Ob Advance Fetal Brain Ultrasound

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Rhombencephalon

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Anencephaly

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Lethal
Means “absence of brain”
Caused by the neural tube failing to close at the cranial end

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The most common NTD

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Anencephaly

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Anencephaly causes

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: isolated (spontaneous, low folic acid), genetic (T13, T18), Syndrome related (Meckel-Gruber, ABS)

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ANENCEPHALYSonographic and Clinical Signs

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No brain or cranial vault above level of orbits
Brainstem remains
Mostly in females
Elevated AFP
Frog Like appearance
Polyhydramnios
Other NTD’s common
Often contiguous with cervical spine defect

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Precursor to anencephaly

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Exencephaly

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Lack of cranial vault leads to brain exposure to amniotic fluid.
Exposure and movement lead to destruction of brain content

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Exencephaly

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Exencephaly Most commonly seen in

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1st trimester

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Exencephaly US

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Cephalocele

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BONY DEFECT: Opening in skull that allows brain tissue to protrude through
Usually posterior (occipital)

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Cephalocele Top differential:

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Cystic hygroma

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cephalocele Imaging

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Bony defect with paracranial mass
Diverse appearance dependent on what is herniating
Gyral pattern
Cyst like: prolapsed 4th ventricle
Ventriculomegaly 70-80%
Microcephaly 25%
Polyhydramnios AND oligohydramnios
Other CNS anomalies common

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cephalocele Imaging

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Front 14

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cephalocele Imaging

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Frontal Cephalocele

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Frontal Cephalocele

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Usually small in size
Appears as forehead mass in profile view
May have hypertelorism

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Agenesis of the Corpus Callosum
Abnormal anterior cerebral artery branching along region of CC

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Agenesis of the Corpus Callosum

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Absent Corpus Callosum
Absent CSP
Elevated and dilated 3rd Ventricle
Parallel lateral ventricles
Mild ventriculomegaly with teardrop shape
Other CNS anomalies 50%
Fetal body anomalies 60%
Fetal MRI: finds other anomalies missed on U/S >50%
Karyotype recommended

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HOLOPROSENCEPHALY

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Forebrain (prosencephalon) fails to divide or only partly divides into cerebral hemispheres

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HOLOPROSENCEPHALY Different forms

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Alobar (C-shaped monoventricle, fused thalami)
Semi-lobar
Lobar

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Facial anomalies (proboscis, cyclops, hypotelorism)
Chromosome anomalies (Trisomy 13)

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HOLOPROSENCEPHALY

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Alobar HOLOPROSENCEPHALY

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single monoventricle (cup, ball, pancake look)
Fusion of thalamus
Absence of normal incracranial anatomy
Facial anomalies 70%
Cyclopia – above or below proboscis
Proboscis
Median clefts

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ALOBAR

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Alobar

http://www.ultrasoundlink.net/holoprosencephaly-face

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Semilobar

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Mid-severity within holo
Singular ventricular cavity
Partial formation of occipital horns
Partial/complete fusion of thalamus
Rudimentary formation
Absence of some intracranial structures

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http://www.ultrasoundlink.net/holoprosencephaly-semilobar

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“Mild” end of holo spectrum
Separate hemispheres
Separate lateral ventricles
Fused fornices
Thalami generally separate
Face may show mild hypotelorism or be normal

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Lobar

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ALOBAR vs. Lobar US

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Front 29

ALOBAR vs. Lobar US

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Front 30

Considered to be the MILDEST form of holo

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Septo-Optic Dysplasia

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Septo-Optic Dysplasia

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Absent CSP – frontal horns of lateral ventricles communicate
Hypoplastic optic nerves
Hypothalamic pituitary dysfunction

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Ultrasound Imaging:
Septo-Optic Dysplasia

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Absent CSP with communicating frontal horns
Mild ventriculomegaly
CC present, partially present, thinned

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Septo-Optic Dysplasia

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Septo-Optic Dysplasia

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Grey matter lined cleft in brain parenchyma
Extends from inner table of skull to ventricle

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Schizencephaly

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Schizencephaly Imaging

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Absent CSP 70% (nearly 100% when bilateral)
If cleft is visible: wedge shaped CSP filled defect through brain parenchyma
Apex points towards lateral ventricle
Face, profile normal
Calcifications seen within interior walls of lateral ventricle of affected side
Ventriculomegaly

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Schizencephaly Imaging

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Schizencephaly Imaging

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Fluid trapped in choroid plexus creates?

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Choroid Plexus Cyst

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Choroid Plexus Cyst resolve by?

