Colorectal Quiz Episode 30: Tethered Cord

Published: 2022-03-21

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Inside this episode

Kai, the Library's AI content creator, listened to this episode and mapped who's speaking, the chapters, key claims, and cases. Every item links to the exact moment in the recording.

AI-enriched

Who's speaking

Shimon Jacobs — host
Doctor Levitt — host
Christina Ho — guest
John Maceros — guest

Chapters

0:00Introduction and Spinal Screening in Anorectal Malformations — Introduction of hosts and guests. Discussion of spinal anomaly screening in newborns with anorectal malformations, including ultrasound timing, limitations, and MRI indications. Review of normal conus anatomy and definition of tethered cord.
3:20Clinical Manifestations and Physical Examination Findings — Review of neurologic, urologic, and orthopedic symptoms of tethered cord. Discussion of cutaneous manifestations including lipomas, hemangiomas, and dimples. Clarification of which sacral dimples require imaging versus observation.
7:30Case Presentation: 12-Month-Old with Urinary Retention — Presentation of a 12-month-old boy with anorectal malformation, bladder neck fistula, post-PSARP urinary retention, bladder trabeculation on cystoscopy, and MRI showing conus at L4. Urodynamic findings demonstrate neurogenic bladder with detrusor overactivity, sphincter dyskinesia, and hostile bladder parameters.
13:30Surgical Indications and Technique — Discussion of surgical indications for tethered cord release, including anatomic criteria (below L2-3) and clinical symptoms. Detailed description of surgical technique for filum sectioning and lipomyelomeningocele repair. Review of retethering risks and factors affecting outcomes.
19:30Post-Operative Management and Summary — Post-operative urodynamic follow-up at 3 months. Summary of key teaching points including diagnostic criteria, urodynamic findings, surgical timing, and follow-up protocols.

