Utility of spinal MRI in patients with imperforate anus
†Results 2-1 Incidence of spinal cord anomalies (Figure 3)
Introduction
Anorectal malformations (ARMs) include a relatively complex set of congenital
malformations 1, 2）. Some patients with ARMs suffer late onset of neurovesical
dysfunction and/or orthopedic symptoms 3）, which may include fecal and urinary
incontinence, lower extremity weakness, numbness, changes in muscle tone,
and back and leg pain 4）. The association between spinal cord anomalies and
imperforate anus has been well recognized 4）. Until now, the incidence of
tethered cord has been assumed to be more significant in patients with a high
lesion of the imperforate anus 4）. However, recent reports suggest that the
incidence of tethered cord in patients with low lesions is no lower than that in
those with high lesions 4）.
Purpose
To review the incidence of spinal cord anomalies and to compare them between
imperforate anus patients with low and high lesions, including intermediate
lesions.
Materials and Methods
During the period from March 2002 to October 2006, 50 post operatively
patients with imperforate anus underwent lumbar magnetic resonance imaging
(MRI) at our institution.
„ Males, 30 cases; females, 20 cases.
„ Mean age of 9 years at the time of the lumbar MRI (range, 11 days to 25
years old).
„ Low lesions, 11 cases; 39 cases with intermediate and high lesions (all
defined as high lesions for the purpose of this study).
„ Anatomical reconstruction of imperforate anus was successful in all 50 cases.
MRI technique
T1weighted image (SE, 500/20)
†MRI machine
„ Intera 1.5T or 1.0T (Philips)
†MRI protocol (Table)
„ Slice thickness, 3-5mm
†General anesthesia or sedation
Axial
T2 weighted image (SE, 4200/100)
T1 fat-suppressed image
T2 fat-suppressed image
MR myelography
Axial
Sagittal
Axial
Sagittal
Results
„ The overall incidence of symptoms was 31 of 50 (62%) cases.
„ Symptoms were present in 7 of 11 (64%) cases with low lesions and in 24 of
39 (62%) cases with high lesions.
†Results 1-2 Description of symptoms (Figure 2)
„ The symptoms included urinary and fecal incontinence, lower extremity
numbness and leg pain.
„ Urinary and fecal incontinence were the most frequent symptoms in both the
low and high lesion groups. Both of urinary/fecal and lower extremity
symptoms were present in 2 of 7 cases with low lesions and in 2 of 24 cases
with high lesions.
Figure 2. Description of symptoms
Figure 1. Incidence of symptoms
Low
(n=11)
15 cases
38% 24 cases
62%
High
†Results 2-3 Incidence of tethered cord (Figure 5)
„ Tethered cord was revealed in 4 of 11 (36%) cases with low lesions and
in 17 of 39 (44%) cases with high lesions.
„ Among the 21 cases with tethered cord, 4 (1 case with low lesions and
3 cases with high lesions) also showed syringomyelia.
Figure 3.
Incidence of spinal cord anomalies
3 cases
27%
Low
Figure 4.
Findings of spinal cord anomalies
Spinal cord
anomalies
8 cases
73%
17 cases
44% 22 cases
No abnormalit ies
56%
High
(n=11)
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
(n=39)
Figure 5. Incidence of tethered cord
7 cases 4 cases
36%
64%
Low
†Results 1-1 Incidence of symptoms (Figure 1)
Asymptomatic
„ MR images showed spinal lipoma (lipomyelomeningocele, intradural
lipoma, fibrolipoma of the filum terminale), anterior sacral meningocele,
and caudal regression syndrome. The other findings showed tethered
cord without spinal lipoma and unrecognized syringomyelia.
„ Of the above anomalies, spinal lipoma was most frequent in both
groups. Anterior sacral meningocele and caudal regression syndrome
were identified in 1 case with low lesions and 1 case with high lesions.
Tethered cord
No tethered cord
17 cases
44%
22
cases
56%
13%
9%
13%
4.5%
4.5%
13%
Others
Anterior sacral
meningocele
Caudal regression
syndrome
61%
82%
Low
Spinal lipoma
High
for neonates, infants and young children.
1. The incidence and description of symptoms for both the low and high lesions.
2. The incidence and findings of spinal cord anomalies between the low and high
lesions.
3. The presence of vertebral anomalies between the low and high lesions.
Symptomatic
†Results 2-2 Findings of spinal cord anomalies (Figure 4)
Sagittal
We retrospectively reviewed the following factors:
4 cases
36% 7 cases
64%
„ Eight of 11 (73%) cases with low lesions had spinal cord anomalies, as
did 22 of 39 (56%) cases with high lesions.
