Title: The Neonatal Spine Holdorf PhD, MPA, RDMS, RVT, LRT(AS)
1The Neonatal SpineHoldorf PhD, MPA, RDMS, RVT,
LRT(AS)
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2The Neonatal Spine
- Embryology
- Anatomy
- Function
- Indications
- Sonographic Technique
- Sonographic Appearance
- Pathology
3Embryology
- Neural plate - a thickened piece of ectoderm that
becomes the neural tube - Spinal meninges - membranes that cover the
nervous system dura, arachnoid, pia mater - Paraxial mesodern - tissue that forms on the
lateral aspect of neural tube that eventually
form the vertebral column
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4Embryology
- Primary Neurulation process by which the
ectoderm becomes the neural tube forms cervical
through second sacral segment occurs between day
18 to 28 of gestation - ectoderm...neural plate...neural folds...neural
tube (Medscape) - Disjunction process by which neuroectoderm
separates from cutaneous ectoderm
5Embryology
- Secondary Neurulation process that forms the
conus medularis, cauda equina and filum terminale
distal to S2 level - Canalization - Distal neural tube forms from the
caudal cell mass undifferentiated cells...caudal
cell mass...neural tube. the ventriculus
terminalis forms at the terminal end of the
neural tube near the coccyx, marking the site of
the future conus medularis. - Retrogressive differentiation - tissue caudal to
ventriculus terminalis forms the filum
terminalle, cauda equina and the ascention of the
conus (Medscape)
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6Anatomy
- Vertebrae - Cervical, thoracic, lumbar
- Sacrum consists of 5 fused vertebrae
- Spinal cord extends from medulla oblongata and
terminates at the filum terminale - Conus medularis inferior end of cord that
tapers into a V shape the tip should be lie at
the L2-L3 interspace or above - Filum terminale cordlike extension of the conus
medularis should be less than 2 mm in diameter - Cauda Equina group of nerve fibers that extend
from the tip of the conus medularis
7Anatomy
8Vertebrae
9Sacrum
10Function
- Spinal column protects the spinal cord and nerves
- Provides support for body in upright position
- Provide base to which ribs can attach
- Nerves with cord carry impulses to/from brain
11Why Sonography? (Westbrook)
- Can be done on infants less than 6 months old
- Posterior spinous processes have not ossified
- Inexpensive
- No radiation
- Allows real-time visualization of cord movement
- No sedation
- Can be performed almost anywhere
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12Indications (JRC-DMS)
- Sacral dimple (most common reason US ordered)
- Hemangioma
- Raised midline
- Hairy patch
- Tail-like projection of lower spine
- Dx of myelomeningocele or myeloschisis
- Lower extremity deformities
13Sonographic Technique
- Transducer - Highest frequency linear that
enables visualization of anatomy - Cervical spine use curvilinear tx
- Select appropriate system presets
- Patient Positions
- Prone
- Decubitus
- Upright (JCR-DMS)
- Scan entire back in long and transverse
14Sonographic Technique (AIUM)
- Determine level of conus medullaris
- Determine L5, then count cephalad
- Determine S1, then count cephalad (1st coccygeal
segment is more rounded, sacral more squared) - Last rib bearing vertebra is T12, then count
caudal - Skin marker at location of conus can be
correlated with radiograph
15Sonographic Appearance (Rumack)
- Spinal Cord is hypoechoic size and shape vary
with location - Cerivcal oval
- Thoracic circular
- Thoracolumbar - thicker
- Central Echo complex echogenic line within the
cord may see fluid within (see Rumack p 1797
Figure 55-5). - Filum Terminale Center is relatively hypoechoic
with bright outer margins (see Rumack p 1797
Figure 55-6) may not be distinguishable from
nerve fibers
16Sonographic Appearance
- Nerve root interfaces are echogenic
- Filar Cyst Cystic structure at the tip of the
conus medullaris at origin of filum terminale - Also referred to as terminal ventricle
- Causes no clinical symptoms
- See Rumack p 1798 fig. 55-7.
- Under normal conditions, the spinal cord should
float freely within CSF - Will move with breathing and pulsations from
vasculature
17Normal Neonatal Spine
18Normal Neonatal Spine
19Conus medularis
20Transverse lumbar sonogram shows normal anatomy
as labeled. V vertebra, transverse process
(arrowhead).