Key claims

0:51Babies with an anorectal malformation have approximately 25% association with spinal problems — Doctor Levitt
0:51All babies with anorectal malformations need screening in the newborn period with spinal ultrasound — Doctor Levitt
1:09After 3-4, maybe 5 months of age, the lamina get broad enough that ultrasound waves cannot penetrate for spinal imaging — John Maceros
1:22If ultrasound shows conus in normal position, no further imaging is needed — John Maceros
1:27If conus is clearly low on ultrasound, MRI should be delayed until after 3 months of age when resolution is better and of surgical quality — John Maceros
1:47The conus medullaris is the very end of the spinal cord; below it the filum terminale has no neural tissue, which is why it can be cut — John Maceros
2:06In normal development, the spinal cord ascends as the child grows — John Maceros
2:21A tethered cord occurs when the cord is low because it became attached or fixed during development, with all tension from growth felt at the bottom of the cord — John Maceros
2:34Tension on the spinal cord affects the bottom of the cord, not the cervical cord, because the cord is attached to dura by dentate ligaments — John Maceros
2:53The mechanism of tethered cord injury is likely ischemia from occlusion or stenosis of micro vessels in the taut, distorted cord, particularly affecting lower sacral nerve roots to bowel and bladder — John Maceros
3:37The conus does not find its final resting spot until about 4 months of age — John Maceros
3:41If ultrasound at 1 month shows conus at mid-L3, it may ascend to normal level and should be re-evaluated at 3-4 months rather than proceeding immediately to MRI — John Maceros
4:27Urologic manifestations of tethered cord include recurrent febrile UTIs, bladder stones, hematuria, inability to potty train, and urinary incontinence — Christina Ho
4:47It is very hard, almost impossible, to pick up subtle neurologic issues in a baby — John Maceros
4:56Orthopedic manifestations of tethered cord include leg length discrepancy, foot size asymmetry, reduced leg movement, and hip dislocation — John Maceros
5:14In non-walking infants, tethered cord may present with asymmetric reflexes or asymmetric movement — John Maceros
5:21Delayed walking or asymmetric gait in toddlers may indicate tethered cord — John Maceros
5:34Children should not complain of back pain; back pain in a 4-year-old is concerning for spinal pathology — John Maceros
6:22Midline cutaneous manifestations above the gluteal cleft indicate tethered cord — John Maceros
7:06Dimples within the gluteal cleft seldom indicate tethered cord; most show coccygeal tracts going caudal, not rostral toward the cord — John Maceros
11:54Bladder trabeculation on cystoscopy is a red flag for neurogenic bladder changes — Christina Ho
11:59Urodynamics is the gold standard for diagnosing neurogenic bladder when clinical symptoms cannot be relied upon — Christina Ho
9:17Normal conus position is between T12-L1 and L2-L3 disc spaces — John Maceros
9:46Fat should not be present inside the spinal canal; while some normal children have fat in the filum, children with tethered cords have higher incidence of fatty filum — John Maceros
10:35In some tethered cord cases, the actual pathology is a thick, non-flexible, noncompliant filum that does not stretch — John Maceros
13:36Approximately 80% of children with radiographically tethered cords will eventually become symptomatic — John Maceros
13:36The tendency is to untether babies with radiographic tethering upfront to avoid missed symptoms, regardless of anorectal malformation or bladder dysfunction status — John Maceros
14:10Conus below L2-3 disc or mid-L3 or lower is considered radiographically tethered — John Maceros
14:35For conus at L2-3 level, surgery would not be performed regardless of clinical symptoms — John Maceros
14:42For conus below L2-3 disc space with any concerning clinical findings, untethering should be strongly recommended — John Maceros
14:57Higher type anorectal malformations are more likely to have associated spinal and sacral problems — Doctor Levitt
15:05Bladder dysfunction with normal spine in anorectal malformation patients usually represents iatrogenic injury to the bladder neck — Doctor Levitt
15:35Filum sectioning in a little baby is a 45-minute operation with relative risks close to zero and potential benefits that are huge — John Maceros
15:54If neurologic dysfunction, weakness, numbness, prolonged pain, or bladder dysfunction persists for a long period, recovery after untethering is unlikely; surgery may prevent worsening but probably will not restore function — John Maceros
16:13Tethered cord repair in infants prevents bladder dysfunction from worsening and protects against future renal dysfunction, though it may not reverse existing damage in older children — Christina Ho
17:41Blood and infection during tethered cord surgery increase risk of retethering by causing inflammatory processes that allow nerve roots to clump and cord to retether — John Maceros
17:57The incidence of retethering from sectioning a filum is exceedingly low, pretty close to zero — John Maceros
18:45Taking out the entire lipoma in lipomyelomeningocele is not necessary and not safe because it risks entering the spinal cord — John Maceros
18:51Children with lipomyelomeningocele repairs have larger dorsal scar surface area and the cord falls back against dura during supine positioning, leading to retethering — John Maceros
19:05Essentially all tethered cord patients look radiographically tethered on re-imaging, but not that many are clinically tethered — John Maceros
19:18Clinical retethering rate for complex tethered cords is quoted at 40%, probably between 20-40%; for filum sectioning it is pretty close to zero — John Maceros
19:32Repeat urodynamics should be performed 3 months after tethered cord release to allow inflammation to settle and assess bladder effects — Christina Ho
20:25Urodynamic findings indicating neurogenic bladder include decreased functional capacity, incomplete bladder emptying, detrusor overactivity, detrusor sphincter dyskinesia, and impaired compliance with high storage pressures — Christina Ho

Cases discussed

7:3912-month-old boy with anorectal malformation and bladder neck fistula who developed urinary retention after PSARP, found to have bladder trabeculation and tethered cord at L4

Open questions

In cases where bladder dysfunction occurs after PSARP in a patient with a tethered cord, how can clinicians definitively distinguish iatrogenic bladder neck injury from neurogenic bladder due to tethering?
What is the optimal follow-up interval and imaging protocol for infants with borderline conus position (L2-3 to upper L3) who are being observed rather than immediately untethered?
For patients with established neurogenic bladder changes prior to untethering, what percentage show improvement versus stabilization versus continued deterioration after surgery?

