Ultrasound Evaluation of the Ultrasound Evaluation of the Central Nervous System Central Nervous System ••CNSCNS malformations are the second most Mani Montazemi, RDMS frequent category of congenital anomaly, Director of Ultrasound Education & Quality Assurancee after congenital heart disease Baylor College of Medicine Division of Maternal-Fetal Medicine ••PoorPoor timing of the examination, rather than Department of Obstetrics and Gynecology Texas Children’s Hospital, Pavilion for Women poor sensitivity, can be an important factor Houston Texas & in failing to detect a CNS abnormality Clinical Instructor Thomas Jefferson University Hospital Radiology Department
Fetal Head Philadelphia, Pennsylvania Fetal Head
Central Nervous System Brain Development
9 -13 weeks Rhombencephalon 5th Menstrual Week •Gives rise to hindbrain •4th ventricle Arises from the posterior surface of the embryonic ectoderm Mesencephalon •Gives rise to midbrain A small groove is found along •Aqueduct the midline of the embryo and the edges of this groove fold over to form a neuro tube that Prosencephalon gives rise to the fetal spinal •Gives rise to forebrain rd cord and brain •Lateral & 3 ventricles
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Ventricular view Neural Tube Defects ••LateralLateral ventricles ••ChoroidChoroid plexus Group of malformations: Thalamic view • Anencephaly ••MidlineMidline falx •Anencephaly ••CavumCavum septiseptipellucidi pellucidi ••CephalocelesCephaloceles ••ThalamiThalami ••SpinaSpina bifida Cerebellar view ••CerebellumCerebellum ••CisternaCisterna magna
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1 Anencephaly Anencephaly
••LethalLethal abnormality • Defect is covered by a membrane known as ••AbsenceAbsence of the brain & •Defect is covered by a membrane known as lack of the cranial vault cerebrovasculosa ––NoNo soft tissue above ••OftenOften contiguous with cervical spine defect orbits ••TheThe prevalence of anencephaly in the United States in 2001 was 9.40 per 100,000 live births National Center for Health Statistics
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Anencephaly Anencephaly
••FetalFetal face from the orbits to the ••BulgingBulging eyes chin is usually normal ••LargeLarge tongue ••FrontalFrontal bone is defective above the ••VeryVery short neck orbits ••ParietalParietal bones & occipital bone are absent
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Anencephaly Anencephaly
••ElevatedElevated MSAFP ––LeakageLeakage thru open neural tube ••PolyhydramniosPolyhydramnios after 25 wks ––FailureFailure to swallow ––ExcessiveExcessive micturition ––FailureFailure of reabsorption of CSF
Preterm labor and delivery Routine 2nd ultrasound 96% MSAFP 78% Fetal Head Kooper et al, Prenat Diagn. 2007 Jan;27(1):29-33 Fetal Head
2 Early Recognition of Anencephaly Anencephaly
••MoreMore common ––inin girls than boys ––inin whites than blacks ––inin Irish compared to other ethnic groups ––inin mothers at the younger and older extremes of age ••AssociatedAssociated malformations ––SpinaSpina bifida “crown-chin to crown-rump length ratio” ––CleftCleft lip or palate SepulvedaW, Sebire NJ, FungTY, Pipi E, Nicolaidas KH – Clubfoot Am J Obstet Gynecol. 1997, 176(4):852 –Clubfoot Fetal Head Fetal Head
Cephalocele Cephalocele
••ProtrusionProtrusion of intracranial contents through a ••HerniatedHerniated bony defect of the skull ––BrainBrain tissue & CSF ––85% 85% • Size - variable •Size -variable ••EncephaloceleEncephalocele ––MeningesMeninges & CSF ––15% 15% ••CranialCranial meningocele
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Cephalocele Cephalocele
••75%75% Occipital ••OtherOther CNS anomalies common ––WesternWestern hemisphere ––AbsentAbsent cavum septiseptipellucidi pellucidi ••13%13% Frontal ––AnomalousAnomalous corpus callosum ––AsianAsian population ––DorsalDorsal interhemisphericinterhemisphericcysts cysts ••12%12% Parietal ––ChiarimalformationsChiari malformations ––DandyDandy Walker malformation ––CerebellarcorticalCerebellar cortical dysplasia
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3 Occipital meningocele with an Cephalocele associated Dandy-Walker cyst
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Cephalocele Cephalocele
Usually occurs as an isolated lesion, but may be a part of a syndrome ••Meckel-GruberMeckel-Gruber syndrome ––Cepahalocele+Cepahalocele + B/L polycystic Kid + post-axial polydpolydactylyactyly ••Walker-WarburgWalker-Warburg syndrome ––Lissencephaly+Lissencephaly + cerebellarcerebellarhypoplasia+ hypoplasia + Dandy-Walker ccystyst + occular abnormalities ••AmnioticAmniotic band Syndrome ––CanCan involve any part of skull
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Structural Midline Defects NTD – Cranial Signs