21Pathology Tethered Cord (Westbrook)
- Fixation of the spinal cord in an abnormal
location - Conus medullaris positioned below the level of L3
- Can be due to a thickened filum terminale
(greater than 2 mm) or a meningomyelocele - Can be associated with a lipoma, dermal sinus
diastematomyelia - Limited cord motion
22Pathology Tethered Cord
- Can be associated with other anomalies, ie spinal
bifida, anorectal malformations, etc. - May not be discovered until later in life when
growth may strain cord and cause symptoms - Weakness in muscles
- Scoliosis
- Changes in bladder function
- Sensory loss
23Pathology
- Spinal Dysraphism general term for congenital
disorders that involve incomplete fusion of
mesenchymal, bone and neural elements of the
spine (Westbrook). - Overt Open or uncovered lesions due to
incomplete closure of posterior bony elements of
spine - Occult spinal anomalies that occur beneath
intact skin
24Overt Lesions - Myelocele
- Cyst-like spinal lesion that exposes the neural
placode (spinal cord) to the environment - Spinal cord is flush with the plane of the dorsal
skin. See Rumack p 1802, fig 55-14. - Not covered with meninges or skin
- Usually at lumbosacral level
- Always associated with tethering of the spinal
cord (Unsinn). - Chiari II syndrome occurs in 99 of patients with
myelocele or myelomeningocele (Unsinn).
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25Overt Lesions - Myelomeningocele
- Low termination of cord with herniation of neural
elements (CSF and nerves) beyond bony defect and
through the skin - Cord tethering is almost always involved
(Westbrook). - Almost always associated with Chiari II
malformation - Sonographic Findings - differentiate from
meningocele detect associated anomalies
(hydromelia, lipoma, etc.) - See Rumack, p 1804, fig 55-15.
26PathologyOccult Spinal Dysraphism
- Spinal anomalies that occur beneath intact skin
- Frequently there are visual indications that a
problem exists - Some examples of occult lesions are
- Spinal lipoma
- Meningocele
- Myelocystocele
- Diastematomyelia
- Hydromyelia
- Dorsal Dermal Sinus
27Spinal Lipoma
- Fatty mass that extends into the spinal canal and
can extend into subcutaneous tissue. - Usually located at the level of the conus or
filum terminale - Can be associated with tethered cord
- Can be difficult to differentiate from teratoma
use location of lesion to differentiate - Sonographical findings echogenic mass
- See Rumack p 1805, fig. 55-16.
28Meningocele (Rumack)
- Simple - dorsal herniation of dura, arachnoid and
CSF into subcutaneous tissue of the back neural
elements not involved - Complex - involves neural elements
- Lateral - extends laterally through an
intervertebral foramen
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29Myelocystocele
- Malformation in which the dilated central canal
of the spinal cord protrudes dorsally through a
bony defect (Rumack) - Can occur in any region of spine
- Not usually associated with Chiari II malformation
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30Diastamatomyelia
- A sagittal division of the cord into hemicords,
each containing a central canal and nerve roots
(Rumack) See Figure 55-22 p1809 - About ½ of patients will present with a surface
stigmata of an underlying malformation - Diagnosis sometimes delayed until child develops
orthopedic and/or neurologic symptoms - May occur alone or with other anomalies
31Hydromyelia (JRC)
- Dilatation of the central canal which may be
diffuse or focal - Associated with myelomeningocele and
diastamotomyelia - Sonographic findings separation of echogenic
linear structures of the central canal
32Dorsal Dermal Sinus (Rumack)
- Fluid tract extending from skin that may or may
not penetrate the dura - Results from incomplete disjunction
- Most often seen in the lumbosacral area
- Skin opening usually is located cephalad to the
sinus connection with the dura - Can be attached to cord and cause tethering
- See Rumack p 1809, fig 55-20
33References
- ACR-AIUM Practice Guidelines for the Performance
of an Ultrasound Examination of the Neontal
Spine October, 2007. - Images on slides 17-20 were obtained from The
pediatric spinal canal.ppt. Original author
unknown. - Tethered Cord Syndrome a review of the
literature embryology. Medscape News Today
retrieved on May 30, 2011 from http//www.medscape
.com/viewarticle/725080_2 - Unsinn, K., Geley T., Freund, M Gassner, I. US
of the Spinal Cord in Newborns Spectrum of
normal findings, variants, congenital anomalies,
and acquired diseases - Westbrook, C., Rouse, G. and DeLange, M.
Sonographic evaluation of the Spine in infants
and neonates. Journal of Diagnostic Medical
Sonography 7325-331, 325-331.
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