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124
3 Neurosonography in Neonates, Infants and Children
3.5.3 MRI
Ideal non-ionising imaging modality
• Assessment of brain parenchyma, maturation and myelination, metabolic dis-
ease, tumours, malformations, etc.
• MR angiography, diffusion weighted imaging, perfusion imaging, MR spectros-
copy – helpful additional tools for dedicated queries.
NOTE : Small children require sedation.
3.5.4 Catheter Angiography
For assessment of vascular problems, if interventional treatment is an option.
3.5.5 Additional Supporting Procedures
Fundoscopy, US of eye and orbit, lumbar puncture, brain pressure monitoring,
EEG, laboratory tests, etc.
NOTE : Choice of diagnostic test depends on the clinical query, potentially also on
laboratory fi ndings, but mainly on patient age. Consider US fi rst whenever brain
sonographically accessible, even if only providing an orienting imaging approach
(allowing tailoring of additional diagnostic imaging).
3.6 Ultrasound of the Eye and the Orbit
3.6.1 Introduction
Ocular globe – ideal US window into orbit. Many queries can be approached, not
only within eye but also in deeper spaces. This is a simple and easy applicable technique that may reveal all necessary information and should be promoted, particularly in terms of radiation protection.
How To Perform :
• Eyelid closed, warmed US gel placed and avoid pressure.
• Globe and orbit are visualised through closed eye lid with high-resolution linear
and sector arrays.
NOTE : Reduce output gain to avoid heating of bulb fl uid (MI at lowest possible
limit, ~ 0.1–0.2 up to maximal 0.5) and avoid aCDS unless necessary for enabling
diagnosis.
3.6.2 Normal Findings
Typically all major structures seen should document in two planes: anechoic lense,
corpus vitreum, smooth border of retina, outer contour of spheric bulb and papilla
just in front of attachment of optic nerve (Fig. 3.44 ).
3.6 Ultrasound of the Eye and the Orbit
125
a
Fig. 3.44 Normal eye US. ( a ) Normal US appearance of eye ball and optic nerve. ( b ) CDS with
central vessels
b
Fig. 3.45 Retrobulbar magnifi ed view: dilated optic nerve sheath ( arrow ). Dilated optic nerve
sheet (↔) in hydrocephalus
Behind eye: retrobulbar fat, optic nerve accompanied by nerve sheet and vessels
and major eye muscles.
NOTE : Pictogram with defi nition of US plane using clocklike descriptions is help-
ful for follow-up.
3.6.3 Sonographically Depictable Pathology
Congestion of Papilla: Papilla swollen, elevation from retina can be measured, mea-
surements vary with equipment and age.
Optic nerve sheet widened – associated with increased intracranial pressure
(Fig. 3.45 ).
Foreign bodies : direct visualisation of foreign object, changes in consistency of
bulbar fl uid (glaucoma) and haemorrhage.
Retinal displacement : with or without adjacent pathology, coloboma, persistent
membranes, microphthalmia, etc.
126
3 Neurosonography in Neonates, Infants and Children
a
c
b
d
Fig. 3.46 Pathology depictable on US of the eye and orbit. ( a ) Retinoblastoma: echogenic mass
fi lling bulb. ( b ) Retinocytoma: partially calcifi ed mass with small complex cystic components
adjacent to optic papilla (+....+). ( c ) Orbital abscess (+ +) adjacent to bony border with ethmoid
sinus. ( d ) Dacryocystocele (+ +) of left eye
Tumours : retinoblastoma, rhabdomyosarcoma, lymphoma, glioma, optic glioma,
orbital lymphangioma/haemangioma, etc. (Fig. 3.46a, b ):
• Orbital abscesses/infl ammation (Fig. 3.46c ):
– Commonly situated at thin osseous margin in median compartment adjacent
to ethmoid sinus, becomes sonolucent in case of thinning and decalcifi cation
from infl ammation.
US of Adjacent Structures
Dacryocystocele – easily diagnosed:
• Cystic structure in median outer compartment of eye with dilated proximal naso-
lacrimal duct, usually containing echoes, which move under slight transducer
pressure (Fig. 3.46d ).
• Helps differentiation from ventral encephalo- or meningocele or tumour conditions.
US for treatment guidance : instillation of sclerotherapeutic agents in lymphatic
malformations (see Chap. 2 ).
NOTE : Eye-US – promising and helpful bedside noninvasive application, but rarely
used. Further details can be found in the literature.
