Congenital brain anomalies
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Transcript of Congenital brain anomalies
Thorsang Chayovan and Chaiyapongse TangsittitumJune 01, 2016
Normal brain development
Dorsal induction
(neural tube formation & dysjunction)
Ventral induction
(vesicle formation & cleavage)
Cortico-genesis
(histogenesis & migration)
Proliferation
Migration
Organization
Myelination
2.66: 1000 births Mechanism: genetic, intrauterine
environment
60% unknown cause
20% inherited disease
10% chromosome
10% environment Most common: anencephaly, spina bifida
Congenital brain malformations
Disorders of dorsal induction
Neural tube defects
Anencepahly
Cranial dysraphism
(cephalocele)
Chiarimalformation
Disorders of ventral induction
holo-prosencephaly
Alobar
Semilobar
Lobar
Septo-optic dysplasia
Dandy Walker spectrum
Corpus callosumagenesis
Disorders of
Cortico-genesis
Proliferation
Migration
Organization
Myelination
Disorders
Hypo-myelination
Dys--myelination
Result in defects of closure
Anencephaly
Encephaloceles
Chiari malformations
Spinal dysraphism
Absence of the cranial vault, cerebral hemispheres, and diencephalic structures.
1: 1000 births
Acrania: no skull + normal brain tissue
Excencephaly: no skull + amorphous brain
Anencephaly: no skull + no brain
Acrania anencephaly sequence
Antenatal USG(detectable at 11 wks, 100% accuracy at 14 wks)
No brain tissue above orbits
Absent calvarium(may found parts of occipital bone and mid brain)
Exencephaly: have small amount of neural tissue
Low CRL
"frog eye" or "mickey mouse" appearance
Polyhydramnios
Defect in skull and dura with extracranialextension of intracranial structures
Most common in midline Causes: several
Failure of neurulation
Herniation after neurulation
Failure induction of bone
Failure of basilar ossification center to unite
Cephaloceles
Meningo-cele
CSF
Meningo-encephalocele
CSF
BRAIN(dysgentic &
nonfunctioning)
Meningo-encephalo-cystocele
CSF
BRAIN
VENTRICLES
Atreticcephalocele
Fibro-fatty tissue
Gliocele
CSF
Glial tissue
Pathological classification
(based on the contents of the sac)
Cephaloceles
Occipital ParietalFronto-
ethmoidalTrans-
sphenoidalNasal
Anatomical classification
(based on the location of the defect)
3 subtype Frontonasal: between frontal and nasal bones
Frontal bone displace superiorly Nasoethmoidal: between nasal bone and nasal
cartilage Nasal cartilage, nasal septum nd wthmoid bone
displace posteroinferiorly Nasoorbital: in bony canal at medial wall of orbit
between maxilla and lacrimal/ethmoid bone Frontal process of maxilla displace anteromedially Lacrimal and lamina papyracea displace posterolaterlly
Cephalocele connect with intracranial cavity via a strand of connective tissue
Defect from persistent of midline neural crest cell that prevent normal induction or ectoderm and mesoderm
Parietal: poor prognosis; associated with porencephaly, interhemispheric cyst, callosalagenesis, venous anomaly Small, hairless midline mass near the vertex
Occipital: good prognosis, low associated brain anomaly Small mass just above external occipital
protuberance, enter the calvarium via a defect and penetrate the dura below the torcular and terminate at falx or tentorium
Hindbrain anomaly which cerebellum descends into cervical canal
Congenital tosillar ectopia Elongated, peg-like, cerebellar tonsil and
displaced inferiorly through the foramen magnum into upper cervical spinal canal
Normal vermis, 4th ventricle and medulla
Association
Cord(20-40%): hydromyelia/ syringomyelia
Bone(25%): atlantooccipital assimilation, platybasia, basilar invagination, fused cervical vertebrae(Klippel-Feil)