••HighHigh incidence of associated anomalies ••LemonLemon sign: head deformity ––StructuralStructural & chromosomal ••BananaBanana sign: cerebellar deformity ••KaryotypingshouldKaryotyping should be offered ••VentriculomegalyVentriculomegaly
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4 Spina Bifida or Spinal Dysraphism
••AA defect that can occur Splayed dorsal ossification centers anywhere along the spinal axis ••LowerLower spine more common than higher ••SpinalSpinal cord and nerve roots exposed
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Remember Spina Bifida
There are several forms of spina bifida ••OssificationOssification occurs from cervical to There are several forms of spina bifida coccygeal •Ventral•Ventraldefectsdefects (rare) ––SplittingSplitting of the vertebral body ––LowerLower levels ossify later ––OccurrenceOccurrence of a cyst that is neuroentericneuroentericin in ––LumbosacralLumbosacral area appears open & wider origin
Higher level Lower level •Dorsal•Dorsaldefectsdefects (most common) ––Occulta(closedOcculta (closed spina bifida) ––Aperta(openAperta (open spina bifida)
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Closed Spina Bifida Skin-Covered NTD
••SpinaSpina bifida occultaocculta(15%) (15%) ––SmallSmall defect completely covered by skin ––Asymptomatic/incidentalAsymptomatic/incidental findings
SpinalThere cordis excess extending soft tissuedown belowdistributed L5, compatible broadly ove witr hthe tethering defect
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5 Skin-Covered NTD NTD
••LesionLesion level is most predictive of ambulatory function ––HigherHigher lesion levels associated with disphagia ––TheThe absence of covering membrane associated with scoliosis
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Open Spina Bifida Classifications of Spina Bifida
••SpinaSpina bifida apertaaperta(85%) (85%) AB ––NeuralNeural canal may be exposed ––DefectDefect may be covered by a thin meningealmeningealmembrane membrane
A) Meningocele – If the tumor contains purely meningesmeninges && CSFCSF B) Myelomeningocele – protrusion of a sac containing CSF & neural elementelementss
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Meningocele Vs. Myeloschisis Myelomeningocele
It contains solid component due to presence of neural elements within the herniated sac
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6 Reversal of Chiari Malformation
“Healed” back at birth
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Cerebellar View - Cisterna Magna
••Size:Size: 2-10 mm ––<< 2 mm spina bifida (ACII) ––>> 10 mm Dandy-Walker
T P FH P CSP T
FH
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Arnold-Chiari II Spina Bifida - Arnold-Chiari
••ShallowShallow posterior fossa ••HerniationofHerniation of the cerebellar vermis through ••SmallSmall cerebellar diameter foramen magnum ••“Banana”sign“Banana” sign if severe ••MalformationMalformation is present in almost every case of ••FourthFourth ventricle is displaced downward thoracolumbar, lumbar, and lumbosacral myelomeningocele myelomeningocele inside the neural canal
Fetal Head Fetal Head Search for ONTD
7 31 yo woman for “size and dates” evaluation MSAFP was normal No risk factors for fetal anomalies
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Coronal sonogram of the sacral spine Mid sagittal sonogram of the sacral spine
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Axial sonogram of the brain Mid sagittal sonogram of the distal spine at the level of ventricular atrium
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8 Axial sonogram of the brain WhatSkin is your Covered best guess Spina at the diagnosis? Bifida at the level of posterior fossa
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Once you have observed the spina bifida cystica, Open neural tube defect WhatWith a closedis thelesion significance one would anticipate of the what is the key sonographic observation that leads to that the mother would demonstrate a normal MSAFP is associatedthe conclusion with that Arnold-Chiari this is a “closed” II malformation lesion? MSAFP test is“normal” only useful for MSAFP?detection of the open NTD
The presence of a normal MSAFP does not exclude the possibility of the open NTD because only 80-85% of open Myelomeningoceles are detected by MSAFP testing
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WhichThe is more AFAFP sensitive is positive for confirming in virtually that the The closedWhich lesions lesion typically has have the a better better prognos is In part this is due to the lack of the Chiari II malformation lesion is “skin ALLcovered”:open NTDsMSAFP or AFAFP? andprognosis: a lack of development open ofor hydrocephalus closed?