3.7 Ultrasound of the Spinal Canal
127
3.7 Ultrasound of the Spinal Canal
3.7.1 Requisites
Spinal US possible as long as non-ossifi ed posterior arches allow access to spinal
canal during fi rst months of life.
Thereafter, sonolucent vertebral disc can be used for limited views, but due to
ossifi ed vertebral bodies and arches continuous assessment of spinal canal becomes
impossible.
3.7.2 Transducers and Technique
Dorsal approach : standard access from midline, high-resolution high-frequency
linear transducers (15–5 MHz).
Sagittal + axial sections, performed throughout entire region of interest:
• Baby or child placed in prone or decubitus position, supporting pillow/towel can
be helpful.
• With increasing ossifi cation of dorsal processes: try parasagittal, slightly tilted
sections for longitudinal views:
– High-contrast post-processing helpful.
– Use high-resolution techniques (image compounding), harmonic imaging and
extended fi eld of view.
• CDS helps to depict major vessels.
• M-Mode : assessment and documentation of cord movement and motion of nerve
roots.
Ventral transabdominal approach: possible in slim patients and neonates, use sec-
tor/(curved) linear arrays with age appropriate frequency:
• Depiction of continuity and pathology of vertebral bodies.
• Assessment of pre-/paravertebral extension of spinal pathology (e.g. ventral
meningocele and teratoma).
Focus of US imaging : assessment of spinal canal and contents:
• Vertebral bodies outlined by (echogenic) surface even if ossifi ed ⇨ pathology
depictable (e.g. hemivertebra).
• Discs not target of US in neonates and infants.
3.7.3 Indications
• Spinal dysraphisms, other pathology of cord and conus (e.g. tethered cord and
dermal sinus).
• Suspicion of spinal trauma – bedside investigation before additional imaging
• Spinal tumours in fi rst months of life:
– Particularly neuroblastoma growing into spinal canal through neuroforamina.
NOTE : Normal sacral dimple – no indication for spinal US, general US screening
of neonatal spinal canal not considered effective.
128
a
3 Neurosonography in Neonates, Infants and Children
b
d
Fig. 3.47 Normal spinal US. ( a ) Extended fi eld of view showing long portion (sacral to thoracic
segments). ( b ) Axial section at level of lumbar intumescence. ( c ) Sagittal section, split image
technique: superior assessment of position of conus, fi lum terminale and nerve roots of cauda
equina. ( d ) Nuchal dorsal sagittal section tilted cranially: visualisation of cranio-cervical junction.
( e , f ) Schematic drawing indicating the relevant, sonographically depictable structures for spinal
US ( a = sagittal, b = axial)
c
e
f
3.7.4 Normal Findings
Cervical and Thoracic Spinal Canal
• Cervical cord shows widening (intumescentia cervicalis) – normal physiologic
thickening, do not mistake for pathology.
• Cord itself: central echogenicity caused by border between anterior commissure
and median anterior fi ssure – not central canal (not seen unless dilated).
• Cord surrounded by more or less hypoechoic subarachnoid space, limited by
echogenic dura (Fig. 3.47 ):
• Modern high-resolution transducers may enable differentiation of gray and white
matter
– Following cervical cord upwards: visualise cranio-cervical junction with its
extension into medulla oblongata and cisterna magna as well as foramen magnum (by transoccipital/nuchal approach).
3.7 Ultrasound of the Spinal Canal
129
• Visualise (dentate) ligaments and nerve roots (axial access), assess motion of
nerve roots
– Spine image varies with ossifi cation; usually ossifi cation centres of spinous
process, posterior arches and vertebral bodies seen. Anechoic gap between
echogenic vertebral body surface – discs, allowing vertebral body counting.
– For counting vertebral bodies, extended fi eld of view/panorama imaging help-
ful and provides conspicuous overview and reliable level assignment.
TIP : Cervical and thoracic cord more easily visualised in fl exed position.
– Axial section: identify cord, central echo complex, duplicated cord (diastema-
tomyelia), paracordal structures (dentate ligaments, nerve roots, vessels) and
paravertebral structures (muscles and adjacent osseous structures, such as
transverse processes or ribs).
Lumbar Spine
• Physiologic thickening (distal thoracic and lumbar cord) – intumescencia
lumbalis.
• Position of conus medullaris: depends on age, should be at L2 from 40 week of
gestation and gradually increasing in height with age.