„ The incidence of spinal cord anomalies did not differ statistically
between cases with low and high lesions (2x2 cross tabs and Fisher’s
exact test, P>0.05).
(n=39)
100%
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
8%
29%
High
(n=39)
†Results 3 Presence of vertebral anomalies (Figure 6, 7)
„ Vertebral anomalies were found in 4 (36%) cases with low lesions and
in 26 (67%) cases with high lesions.
„ The vertebral anomalies found included sacral hypogenesis,
hemivertbra, vertebral fusion, spina bifida and absence of the coccyx.
„ Four of 11 (36%) cases with low lesions and 19 of 39 (49%) cases with
high lesions had both vertebral and spinal cord anomalies. On the
other hand, 4 (36%) cases with low lesions and 3 (8%) cases with high
lesions had spinal cord anomalies anomalies without vertebral
anomalies.
Figure 6.
Incidence of vertebral anomalies
Figure 7. Relationship between
vertebral and spinal cord anomalies
100%
4 cases
36%
80%
Vertebral
anomalies
26 cases
67%
No vertebral
anomalies
60%
40%
20%
Low
12%
(n=11)
(n=11)
High
0%
(n=39)
36
%
36
%
Vertebra(+) Cord (+)
48
%
18
%
8%
28%
26
%
Low
High
Vertebra(+) Cord (-)
Vertebra(-) Cord (+)
Vertebra(-) Cord (-)
Vertebra: Vertebral anomalies
Cord: Spinal cord anomalies
Bot h
29%
80%
42%
Low
High
Lower ext remit y
weakness
Urinary/ fecal
incont inece
References
1) Nievelstein RAJ, Vos A, Valk J. (1998) MR imaging of anorectal malformations and associated anomalies. Eur. Radiol 8: 573-581
2) Leonidas JC, Singh SP, Slovis TL. (2004) Anomalies of the colon and anorectal area. Kuhn JP et al (ed) Caffey’s Pediatric Diagnostic Imaging, !0th ed. Mosby, Philadelphia, 140149
3) De Gennaro M, Ribosecchi M, Lucchetti MC, et al (1994) The incidence of occult spinal dysraphism and the onset of neurovesical dysfunction in children with anorectal anomalies. Eur J Pediatr Surg suppl 1; 12-14
4) Golonka NR, Haga LJ, Keating RP, et al (2002) Routine MRI evaluation of low imperforate anus reveals unexpected high incidence of tethered spinal cord. J Pediatr Surg 37: 966-969
5) Mosiello G, Capitanucci ML, Capitanucci ML, Gatti C, et al (2003) How to investigate neurovesical dysfunction in children with anorectal malformations. J Urol 170: 1610-1613
6) Mittal A, Airon RK, Magu S, et al (2004) Associated anomalies with anorectal malformation. Indian J Pediatr 71: 509-514
7) Nievelstein RAJ, Vos A, Valk A, et al (2002) Magnetic resonance imaging in children with anorectal malformations: embryologic implications. J Pediatr Surg 37: 1138-1145
8) Tsakayannis DE, Shamberger RC (1995) Association of imperforate anus with occult spinal dysraphism. J Pediatr Surg 30: 1010-1012
9) Endo M, Hayashi A, Ishihara M, et al (1999) Analysis of 1,992 patients with anorectal malformations over the past two decades in Japan. Steering Committee of Japanese Study Group of Anorectal Anomalies. J Pediatr Surg 34 435-441
10) Long FR, Hunter JV, Mahboubi S, et al (1996) Tethered cord and associated vertebral anomalies in children and infants with imperforate anus: evaluation with MR imaging and Plain Radiography. Radiology 200: 377-382
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12) Tuuka SE, Aziz D, Drake J, et al. (2004) In surgery necessary for asymptomatic tethered cord in anorectal malformation patients? J Pediatr Surg 39: 773-777
13) Gudinchet F, Maeder P, Laurent T, et. al (1997) Magnetic resonance detection of myelodysplasia in children with Currarino triad. Pediatri Radiol 27: 903-907
National Center for Child Health and Development, Department of Radiology, Japan
*Saitama Children’
Children’s Medical Center, Department of Pediatric surgery
Mikiko Miyasaka，Shunsuke Nosaka，Yoshihiro Kitano*，Yoshiyuki Tsutsumi, Osamu Miyazaki,
Reiko Okamoto, Ikuko Okusu，Kyoko Kashima，Chihiro Tani, Yoshiyuki Okada，Hidekazu Masaki
†Case 1
Fibrolipoma of the filum terminale and tethered cord
†Case 2. Fibrolipoma of the filum terminale with syringomyelia
Low lesion of the imperforate anus in a
7-year-old boy who presented with
lower extremity weakness.