This episode was analyzed and enriched by Kai, the Library's AI content creator. Every item links to the moment it comes from — click a timestamp to listen in context.

Written for:

Tethered Cord in Anorectal Malformations: Screening Through Surgical Decision

The episode's teaching points arranged as a structured lesson, building from the basics up to the finer points. Written by Kai from the episode transcript and reviewed before publishing.

For trainees · Teaching arc · AI-written, human-reviewed

The screening window closes faster than you think

Spinal ultrasound is the initial screen for all newborns with anorectal malformations, given the 25% association with spinal problems 0:51. But the imaging window is narrow: after 3-5 months, the lamina broaden enough that ultrasound waves cannot penetrate 1:09. If the conus is clearly normal on ultrasound, you are done 1:22. If it is clearly low, delay MRI until after 3 months when resolution improves to surgical quality 1:27. The conus does not reach its final position until approximately 4 months of age 3:37, so an intermediate position at mid-L3 in a 1-month-old may ascend to normal — repeat ultrasound at 3-4 months rather than rushing to MRI 3:41. This maturation timeline is not a detail; it is the decision point between appropriate surveillance and premature imaging.

Tethering injures through ischemia, not stretch

The mechanism matters for understanding what you are trying to prevent. A tethered cord is fixed during development, and as the child grows, all tension concentrates at the cord's terminus 2:21. The spinal cord is anchored to dura by dentate ligaments, so pulling affects only the lower cord, not the cervical segments 2:34. The injury is ischemic: the taut, distorted cord occludes or stenoses the small arterial vessels at its end, and the lower sacral nerve roots to bowel and bladder are exquisitely sensitive to this ischemia 2:53. "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" [q3]. This is not a mechanical compression injury — it is vascular compromise at the microcirculation level.

Clinical detection in infants is nearly impossible

"You know, it's very hard in a baby to pick up subtle neurologic issues. It's almost impossible" [q5]. Urologic manifestations — recurrent febrile UTIs, bladder stones, hematuria, incontinence — may not declare themselves until potty training age 4:27. Orthopedic signs are more detectable early: leg length discrepancy, foot size asymmetry, reduced leg movement, hip dislocation 4:56. In non-walking infants, look for asymmetric reflexes or movement 5:14; in toddlers, delayed walking or asymmetric gait 5:21. Back pain in a 4-year-old is abnormal and concerning 5:34. The clinical exam is insensitive in the first year, which is why radiographic screening drives early surgical decisions.

Radiographic thresholds and the 80% rule

Conus below the L2-3 disc space or mid-L3 or lower is radiographically tethered 14:10. At the L2-3 level itself, surgery would not be performed regardless of symptoms 14:35. Below L2-3 with any concerning clinical findings, untethering should be strongly recommended 14:42. Approximately 80% of radiographically tethered children will eventually become symptomatic 13:36, and the tendency is to untether infants upfront to avoid missing the window when intervention is effective 13:36. Fat inside the spinal canal is abnormal, though some normal children have fatty filum; children with tethered cords have higher incidence of this finding 9:46. In some cases, the pathology is a thick, noncompliant filum that does not stretch rather than a structural attachment 10:35.

The window for functional recovery is narrow

"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" [q11]. Tethered cord repair in infants prevents bladder dysfunction from worsening and protects against future renal dysfunction, but it may not reverse established damage in older children 16:13. Filum sectioning in an infant is a 45-minute operation with risks close to zero and potential benefits that are huge 15:35. Blood and infection during surgery increase retethering risk by causing inflammatory processes that allow nerve roots to clump 17:41, but retethering after simple filum sectioning is exceedingly low, nearly zero 17:57. Complex repairs involving lipomyelomeningocele have clinical retethering rates between 20-40%, versus near-zero for filum sectioning 19:18.