Complex malformation involving skull, dura, brain, spine, and spinal cord
Unknown etiology Multiple abnormalities
Skull and dura
Hindbrain, cerebellum, and midbrain
CSF space
Cerebral hemisphere
Spine and spinal cord
Skull and dura Lacunar skull: scooping-out appearance
Scalloping and thinning of the inner calvarial table
Small and shallow posterior fossa with low-lying transverse sinuses and torcular herophili
Large foramen magnum(gapping)
Concave posterior aspect of petrous temporal bones
Short, concave clivus
Dysplastic falx cerebri and dural fold
Heart-shaped incisura
Skull and dura(cont)
Thinned, hypoplastic, or denestrated falx
Irregular serrated interhemispheric fissure
Hindbrain, cerebellum and midbrain
Downward medulla and cerebellum into upper cervical canal
Medullary kink or spur(70%)
Ectopic choroid plexus from 4th ventricle
Towering cerebellum(upward herniation)
Cerebellum wrap around the brainstem
Pointed or beaked tectal plate
CSF space(90%)
Small, elongated, caudally displaced 4th ventricle
Large 3rd ventricle and prominent massa intermedia
Normal to enlarged lateral ventricle
Colpocephaly
Serrated or scalloped margins of lateral ventricles
Frontal horns point anteroinferiorly
Aqueductal stenosis
Small cisterna magna
Cerebral hemisphere
Sulcation and gyration disorder e.g. polymicrogyria, heterotopia, stenogyria, corpus callosal dysgenesis
Spine and spinal cord
Myelomeningocele(all cases)
Syringohydromyelia
Diastimatomyelia
Lipomyelomeningocele(uncommon)
Small posterior fossa Caudally displaced brainstem Low occipital or upper cervical bony defect
with herniation of posterior fossa content
Severe cerebellar hypoplasia without displacement of the cerebellum through the foramen magnum
Chiari V malformation
Absent cerebellum
Herniation of the occipital lobe through the foramen magnum
Chiari 0 malformation
Syrinx
No cerebellar tonsil or brain stem descent
Anterior commissure, hippocampalcommissure, corpus callosum(largest)
Development: anterior commissure→hippocampal commissure→ corpus callosum
Genu→ body → splenium→ rostrum(last) If anomaly occurs in which part, the part
formed later will absent(except in destructive causes and holoprocencephaly)
Primary agenesis: never forms Secondary dysgenesis: forms normally and
subsequently destroyed
Often associated with anomalies of cerebrum and cerebellum
Chiari II: most common
Dandy-Walker malformation
Anomalies of neuronal migration and organization
Encephalocele
Midline facial anomaly
Aicardi syndrome
Fetal alcohol syndrome
Genetic association
Apert syndrome
CRASH syndrome
DiGeorge syndrome
Williams syndrome
Fragile X syndrome
Morning glory syndrome
CT
Axial: parallel lateral ventricle(racing car sign)
Coronal: anterior horns resemble viking helmet, moose head or texas longhorn
Colpocephaly(axial: teardrop configuration)
Pointed frontal horns
± midline cyst or lipoma
MRI T1w Sagittal
Gyri radiate out from 3rd ventricle
Everted cingulate gyrus, absent cingulate sulcus Coronal
Longhorn-shaped anterior horns
Elongated foramina of Monro
Keyhole temporal horn and vertical hippocampi
Ventriculomegaly(type I interhemispheric cyst varient)
MRI T2w Colpocephaly Probst bundle: hypointense like internal
capsule and anterior commissureMRA ACAs “meander”, no CC genu or curve around ± azygous ACA
US Coronal
Absent corpus callosum
Trident lateral ventricle
Wide lateral ventricle, colpocephaly
Sagittal
Radially arranged gyri pointed to 3rd ventricle
Type I: interhemispheric cyst as a diverticulum of ventricular system
Type 2: not connect with ventricular system
Fused 2 hemisphere
Holoprocencephaly
Septo-optic dysplasia
