Imaging of congenital brain diseases

1. ThorsangChayovan andChaiyapongseTangsittitum
June 01, 2016

2. Normal brain
development
Dorsal induction
(neural tube formation
& dysjunction)
Ventral induction
(vesicle formation &
cleavage)
Cortico-genesis
(histogenesis & migration)
Proliferation
Migration
Organization
Myelination

3.  2.66: 1000 births
 Mechanism: genetic, intrauterine
environment
 60% unknown cause
 20% inherited disease
 10% chromosome
 10% environment
 Most common: anencephaly, spina bifida

4. Congenital brain
malformations
Disorders of dorsal
induction
Neural tube
defects
Anencepahly
Cranial
dysraphism
(cephalocele)
Chiari
malformation
Disorders of ventral
induction
holo-
prosencephaly
Alobar
Semilobar
Lobar
Septo-optic
dysplasia
DandyWalker
spectrum
Corpus
callosum
agenesis
Disorders of
Cortico-genesis
Proliferation
Migration
Organization
Myelination
Disorders
Hypo-
myelination
Dys--
myelination

5.  Result in defects of closure
 Anencephaly
 Encephaloceles
 Chiari malformations
 Spinal dysraphism

6.  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

7.  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

9.  Defect in skull and dura with extracranial
extension 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

10. Cephaloceles
Meningo-cele
CSF
Meningo-
encephalocele
CSF
BRAIN
(dysgentic &
nonfunctioning)
Meningo-
encephalo-
cystocele
CSF
BRAIN
VENTRICLES
Atretic
cephalocele
Fibro-fatty
tissue
Gliocele
CSF
Glial tissue
Pathological classification
(based on the contents of the sac)

12. Cephaloceles
Occipital Parietal
Fronto-
ethmoidal
Trans-
sphenoidal
Nasal
Anatomical classification
(based on the location of the defect)

13. 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

14.  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

15.  Parietal: poor prognosis; associated with
porencephaly, interhemispheric cyst, callosal
agenesis, 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

17.  Hindbrain anomaly which cerebellum
descends into cervical canal

18.  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

19.  Association
 Cord(20-40%): hydromyelia/ syringomyelia
 Bone(25%): atlantooccipital assimilation,
platybasia, basilar invagination, fused cervical
vertebrae(Klippel-Feil)

20.  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

21.  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

22.  Skull and dura(cont)
 Thinned, hypoplastic, or denestrated falx
 Irregular serrated interhemispheric fissure

23.  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

24.  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

25.  Cerebral hemisphere
 Sulcation and gyration disorder e.g.
polymicrogyria, heterotopia, stenogyria, corpus
callosal dysgenesis

26.  Spine and spinal cord
 Myelomeningocele(all cases)
 Syringohydromyelia
 Diastimatomyelia
 Lipomyelomeningocele(uncommon)

30.  Small posterior fossa
 Caudally displaced brainstem
 Low occipital or upper cervical bony defect
with herniation of posterior fossa content

31.  Severe cerebellar hypoplasia without
displacement of the cerebellum through the
foramen magnum

32.  ChiariV malformation
 Absent cerebellum
 Herniation of the occipital lobe through the
foramen magnum
 Chiari 0 malformation
 Syrinx
 No cerebellar tonsil or brain stem descent

34.  Anterior commissure, hippocampal
commissure, 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)

35.  Primary agenesis: never forms
 Secondary dysgenesis: forms normally and
subsequently destroyed

36.  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

37.  Genetic association
 Apert syndrome
 CRASH syndrome
 DiGeorge syndrome
 Williams syndrome
 Fragile X syndrome
 Morning glory syndrome

38.  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

40. MRIT1w
 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)

41. MRIT2w
 Colpocephaly
 Probst bundle: hypointense like internal
capsule and anterior commissure
MRA
 ACAs “meander”, no CC genu or curve around
 ± azygous ACA

43. US
 Coronal
 Absent corpus callosum
 Trident lateral ventricle
 Wide lateral ventricle, colpocephaly
 Sagittal
 Radially arranged gyri pointed to 3rd ventricle

48.  Type I: interhemispheric cyst as a
diverticulum of ventricular system
 Type 2: not connect with ventricular system

49.  Fused 2 hemisphere
 Holoprocencephaly
 Septo-optic dysplasia

50.  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

54. 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
Interhemispheric
fissure
absent partial present(some
anterior fusion)
Basal ganglia,
thalami
fused partially
separated
separated

58.  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

59.  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)

62.  Lissencephaly (agyria)
 Pachygyria
 Heterotopia
 Polymicrogyria
 Schizencephaly

63. Migration disorders
Under-migration
Classic
lissencephaly
(type I)
Over-migration
Cobble stone
lissencephaly
(type II)
Ectopic migration
Heterotopia
Subependymal
Subcortical
Band
heterotopia

