2. Over view
1.Introduction
2.Normal development of Brain
3.Classification of malformations
4.Imaging features of anomalies
5.conclusion
Imaging in developmental Malformations of the brain
3. Introduction
Congenital anomalies of the brain
Extremely complex
Best studied by correlating with embryological
development.
Imaging in developmental Malformations of the brain
4. NORMAL BRAIN DEVELOPMENT
MYELINATION
DORSAL INDUCTION
Formation of neural
tube
VENTRAL INDUCTION
Formation of vesicles
and Segmentation
MYGRATION, and
PROLIFERATION
a.Primary
Neurulation
b.Secondary
neurulation
Imaging in Developmental malformations of the brain
5. Stages of brain development
Imaging in Developmental malformations of the brain
Three phases:
Neurulation,
Canalization,
Retrogressive differentiation
Stage 1: Dorsal Induction: Formation and closure of the neural tube
Occurs at 3-5 weeks
6. Dorsal induction defects:
.
Imaging in Developmental malformations of the brain
Stages of brain development
Neural tube defects -Anencephaly,
-Cephalocele,
- Chiari malformations and
-Spinal dysraphic disorders
7. Stage 2: Ventral Induction: Formation of the
brain segments and face
Occurs at 5-10 weeks of gestation
Stages of brain development
Imaging in Developmental malformations of the brain
Three vesicles
Prosencephalon - cerebral hemispheres/thalamus,
Mesencephalon- midbrain and
Rombencephalon- cerebellum/brain stem
8. Ventral induction disorders:
Imaging in Developmental malformations of the brain
Stages of brain development
Holoprosencephalies,
Dandy Walker malformation,
Cerebellar hypoplasia/dysplasia
Joubert syndrome,
Rhombencephalosynapsis,
Septo -optic dysplasia, and
Facial anomalies.
9. Stage 3: Migration and Differentiation
Occurs at 2-5 months of gestation
.
Imaging in Developmental malformations of the brain
Stages of brain development
Neuronal migration from germinal matrix to the surface
resulting in Cortical organization
10. Migration Disorders:
Imaging in Developmental malformations of the brain
Stages of brain development
Heterotopias,
Agyria-pachygyria,
Polymicrogyria,
Lissencephaly,
Schzencephaly,
Corpus callosal agenesis,
Lhermitte-Duclos disease
11. Differentiation and proliferation disorders:
Imaging in Developmental malformations of the brain
Stages of brain development
Aqueductal stenosis,
Arachnoid cyst,
Megalencephaly,
Micoencephaly,
Neurocutaneous syndrome (phakomatoses)
Congenital vascular malformation, and
Congenital neoplasms
12. Stage 4: Myelination
Begins at 6 months of gestation, Matures by 3 years.
Imaging in Developmental malformations of the brain
Stages of brain development
Progresses from Caudal to Cephalic,
Dorsal to Ventral, and
Central to Peripheral
Disorders of Myelination
Dysmyelinating diseases,
Leukodystrophies.
13. DISORDERS OF
NEURAL TUBE
FORMATION
DISORDERS OF
SEGMENTATION
DISORDERS OF
MYGRATION and CORTICAL
ORGANISATION
DISORDERS OF
MYELINATION
a.Anencephaly
b.Cephaloceles
c.Chiari
Malformations
a.Holoprosencephaly
1.Alobar
2.Semilobar 3.Lobar
b.Corpus callosal
agenesis
c.Dandy Walker
malformations
a.Hetrotropias
b.Lissencephaly,
Schizencephaly
Classification of congenital malformation of brain
a.Leukodystrophies
b.Dysmyelinating
Disorders
Imaging in Developmental malformations of the brain
15. Anencephaly
Neural Tube Defects
Imaging in Developmental malformations of the brain
complete or partial absence of the cerebral
structures, cranial vault and skull base.
It results from failure of closure of the cephalic
portion of the neural tube
16. Cephaloceles
Herniation of intra cranial structures through
congenital defects in Dura and skull
Cephaloceles
MeningoencephalocystoceleMeningoencephaloceleMeningocele
MeningesMeninges Meninges
Neural tissue
Neural tissue
Ventricles
Neural Tube Defects
Imaging in Developmental malformations of the brain
Neural Tube Defects
17. Encephalocele
Fronto Nasal Encephalocele Occipital Encephalocele
Imaging in Developmental malformations of the brain
Neural Tube Defects
Herniation of brain and Meninges through a defect in the skull.
It is typically covered by skin (closed defect) or a Thin layer of epithelium (open defect).