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resolve by 32 weeks

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40-50% T18 fetuses have

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Choroid Plexus Cyst

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Not associated with T18 with low-risk patients

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Choroid Plexus Cyst

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Choroid Plexus Cyst size matters

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>10mm increases risk

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Choroid Plexus Cyst

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Narrowing or occlusion of the aqueduct of sylvius causing obstructive hydrocephalus

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Aqueductal Stensosis

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Hydrocephalus

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Narrowing or occlusion of the aqueduct of sylvius causing obstructive hydrocephalus
Hydrocephalus: >15 mm

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Aqueductal Stensosis US

http://sonoworld.com/TheFetus/page.aspx?id=3089

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Hydrocephalus with normal posterior fossa
3rd ventricle dilated
Dilatation can be so extreme that normal ventricular anatomy is not discernable
Dangling choroid plexus
CC thinned and often not visible
+/- CSP
Head often measures large

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Top differentials for Aqueductal Stensosis

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Top differentials: holoprosencephaly, hydrancephaly

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Aqueductal stenosis causing obstructive hydrocephalus

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Hindbrain herniation
Almost always with spina bifida

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Arnold Chiari Malformation

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Arnold Chiari Malformation

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Posterior fossa obliterated by hernation of cerebellum
Cerebellum is banana shaped
Lemon Head Sign of skull
Ventriculomegaly – progresses during pregnancy
Head size small to normal
Neural Tube Defect of spine

http://www.youtube.com/watch?v=oiF4UrVUosE

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Posterior fossa obliterated by hernation of cerebellum

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Arnold Chiari Malformation

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Arnold Chiari Malformation

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Dandy-Walker Malformation

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Abnormal cerebellum, 4th ventricle, and posterior fossa

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Dandy-Walker Malformation with additional other anomalies

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70-90%

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Ultrasound Findings:
Partial/complete agenesis of cerebellar vermis
Abnormal 4th ventricle – communicates with posterior fossa cyst
Splayed cerebellum
+/- hydrocephalus

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Dandy-Walker Malformation

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Dandy-Walker Malformation

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Used to be known as Dandy Walker Variant

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Vermian Agenesis: partial or complete

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Vermian Agenesis: partial or complete

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Vermis should cover 4th ventricle
Failure of closure = communication of 4th vent with posterior fossa
No large posterior fossa cyst

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Keyhole appearance of 4th vent

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Vermian Agenesis: partial or complete

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Mega Cisterna Magna

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Mega Cisterna Magna

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Cisterna Magna measures >10 mm
Cerebellum normal
More often in male fetuses

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Cranial vault filled with cerebrospinal fluid
Midbrain, cerebellum and basal ganglia remain

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Hydranencephaly

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Hydranencephaly Head size =

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Head size = normal

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Near complete destruction of cerebral hemispheres
Fluid filled skull with residual brainstem present
No cerebral hemispheres present
Destruction of cerebral hemispheres by occlusion of the internal carotid arteries

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Hydranencephaly

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Other causes of Hydranencephaly

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viral, hemorrhage, toxins, others

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Imaging
Fluid filled cranium with diffuse echos within fluid
Falx usually present
Normal posterior fossa
Normal head size

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Hydranencephaly

http://sonoworld.com/TheFetus/page.aspx?id=116

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Hydranencephaly Main differential:

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severe hydrocephalus

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Circle of Willis intact with ___________ and absent in Hydrancephaly

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hydrocephalus

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Hydranencephaly

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Arachnoid Cyst

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CSP fluid collection within layers of arachnoid
Remaining brain sonographically normal

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Arachnoid Cyst

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Cystic space irregular in shape in cranial midline posterosuperior to third ventricle
Turbulent flow with Doppler
Doppler helps distinguish from cysts

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Vein of Galen Aneurysm

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Microcephaly

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head circumference more than 2 standard deviations below mean
IUGR vs abnormality

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In what time period does HELLP syndrome usually present?

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Presents in 3rd trimester

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What is the best diagnostic clue to identify the HELLP syndrome on ultrasound?

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Intrahepatic or subcapsular fluid collection

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3.What does the acronym HELLP stand for?

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Hemolysis • Elevated Liver enzymes • Low Platelet count

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The most common reason for misdiagnosing Lissencephaly is due to what?

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-Wrong Dates

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What is the best diagnostic clue when suspecting Lissencephaly?

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-Failure to reach normal cortical developmental milestones.

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True or false? In Type 1 Lissencephaly the cortex has a
cobblestone appearance.

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- False

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What does VACTERL association stand for?

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vertebral defects
anal atresia
cardiac defects
transesophageal fistula
renal anomalies
limb
abnormalities

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) List 3 VACTERL association sonographic findings

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Polyhydramnios, Hemivertebrae or scoliosis , Limb defects

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True/False VACTERL association disorder is genetic and occurs in individuals with family history of the disorder?

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FALSE

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T/F Porencephaly is a neurological disorder of the CNS characterized by cysts within the spinal cord

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False within the cerebral hemisphere

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What are the types of porencephaly?

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—Developmental porencephaly caused by
- cytomegalovirus
- stroke during brain development
—Congenital porencephaly autosomal dominant
- clotting factors affected

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T/F Porencephaly is a common condition.

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FALSE

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What can caregivers do to help a baby with Pierre Robin?

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: lay baby on tummy / side, not on back!

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T/F: Palate surgery occurs immediately after birth to prevent feeding problems

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FALSE