technique of infant spinal ultrasound examination

1. DR. AMEEN RAGEH

2. Introduction
•Ultrasonography (US) is a well-established method of
investigating the spinal canal and cord as well as the
meningeal coverings in newborns and infants
•It is the first line screening test in neonates suspected
of spinal dysraphism, and also useful in detecting
tumours, vascular malformations and cases of trauma

3. • In experienced hands diagnostic accuracy equal to MRI
• performed portably, without the need for sedation or general anaesthesia
• 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
Spinal U/S VS MRI

4. • Lumbosacral stigmata known to be associated with spinal
dysraphism
• Evaluation of suspected defects such as cord tethering,
diastematomyelia, hydromyelia, and syringomyelia
• Detection of sequelae of injury
• Visualization of fluid with characteristics of blood products within
the spinal canal in patients with intracranial hemorrhage;
• Guidance for lumbar puncture
• Postoperative assessment for cord retethering
When to request for spinal U/S

5. •Preoperative examination in patients with open spinal
dysraphism;
• Examination of the contents of a closed neural tube
defect if the skin overlying the defect is thin or no longer
intact.
Contraindications

6. •Best time is before the 6 month of age as neonate
owing to a lack of ossification of the predominantly
cartilaginous posterior arch of the spine
•However the quality of ultrasound assessment
decreases after the first 3–4 months of life as
posterior spinous elements ossify.
•In most children SUS is not possible beyond 6
months of age
When best time to perform?

7. • Primary neurulation
• Secondary neurulation
canalization and retrogressive differentiation
Embryology

8. • 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.
• Is lined with the arachnoid sheet, which exhibits
an echogenic line parallel to the cord’s surface
• It lies one third to one half of the way between
the dorsal and ventral walls of the spinal canal.
• Cervical spinal cord appears as an oval shape,
whereas the thoracic and lumbar portions are
more circular
Anatomy- the spinal cord

9. • The filum terminale images as an echogenic cordlike structure that is
surrounded by echogenic nerve roots of the cauda equin.
• The filum terminale is commonly more echogenic than the surrounding
cauda equina.
• The filum terminale normally measure less than or equal to 2 mm.
Anatomy- filum terminale

10. • The level of the conus usually ends
between T12 and L1 or L2 .
• 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
Anatomy- conus medullaris

11. • The normal nerve roots pulsate freely with cardiac and respiratory
motion.
• M-mode imaging can also be very helpful in documenting motion of
the cord and nerve roots.

12. • 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 .
• The knees may be flexed to the abdomen to
allow adequate spacing of the spinous
processes and visualization of the spinal
canal contents.
Preparation

13. • Should be performed with real-time scanners using high frequency
linear array transducers, typically 7 to 10 MHz or higher in neonates.
• Extended field-of-view (EFOV) / panoramic views are very helpful in
providing an overview of the anatomy and termination of the cord and
thecal sac.
Equipment Specifications

14. SURVEY
• Firstly in transverse, sweep from the mid
thoracic region to the sacro-coccygeal
region.
• Then a sagittal sweep from one side to
the other.
Are the posterior neural arches, paired and uniform.
- Are there any obvious, gross pathologies.
Scanning Technique

15. DETAIL SCANNING:
•Is the cord and CSF space uniform in shape?
•Where is conus? (i.e. what spinous level)
•Identify Filum Terminale.
•Examine Cauda Equina
•Examine the bony anatomy
•Examine the Dimple
Scanning Technique

16. • Follow the cord along in transverse
assessing the shape and central position.
• -Any variation in position or shape of the
cord is suggestive of mass effect and
scrutiny for the cause is needed.
• Similarly the CSF space should be
uniform.
Scanning Technique Is the cord and CSF space uniform in shape?

17. There are two primary methods to
determine the level of conus.
• Identify the 12th rib, and thus
T12 and count down.
• identify the lumbo-sacral
junction and count up from L5.
• Normal conus position is: No
lower than the top of L3 in a
term infant or the bottom L3 in a
pre-term infant.
Scanning Technique Where is conus? (i.e. what spinous level)
Search for cause

18. • It should appear as thin closely
related parallel lines extending from
conus to the lowest reaches of the
thecal space (approximately S2).
• - Filum is approximately 2mm in
diameter.
Scanning Technique Identify Filum Terminale.

19. • The nerve roots comprising cauda
equina should lie in the dependent
portion of the thecal sac.
• - Should see gentle oscillating
movements with the baby's cardiac
pulsations and respiration.
• - Symmetry. Look for asymmetry
indicative of pathology (space
occupying mass or unilateral
abnormality)
Scanning Technique Examine Cauda Equina.

20. • Particular attention
should be paid to the
integrity the posterior
neural arches in the
transverse plane.
• - Check the vertebral
bodies for alignment,
shape and symmetry in
both transverse and
sagittal planes.
Scanning Technique Examine the bony anatomy

21. • If there is a dimple or skin
defect, this should be
carefully examined with a
high frequency probe to
look for a skin - thecal sac
fistula.
• - If CSF is leaking, an MRI
should be performed.
Scanning Technique Examine the Dimple

22. • Filar Cyst
• Cystic ventriculus
terminalis
• Pseudomass” due to
Positional Nerve Root
Clumping
• Pseudosinus Tract
• Dysmorphic Coccyx
Normal Variants

23. • Spinal dysraphism is defined as incomplete or
absent fusion of midline neural, mesenchymal,
and cutaneous structures and can be classified
into three categories:
• OVERT DYSRAPHISM
spina bifida aperta represents the most severe
form of a midline fusion defect with protrusion
of non–skin-covered neural tissue
• OCCULT DYSRAPHISM
cleft or tethered spinal cord covered by intact
skin
• Caudal spinal anomalies that correspond to an
association of malformations of the distal spine
and spinal cord and hindgut, renal, and
genitourinary anomalies
Spinal dysraphism