18. Fronoto Nasal, Naso
Orbital Encephalocele
Nasal Glioma
(D/d for
encephaloele)
Imaging in Developmental malformations of the brain
Neural Tube Defects
19. Type of Chiari
malformation
Imaging features(core) Associated findings
Type 1
(Tonsillar Ectopia)
Elongated cerebellar tonsils with
herniation into cervical canal
Syringohydromyelia(30-60%)
Type 2
(Arnold Chiari)
Herniation of vermis ,tonsils, medulla 1.Small and shallow posterior fossa
2.Myelomeningocele (nearly 100%)
3.Upward herniation of cerebellar
hemispheres
4.Corpus callosal dysgenesis,
heterotopias, polymicrogyria
Type 3 Type 2
+
occiputal encephalocele
Type 4 Cerebellar Aplasia/Sever Hypoplasia
The chiari malformations
Imaging in Developmental malformations of the brain
Neural Tube Defects
20. Chiari I Malformation
Imaging in Developmental malformations of the brain
Neural Tube Defects
Level below the Foramen Magnum
First Decade: 6mm
Second /Third decade: 5mm
Fourth-Eight Decade:4mm and
Nienth Decade:3mm
22. Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
23. Holoprosencephaly
Disorders of Diverticulation and Segmentation
Cerebellum and brain stem are relatively normal
Imaging in Developmental malformations of the brain
Developing Forebrain (prosencephalon) fails to divide into hemispheres
and lobes.
24. Normal brain Alobar Holoprosencephaly
semilobar Holoprosencephaly Lobar Holoprosencephaly
Types of Holoprosencephaly
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
25. Alobar Holoposencephaly
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
• Single cresent shaped ventricle
• No Separation of the cerebral hemispheres
• Fused thalami and basal ganglia
• Absence of
septum pellucidum,
corpus callosum,
falx cerebri, and
interhemispheric fissure
26. Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
Semilobar holoprosencephaly
• Interhemispheric fissure is formed
posteriorly
•Rudimentary occipital and temporal
horns
•Thalami and basal ganglia are partially
separated
•Septum pellucidum is absent
• callosal splenium may be formed
27. Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
Lobar holoprosencephaly
• Ventral portions of the frontal lobes
remains fused
• Rudimentary frontal horns are formed
• Septum Pellucidum is absent
• Thalami and basal ganglia well separated
28. Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
Septo optic Dysplasia (de Morsier syndrome)
• Milder form of lobar
holoprosencephaly
• Hypoplastic optic
nerves, optic
chiasma,
• Absent septum
pellucidum
•Squared frontal
horns
Associated hypoplasia of Hypothalamic-Pituitary axis seen in 2/3rd cases
29. Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
Corpus Callosum Agenesis
Corpus callosal development starts at 12 weeks , and completes by 20 weeks
Formation is from anterior to posterior direction,
Starts with Genu- Body-Splenium.
The rostrum is last to develop
Corpus Callosum Agenesis
Complete agenesis Partial agenesis
30.
31. Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
Complete callosal agenesis
•Entire corpus callosum, cingulate gyrus and sulcus are absent
•Widely separated, parallel and non-converging lateral ventricles.
• Colpocephaly (dilated occipital horns)
•Frontal horns are small and pointed
32. Complete corpus callosal agenesis
colpocephaly
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
33. Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segemtation
Partial callosal agenesis
•Splenium and rostrum absent
• Genu and body present
34. Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
Associated anomalies
•Migration disorders (heterotopias, lissencephaly, schizencephaly)
• Chiari II malformation
• Dandy-Walker malformation
• Holoprosencephaly
• Corpus callosal lipoma
35. Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation
of
Posterior fossa
36. Dandy walker spectrum
Dandy Walker
syndrome
Dandy Walker
variant
Mega Cysterna
Magna
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation of Posterior fossa
37. Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation of Posterior fossa
Joubert’s Syndrome (Congenital Vermian Hypoplasia)
• Vermian dysgenesis
•Enlarged superior cerebellar peduncles and
• High riding fourth ventricle.
38. Imaging in Developmental malformations of the brain
Associated anomalies
• Occipital encephalocele (30%),
• Callosal dysgenesis,
• Cortical dysplasia,
• Hypothalamic hamartoma, and
• Ocular, hepatic & renal diseases.
Disorders of Diverticulation and Segmentation of Posterior fossa
39. Classified into two groups:
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation of Posterior fossa
Pontocerebellar hypoplasia (PCH).