• Always include axial sections: assess fi lum terminale (thickened?), identify cord
(single, duplicated, diastematomyelia), central echo, paracordal structures (den-
tate ligaments, nerve roots, vessels) and paravertebral structures (muscles and
adjacent osseous structures, such as transverse processes or ribs).
• Nerve roots of cauda equina with central fi lum terminale (should not measure
>2 mm axial diameter) usually identifi able as slightly thicker echogenic band
cursing sacrally:
– Motion of nerve roots and fi lum – some respiratory as well as pulse synchro-
nous movement.
Normal variant: little cyst in conus or fi lum terminale (e.g. ventriculus terminalis or
fi lum cyst) (Fig. 3.48a ).
For reliable assignment of level of conus :
(a) Extended fi eld of view, starting from coccyx, going up to thoracolumbar spine –
count vertebrae.
(b) Wide view (“phased”/trapezoid/convex mode) linear transducer, view includes
sacral promontory to level of lower thoracic spine; count vertebrae form lowest
lumbar vertebral body (identifi ed by direction change of lumbar spine towards
sacrum – promotory – L5/S1) – additional dual image helpful.
(c) Identifi cation of highest level of posterior pelvic crest – usually at level of L4
(axial section).
(d) Identifi cation of lowest rib insertion at level T12 (axial view).
NOTE : Additional vertebral bodies or sacralisation of a lumbar vertebral body may
cause errors – in these cases an extended view of entire spine or plain fi lm of entire
spin mandatory.
Sacrum and Coccyx
• Usually not much content in spinal canal, thecal sac end at S2, may be echogenic
due to physiological fat.
• Sacral centres ossify earlier than in coccyx.
130
3 Neurosonography in Neonates, Infants and Children
a
b
c
Fig. 3.48 Physiologic fi ndings on spine US. ( a ) Filum cyst (+ +) in conus or at origin of fi lum
terminale – also called terminal ventricle or fi fth ventricle. ( b ) Dorsally bent distal end of non-
ossifi ed coccyx – a normal variant. A small sacral skin dimple seen. ( c ) US in normal sacral dimple
(+ +), with narrow tract leading from skin to distal end of coccyx and anecholic small air bubble at
the deepest part of the sacral dimple tract ( arrow )
• Sometimes lowest coccygeal body bent dorsally, ending in “dorsal dimple” – tail
remnant, a normal variant (Fig.
3.48b ).
• If cystic-tubular or band-like structure connects from lowest coccygeal body
upwards to skin – “sacral porus”, “pilonidal sinus”, may get infected, sometimes
excised but not to be mistaken for dorsal dermal sinus tract (Fig.
3.48c ).
3.7.5 Pathologic Findings of the Spinal Cord
3.7.5.1 Dysraphism
Defi nition
Caused by disruption of development of osseous and neural structures, commonly
combined fi ndings of meningeal and/or cord pathology and vertebral body anomalies – plain fi lm of spine helpful.
3.7 Ultrasound of the Spinal Canal
a b
Fig. 3.49 US in spinal dysraphism. ( a ) MMC covered by skin. ( b ) Tethering of deep-reaching
cord (+ +) attached to intraspinal sacral lipoma (*)
Pathology may be:
• Obvious/visible (palpable mass with/without cutaneous defect).
• Occult (covered by skin without any visible or palpable mass).
NOTE : Open and visible dysraphic pathology with skin defect very susceptible to
infection, no initial US assessment routinely performed prior to early surgery;
potentially examine higher parts of cord + brain for depiction of associated malformations, add abdominal US (e.g. kidneys and VACTERL malformation).
Myelocele/Myelomeningocele (MMC)
Meninges and/or cord herniated dorsally through defect of posterior arches and
form typical terminal placode (band-like dorsal insertion of conus).
Associated with syringomyelia, diastematomyelia, cerebral fi ndings (e.g. Arnold
Chiari malformation):
– Syringomyelia and hydrocephalus may only develop after closure of defect.
US performed only for additional assessment of associated malformations and
postoperatively :
• Follow-up, neurological symptoms with suspicion of tethering, increasing
hydrocephalus, etc.
Lipomyelocele/Myelocystocele/Meningocele
Covered by skin, constitute defect of dorsal containment with herniation of
meninges with/without cord through dysraphic defect and potentially associated
with lipoma.