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9 Dandy-Walker Complex Dandy-Walker Malformation
••DefectDefect in the cerebellar vermis through which the •Dandy-Walker malformation cyst communicates with the 4thth ventricle – Complete or partial agenesis of the cerebellar vermis –Complete or partial agenesis of the cerebellar vermis ••CerebellarCerebellar hemispheres are separated ––EnlargedEnlarged posterior fossa •Dandy-Walker variant ––PartialPartial agenesis of the cerebellar vermis ––WithoutWithout enlargement of the posterior fossa •Mega cisterna magna ––NormalNormal vermis & 4thth ventricle
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Cisterna Magna – Caution Cisterna Magna – Caution
InferiorInferior vermisvermis << 1818 wkswks Reevaluation at 20 to 22 postmenstrual weeks is crucial to confirm presence or absence of a normal vermis Fetal Head Fetal Head
Dandy-Walker Varient Absence of inferior cerebellar vermis Dandy-Walker Variant
••LessLess severe malformation ••SmallerSmaller 4th ventricle cyst
Superior cerebellar vermis is present ••VentriculomegalyVentriculomegaly usually absent Superior scanning plane ••HarderHarder to see ••MoreMore associated with chromosomal abnormalities
InferiorInferior scanningscanning planeplane
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10 Ventriculomegaly Lateral Ventricle
••EnlargedEnlarged cerebral ventricles ••“Hydrocephalus”implies“Hydrocephalus” implies obstruction ••HighHigh association with ––CNSCNS & non CNS anomalies ––ChromosomalChromosomal anomalies
Stable in size from 16-40 wks – age independent CHOROID PLEXUS Usually fills 90% of atrium
Fetal Head ManiFetal Montazemi, Head RDMS Always fills 60% of atrium FetalFetal SurveySurvey
Ventriculomegaly Ventriculomegaly
••ThreeThree major pathologic processes can result in ventricular enlargement ••EnlargedEnlarged atrial measurement 1. Obstructive hydrocephalus ––<< 25 weeks: > 8mm --CommunicatingCommunicating ––>> 25 weeks: >10mm --Non-communicatingNon-communicating 2. Maldevelopment of the ventricle or surrounding brainbrain Male fetuses have wider measurements tissue ••ChoroidChoroid fills < 50% atrial diameter 3. Destruction of surrounding brain tissue --CongenitalCongenital infection --bacterial bacterial meningitis or viralviral infectionsinfections ••DanglingDangling choroid sign --VascularVascular mechanism --TumorsTumors 4. Over production of CSF 2o to the CP tumor – Rare
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Hydrocephalus Hydrocephalus
••AbnormalAbnormal accumulation of CSF results in ••EnlargedEnlarged lateral ventricles enlargement of the ventricular system Plus at least one of the following ––33rd & 4thth ventricular dilatation ––DisruptedDisrupted falx midline echo ––PosteriorPosterior fossa abnormalities ––HeadHead enlargement ––IncreasingIncreasing ventricular size ••IntervalInterval study
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11 Hydrocephalus Cerebrospinal Fluid Circulation
••ResultsResults from an imbalance between the production and absorption of CSF
3 major forms: ––AqueductalAqueductal stenosis, 43% ––CommunicatingCommunicating hydrocephalus, 38% ––Dandy-WalkerDandy-Walker syndrome, 13% Foramina of Monro
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Cerebrospinal Fluid Circulation Cerebrospinal Fluid Circulation
Aqueduct of Sylvius Subarachnoid space Foramina of Luschka
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Cerebrospinal Fluid Circulation Aqueductal Stenosis
••AA form of obstructive hydrocephalus caused by narrowing of the aqueduct of sylvius ••NarrowedNarrowed connection between 3rd & 4thth ventricle
Subarachnoid space Foramina of Magendie
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12 Aqueductal Stenosis Communicating Hydrocephalus
••EnlargedEnlarged lateral & 3rd ventricles ••AA form of enlargement of the ventricles and thth ••NormalNormal posterior fossa (4 ventricle) subarachnoid system caused by an obstruction to ••ThinningThinning of cortical mantle CSF flow outside the ventricular system
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Communicating Hydrocephalus Midline Anomalies of the Brain