Midline hemisphere fusion Failure of normal prosencephalic cleavage 1:13000 live births Materal DM, rubella, toxoplasmosis, syphillis,
fetal alcohol syndrome, trisomy(13, 15, 17, 18), triploidy
4 forms Alobar Semilobar Lobar Syntelencephaly
Finding alobar semilobar lobar
Craniofacial anomaly
severe variable absent of mild
Ventricles monoventricle rudimentary occipital horn
squared-off frontal horns
Septum pellucidum
absent absent absent
Falx cerebri absent partial well-formed
Interhemisphericfissure
absent partial present(some anterior fusion)
Basal ganglia, thalami
fused partially separated
separated
2 major findings
Hypoplasia of optic nerve
Hypoplasia or absent septum pellucidum
2/3 have hypothalamic-pituitary dysfunction
Growth retardation
Presentation: nystagmus, diminish visual acuity, hypotelorism
Imaging
Hypoplasia or complete absence of septum pellucidum→ box-like frontal horns
Hypoplasia of optic nerve(50%) ± optic canal
Bulbous dilatation of anterior recess of 3rd
ventricle(from hypoplasia of optic chiasm and hypothalamus)
Lissencephaly (agyria) Pachygyria Heterotopia Polymicrogyria Schizencephaly
Migration disorders
Under-migration
Classic lissencephaly
(type I)
Over-migration
Cobble stone lissencephaly
(type II)
Ectopic migration
Heterotopia
Subependymal
Subcortical
Band heterotopia
Category Types
Classic (or Type 1) lissencephaly
•LIS1: lissencephaly due to PAFAH1B1 mutation
• type 1 isolated lissencephaly• Miller-Dieker syndrome
•XLIS: lissencephaly due to doublecortin(DCX) mutation•lissencephaly, type 1, isolated
Cobblestone (or Type 2) lissencephaly•Walker-Warburg syndrome•Fukuyama syndrome•Muscle-eye-brain disease
Other types
•LIS2: Norman-Robert syndrome (RELN mutation)•LIS3: TUBA1A•LISX2: ARX•Microlissencephaly
Complete—Agyria Incomplete—Pachygyria-agyria
Type I: Classic Agyria/pachygyria Thick inner band GM Cell sparse WM zone ↓T1↑T2 Thin outer layer GM Shallow sylvian fissure;
hourglass cerebrum CC/SP agenesis/hypoplasia LIS1: parietal/occipital XLIS(DCX):
subfrontal/temporal
Classic lissencephaly
Premature brains (up to 26 wks)
Smooth
Mimic lissencephaly
Microcephaly with simplified gyral pattern
Brain ≥ 3 standard deviations below normal
Pachygyria
More localized, often multifocal, and usually asymmetric
Indistinct GM-WM junction
Arrested neuronal migration with ectopic gray-matter nodules or band-like areas
Periventricular germinal zone to cortex Often asymptomatic but can be seizure focus Must distinguish from tumor Temporal and occipital horns Congenital Acquired e.g. maternal trauma, infection,
toxin
Multiple small nodules/bands
Periventricular germinal zone to cortex
Match gray-matter signal
Lack enhancement Lack calcification Margin maybe indistinct Mass-like; mimic tumor
Subependymalheterotopia
Double cortex
Thick deep to thin >> seizure risk
90% in girls
Thin and dysplastic overlying cortex
Associated anomalies
Zellweger syndrome
▪ Peroxisomal disorder
▪ Abnormal migration, hypomyelination, band heterotopia
Agenesis CC
Chiari 2 malformations
Dandy-Walker spectrum
Organization disorders
Superficial cortex
Focal cortical dysplasia
without Balloon cells
Whole cortex
Polymicrogyria Schizencephaly
Cortical dysplasia Irregular cortex with numerous small
convolutions and shallow or obliterated sulci Late migration and organization: Unequal
distribution of final migrating neurons (at GA 20-24 wks)
Derangement of six layered lamination of cortex
2 patterns by degree of myelination: <12 months: thin, small, fine undulating cortex
with normal thickness (2-3 mm)
>18 months: thick, bumpy cortex (5-8 mm), hypomyelination, cortical infolding