As defects usually covered by skin, initial US possible to defi ne content
(Fig.
3.49 ):
• Lipomeningocele – echogenic tumorous lesion, may be connected to subcutane-
ous fat and may cause tethering of cord – conus medullaris commonly positioned
caudal to L2.
• Myelocystocele – hydromyelia (dilatation of central canal), often ends in bag-
like cyst herniated into subcutaneous space. Associated with (partial) sacral
agenesis ⇨ carefully assess lower spine/sacrum and/or perform plain fi lm.
• Simple meningocele – anechoic CSF-fi lled cystic structure, caused by herniation
of meninges through posterior defect, usual in lumbosacral region. Can be
through ventral defect – “ventral meningocele”.
131
132
a
Fig. 3.50 Spine US pathology. ( a ) Lipomatous, thickened and somewhat irregularly shaped fi lum
(+ +). ( b ) Deep ending conus with obvious hydro-/syringomyelia (+ +)
3 Neurosonography in Neonates, Infants and Children
b
NOTE : Usually not associated with a “simple sacral dimple”, but have other cuta-
neous stigmata: externally visual hyperpigmentation, hairy naevus, mass, etc. –
these fi ndings as well as posterior cutaneous haemangioma in midline indicate US.
3.7.5.2 Other Associated Pathology
Dural Lipoma
Positioned sub- or intradural, may be attached to cord dorsally, may completely fi ll
spinal canal, may reach into central canal and may grow exophytically and cause
mass effect of cord surface.
Symptoms depend on size, position and affected tissue.
US Findings : more or less echogenic mass (Fig. 3.49b ). Cord tethering, potentially
hydromyelia.
Filum Terminale
Thickened fi lum (either lipomatous or fi brous) usually attached sacrally, measuring
>2 mm diameter (Fig. 3.50a ) ⇨ cord tethering increases during growth - eventually
conus ends inferior than level of L2. Clinical symptoms comparable to any form of
tethered cord syndrome.
Hydromyelia – dilatation of central canal, in extreme forms called syringomyelia
(Fig. 3.50b ):
• Primary malformation, or secondary by CSF-drainage/secretion problems.
• Secondary to parenchymal damage and atrophy of cord tissue.
3.7.5.3 Other “Occult” Dysraphisms
Diastematomyelia
Defi nition : Complete/partial splitting of cord for one to several segments, vary-
ing coverage of individual hemicord by single or separate meninges, sometimes
with central dividing cartilaginous/osseous spur.
US Findings : Best seen in axial views – any spinal cord US always must include
axial assessment (Fig. 3.51 ). At level of diastematomyelia two adjacent cords, usu-
ally some hydromyelia cranially; caudally intradural lipoma may be present.
3.7 Ultrasound of the Spinal Canal
Fig. 3.51 Diastematomyelia. Axial dorsal view in
lower thoracic level: two cords slightly differing in
size adjacent to each other, consistent with
diastematomyelia
Fig. 3.52 Large dermal sinus tract (from skin into
spinal canal). Sagittal dorsal section at lumbosacral
level: hypoechoic tract disrupting normal (echoic)
skin, coursing from skin at lumbosacral junction
level upwards to eventually enter lumbar spinal
canal, consistent with a large dermal sinus tract
Dermal Sinus Tract
Defi nition : Connection between spinal canal and midline skin surface dimple.
Commonly located lumbosacral, but also cervical or thoracic. Associated epidermoid cysts may compress cord.
Fistula track facilitates extension of infection from skin into CSF-space ⇨ meningitis, subdural abscess.
US Findings : Usually very tiny anechoic lumen of echoic band connecting skin with
spinal canal and may be diffi cult to visualise lumen if very narrow (Fig. 3.52 ).
Differentiation against pilonidal sinus (no connection to spinal canal) – assess
course of connection :
• Dermal sinus tract usually travels from dorsal cutaneous opening to cranial inser-
tion into spinal canal.
• Sinus pilonidalis typically travels from more cranially from cutaneous dimple to
end of (cartilaginous) coccyx.
TIP : Use plenty US gel or standoff pad.
Caudal Regression Syndrome
Complex malformation, US reveals spinal/cord contribution/involvement, conus
often appears squared or blunted as opposed to normal tapered shape.
• Associated malformations common – perform perineal US, complete abdominal
US and sometimes MRI.
Others
Anterior sacral, lateral or thoracic and ventral meningoceles - very rare.
133