• Combined hypoplasia of both the cerebellum and the pons
•These are primarily genetic disorders
40. • Hypoplastic Brain stem and cerebellum that is close to the tentorium
• Cerebellar hemisphares are wing like, appear to float in posterior fossa
.
Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation of Posterior fossa
-
41. Imaging in Developmental malformations of the brain
Disorders of Diverticulation and Segmentation of Posterior fossa
Differentials of pontocerebellar hypoplasia
CDG syndromes-(disialotransferrin) will be elevated in CDG
Dandy-Walker syndrome - Normal Pons
Dandy-Walker variant -Normal Pons
43. Ectopic Migration
Cobble stone-Lissencephaly
(type 2)
Over Migration
Classic Lissencephaly
(type1)
Under Migration
Migration Disorders
Band Heterotropia
Subcortical
Subependymal
Heterotrpia
Imaging in Developmental malformations of the brain
Disorders of Migration
44. Imaging in Developmental malformations of the brain
Disorders of Migration
Lissencephaly (Agyria-Pachygyria):
Refers to “smooth brain” with absent or poor sulcation.
Types:
Complete (agyria)
Incomplete (pachygyria).
45. .
Imaging in Developmental malformations of the brain
Disorders of Migration
• Thickened cortex with
flat broad gyri
•Smooth gray-white matter
Interface
• Colpocephaly
Oblique and shallow
• Sylvian fissures- figure eight
Type I (classical) Lissencephaly
Associated with Miller-Dieker syndrome
46. Type II(Cobblestone) Lissencephaly
Imaging in Developmental malformations of the brain
Disorders of Migration
• Thickened cortex
• Polymicrogyric appearance.
• Hypomyelination of
underlying white matter
Associated with
Fukuyama congenital muscular dystrophy,
Walker-Warburg syndrome and
muscle-eye-brain syndrome
47. Two types: Nodular type(common),
Band/laminar type (uncommon)
Imaging in Developmental malformations of the brain
Disorders of Migration
Heterotopias
Presence of normal neurons at abnormal sites
Best appreciated on medium tau inversion recovery sequences
Nodular type:
48. Imaging in Developmental malformations of the brain
Disorders of Migration
• A layer of neurons interposed between the ventricle and cortex
•Overlying cortex has pachygyria or polymicrogyria
Band or laminar type
49. Disorders of Cortical organisation
Imaging in Developmental malformations of the brain
50. Non lissencephalic Cortical Dysplasia
Disorders of Cortical organisationImaging in Developmental malformations of the brain
Disorders of Cortical organisation
Polymicrogyria
• Thickened cortex
•Irregular, bumpy gyral pattern
• Irregular gray-white matter junction
• Underlying white matter signal changes
51. Pachygyria
Imaging in Developmental malformations of the brain
Disorders of Cortical organisation
•Thickened and flattened cortex
• Blurred gray-white matter Junction
• Underlying white matter signal changes
52. Schizencephaly
Imaging in Developmental malformations of the brain
Disorders of Cortical organisation
Cleft lined by Heterotopic gray matter extends from
the ventricular (ependyma) to the periphery (pial surface) of the
brain, traversing through the white matter.
Two types: Closed lip (type I)
Open lip (type II)
53. Closed lip (type I) schizencephaly
Openlip (type2) schizencephaly
Imaging in Developmental malformations of the brain
Disorders of Cortical organisation
54. Porencephalic cyst resembles schizencephaly
but CSF space is lined by gliotic white matter,
in contrast to gray matter as in Schizencephaly
Porencephalic cyst
Imaging in Developmental malformations of the brain
Disorders of Cortical organisation
55. Anomalies Associated with Schizencephaly :
Heterotopias,
Septo-optic dysplasia,
Absence of septum pellucidum
Callosal dysgenesis
Imaging in Developmental malformations of the brain
Disorders of Cortical organisation
56. Hemimegalencephaly
Hamartomatous overgrowth of a part or all of one
cerebral hemisphere
Imaging in Developmental malformations of the brain
Disorders of Cortical organisation
Associated with :
• Epidermal nevus syndrome,
• Klippel-Trenaunay–Weber syndrome,
• Neurofibromatosis type 1
57. • Linear Nevus Sebaceous Syndrome(LNSS)
Imaging in Developmental malformations of the brain
Disorders of Cortical organisation
58. Conclusion
• Variety of congenital anomalies of brain of
brain coexist
• Clinical Presentation of various anomalies is
more or less same
• Imaging plays an important role in diagnosing
them