64. Category Types
Classic (orType 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 (orType 2) lissencephaly
•Walker-Warburg syndrome
•Fukuyama syndrome
•Muscle-eye-brain disease
Other types
•LIS2: Norman-Robert syndrome (RELN
mutation)
•LIS3:TUBA1A
•LISX2:ARX
•Microlissencephaly

65.  Complete—Agyria
 Incomplete—Pachygyria-agyria

66.  Type I: Classic
 Agyria/pachygyria
 Thick inner band GM
 Cell sparseWM zone ↓T1↑T2
 Thin outer layer GM
 Shallow sylvian fissure;
hourglass cerebrum
 CC/SP agenesis/hypoplasia
 LIS1: parietal/occipital
 XLIS(DCX):
subfrontal/temporal

67. Classic lissencephaly

68.  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

69.  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

70.  Multiple small
nodules/bands
 Periventricular germinal
zone to cortex
 Match gray-matter
signal
 Lack enhancement
 Lack calcification
 Margin maybe indistinct
 Mass-like; mimic tumor

71. Subependymal
heterotopia

73. Double cortex
 Thick deep to thin >> seizure risk
 90% in girls

75.  Thin and dysplastic overlying cortex

76.  Associated anomalies
 Zellweger syndrome
▪ Peroxisomal disorder
▪ Abnormal migration, hypomyelination, band
heterotopia
 Agenesis CC
 Chiari 2 malformations
 Dandy-Walker spectrum

77. Organization disorders
Superficial cortex
Focal cortical
dysplasia
without Balloon
cells
Whole cortex
Polymicrogyria Schizencephaly

78.  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

79.  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

80. Thickened cortex with nodular surfaces and irregular gray-white
matter interfaces

81. Polymicrogyria

86.  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

87.  Type I = closed lips
 Absent CSF cavity
 Type II = open lips
 Clefts filled with CSF
 Communication of
extraaxial fluid-
ventricle at cleft site

88. • Cerebral clefts lined with gray matter
extending from cortex to ventricle
• CSF within clefts
Schizencephaly

91. DandyWalker
spectrum
DandyWalker
malformation
DandyWalker
variant
Persistent
Blake’s pouch
Mega cisterna
magna

92. DWM DWV Persistent Blake’s
pouch
Mega cisterna
magna
Anterior membranous area anomaly Posterior membranous area anomaly
Retro-cerebellar cyst

93.  Large posterior fossa
 High-inserting venous
confluence
 Large posterior fossa
cyst extending dorsally
from fourth ventricle
 Vermian
aplasia/hypoplasia
 +-Hydrocephalus 80%

94.  More common
 Smaller
retrocerebellar cyst
 Milder vermian
agenesis
 Normal-sized
posterior fossa
 Normal brainstem

95. DDx for normal-sized posterior fossa
with cystic collection
 Retrocerebellar arachnoid cyst
 Giant cisterna magna
 Dandy-Walker variant

96.  Ependyma-lined
protrusion of fourth
ventricle through
foramen of Magendie
into retrovermian
cistern
 Displaced fourth
ventricle choroid
plexus

97.  Increased
tegmentovermian
angle
 Normal-sized vermis
and configuration
http://roentgenrayreader.blogspot.com/2010/04/tegmento-vermian-angle.html

98.  Large posterior fossa
 Normal fourth
ventricle, vermis,
and supratentorial
brain
 Mildest DWS

99. DWM DWV Persistent
Blake’s pouch
Mega cisterna
magna
Vermis Hypo-plastic
Rotated 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

106. Destructive lesions
Hydranencephaly Porencephaly

107.  Formed brain tissue
destruction
 CSF cavity
communicates with
ventricular system
 Etiology: probably
acquired
 Vascular/infectious in
utero

108.  Destruction of cerebral hemisphere
 Extreme form of porencephaly
 Caused by bilateral ICA occlusion
 Replaced byCSF-filled sacs
 Preserved thalami, brainstem, posterior
fossa (posterior circulation)
 Must differentiate from hydrocephalus

109.  Fluid-filled cranial vault above tentorium
 No supratentorial cortical tissue

111.  Osborn's Brain: Imaging, Pathology, and Anatomy
 Diagnostic Neuroradiology: AText/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

112.  Which one is primary neurulation
abnormality?
 Chiari I
 Chiari II
 Holoprocencephaly
 Hydranencephaly
 Syntelencephaly

113.  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

114.  Dandy-Walker malformation, false?
 Torcular and transverse sinus >> superior
displacement
 Cystic dilatation of fourth ventricle
 Small posterior fossa