Urodynamics define the hostile bladder

When clinical symptoms are unreliable, urodynamics is the gold standard for diagnosing neurogenic bladder 11:59. Pathologic findings include decreased functional capacity, incomplete emptying, detrusor overactivity, detrusor-sphincter dyskinesia, and impaired compliance with high storage pressures 20:25. Bladder trabeculation on cystoscopy is a red flag for neurogenic changes 11:54. Repeat urodynamics 3 months after tethered cord release allows inflammation to settle and assesses bladder effects 19:32. Nearly all tethered cord patients appear radiographically tethered on re-imaging, but far fewer are clinically symptomatic — radiographic appearance alone should not drive reoperation 19:05.

Takeaways from this story

Spinal ultrasound screening must occur before 3-5 months when lamina broaden and block ultrasound penetration.
Conus position at 1 month may not be final; intermediate positions warrant repeat ultrasound at 3-4 months, not immediate MRI.
Tethered cord injury is ischemic from microvascular occlusion, not mechanical stretch — lower sacral roots are most vulnerable.
80% of radiographically tethered infants become symptomatic; early untethering prevents dysfunction but cannot reverse it once established.
Urodynamics showing detrusor overactivity, dyskinesia, or impaired compliance defines neurogenic bladder when clinical symptoms are unreliable.

Tethered Cord in Anorectal Malformations: Screening Through Surgical Decision-Making

The episode's teaching points arranged as a structured lesson, building from the basics up to the finer points. Written by Kai from the episode transcript and reviewed before publishing.

For specialists · Teaching arc · AI-written, human-reviewed

The screening window closes faster than you think

Spinal ultrasound is effective for newborn screening but has a narrow technical window 1:09. After 3-5 months, the lamina broaden enough that ultrasound waves cannot penetrate — you lose visualization entirely, not just resolution. This timing constraint shapes the entire screening protocol. If the initial ultrasound shows a clearly low conus, delay MRI until after 3 months when image quality reaches surgical grade 1:27. Imaging too early wastes the study; you will need to repeat it anyway.

The conus itself does not reach its final position until approximately 4 months of age 3:37. An intermediate position at mid-L3 on a 1-month ultrasound may ascend to normal by 3-4 months. Serial ultrasound at the outer edge of the technical window — not immediate MRI — is the correct next step for borderline cases 3:41. This is not conservative management; it is recognizing that the anatomy has not yet declared itself.

Ischemia, not stretch, destroys the nerve roots

The mechanism matters because it explains the clinical pattern. A tethered cord becomes taut and distorted with growth, but the injury is not mechanical 2:21. The small arterial vessels at the cord terminus occlude or stenose under tension, causing local ischemia 2:53. The lower sacral nerve roots controlling bowel and bladder function are exquisitely sensitive to this ischemic insult — more so than motor roots. This is why bladder dysfunction often precedes obvious motor findings and why early untethering, before prolonged ischemia establishes irreversible damage, offers the best chance of preserving function 15:54.

Dentate ligaments anchor the cord to dura along its length, so tension concentrates at the bottom 2:34. You cannot injure the cervical cord by pulling on a tethered terminus — the physics do not allow it. All pathology localizes to the lower sacral segments.

Radiographic tethering is not the same as clinical tethering

Nearly every patient re-imaged after tethered cord surgery appears radiographically tethered 19:05. The cord falls back against dura during supine positioning, scar forms on the dorsal surface, and the imaging looks concerning. But clinical retethering — new or progressive symptoms — occurs in 20-40% of complex repairs and nearly zero percent after simple filum sectioning 19:18. Do not operate on an MRI. Operate on symptoms in the context of an MRI.

For conus position, the threshold is the L2-3 disc space 14:10. Below that level, the cord is radiographically tethered. At exactly L2-3, surgery would not be performed regardless of clinical findings 14:35. Below L2-3 with any concerning clinical findings — urodynamic abnormalities, asymmetric reflexes, orthopedic asymmetry — untethering should be strongly recommended 14:42.

