1. Spinal evaluation in children with imperforate anus
Simone Montoya, R1
December 15, 2011

2. Objective
Anorectal malformations are often associated with vertebral and/or spinal cord abnormalities
Fecal incontinence/constipation may be due to anorectal and/or neurological pathology
Magnetic resonance imaging is the gold standard for spinal cord imaging, but sonography is an effective screening tool before ossification has taken place
… So should a spinal MRI be part of the work-up of a newborn with an anorectal malformation?

3. Case: BS Born at OSH on 12/7/2011 Imperforate anus noted upon delivery
41wk GA
Imperforate anus noted upon delivery
Passing meconium through small defect in perineum anterior to presumed proper location of anus
“Bucket handle” deformity
Physical exam also notable for LGA and sacral dimple
Underwent anoplasty on DOL1
Discharged to home on POD5

4. Perineal fistula
Low-lying lesion

5. Anatomic Classification of Anorectal Malformations (Wingspread)
Female
Male
HIGH: (blind) rectal pouch above the pubococcygeal line
Anorectal agenesis with/without rectovaginal fistula
Anorectal agenesis with/without rectoprostatic urethral
Rectal atresia
INTERMEDIATE
Rectovestibular fistula
Rectobulbar urethral fistula
Rectovaginal fistula
Anal agenesis without fistula
LOW: rectal pouch below the pubococcygeal line (within the levator ani)
Anovestibular fistula
Anocutaneous fistula
Anal stenosis
Rare/Cloacal malformations

6. VACTERL Association
Anomalies not pathogenetically related, but occur together more frequently than expected by chance
Vertebral anomalies
Anal atresia
Cardiac defects
TracheoEsophageal fistula
Renal malformations
Limb defects
VATER: 2 anomalies; VACTERL: 3 anomalies
Currarino triad: anorectal malformation, sacral bony abnormality, presacral mass
OEIS:Omphalocele, Exstrophy of the bladder, Imperforate anus, Spinal defects

7. Other Investigations Renal ultrasound Echocardiogram Spinal x-rays
Essentially normal renal ultrasound save for a tiny right cortical cyst. Normal renal size. No collecting system dilatation.
Echocardiogram
Patent ductus arteriosus, left to right shunt, trivial.
Small secundum atrial septal defect measuring 4 mm with left to right flow.
Spinal x-rays
6 lumbar-type vertebrae.
Sacral ultrasound
The conus terminates normally at the level of L2/3.
The conus and cauda equina layer dependently, without evidence of tethering or thickening of the filum.
There is no intraspinous mass.
There is no meningocele.

9. Tethered Spinal Cord Syndrome
Due to traction on spinal cord
Occurs with spinal dysraphism
Manifestations
Cutaneous: birthmark, tuft, sacral dimple (not coccygeal)
Orthopedic: club feet, asymmetric leg length, scoliosis
Neurologic: low back/leg pain, leg weakness
Urologic: incontinence, recurrent UTIs
Anorectal: incontinence, constipation
Radiologic criteria
Low-lying conus medullaris (below L1-2)
Tight/fatty filum terminale
Conus at L2-3 only in ~10% even at newborn age
Thickened filum >1mm

10. Tsakayannis and Shamberger, 1995
Prospective study of 45 infants with imperforate anus
6 infants (14%) found to have tethered cord
No correlation with type of lesion
No correlation with bony sacral abnormalities
All participants had either US or MR
10 infants had both
No indication of how/why imaging modality chosen
Conclusion: screen all infants with imperforate anus to allow for early surgical correction of TSC

11. Levitt et al, 1997 Review of 934 cases of anorectal malformation
111 patients underwent spinal MRI
27 (24%) had evidence of TSC
Increasing prevalence with increasing severity of malformation
Not statistically significant
18 underwent surgical release
6 were asymptomatic
None had significant improvement in bowel/urinary function
Patients with TSC more likely to have incontinence
Not able to determine causality vs coincidence
Less likely to have constipation
May be related to severity of anorectal malformation

12. Indications for Screening
Mandatory
Recommended
Myelodysplasia
Recto-bladder neck fistula
Lateral sacral ratio <0.6
Cloaca common channel >3cm
AP sacral ratio <0.4
Presacral mass
Complex defect
Sacral hemivertebra
Cloacal exstrophy
Single kidney
Ectopic kidney
Hypospadias
Spinal hemivertebra

13. Golonka et al, 2002
Retrospective review of 79 patients with imperforate anus
63 evaluated with spinal MRI
22 had TSC
11 of 41 (26.8%) with high lesions
11 of 22 (50%) with low lesions
No specific predictors
All confirmed upon surgical release
Conclusion: all with anorectal malformations regardless of level of lesion should undergo MRI screening
Those with TSC should undergo untethering to avoid incontinence due to neurologic deficit, as surgery only halts progression (does not reverse symptoms)

14. O’Neill et al, 2010
Hospital policy that all neonates with VACTERL, TEF, or imperforate anus screened with echo, renal US, spinal US
Abnormal spinal US followed by MRI
Retrospective analysis of 112 cases
36 met criteria for VACTERL
13 (39%) had TSC
All had vertebral anomaly
More likely to have anal atresia
38 had non-VACTERL anal atresia
3 (7.9%) had TSC
3 of 14 (21.4%) MRI-confirmed TSC had false-negative US
Conclusion: screening spinal MRI for all children with VACTERL

15. Literature Take Home Points
Anorectal malformations and spinal dysraphisms are associated, but exact relationship not established
Spinal imaging in infants with imperforate anus to screen for both VACTERL and TSC
Stooling issues in those with imperforate anus – difficult to determine anorectal vs neurologic causality
MRI is best imaging modality for occult spinal dysraphisms

16. Considerations with BS
Conus level
Supernumerary lumbar vertebra
Limitation of US as screening tool
Indications for surgical untethering
Potential prevention of neurological progression

17. My Conclusions
Given the finding of 6 lumbar vertebra and the limitations of US, I would have gotten a spinal MRI
If TSC found, would recommend untethering by 6mo
Institution-based (no consensus)
Low morbidity, great potential benefit

18. References
Tsakayannis DE, Shamberger RC. Association of imperforate anus with occult spinal dysraphism. J Pediatr Surg Jul;30(7):
Long FR, Hunter JV, Mahboubi S, Kalmus A, Templeton JM Jr. Tethered cord and associated vertebral anomalies in children and infants with imperforate anus: evaluation with MR imaging and plain radiography. Radiology Aug;200(2):
Melhem ER. Tethered cord and associated anomalies in children and infants with imperforate anus: evaluation with MR imaging and plain radiography. Radiology Aug;200(2):318-9.
Levitt MA, Patel M, Rodriguez G, Gaylin DS, Pena A. The tethered spinal cord in patients with anorectal malformations. J Pediatr Surg Mar;32(3):462-8.
Golonka NR, Haga LJ, Keating RP, Eichelberger MR, Gilbert JC, Hartman GE, Powell DM, Vezina G, Newman KD. Routine MRI evaluation of low imperforate anus reveals unexpected high incidence of tethered spinal cord. J Pediatr Surg Jul;37(7):966-9.
O'Neill BR, Yu AK, Tyler-Kabara EC. Prevalence of tethered spinal cord in infants with VACTERL. J Neurosurg Pediatr Aug;6(2):
“Spinal dysraphisms.” In: Principles of Neurological Surgery.
“Pediatric abdomen.” In: Greenfield’s Textbook of Surgery.
“Tethered cord syndrome.” In: Greenberg;s Manual of Neurosurgery.