Irregular, indistinct outer and inner cortical surfaces
Shallow/flat sulci Small, isolated, unilateral to bilateral Predilection for perisylvian regions
Thickened cortex with nodular surfaces and irregular gray-white matter interfaces
Polymicrogyria
Split brain Clefts in cerebral hemispheres-
ventricle/subarachnoid space lined by gray matter
Causes Destructive vascular lesions (e.g., MCA occlusion) Infections (e.g. TORCH) before 28 fetal wks
Up to half are bilateral Location: Frontal/parietal Associated with absent septi pellucidi (70%),
dysgenesis of CC and heterotopia
Type I = closed lips
Absent CSF cavity
Type II = open lips
Clefts filled with CSF
Communication of extraaxial fluid-ventricle at cleft site
• Cerebral clefts lined with gray matter extending from cortex to ventricle
• CSF within clefts
Schizencephaly
Dandy Walker spectrum
Dandy Walker malformation
Dandy Walker variant
Persistent Blake’s pouch
Mega cisternamagna
DWM DWV Persistent Blake’s pouch
Mega cisternamagna
Anterior membranous area anomaly Posterior membranous area anomaly
Retro-cerebellar cyst
Large posterior fossa High-inserting venous
confluence Large posterior fossa
cyst extending dorsally from fourth ventricle
Vermianaplasia/hypoplasia
+-Hydrocephalus 80%
More common Smaller
retrocerebellar cyst Milder vermian
agenesis Normal-sized
posterior fossa Normal brainstem
DDx for normal-sized posterior fossawith cystic collection
Retrocerebellar arachnoid cyst Giant cisterna magna Dandy-Walker variant
Ependyma-lined protrusion of fourth ventricle through foramen of Magendieinto retrovermiancistern
Displaced fourth ventricle choroid plexus
Increased tegmentovermianangle
Normal-sized vermisand configuration
http://roentgenrayreader.blogspot.com/2010/04/tegmento-vermian-angle.html
Large posterior fossa Normal fourth
ventricle, vermis, and supratentorialbrain
Mildest DWS
DWM DWV PersistentBlake’s pouch
Mega cisternamagna
Vermis Hypo-plasticRotated upwards
Hypo-plastic No or mild hypoplasia
No or mild hypoplasia
4th ventricle Markedly dilated Dilated Dilated Normal
Posterior fossa Expanded Normal size Normal size Expanded
hydrocephalus 75 % of cases 25% of cases Present No
Destructive lesions
Hydranencephaly Porencephaly
Formed brain tissue destruction
CSF cavity communicates with ventricular system
Etiology: probably acquired
Vascular/infectious in utero
Destruction of cerebral hemisphere
Extreme form of porencephaly
Caused by bilateral ICA occlusion
Replaced by CSF-filled sacs Preserved thalami, brainstem, posterior
fossa (posterior circulation) Must differentiate from hydrocephalus
Fluid-filled cranial vault above tentorium No supratentorial cortical tissue
Osborn's Brain: Imaging, Pathology, and Anatomy Diagnostic Neuroradiology: A Text/Atlas Anne G.
Osborn Grainger & Allison's Diagnostic Radiology Pediatric Neuroimaging A. James Barkovich MD
and Charles Raybaud MD Diagnostic Imaging: Pediatric Neuroradiology
A Barkovich http://www.slideshare.net/hytham_nafady/congenital
-brain-malformations/35 http://roentgenrayreader.blogspot.com/2010/04/teg
mento-vermian-angle.html
Which one is primary neurulationabnormality?
Chiari I
Chiari II
Holoprocencephaly
Hydranencephaly
Syntelencephaly
Chiari, false?
Meningoencephalocele almost always associated with Chiari II
Myelomeningocele associated with Chiari I
Syringohydromyelia associated with Chiari II
Chiari III = Chiari II+exernal brain herniation into cephalocele
Chiari I, sagittal spine is necessary
Dandy-Walker malformation, false?
Torcular and transverse sinus >> superior displacement
Cystic dilatation of fourth ventricle
Small posterior fossa