Approximately 80% of radiographically tethered infants will eventually become symptomatic 13:36

This statistic drives the tendency toward prophylactic untethering in babies with clear radiographic tethering, regardless of current symptoms 13:36. The operation in an infant — sectioning a 3-4mm filum through a 1cm exposure — carries risks close to zero and takes 45 minutes 15:35. The alternative is waiting for symptoms that may be subtle and missed, then operating after prolonged dysfunction when recovery is unlikely 15:54. Early surgery prevents bladder dysfunction from worsening and protects against future renal deterioration, even if it cannot reverse established damage 16:13.

Blood and infection during surgery increase retethering risk by causing inflammatory processes that allow nerve roots to clump and the cord to re-adhere 17:41. Meticulous hemostasis is not aesthetic preference — it is the primary technical factor under surgical control that affects long-term outcome. For lipomyelomeningocele, complete lipoma resection is neither necessary nor safe; entering the cord to chase residual fat guarantees worse outcomes than leaving it 18:45. The larger dorsal scar surface area in these repairs explains their higher retethering rate compared to simple filum sectioning 18:51.

Urodynamics define the hostile bladder before clinical symptoms declare themselves

In infants, clinical symptoms are unreliable 4:47. Urodynamics is the gold standard for diagnosing neurogenic bladder when you cannot trust the history 11:59. The pathologic findings are decreased functional capacity, incomplete emptying, detrusor overactivity, detrusor-sphincter dyskinesia, and impaired compliance with high storage pressures 20:25. These parameters define a hostile bladder at risk for upper tract deterioration. Bladder trabeculation on cystoscopy is a red flag 11:54, but urodynamics quantify the threat. Repeat urodynamics 3 months after untethering to allow inflammation to settle and assess the bladder's response 19:32.

Takeaways from this story

Spinal ultrasound loses technical feasibility after 3-5 months when lamina broaden; time your screening and follow-up imaging accordingly.
Conus position finalizes at 4 months; mid-L3 at 1 month may ascend to normal — serial ultrasound beats premature MRI in borderline cases.
Tethered cord injury is ischemic, not mechanical: microvascular occlusion under tension destroys lower sacral roots before motor findings appear.
80% of radiographically tethered infants become symptomatic; prophylactic untethering in babies carries near-zero risk and prevents irreversible damage.
Nearly all post-op imaging looks tethered; clinical retethering is 20-40% for complex repairs, near-zero for filum sectioning — operate on symptoms, not scans.

Topic overview

A multidisciplinary discussion on tethered spinal cord in the context of anorectal malformations. Approximately 25% of infants with anorectal malformations have associated spinal problems requiring screening with spinal ultrasound in the newborn period. A tethered cord occurs when the spinal cord is fixed in a low position (below L2-3), causing tension on the lower cord and potential ischemia affecting bowel, bladder, and lower extremity function. Radiographically tethered cords at L3 or below in infants should be strongly considered for surgical release to prevent progressive neurologic dysfunction, particularly neurogenic bladder. The surgical approach and retethering risk vary significantly based on the underlying pathology—simple filum sectioning carries near-zero retethering risk, while lipomyelomeningocele repairs have 20-40% clinical retethering rates.

Key takeaways

Screen all ARM infants with spinal US in newborn period; 25% have spinal problems requiring evaluation. (0:51)
Conus below L2-3 disc with clinical concerns warrants untethering; 80% become symptomatic if left untreated. (13:36)
Early untethering prevents bladder dysfunction progression; delayed surgery unlikely to restore established deficits. (15:54)
Simple filum sectioning has near-zero retethering risk; complex repairs (lipomyelomeningocele) carry 20-40% risk. (17:57)
Urodynamics at 3 months post-op is gold standard to assess neurogenic bladder response to untethering. (11:59)

Keywords

anorectal malformation tethered spinal cord spina bifida neurogenic bladder lipomyelomeningocele urinary retention detrusor overactivity detrusor sphincter dyskinesia bladder trabeculation recurrent UTI bladder stones hematuria urinary incontinence hip dislocation back pain

Hashtags

#TetheredCord #PediatricNeurosurgery #AnorectalMalformation #SpinaBifida

Transcript

Click "Show Transcript" to view the full text (21548 characters)

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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