• Ventriculomegaly •Ventriculomegaly ••HoloprosencephalyHoloprosencephaly ––DilatationDilatation of the lateral, 3rd, & 4th ventricles ••Septo-opticSepto-optic dysplasia ••BrainBrain has shrunk ••AgenesisAgenesis of corpus callosum ••SurfaceSurface has fallen away from the skull ••CSFCSF filled subarachnoid space
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Holoprosencephaly Holoprosencephaly
••HeterogeneousHeterogeneous entity of central nervous ••IncompleteIncomplete cleavage or diverticulationdiverticulationof of system anomalies the premitive forebrain into two cerebral hemispheres ••SingleSingle ventricle with no separation of the Categorization introduced by DeMyer & Zeman in 1963 frontal lobes Recognition by ultrasound by Kurtz in 1980
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13 Holoprosencephaly Alobar Holoprosencephaly
• Classifications: ••NoNo cerebral separation into •Classifications: two hemispheres ––AlobarAlobar (lethal) ••SingleSingle ventricle ––SemilobarSemilobar (lethal) ••FusedFused thalami ––LobarLobar (mental retardation) ••NoNo interhemisphericinterhemisphericfissure fissure ••AbsenceAbsence of the 3rd ventricle ••AbsentAbsent corpus callosum
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Alobar Holoprosencephaly Alobar Holoprosencephaly
• Facial abnormalities common • “Face Predicts the Brain” ~ 70% of time – proboscis, cyclopia, cebocephaly, B/L cleft lip • Converse is NOT true, 20% of alobar HPE & palate with premaxillary agenesis, have only minor facial dysmorphism hypotelorism
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Semilobar Holoprosencephaly Absence of the CSP & fused frontal horns
••LethalLethal ••PartiallyPartially separated two hemispheres ••AbsenceAbsence of falx ••PartialPartial fusion of the thalami T ••PartialPartial Agenesis of the CC T ••SingleSingle ventricular cavity T T
Septooptic dysplasia
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14 Agenesis of the Corpus Callosum Agenesis of the Corpus Callosum
••CanCan be completecompleteoror partialpartial,, depending upon ••NoNo cavum septum pellucidi the stage of development at which growth ••TeardropTeardrop configuration of the lateral ventricle was arrested was arrested ••UpwardUpward displacement of the 3rd ventricle ••OutcomeOutcome is heavily dependent on the presence or absence of associated anomalies
Colpocephally Fetal Head Fetal Head
Agenesis of the Corpus Callosum Agenesis of the Corpus Callosum
InterhemisphericInterhemispheric Cisterna Cisterna
CC CC CSP
3V CV 3V
CSP
Sunburst radiation of interhemispheric Normal sulcisulci from from thethe thalamusthalamus Widely spaced lateral ventricles 3rd ventricle is elevated and is contiguous Fetal Head Fetal Head dorsally with the interhemispheric fissure
Agenesis of the Corpus Callosum Head Measurements
Pericallosal Artery
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15 Columns of the Fornix
CC
CSP T
T
Paired nerve columns CSP appears as a fluid-filled box between its septi, Can be mistaken for the CSP which separate this space from the frontal horns of the LVs
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Thalamic View
Peter W. Callen et al JUM January 1, 2008 vol. 27 no. 1 25-31 Fetal Head Thomas C Winter et al JUM March 1, 2010 vol. 29 no. 3 427-444 Fetal Head
Agenesis of the Corpus Callosum Diffusion Tensor Imaging
••FailureFailure of axons to cross midline and form CC ••TheThe motion of protons within different tissue types, and, by measuring the amount and directionality of diffusion, it provides information on 3D tissue properties
G Kasprian et al, Brain Journal of Neurology 2013: 136; 168–179 Medical University of Vienna
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16 Normal development Callosal abnormality? 3D Fiber architecture 32GW ••MRIMRI --Tractography Tractography
Rostrum Genu Truncus Splenium G Kasprian et al, Brain Journal of Neurology, 2013: 136; 168–179 Fetal Head Fetal Head Medical University of Vienna
Thank You
G Kasprian et al, Brain Journal of Neurology, 2013: 136; 168–179 Fetal Head Medical University of Vienna Fetal Head
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