T2 weighted sagittal image shows the
low level of the conus medullaris at the
L3 level. Vertebral anomalies were not
found.
T1 weighted axial image reveals a
fibrolipoma of the filum terminale
(arrow).
T1 weighed axial image
T2 weighted sagittal image
†Case 3. Anterior sacral meningocele
A 25-year-old female
presented with urinary
incontinence.
T2 weighted axial image
shows a cystic mass in the
presacral space. T1 and T2
weighted sagittal images
reveal the anterior sacral
meningocele extending
into the pelvis from the
sacrum. Scimitar sacrum
is seen. A diagnosis of
Currarino syndrome was
made.
T2 weighted axial image
T1 weighted sagittal image
T2 weighted axial image
at the level of the thoracic spine
T1 weighed axial image
T2 weighted sagittal image
High lesion of the imperforate anus in a 5-year-old boy who
presented with urinary and fecal incontinence.
T1 weighted axial image shows a high-intensity lesion of the
filum terminale (arrow). A diagnosis of fibrolipoma was made.
On T2 weighted sagittal image, the conus medullaris is at the
level the L3/4 level, and tethered cord was diagnosed.
Vertebral anomalies were not present.
T2 weighted axial image of the thoracic spine reveals
syringomyelia (open arrow).
†Case 4. Caudal regression syndrome
A 9-year-old girl with low imperforate
anus presented with a complaint of
urinary incontinence.
T2 weighted sagittal image and MR
myelography show that the cord terminus
is blunted (arrows). Sacral hypogenesis
was revealed.
T2 weighted sagittal image
Discussion
ARMs are frequently associated with other anomalies, especially of the
spinal cord, spine and urogenital system 8）. The overall incidence of
patients having one or more associated anomalies was 45.2% 9）.
T2 weighted sagittal image
MR myelography
†Case 5. Lipomyelomeningocele
†Incidence and description of symptoms
The symptoms found in conjunction with imperforate anus include fecal
incontinence, neurovesical dysfunction, gait disturbance and spastic
abnormalities of the lower extremities 8）. The onset of symptoms is
variable but usually occurs in childhood and may be slowly progressive 10).
Neurovesical dysfunction is primarily related to tethered cord or to an
iatrogenic nerve injury 11）. Once symptoms appear, they are often
irreversible despite surgical intervention and may have a significant impact
on the continence of patients with imperforate anus. Surgical release of a
tethered cord before the onset of neurological problems may prevent the
onset of these symptoms.
T1 weighted axial image
†Incidence and findings of spinal cord anomalies
Heij et al. have demonstrated that the incidence of tethered cord is higher
in patients with high lesions (50%) than in patients with low lesions (30%)
4）. However, Golonka et al. report that the incidence of tethered cord in
children with low lesions is no lower than that in those with high lesions 11）.
In the present study, patients with spinal cord anomalies accounted for
73% of those with low lesions and for and for 56% of those with high
lesions, tethered cord was identified in 36% of low lesion patients and 44%
of the high lesion group. These results are similar to those reported in
previous studies 4,5）.
†Presence of vertebral anomalies
Vertebral anomalies have been reported to be twice as common in
patients with high lesions than in those patients with low lesions 10）.
In the present study, the presence of vertebral anomalies were 36% in the
low lesion groups and 67% in the high lesion group. This result is similar to
previous reports 10）. On the other hand, spinal cord anomalies without
vertebral anomalies were frequently found in patients with low lesions in
the present study. Some authors recommend MRI evaluation of all patients
with ARMs because spinal cord anomalies, including tethered cord, are
known to occur in patients without sacral anomalies as well as in those with
low ARMs 4, 5, 10） .
MR myelography
T2 weighted axial image
A 2-year-old girl with high imperforate anus underwent lumbar
MRI for screening.
MR myelography shows the spinal cord tethered by a large
lipoma that extends from the subcutaneous fat through a spina
bifida into the dorsal subarachnoid space.
T1 and T2 axial images reveal a lipomyelomeningocele through
the spina bifida.
A number of authors have recommended ultrasound screening of infants
with imperforate anus followed by MRI to confirm abnormal findings 5, 10, 12）.
Ultrasound is an ideal screening tool for infants less than 3 month of age.
Mosiello et al. recommend that all patients be screened with MRI at age 6
to 12 months 5, 12）. MRI is the most sensitive modality for detecting spinal
cord anomalies as well as for detecting vertebral anomalies.
Conclusion
Owing to the high incidence of spinal cord anomalies in patients with
imperforate anus, MRI is the best type of imaging study to detect such
anomalies regardless of the type of imperforate anus.