SUS is an accepted first-line screening test for spinal dysraphism in neonates. It has diagnostic sensitivity equal to MRI but can be performed portably without sedation. The document discusses the advantages of SUS over MRI and appropriate use in neonates. Key points covered include normal spinal anatomy visualized by SUS, common variants seen in neonates, and classifications and features of various spinal dysraphism anomalies detectable by SUS.

1. Dr/Ahmed Bahnassy
Consultant Radiologist
Riyadh Military Hospital

2. Why US spines ?
Spinal ultrasound (SUS) is becoming
increasingly accepted as a first line
screening test in neonates suspected of
spinal dysraphism .

3. Challenging MRI
The advantages of SUS are not only a diagnostic sensitivity
equal to MRI but that, unlike MRI, SUS can be
performed portably, without the need for sedation or
general anaesthesia.
In addition, MRI is highly dependent on factors affecting
resolution, including patient movement, physiological
motion from cerebral spinal fluid (CSF) pulsation and
vascular flow, factors that do not affect SUS .
New generation high frequency ultrasound machines
with extended field of view capability now permit
imaging of high diagnostic quality in young
babies.

4. When to perform ?
SUS is possible in the neonate owing to a lack
of ossification of the predominantly cartilaginous
posterior arch of the spine . The quality of
ultrasound assessment decreases after the first
3–4 months of life as posterior spinous elements
ossify, and in most children SUS is not possible
beyond 6 months of age. However, the persisting
acoustic window in children with posterior spinal
defects of SD enables ultrasound to be performed
at any age

5. When to request US spines ?
Current RCR guidelines are that
all neonates with a hairy patch or sacral
dimple should undergo SUS . However,
while more than 90% of patients with occult
SD have a cutaneous abnormality over the
lower spine , a cutaneous marker may have
a low yield in predicting the presence of a
clinically significant abnormality. In a recent
review of 200 SUS examinations performed
over an 11-year period, SD was found in
less than 1% of cases when a cutaneous
marker was the only clinically detected
abnormality .

6. Gastrulation stage

7. Neurulation stage

8. Retrogressive differentiation and
relative cord ascent
Formation of the
ventriculus terminalis, the
caudal portion of the
conus medullaris, and the
filum terminale through the
processes of canalization
and retrogressive
differentiation.

9. Sonographic examination of the neonatal spine
is performed with the infant in a warm room lying
in a prone, lateral decubitus, or semi-erect
position.
Feeding the infant before examination helps him
or her to relax.
Placing a towel under the infant’s pelvis will flex
the spine enough to separate the midline
posterior arches .
.

10. A high frequency (7- to 15-MHz) lineararray transducer should be used .. higher
frequency transducers are beneficial for
optimization of superficial structures such
as skin lesions and sinus tracts.
Extended field-of-view (EFOV) imaging is
an additional feature that can demonstrate
the whole neonatal spine from T12 to the
coccyx

11. • Mark T 12 in
transverse
plane
(presence of
ribs
witnessing)
• Then count
downwards to
end of cord.

12. Alternatively by
Locating the last lumbar vertebra, L5, by
evaluating the lumbosacral junction. Then
count cephalad to the conus medullaris.
Locating the last ossified vertebral body,
the first coccygeal segment. Then count the
five sacral segments cephalad into the
lumbar vertebra.

13. The spinal cord lies in the spinal canal within anechoic
CSF of the subarachnoid space. Surrounding
the canal is the dura mater, which is shown by
anechogenic line dorsal and ventral to the canal. The
cord is lined with the arachnoid sheet, which exhibits an
echogenic line parallel to the cord’s surface.
Caudally, the lumbar enlargement tapers, forming the
conus medullaris, which extends and becomes the filum
terminale.

14. Filum teminale
The filum terminale images as an echogenic
cordlike structure that is surrounded by
echogenic nerve roots of the cauda
equina. For that reason, separation of the two is
difficult.
However, the filum terminale is commonly more
echogenic than the surrounding cauda equina.
The filum terminale normally measure less than
or equal to 2 mm.

15. Cord
On a sagittal image, the spinal cord appears as
a hypoechoic cylindrical structure with two echogenic
complexes centrally. These represent the
central echo complex. The normal cord lies one
third to one half of the way between the dorsal and
ventral walls of the spinal canal
On a transverse image, the cervical spinal cord
appears as an oval shape, whereas the thoracic and
lumbar portions are more circular.

16. Conus level
The level of the conus usually ends between
T12 and L1 or L2 .If it ends at the L2-L3 disk space or
lower, it is abnormal, and one should explore for any
tethering masses. However, it must be noted that a
normal cord may lie around L3, mainly in preterm infants.
The normal position of the cord should be central
in the spinal canal. The spinal cord is held in place
by echogenic dentate ligaments passing laterally
from each side of the cord.
The normal spinal cord produces a rhythmic movement

17. • Standard views

19. Cystic ventriculus terminalis
(normal variant)

20. Cystic distension of distal spinal
canal (normal variant )
Size smaller
than
5 mm and
stability over
time
distinguish this
normal variant
from small
syrinx.

21. Filar cyst (normal variant)
criteria for filar
cyst:
location just below
conus medullaris,
fusiform shape,
well defined, thin
walled, and
hypoechoic.

22. Pseudo-masses
• Clumped nerve
roots..
• Use 2
planes..to see
the whole
length of nerve
root.

23. Dysmorphic coccyx
• Cartilagenous
angulated
lesion.
• Not dermal
sinus track.

24. Three processes can lead to
congenital anomalies:
First, premature separation of the skin
ectoderm from the neural tube
can lead to entrapment of
mesodermal elements, such as
fat.
Second, failed neurulation leads to
dysraphisms,
such as myelomeningocele(overt
or closed )

25. Last ,anomalies of the
filum terminale, such as
fibrolipomas and caudal
regression syndrome
caused by
disembryogenesis of the
caudal cell mass

26. Classification
Congenital spinal dysraphisms can be classified on the
basis of the presence or absence
of a soft-tissue mass and skin covering .
Those without a mass include tethered cord,
diastematomyelia, anterior sacral meningocele,
and spinal lipoma.
Those with a skin covered soft-tissue mass include
lipomyelomeningocele and myelocystocele.
And those with a back mass but without skin covering
include myelomeningocele and myelocele

29. Lipoma

30. Dorsal dermal sinus track

31. Tethered cord
Search for cause
Sonographically, tethered cord is diagnosed
in neonates by the presence of a low-lying
conus (below the L2–L3 disk space) and
lack of normal nerve root motion during realtime
sonography

32. Intradural lipoma
• Hyperechoic
dural mass..
• Tethered cord.

33. Thick filum terminale

34. Fatty filum

35. Lipoma of filum terminale
L3
Tethered cord

36. Diastematomyelia
• Echogenic spur
between two
hemicords in
transverse
image.

37. Caudal regression syndrome
• Blunted conus
medullaris.
• Fatty filum
• Absence of sacral
vertebrae and
coccyx .

38. Myelomeningocele
• Cystic mass
(CSF)
• +tethered
cord
• +neural
elements.
• +soft tissue
mass

39. Unilocular meningocele

40. Lipomyelomenimgeocyle

42. Neuroblastoma

43. Sacrococcygeal teratoma

44. Other renal anomalies

50. Conclusion
• Spinal ultrasound (SUS) is becoming
accepted as a first line screening test in
neonates with high sensitivity and
specificity.
• Recognizing normal anatomy ,variants
and congenital anomalies early in life help
in futur planning of management .