lead to renal dysfunction in the future. Click on image 5 that shows 3 intraoperative panels that illustrate a tethered chord release. Just to give you some orientation, the right side of the slide is where the bottom is, and the left side of the spine is towards the head. So the skin has been opened, the lamina, the bone in the spine has been removed. The dura, the covering of the spinal cord, has been opened. That's what those black sutures are on. They're on the dura, and that little hook is under the phylum. You can see above it and below it normal nerve roots. So they look quite different. And if the kid's truly tethered, the nerve roots are sort of sitting in that space, and the phylum, it looks like a bow string. It's so tight. And the panel on the right. So this is having cauterized and cut it. You can see two cauterized ends, and there's a big gap in between. The gap is there for two reasons. Number 1, when you cauterize the phylum, it does shrink it a little bit, but also it's under tension. So when you cut it and it snaps apart. It looks very neat. Do you, do you not have Have any blood during your operation? Yeah, so blood just causes me lots and lots of consternation. Blood in these operations, and God forbid an infection are the two things that will increase your risk for retethering. They cause inflammatory processes which allow the nerve roots to clump and the cord to potentially retether. So, yeah, you'd like for it to be nice and clean. The, the incidence of retethering from. Sectioning a phylum is exceedingly low. That picture I showed you was from quite a few years ago. I tried to do that operation through a pretty small incision now. I don't do a complete laminectomy anywhere. I take a little bit of one lamina, the one below, and a little bit of a lamina above, and open the door about 1 centimeter. When you use a microscope, you can make things nice and big so you can see quite well and well illuminated, and essentially you just have two raw. ends of a very small phylum, 3 or 4 millimeters. The chances that those things are going to come back together is essentially zero. The chances that the end attached to the spinal cord is going to go and get itself stuck somewhere are pretty small. Those kids that have big lipomas on the end of their cords, those kids are going to have some residual lipoma when you're done untethering them. Taking out the entire lipoma is not necessary, nor is it safe, because ultimately you're end up in the cord. So those kids have a much bigger surface area of scar that's typically on the dorsal aspect of the spine. And given that kids lie on their back all the time and we do sleep, the cord falls back against the dura and eventually retethers. If we took all of our tethered cord kids who have anything more than a sectioning of a phylum, and even those kids, and you re-image them, essentially all of them look like they're tethered. But not that many of them are clinically tethered. I usually quote for complex tethered cords, 40% retethering clinically, it's probably somewhere between 20% and 40% for a phylum, sectioning, pretty close to zero. After the release, how does our patient do? So we, um, we always repeat urodynamics about 3 months after a tethered chord release. You know, we know in our literature it's enough time to kind of allow for inflammation to settle out and to kind of see the effects on the bladder, uh, of that tethered cord release. Image 6 shows the Repeat urodynamic study tracings. And of course, we continue to follow the patient clinically as well. All right, well, that um ends our conversation today about tethered cord and with a specific focus on the urologic implications. To recap today, we discussed the normal anatomy of the spine and conus that ends between L1 and L2. A radiographically tethered cord at L3 or below in infants should be strongly considered for release to prevent later issues. And in older children without neurological, orthopedic, or neurologic dysfunction, they may be able to watch conservatively. Urodynamic studies can help diagnose the neurogenic bladder, and Doctor Ho, what exactly are we looking for? So the biggest things are decreased capacity, functional capacity, incomplete bladder emptying, detrusor overactivity, to choose your sphincter dyskinesia, or impaired compliance, which would mean, you know, high storage pressures. Sectioning a tethered cord in infants can be easier to perform with lower rates of retethering than lipomyelomeningoceles. And after release, repeat urodynamics and clinical follow-up is vital to determine need for future urologic and bowel management procedures. We were really honored to have my wonderful colleagues, uh, Doctor John Maceros from neurosurgery and Doctor Christina Ho, uh, from urology, and, um, thank you all very much for your time. Our pleasure. Thank you. All right. And now the moment you've been waiting for our joke of the week. It's quite appropriate that we have a urologist here, and I wondered, Christina, if you knew what you would do if you were faced with an elephant who had 3 balls. What, what would I do? And the, and the answer is. You should throw another ball and then pitch to the giraffe, walk the elephant, OK? Thank you for tuning in to this week's episode of the Colorectal quiz. Till next time, I'm Shimon Jacobs from Children's National. It's been a pleasure learning with you because knowledge should be free.
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